bluuebunny/crossref_metadata_2025 huggingface dataset:
Allele-specific motifs characterize HLA-DQ interactions with a diabetes-associated peptide derived from glutamic acid decarboxylase.
Authors: Kwok W W , Domeier M L , Raymond F C , Byers P , Nepom G T
Published: January 2023

Polymorphic residues of HLA class II molecules influence immune activation in part by determining specific structural constraints for binding antigenic peptides. We identified a peptide from glutamic acid decarboxylase, a diabetes-associated autoantigen that preferentially bound to HLA-DQ3.2 molecules, one of the HLA determinants highly associated with insulin-dependent diabetes. We analyzed interactions of specific HLA-DQ residues with modified peptide analogues and found a pattern of permissive site-specific amino acids that accommodated allele-specific binding. Four anchor residues constrain binding to different DQ alleles; limited variation at two of these sites, residues 4 and 9, accounts for the unique pattern of peptide binding to HLA-DQ3.1 or HLA-DQ3.2.
Specificities and functions of CD4+ HLA class II-restricted T cell clones against a human sarcoma: evidence for several recognized antigens.
Authors: Heike M , Schlaak J , Schulze-Bergkamen H , Heyl S , Herr W , Schmitt U , Schneider P M , Meyer zum Büschenfelde K H
Published: January 2023

CD4+ T cells play an important role for tumor immunity in animal tumor models, yet there are few reports about the role of CD4+ HLA class II-restricted T cells in the immune response against human tumors. Against a human sarcoma exclusively CD4+, T cell clones could be established. These T cell clones were cytotoxic and secreted TNF and additional cytokines in response to the IFN-gamma-treated, HLA class II-positive autologous sarcoma cells. Several Ags were recognized by representative T cell clones: an Ag presented by HLA-DR and specific for the sarcoma; Ags presented by both HLA-DR alleles of the sarcoma, HLA-DR4 and -15, and shared by allogenic HLA-DR matched cell lines of different tissue lineages, including B cell blasts; and a sarcoma Ag presented by HLA-DP or DQ. Cytokine profiles of sarcoma-reactive T cell clones were dependent on the cytokine environment present during establishment of the T cell clones. The addition of exogenous IL-4 shifted the cytokine patterns of sarcoma-reactive T cell clones from Th1-like patterns to Th0/Th2-like patterns and decreased IL-10 production. TNF, IFN-gamma, IL-4, and supernatants of T cell clones induced HLA-DR expression on the sarcoma cells and, thus, were able to enhance Ag presentation. This autologous T cell response to a human sarcoma represents a new model for HLA class II-restricted T cell responses to human tumors.
Response of a gamma delta+ T cell receptor invariant subset during bacterial infection.
Authors: Roark C E , Vollmer M K , Campbell P A , Born W K , O'Brien R L
Published: January 2023

Murine gamma delta T cells can be divided into subsets based on the TCR gamma-chains they express. Most of these subsets have variable TCR junctions, but two, both associated with epithelia, express invariant TCRs. The absence of receptor variability in these cells implies uniformity of their ligands. This was previously taken as evidence to suggest that gamma delta T cells recognize host-derived, stress-induced ligands. We now demonstrate, for the first time, the response of a gamma delta TCR invariant subset during bacterial infection, a potential cause of stress. After infection with Listeria monocytogenes, absolute numbers of all T cells in the liver, including alpha beta and gamma delta T cell subsets, increased markedly. However, responses of a gamma delta T cell subset varied. We noted a decrease in the relative frequency of V delta 6.3+ cells, which are, for the most part, included in the V gamma 1+ subset. In contrast, cells bearing the invariant V gamma 6/V delta 1 TCR increased substantially in proportion to other gamma delta T cells, as determined by PCR analysis of liver T cell RNA and by comparing liver gamma delta T cell hybridomas made from normal mice to those from mice infected with Listeria. V gamma 6/V delta 1+ cells have been previously reported as a TCR invariant intraepithelial subset in the female reproductive tract and tongue. We show here that V gamma 6/V delta 1+ cells reactive in Listeria-infected liver are polyclonally derived, but still bear TCR chains with invariant junctional sequences, identical with those of the female reproductive tract. Although the Ag that stimulates these cells is unknown, our results indicate that only diverse, but also invariant, gamma delta T cell subsets can become involved in the host response to a bacterial infection.
Lipoxin A4 and B4 inhibit leukotriene-stimulated interactions of human neutrophils and endothelial cells.
Authors: Papayianni A , Serhan C N , Brady H R
Published: January 2023

Lipoxins are bioactive eicosanoids that are generated within the vascular lumen by leukocytes and transcellular biosynthetic routes during multicellular responses. Polymorphomuclear neutrophils (PMN) and endothelial cells express high affinity receptors for lipoxins, engagement of which invokes profiles of signaling events that differ from other lipid mediators. In this work, we report that lipoxins are potent inhibitors of PMN-endothelial cell interactions triggered by leukotrienes via dual-pronged actions with PMN and endothelial cells. Both lipoxin A4(LXA4) and B4(LXB4) blocked PMN migration stimulated by leukotriene B4 (LTB4), a well established agonist for PMN recruitment, a transmigration assay in vitro. Lipoxins were almost as effective in this regard as the pharmacologic LTB4 receptor antagonist, ONO 4057, and the blocking anti-CD18 mAb, R15.7. LXA4 and LXB4 blunted PMN transmigration, in part by inhibiting beta 2 integrin-dependent PMN adhesion. These modulatory actions of lipoxins were evident at subnanomolar concentrations, rapid in onset, and attenuated by prior exposure of PMN to a tyrosine kinase inhibitor, genistein. The peptidoleukotrienes, leukotriene C4 (LTC4) and leukotriene D4 (LTD4) also provoked PMN-endothelial cell adhesion, but via a different mechanism than LTB4. Both LTC4 and LTD4 enhanced endothelial adhesiveness for PMN, in part, by stimulating mobilization of P-selectin from intracellular Weibel-Palade bodies. LXA4 and LXB4, but not other lipoxygenase products, blocked P-selectin mobilization induced by peptidoleukotrienes and attenuated P-selectin-mediated PMN-endothelial cell adhesion. These results indicate that lipoxins attenuate PMN-endothelial cell interactions supported by selectins and beta 2 integrins in vitro, and are potential endogenous lipid-derived modulators of PMN trafficking in host defense, inflammation, and other vascular events.
T cells bound by vascular cell adhesion molecule-1/CD106 in synovial fluid in rheumatoid arthritis: inhibitory role of soluble vascular cell adhesion molecule-1 in T cell activation.
Authors: Kitani A , Nakashima N , Matsuda T , Xu B , Yu S , Nakamura T , Matsuyama T
Published: January 2023

Elevated levels of soluble vascular cell adhesion molecule-1 (sVCAM-1)/CD106 have been reported in synovial fluid (SF) from patients with rheumatoid arthritis (RA). In the present study, VCAM-1-positive lymphocytes were found in SF from RA patients. The data strongly suggest that sVCAM-1 might be bound to lymphocytes in SF. rsVCAM-1 in the fluid phase can bind to both SF lymphocytes and IL-2-dependent T cell lines with up-regulated expression and binding activity of VLA-4. Furthermore, proliferative responses of SF mononuclear cells (SFMC) with PHA, immobilized anti-CD3, or anti-CD2 and PMA were inhibited to various extents in the presence of rsVCAM-1, but only PMA-induced proliferative response of PBMC from normal individuals was inhibited notably in the presence of rsVCAM-1. rsVCAM-1 also drastically reduced IL-2 production of Jurkat leukemic T cells possessing high affinity VLA-4 with the stimulation of anti-CD3 and PMA, suggesting that the T cell hyporesponsiveness induced by rsVCAM-1 might stem from impairment of IL-2 production. These results indicate that sVCAM-1 provides a negative signal to T cell activation, probably by affecting the pathway of protein kinase C activation. Thus, binding of sVCAM-1 to SF lymphocytes might partly explain the anergic state of these lymphocytes.
Different susceptibility of cytotoxic T cells to CD95 (Fas/Apo-1) ligand-mediated cell death after activation in vitro versus in vivo.
Authors: Ehl S , Hoffmann-Rohrer U , Nagata S , Hengartner H , Zinkernagel R
Published: January 2023

To address the question of whether cytotoxic CD8+ T cells (CTL) activated in vivo are susceptible to cell death mediated by CD95 (Fas/Apo-1) ligand, a recombinant vaccinia virus expressing murine CD95L (vacc CD95L) was constructed, which drives CD95L expression to infected cells. T cells contacting virus-infected cells during priming, killing, or restimulation therefore encounter CD95L on the same cells. CD95L expression in vivo after infection with the vaccinia recombinant was sufficient to induce extensive necrosis in the liver of normal but not of CD95 mutant lpr mice. Fibroblast cell lines infected with this virus specifically killed CD95-transfected target cells and in vitro activated T cells. In contrast, when T cells were activated by a viral infection in vivo, they were not susceptible to CD95L-mediated cell death during the induction, effector, or memory phase in vitro or in vivo. These results suggest no direct role for CD95L in regulating CTL responses in vivo.
Complexes generated by the binding of free peptides to class II MHC molecules are antigenically diverse compared with those generated by intracellular processing.
Authors: Viner N J , Nelson C A , Deck B , Unanue E R
Published: January 2023

We investigated the specificity of T cell hybridomas isolated from mice immunized with synthetic peptides identical in sequence with the dominant, naturally processed, I-Ak-restricted peptides of hen egg lysozyme (HEL). Surprisingly, the majority of hybridomas showed little or no recognition of intact HEL after processing by different APCs. This was not an artifact caused by the use of synthetic peptides since the peptide-specific hybridomas responded to a tryptic digest of HEL or to naturally processed HEL peptides extracted from I-Ak. Thus, the interaction of free peptides with class II MHC molecules can generate complexes that are antigenically dissimilar to those resulting from intracellular processing of intact Ag. This has important implications both for the interpretation of experimental studies that involve peptide immunization and for the efficacy of peptide vaccination as a strategy for intervention in human disease.
Induction of cytotoxic T lymphocytes and antitumor immunity with DNA vaccines expressing single T cell epitopes.
Authors: Ciernik I F , Berzofsky J A , Carbone D P
Published: January 2023

Delivery of genetic expression constructs into living animals can effectively induce both humoral and cellular immunity to the expressed proteins. Here we test the effectiveness of genetic immunization with a minigene coding for single epitopes derived from mutant p53 or from HIV gp120. We show that when these constructs are delivered by particle bombardment-mediated DNA transfer into the skin of mice, it results in efficient induction of tumor protective CTL. The immunogenicity of the epitope derived from mutant p53 is significantly enhanced if the epitope sequence is fused in frame with the adenovirus E3 leader sequence to target the epitope to the endoplasmic reticulum, thus acting like a "genetic adjuvant." We conclude that genetic T cell epitope immunization is an alternative to peptide-based techniques for eliciting an effective immune response targeted against a single defined epitope. in some cases, the fusion of the gene product of the DNA vaccine vector with an endoplasmic reticulum targeting sequence may enhance immune induction.
Effects of nicotine on the immune response. II. Chronic nicotine treatment induces T cell anergy.
Authors: Geng Y , Savage S M , Razani-Boroujerdi S , Sopori M L
Published: January 2023

Previously, we have shown that both T and B lymphocytes from chronically nicotine-treated (NT) animals exhibit tolerance to activation by Ags (ligation of Ag receptors), as indicated by their decreased ability to mobilize intracellular calcium and, at least in T cells, arrest of cells in the G0/G1 phase of the cell cycle. Herein, we demonstrate that NT T cells significantly lose their ability to up-regulate inositol trisphosphate synthesis in response to TCR ligation or nonspecific activation of G proteins by AIF-4. However, increases in cAMP concentrations of T cells following activation of G protein-sensitive adenylate cyclase by cholera or pertussis toxin were not significantly affected by the nicotine treatment. Interestingly, compared with control T cells, the background levels of inositol trisphosphate were significantly elevated in NT T cells, indicating some degree of activation in these cells. This inference was further supported by observations that naive T cells from NT animals exhibit tyrosine phosphorylation of several substrates, including phospholipase C-gamma1, which were either absent or underphosphorylated in unstimulated control T cells. Moreover, when, after 4-wk nicotine treatment, nicotine pumps were removed and serum cotinine levels fell to background, inhibition of the Ab-forming cells and Ca2+ responses continued for at least 2 more wk. These results suggest that chronic in vivo nicotine exposure leads to T cell anergy and may contribute to nicotine/cigarette smoke-induced immunosuppression.
Glucocorticoids promote a TH2 cytokine response by CD4+ T cells in vitro.
Authors: Ramírez F , Fowell D J , Puklavec M , Simmonds S , Mason D
Published: January 2023

Purified rat CD4+ T cells were activated in vitro in the presence or absence of the glucocorticoid dexamethasone. They were then expanded in IL-2 and subsequently restimulated, this time in the absence of the hormone. The results indicate that the exposure of the cells to dexamethasone in the primary stimulation changed the cytokine synthesis induced by the secondary stimulation. The mRNA levels for IL-4, IL-10, and IL-13 were all increased by the pretreatment, whereas synthesis of IFN-gamma and TNF-alpha was diminished. Further studies in which IL-4 was used together with dexamethasone showed that the cytokine potentiated the effect of the hormone. These data suggest that the neuroendocrine system can influence the cytokine response to pathogens and autoantigens in a way that favors Th2-type reactions. There are similar implications for therapy with glucocorticoids, and these drugs may be expected to have long term immunologic effects as well as short-lived immunosuppressive ones. The production of a mouse mAb, MRC-OX81, against rat IL-4 is also described.
LPS induces NK1.1+ alpha beta T cells with potent cytotoxicity in the liver of mice via production of IL-12 from Kupffer cells.
Authors: Takahashi M , Ogasawara K , Takeda K , Hashimoto W , Sakihara H , Kumagai K , Anzai R , Satoh M , Seki S
Published: January 2023

We recently reported that systemic administration of IL-12 into mice activates NK1.1+ alpha beta T cells with intermediate TCR (NK1+TCRint) and induces strong MHC-unrestricted cytotoxicity in C57BL/6 mice. In the present report, we examined the effect of LPS on Kupffer cells and NK1+TCRint, cells in C57BL/6 mice. Administration of LPS, as well as synthetic lipid A analogue (ONO-4007), but not detoxified LPS, induces the increase of NK1 expression of NK1+TCRint cells (NKlhighTCRint) and the acquisition of strong MHC-unrestricted cytotoxicity of these cells against NK-sensitive and NK-resistant targets as does IL-12 administration. LPS as well as ONO-4007 induced IL-12 mRNA in hepatic mononuclear cells, mainly in plastic-adherent Kupffer cells. LPS-induced cytotoxicity of hepatic mononuclear cells was greatly reduced by in vivo injections of anti-IL-12 Ab, to a lesser extent by anti-IFN-gamma Ab, but not by anti-IL-1 nor anti-TNF-alpha Ab. Pretreatment of mice with LPS induced inhibition of hepatic metastases of i.v. injected EL4 cells in C57BL/6 euthymic and athymic mice and this antimetastasis was inhibited by injection of anti-IL-12 Ab. This antimetastatic effect of LPS in the liver was also observed in different strains of mice and tumors, In contrast to IL-12, however, LPS was not so effective when administered after tumor inoculation. These results revealed that LPS (lipid A) stimulates NK1+TCRint cells through IL-12 production from Kupffer cells and suggest that bacterial components, probably including those from intestine, are activators of Kupffer cells and NK1+TCRint, cells in the liver. It is also suggested that the host condition as well as LPS-induced cytokines other than IL-12 may affect antitumor effect induced by LPS in the liver.
Suppression of the antibody response to a polymorphic peptide from the platelet alloantigen integrin beta3 with low molecular weight antigen arrays.
Authors: Watson D C , Reim J , Dintzis H M
Published: January 2023

The allelic human platelet alloantigens PIA1/PIA2 are determined by a 33 Leu-Pro substitution in the second disulfide loop of the integrin beta3 subunit of the fibrinogen receptor, alphaIIb beta3 (GPIIb-IIIa). Alloantibodies to PIA1 cause neonatal alloimmune thrombocytopenia. We studied the suppression of specific Ab production to a disulfide-looped peptide spanning the polymorphic region of integrin beta3, 24AWCSDEALPLGSPRCD39 (LPL). Mice immunized with LPL coupled to OVA (LPL-OVA) produced Abs specific for LPL. When immunized animals were injected with low m.w. dextran heavily derivitized with LPL (Dex(low)LPL(high)), levels of Ab to LPL fell immediately and remained low 1 mo later. Both high affinity and total Abs were affected. Arrays with lower peptide density or a high m.w. backbone did not induce well sustained suppression. Abs to OVA were unaffected by the arrays. Naive mice given Dex(low)LPL(high) were tolerant to subsequent immunization with LPL-OVA. In transfer experiments, irradiated recipients of spleen cells or purified 8 cells from animals suppressed with Dex(low)LPL(high) did not respond to LPL-OVA. Spleen cells from suppressed animals did not suppress the response to LPL-OVA in recipients of immune B cells. These results demonstrate that peptide arrays, by a mechanism sensitive to molecular configuration, induce tolerance to peptide immunization and suppress an ongoing, high affinity Ab response. Peptide arrays induce the elimination or irreversible anergy of specific memory B cells and do not require a non-B spleen cell population to maintain suppression.
Importance of MHC class 1 alpha2 and alpha3 domains in the recognition of self and non-self MHC molecules.
Authors: Newberg M H , Smith D H , Haertel S B , Vining D R , Lacy E , Engelhard V H
Published: January 2023

The importance of the species of different domains of class I MHC molecules in peripheral T cell recognition and positive and negative selection was evaluated in a single system. In transgenic mice expressing AAD (containing the alpha1+alpha2 domains of HLA-A2.1 and the alpha3 domain of H-2Dd), the CTL response to influenza peptide M1(58-66) in the context of the alpha1+alpha2 domains of HLA-A2.1 was as strong as the influenza-specific H-2Db-restricted response. However, this strong response was only discernible if the target cell MHC molecule also contained a murine alpha3 domain. In contrast, the response in HLA-A2.1 transgenic mice was about 30-fold weaker, and these CTL were indifferent to the origin of the target molecule alpha3 domain. Further analysis suggested that the major impact of the murine alpha3 domain of the transgene product was to enhance positive selection of a low affinity population of AAD-restricted T cells, presumably through species-specific interaction with CD8. Surprisingly, the response to non-self human class I MHC determinants was not augmented in AAD mice, indicating that the T cells selected are narrowly focused on AAD-related structures. Further analysis indicated that the alphal+alpha2 domains as well as the alpha3 domain influenced the magnitude of the response to non-self human class I MHC determinants, and this effect was mapped to alpha2. We suggest that the alpha2 domains of murine class I molecules contain conserved structural elements that augment the avidity of T cell-class I interactions, and this is particularly important in the recognition of non-self MHC molecules.
Loss ability to produce IFN-alpha in response to HIV-1 as monocytes differentiate into macrophages. Induction through a mechanism independent of double-stranded RNA.
Authors: Francis M L , Fan X S , Meltzer M S
Published: January 2023

IFN-alpha is an antiviral cytokine detected in plasma of HIV-1-infected patients during acute viremia and during late-stage disease. Monocytes produced IFN-alpha in response to HIV-1:1) IFN-alpha was produced predominantly by adherent cells; 2) depleting CD14+ cells nearly abolished HIV-1-induced IFN-alpha production; and 3) intracytoplasmic IFN-alpha was detected in CD14+ cells. During cell culture, monocytes differentiated into macrophages and lost their ability to produce IFN-alpha when challenged with HIV-1. These cells remained capable of producing IFN-alpha in response to other stimuli such as poly(I:C), a synthetic dsRNA. Thus, we examined two negative-stranded RNA viruses that have dsRNA intermediates, Newcastle disease virus and Sendai virus, and a DNA virus, herpes simplex virus type I (HSV-1). Macrophages lost their ability to produce IFN-alpha in response to HSV-1, but not to Sendai virus or to Newcastle disease virus. Thus, HIV-1 and other viruses were capable of inducing IFN-alpha through a mechanism that was independent of dsRNA. In conclusion, these data suggest that there are dsRNA-dependent and -independent mechanisms for the induction of IFN-alpha production, and that as monocytes differentiate into macrophages, they selectively lose their ability to produce IFN-alpha through the dsRNA-independent mechanism.
Apoptosis-independent retinoblastoma protein rescue of HLA class II messenger RNA IFN-gamma inducibility in non-small cell lung carcinoma cells. Lack of surface class II expression associated with a specific defect in HLA-DRA induction.
Authors: Lu Y , Boss J M , Hu S X , Xu H J , Blanck G
Published: January 2023

Work from our laboratory indicates that HLA class II induction by IFN- gamma in the retinoblastoma (RB) protein-defective breast carcinoma line MDA-468-S4 (S4) requires reconstitution of functional RB. To determine whether RB is required for HLA class 11 expression in multiple tumor types, the RB-defective non-small cell lung carcinoma line H2009 and its RB-reconstituted subclones were examined for class II inducibility. Surface HLA-DR (DR) was not inducible by IFN-gamma in H2009. However, unlike the RB-reconstituted subclones of S4, DR surface expression was not detected in the H2009 RB-positive subclones. IFN-gamma induction of CIITA, a major regulator of class II transcription, suggested that H2009 retained at least part of the IFN-gamma signaling pathway leading to class II expression. Examination of class II mRNA indicated that IFN-gamma induction of RB was rescued in the RB-positive subclones of H2009, confirming the requirement for RB for HLA class II inducibility and revealing that RB is required for inducibility in developmentally distinct tumor types. However, DRA inducibility was not rescued in the H2009 RB-positive subclones, which explained the lack of surface DR induction in the RB-positive H2009 subclones. DPA and DPB were also only weakly inducible in the RB-reconstituted H2009 subclones, compared with the previously described, S4 RB-positive subclones. Finally, data reported here indicates that RB's ability to inhibit IFN-gamma-induced apoptosis is not a viable explanation for why RB expression rescues DRB inducibility in H2009.
Regulated expression and release of the IL-1 decoy receptor in human mononuclear phagocytes.
Authors: Colotta F , Saccani S , Giri J G , Dower S K , Sims J E , Introna M , Mantovani A
Published: January 2023

The aim of this study was to investigate the expression and release of the IL-1 type II decoy receptor (R) in mononuclear phagocytes, which play a central role in immune and chronic inflammatory reactions. Human monocytes expressed both type I and type II R transcripts, the latter being two- to threefold more represented. By cross-linking and Ab blocking, the predominant surface IL-1-binding molecule was the decoy RII. IL-4, IL-13, and dexamethasone induced RI and RII transcripts and augmented the number of IL-1-binding sites with no modification of Kd values. The induced surface receptor was identified as the decoy RII. These stimuli induced the release of a soluble R with a m.w. of approximately 60 kDa, of which N-glycosylation contributed 22 kDa compared with 45 kDa released from polymorphonuclear leukocytes, of which N-glycosylation contributed 15 kDa. IL-13 and dexamethasone induced a release of 24 ng/ml/2 x 10(7) cells (from 8.7 to 43.2 ng/ml) and 25.6 ng/ml/2 x 10(7) cells (from 9.7 to 36.8 ng/ml) of decoy RII in 18 h, respectively (six donors). Thus, for instance, IL-13-treated (18 h) cells expressed 3.5 x 10(3) sites/cell and released 12 x 10(3) decoy RII/cell. The released decoy RII from monocytes bound IL-1apha and IL-1 receptor antagonist 30- and 2-fold less avidly than IL-1beta, respectively. In vitro-matured, monocyte-derived macrophages showed higher levels of surface expression and release of the IL-1 decoy RII. The results show that, on exposure to diverse molecules with anti-inflammatory properties, mononuclear phagocytes express and release copious amounts of a novel version of the soluble IL-1 decoy RII.
Identification of haptoglobin as an alternative ligand for CD11b/CD18.
Authors: El Ghmati S M , Van Hoeyveld E M , Van Strijp J G , Ceuppens J L , Stevens E A
Published: January 2023

Haptoglobin is an acute phase protein with presumed anti-inflammatory activities. We report that purified fluorescein-labeled haptoglobin 1-1 binds to THP1 and U937 promonocytic cell lines, to monocytes, to granulocytes, and to a subset of CD8+ T cells and to NK cells. Studies with radioiodinated haptoglobin on THP1 cells were consistent with specific binding to one class of receptors with a density of 1.7 x 10(5) binding sites per cell and a low affinity of 6.5 x 10(-6) Kd. Binding was increased by Ca2+ and by Ca2+ and ADP. Binding to THP1 and U937 cells could be inhibited by preincubation with nonfluoresceinated haptoglobin and by fibrinogen, but not by albumin, transferrin, or alpha1-acid glycoprotein. Fibrinogen binds to the CD11b/CD18 integrin. We therefore examined whether haptoglobin has the same receptor. The anti-CD11b mAb44 indeed inhibited the binding of fluoresceinated haptoglobin to THP1 and U937 cell lines, and haptoglobin inhibited the binding of the anti-CD11b mAb anti-Leu15 and mAb44 to both cell lines. An anti-CD18 mAb partly inhibited the binding of fluoresceinated haptoglobin to THP1 and U937, indicating that the beta-chain of MAC-1 is also involved in haptoglobin binding. There was no interference between the binding of anti-CD4, anti-CD11a, or anti-CD11c mAb and haptoglobin binding to THP1 cells. Binding of haptoglobin to purified CD11b/CD18 indicates that it binds directly to the receptor. Haptoglobin is an alternative low affinity ligand for the CD11b/CD18 integrin, suggesting that this acute phase protein might regulate MAC-1-dependent cell function in vivo.
Cytokine-regulated expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in human microvascular endothelial cells.
Authors: Haraldsen G , Kvale D , Lien B , Farstad I N , Brandtzaeg P
Published: January 2023

Endothelial cells (EC) recruit circulating leukocytes to sites of inflammation, partly by expression of endothelial-leukocyte adhesion molecules. Whereas the regulation of some adhesion molecules is well characterized in cultured HUVEC, similar data for microvascular human test systems are limited. We studied the cytokine-regulated expression of vascular cell adhesion molecules E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) in cultured human intestinal microvascular endothelial cells (HIMEC). E-selectin and VCAM-1 were induced, and ICAM-1 was enhanced, in a dose-dependent fashion after stimulation with IL-1beta, TNF-alpha, and LPS. Each adhesion molecule displayed characteristic time-related responses comparable to those obtained with HUVEC, and each molecule supported adhesion of leukocytes. Notable disparities between the two endothelial test systems were that 1) expression of total cellular E-selectin (but not surface membrane expression) was sustained after 72 h of IL-1beta stimulation in HIMEC, contrasting a rapid biphasic response in HUVEC; 2) LPS did not maintain prolonged expression of ICAM-1 and VCAM-1 in HIMEC; and 3) VCAM-1 protein was dose-dependently up-regulated by IL-4 in HUVEC, peaking after 8 h, while IL-4 had only a negligible effect on the expression of this protein in HIMEC. In conclusion, the regulation of these adhesion molecules appears to be somewhat different in HIMEC compared with HUVEC, and the differences from available data on skin-derived microvascular endothelial cell cultures are to some extent substantial. Our findings document the importance of using relevant endothelial cell culture systems for studies of leukocyte-endothelial cell interactions.
Human eosinophils elaborate the lymphocyte chemoattractants. IL-16 (lymphocyte chemoattractant factor) and RANTES.
Authors: Lim K G , Wan H C , Bozza P T , Resnick M B , Wong D T , Cruikshank W W , Kornfeld H , Center D M , Weller P F
Published: January 2023

Eosinophils and CD4+ lymphocytes are preferentially recruited into sites of allergic inflammation. A role for eosinophils in the recruitment of CD4+ lymphocytes has not been defined. We studied the capacity of human eosinophils to release chemoattractants for T lymphocytes. Supernatants of cultured eosinophils contained chemoattractant activity for lymphocytes, which was predominantly due to IL-16 (lymphocyte chemoattractant factor) and RANTES. With neutralizing Abs, eosinophil-derived lymphocyte chemotactic activity was diminished by a mean (+/- SEM) of 60 +/- 3% with polygonal anti-IL-16 Ab, 69 +/- 4% with anti-IL-16 mAb, 48 +/- 3% with anti-CD4 F(ab) (IL-16 receptor blockade), 40 +/- 4% with anti-RANTES mAb, and 88 +/- 5% with a combination of anti-IL-16 and anti-RANTES mAbs. IL-16 and RANTES were detectable in eosinophil-derived supernatants by ELISA. Eosinophils constitutively expressed mRNA transcripts for both IL-16 and RANTES detectable by reverse transcription-PCR and contained preformed IL-16 and RANTES demonstrable by ELISA of cell lysates and by immunocytochemistry of freshly isolated eosinophils. Thus, eosinophils are a source of two cytokines, IL-16 and RANTES, that are chemoattractants for lymphocytes as well as eosinophils. These data indicate that eosinophils could contribute cytokines to enhance the recruitment of additional populations of CD4+ lymphocytes and eosinophils.
Ligation of the functional domain of complement receptor type 2 (CR2, CD21) is relevant for complex formation in T cell lines.
Authors: Prodinger W M , Larcher C , Schwendinger M , Dierich M P
Published: January 2023

We investigated the potential of CD21, the complement receptor type 2, to form receptor complexes with other membrane molecules on T cell lines. CD21 from T cell lines transformed with human T cell leukemia virus type I (MT2, HUT-102, C5.MJ, Mondi, and C91.PL) and T cell lines that were not virus transformed was analyzed by coprecipitation following cell lysis with digitonin. mAbs binding to functional and nonfunctional epitopes of CD21 and a polyclonal antiserum against its intracellular portion precipitated CD21, which was indistinguishable from CD21 on B cell lines. In contrast to B cells, where CD21 is complexed with CD19 and CD81 (target of anti-proliferative Ab 1) or, alternatively, with CD35 (CR1), no surface molecules could be coprecipitated with three of four mAbs from these T cell lines. Therefore, we assume that CD21 is not part of a preformed complex in T cell lines. OKB7, the only mAb directed against the functional C3d binding site, coprecipitated two proteins of 105 and 55 Mr with CD21 from MT2 and Mondi cells and from the T cell lines Jurkat E6-1 and SupT1. These bands were also recovered with CD21 precipitated from MT2 cells with C3d bound to Sepharose via the internal thioester, but were absent in CD21-expressing B cell lines. As C3d and OKB7 are functional ligands for B cells, we propose that upon ligation on T cells, CD21 associates with molecules of 105/55 Mr in the plasma membrane. Whether this is the first event of a signal delivered to the T cell is under current investigation.
The proteolytic environment involved in MHC class II-restricted antigen presentation can be modulated by the p41 form of invariant chain.
Authors: Fineschi B , Sakaguchi K , Appella E , Miller J
Published: January 2023

During biosynthesis, MHC class II associates with invariant chain which exists in two forms, p31 and p41. Both forms of invariant chain prevent peptide binding to class II, facilitate transport, and enhance class II localization to Ag-processing compartments. In spite of these shared functions, presentation of some Ags can be selectively enhanced by expression of p41. Here we show that p41 can function as a protease inhibitor: 1) the functional and biochemical consequences of p41 expression can be mimicked by inhibiting cysteine proteases in vivo; 2) the amount of intracellular active cysteine proteases is dramatically decreased in p41-positive cells; and 3) a polypeptide corresponding to the p41-unique region is a potent inhibitor of cathepsin L in vitro. These data suggest that p41 can enhance Ag presentation by reducing the proteolytic activity of the Ag-processing compartment, thus protecting a subset of antigenic epitopes from excessive degradation.
CD30 expression on human CD8+ T cells isolated from peripheral blood lymphocytes of normal donors.
Authors: Agrawal B , Reddish M , Longenecker B M
Published: January 2023

By direct or indirect immunofluorescence using FITC as a fluorochrome, 0 to 2% of the T cells isolated from peripheral blood of normal healthy individuals was found to be CD30+. Using indirect immunofluorescence and phycoerythrin-labeled Ab, higher percentages of CD30+ T cells (3-31%) were repeatedly found in the peripheral blood of normal healthy donors. The majority (85-90%) of CD30+ T cells obtained from PBLs of normal healthy donors were found in the CD8+ cell population. Following FACS sorting of the T cell populations into CD30+ and CD30- subpopulations, approximately 85 to 90% CD30+ T cells were CD8+, whereas the CD30- T cells were CD4+. Upon activation, the sorted CD30+ T cells produced both IFN-gamma and IL-4. In contrast to previous reports, these results demonstrate that CD30+CD8+ T cells are present in significant numbers in the PBLs of normal healthy individuals.
Infusion of anti-B7.1 (CD80) and anti-B7.2 (CD86) monoclonal antibodies inhibits murine graft-versus-host disease lethality in part via direct effects on CD4+ and CD8+ T cells.
Authors: Blazar B R , Sharpe A H , Taylor P A , Panoskaltsis-Mortari A , Gray G S , Korngold R , Vallera D A
Published: January 2023

Efficient T cell proliferation requires costimulation via CD28/B7 or other pathways. Graft-vs-host disease (GVHD) is caused by activated donor T cells. We have found that the infusion of anti-B7.1 (CD80) + anti-B7.2 (CD86) mAb is effective in eliminating GVHD lethality induced by either CD8+ or CD4+ T cells. Donor CD4+ and CD8+ T cell expansion was inhibited by almost 100-fold as measured by enumerating thoracic duct lymphocytes (TDL) obtained early post-transplant. TDL retained anti-host responsiveness indicating that not all T cells were anergic. Although anti-CD80 or anti-CD86 mAb individually were ineffective in preventing CD8+ T cell GVHD lethality, each mAb was partially effective in CD4+ T cell-mediated GVHD. Because CD80 expression was found to be up-regulated on donor CD4+ TDL post-transplant, the GVHD capacity of donor CD4+ T cells deficient in CD80 was tested and found to be reduced similarly to that seen with anti-CD80 mAb. These studies demonstrate that anti-CD80 + anti-CD86 mAb infusion is effective in preventing GVHD lethality by inhibiting donor CD4+ or CD8+ T cell expansion and provide the first evidence that CD80 expression on donor T cells is critical for optimal GVHD lethality.
Soluble protein but not peptide administration diverts the immune response of a clonal CD4+ T cell population to the T helper 2 cell pathway.
Authors: Degermann S , Pria E , Adorini L
Published: January 2023

BALB/c mice immunized with protein Ags such as OVA in adjuvant mount a Th1-type response. Inhibition of Th1 and development of Th2 cells can be induced by pretreating BALB/c mice with soluble OVA before priming. To investigate some aspects of this immune deviation in vivo, naive TCR transgenic T cells specific for the chicken OVA peptide 323-339 presented by I-A(d) molecules were adoptively transferred into normal BALB/c mice. The frequency and fate of the transferred T cells can be followed with an anti-clonotypic Ab. In response to priming with OVA in CFA, the transferred transgenic T cells expand and differentiate into Th1 cells producing IL-2 and IFN-gamma. If recipient mice are injected with soluble OVA before priming, the frequency of transgenic T cells is not affected, but their expansion in response to Ag priming is inhibited. Yet, the fewer transgenic T cells recovered are not anergic, they proliferate as control cells when restimulated in vitro by plate-bound anticlonotypic Ab or by Ag. Analysis of Th phenotype indicates that pretreatment with soluble OVA has suppressed Th1 cell differentiation in favor of the generation of Th2 cells producing IL-4 and IL-5. Pretreatment with soluble peptide 323-339 also inhibits Th1 cell development, but fails to induce Th2 cell differentiation. Thus, pretreatment with soluble protein Ag or with synthetic peptide inhibits Th1 cell development, but only protein, not peptide, administration can deviate the in vivo response of a clonal T cell population from the Th1 to the Th2 pathway.
Subcellular localization of CD80 receptors is dependent on an intact cytoplasmic tail and is required for CD28-dependent T cell costimulation.
Authors: Doty R T , Clark E A
Published: January 2023

CD28 provides a major costimulatory signal to T cells when it is cross-linked with mAb, immobilized recombinant ligand (CD80Ig or CD86Ig), or ligand-bearing cells but not when it is bound by specific Fab fragments or monomeric ligand. We wanted to determine how monomeric CD80 could cross-link CD28 since CD80 is expressed as a monomer on the surface of APC. We found that CD80 may interact with the actin-based cytoskeleton. To test whether the interaction of CD80 with the cytochalasin B-sensitive cytoskeleton was necessary for T cell costimulation through CD28, we constructed a tailless form of CD80 and generated stable transfectants of Chinese hamster ovary epithelial cells and Reh B cells expressing either the tailless or wild-type CD80 molecules. Unlike control cells expressing wild-type CD80, the tailless CD80 transfectants expressing equivalent levels of surface CD80 were not able to provide a costimulatory signal for anti-CD3-induced T cell proliferation, up-regulation of CD25 (IL-2Ralpha) expression, or the induction of IL-2 secretion. Thus, the cytoplasmic tail of CD80 apparently is required to signal T cells. Confocal microscopic studies revealed that wild-type CD80 and tailless CD80 have different patterns of subcellular distribution in both epithelial and lymphoid cells. Furthermore, T cell contact induces more patching and capping of CD80 in wild-type CD80-expressing cells than in tailless CD80-expressing cells. This suggests that the cytoplasmic region of CD80 functions to localize CD80 in complexes required for effective T cell costimulation.
IL-10 inhibits lipopolysaccharide-induced murine B cell proliferation and cross-linking of surface antigen receptors or ligation of CD40 restores the response.
Authors: Marcelletti J F
Published: January 2023

The effects of IL-10 on murine B cell proliferation in vitro were investigated. IL-10 inhibited LPS-induced B cell proliferation with an EC50 of approximately 500 pg/ml. IL-10-mediated inhibitory activity was not overtly associated with cytotoxicity or induction of apoptosis. The presence or the absence of T cells and mononuclear phagocytes did not affect the inhibitory activity of IL-10 on LPS-induced proliferation. LPS-stimulated, IL-10-exposed B cells progressed from G0 or from M to G1A of the cell cycle, but were inhibited from entry into subsequent phases. IL-10 had no discernible effect on B cell proliferation elicited with goat anti-mouse IgM plus IL-4. Moreover, cross-linking, but not mere ligation, of surface Ag receptors restored LPS-induced B cell proliferation in the presence of IL-10. The proliferative response to ligation of CD40 with anti-CD40 Abs was also not inhibited by IL-10, and as observed with goat anti-mouse IgM, the presence of such Abs in IL-10-containing B cell cultures allowed for the proliferative response to LPS. A variety of other Abs reactive with murine B cell surface markers were ineffective at modulating the response to IL-10. IL-1, IL-2, IL-4, IL-5, IL-6, IFN-gamma, and TGF-beta were also ineffective in this regard. These observations suggest that IL-10 has a role in the suppression of inappropriate B cell proliferation, i.e., proliferation by B cells that have not effectively interacted with relevant Ag or CD40 ligand.
p126 (CDw101), a costimulatory molecule preferentially expressed on mucosal T lymphocytes.
Authors: Russell G J , Parker C M , Sood A , Mizoguchi E , Ebert E C , Bhan A K , Brenner M B
Published: January 2023

Intestinal mucosal lymphocytes are defined by their anatomic location within the epithelium (intraepithelial lymphocytes), the interstitium between the epithelial basement membrane and the underlying muscularis mucosa (lamina propria lymphocytes), or in organized lymphoid tissues (Peyer's patches). Although intestinal intraepithelial lymphocytes have a distinct localization, their function has not been determined. To define cell surface proteins that are involved in intestinal intraepithelial lymphocyte localization or function, cultured human mucosal lymphocytes were used as immunogens to develop mAbs that react predominantly with this cell population in an immunohistochemical screening assay. Three mAbs were selected that subsequently were found by biochemical analysis to identify a 200-kDa homodimeric polypeptide on 88 to 98% of CD3+ mucosal lymphocytes but only 18 +/- 13% of PBLs. Expression on granulocytes and monocytes was also observed. This polypeptide has been termed p126 based on its SDS-PAGE-determined M(r) under reducing conditions. Cleveland digest maps demonstrated similarity between the p126 and CDw101 polypeptides. Determined amino acid sequence analysis of the purified p126 polypeptide revealed that it is the protein product of the recently identified V7 gene, which has structural similarities to members of the Ig gene superfamily. Two of the anti-p126 mAbs were costimulatory with suboptimal concentrations of anti-CD3 mAb inducing proliferation of cultured intestinal intraepithelial lymphocytes. Thus, we conclude that p126 is CDw101 encoded by a gene that predicts a seven-Ig domain chain-like structure. It has restricted expression predominantly on mucosal T lymphocytes and appears to have a costimulatory function of special relevance for CD28- T cells and for mucosal lymphocytes.
Herpes simplex virus blocks intracellular transport of HLA-G in placentally derived human cells.
Authors: Schust D J , Hill A B , Ploegh H L
Published: January 2023

Spontaneous fetal loss is associated with herpes simplex virus (HSV) infection as deduced from epidemiologic data. To date, the underlying mechanisms remain to be elucidated, but an immune component is suspected. HLA-G is a class I MHC molecule selectively expressed on extravillous cytotrophoblast; this cell type does not express conventional HLA-A or -B, whereas expression of novel HLA-C-like products has been reported. While its function remains unclear, a role for HLA-G in silencing NK cells that would otherwise attack cells devoid of classical class I molecules has been invoked. We here show that expression of HLA class I molecules is abrogated in HSV-infected choriocarcinoma cells, a phenomenon mediated by the virally encoded inhibitor of the transporter associated with Ag presentation, ICP47. These observations may provide a link between HSV infection and spontaneous fetal loss.
Changes in the cytoplasmic structure of CTLs during target cell recognition and killing.
Authors: Waters J B , Oldstone M B , Hahn K M
Published: January 2023

CTL play a critical role in immune defense by recognizing and killing virally infected or tumor cells. In this report, the structure of cytoplasm within living CTL was monitored during CTL killing of target cells. Living CTL were simultaneously loaded with fluorescent 70,000- and 10,000-kDa dextran particles. The relative distribution of the large and small dextrans within CTL revealed subcellular heterogeneities in the submicroscopic structure of cytoplasm. Localized alterations in cytoplasmic structure correlated with specific events during CTL killing. Recognition of target cells was accompanied by a transient increase in large dextran accessibility over a broad front near the interface between CTL and target cells. This region narrowed to a smaller area from which pseudopodia were extended toward the target. During extension, there was a large difference between regions of high dextran accessibility within the pseudopod and more structured cytoplasm within the cell body. Areas undergoing structural changes showed localized foci of high dextran accessibility. During retraction, cytoplasmic structure became gradually more uniform throughout the protrusion and cell body. These observations revealed subcellular regions undergoing major changes during early stages of the killing response, and addressed the role of cytoplasmic solation in controlling CTL morphology. They support mechanisms of pseudopod extension driven by hydrostatic pressure and demonstrate a precise regulation of cortical structure to control the direction of pseudopod extension.
Induction of apoptosis by anti-CD3 epsilon F(ab')2 in antigen receptor transgenic murine T cells activated by specific peptide.
Authors: Yu X Z , Zhu L , Davis J E , Tso J Y , Hansen J A , Anasetti C
Published: January 2023

Peripheral T cell tolerance can be achieved through deletion of mature CD4+ cells activated by high dose Ag. We tested whether apoptosis of peripheral CD4+ cells could be induced by a stimulatory dose of Ag plus a soluble ligand to the nonpolymorphic epsilon-chain of the TCR-associated CD3 complex. CD4+ T cells from the DO10 mouse express a transgenic TCR-alphabeta specific for OVA peptide 323-339 presented by I-A(d). OVA alone induced clonal activation and expansion of peripheral CD4+/TCR transgene+ cells. Simultaneous exposure to specific Ag plus soluble anti-CD3 Fos, a nonmitogenic anti-CD3epsilon genetically engineered F(ab')2-like Ab, blocked expansion and induced death of CD4+/TCR transgene+ cells, but not CD4+/TCR transgene- T cells. In contrast, a mitogenic anti-CD3epsilon Ab induced polyclonal activation and nonselective T cell death. Sequential stimulation by Ag followed by anti-CD3 Fos also induced death of TCR transgene+ cells, whereas stimulation by anti-CD3 Fos followed by Ag did not affect cell viability or function. Anti-CD3 Fos-induced death was associated with DNA fragmentation characteristic of apoptosis, was facilitated by IL-2, and was initiated by stimulation during the S-G2 phases of the cell cycle. Anti-CD3 Fos could induce deletion of Ag-activated T cells by apoptosis in vivo. Thus, a soluble, non-Fc-binding anti-CD3 Ab can induce programmed cell death of Ag-activated peripheral CD4+ T cells by CD3epsilon cross-linking during S or G2. Peripheral T cell deletion by activation-driven apoptosis is under cell cycle control and can be exploited to achieve selective immunosuppression by nonmitogenic anti-CD3epsilon Abs.