bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of human thymocytes after infection by EBV.
Authors: Paterson R L , Kelleher C A , Streib J E , Amankonah T D , Xu J W , Jones J F , Gelfand E W
Published: December 2022

The discovery of EBV in certain T cell malignancies and the expression of the EBV receptor, CR2/CD21, on a population of immature thymocytes, T lymphoblastoid cell lines, and childhood acute T lymphoblastic leukemia cells suggested that EBV-receptor interactions on T cells may be of importance. We have shown that, within the thymus, a population of large, immature cells expresses CD21. EBV altered the activation responses of immature thymocytes in vitro. Triggering through CD2 is mitogenic for mature, but not immature, T cells. However, during infection by EBV, ligation of CD2 caused thymocytes to proliferate in the absence of exogenous cytokines. This function was a result of the interaction of EBV with its receptor, CD21, but was caused by infection rather than surface signaling, because neither specific mAb nor the P3HR-1 strain of virus mimicked the effect of B95-8. Immature thymocytes were infected by EBV, as determined by the internalization of the viral genome and its transcriptional activity. Consistent with the activity of B95-8, EBNA-2 transcripts were identified within infected thymocyte populations. In addition, components of the viral replicative pathway were expressed during infection of thymocytes. These components included transcription of BZLF-1, an early gene that characterizes EBV-infected B cells after disruption of latency. A second transcript was identified as encoding the recently characterized RAZ, which also is associated with replicative infection. The consequences of EBV infection of T cells at an early stage of differentiation may lead to failure of normal T cell repertoire development, autoimmunity, or malignancy.
Direct cellular communications between CD45R0 and CD45RA T cell subsets via CD27/CD70.
Authors: Agematsu K , Kobata T , Sugita K , Hirose T , Schlossman S F , Morimoto C
Published: December 2022

The engagement of CD27 with its ligand CD70 is considered to play an important role in T cell costimulation. In the present study, we investigated both the kinetics of CD70 expression and the contribution of its interaction with CD27 in T cell immune responses. CD70 was found to be expressed almost equally on both activated CD4 and CD8 T cells. On subsets of CD4 T cells, however, CD70 expression was induced preferentially on the CD45R0 T cell population after activation, whereas its expression was not noted on CD45RA T cells for almost 2 wk following activation. In long-term culture with media containing T cell growth factor (TCGF) and rIL-2, the expression of CD70 was increased markedly on CD45R0 T cells and minimally expressed on CD45RA T cells. In addition, strong surface expression of CD70 was observed on T cell clones originally derived from CD45R0+ CD4 T cells, whereas T cell clones originally derived from CD45RA+ CD4 T cells showed lower levels of expression. The addition of irradiated, activated CD45R0 T cells to CD45RA T cells caused a down-regulation of CD27 expression and an up-regulation of CD25 expression. These changes were blocked by addition of the anti-CD70 mAb, suggesting that direct contact between CD45R0 T cells and CD45RA T cells via CD27/CD70 occurred, leading to the activation of CD45RA T cells as measured by CD25 expression. These observations strongly support the notion that the engagement of CD27 plays an important regulatory role in the communication of subsets of CD45R0 and CD45RA T cells.
Daudi lymphoma killing triggers the programmed death of cytotoxic V gamma 9/V delta 2 T lymphocytes.
Authors: Ferrarini M , Heltai S , Toninelli E , Sabbadini M G , Pellicciari C , Manfredi A A
Published: December 2022

A common feature of human V gamma 9/V delta 2 gamma delta T lymphocytes is their ability to kill Daudi lymphoma cells. We show here that during this killing a substantial fraction of cytotoxic gamma delta T cells dies as well. Their death has morphologic, cytometric, and biochemical features of apoptosis and depends on TCR triggering. We suggest that interaction with the target physiologically induces the programmed death of the cytotoxic gamma delta effector. The death of activated gamma delta T cells upon challenge with the relevant Ag may represent a negative feedback mechanism and contribute to explain the limited time span of gamma delta T cell expansions during infectious diseases, even when pathogens are not eliminated and persist in the host.
Characterization of the autoreactive T cell repertoire in cyclosporin-induced syngeneic graft-versus-host disease. A highly conserved repertoire mediates autoaggression.
Authors: Fischer A C , Ruvolo P P , Burt R , Horwitz L R , Bright E C , Hess J M , Beschorner W E , Hess A D
Published: December 2022

Syngeneic graft-vs-host disease (SGVHD) is a MHC class II-restricted T cell-mediated autoimmune syndrome that occurs following syngeneic bone marrow transplantation and the administration of cyclosporin (CsA). The present studies evaluated the V beta repertoire of T lymphocytes that mediate SGVHD. To facilitate analysis, SGVHD effector cells were adoptively transferred into thymectomized syngeneic recipients reconstituted with T cell-depleted bone marrow to provide an environment that allows for the selective clonal expansion of autoreactive T cells. Analysis of target tissues and PBL by reverse transcriptase PCR using oligonucleotide V beta-specific primers revealed a predominance of V beta 8.5+ T cells and a minor population expressing V beta 10. The majority of infiltrating lymphocytes in target tissues was confirmed to be V beta 8.5+ by in situ hybridization and by immunoperoxidase staining. A small population of V beta 10+ cells could also be detected. Furthermore, SGVHD effector T splenocytes depleted of lymphocytes expressing either the TCR-alpha beta or the V beta 8.5 determinant could not adoptively transfer SGVHD. Depletion of T cells expressing the V beta 10 determinant delayed the onset of this autoaggression syndrome. Subset analysis of the autoreactive T cell compartment revealed that the V beta 8.5 determinant was expressed on both CD4+ and CD8+ lymphocytes whereas the V beta 10 determinant was principally expressed on a minor population of CD4+ autoreactive T cells. These data were confirmed by limiting dilution analysis. Additional studies examining the effect of CsA on thymic differentiation revealed that although V beta 8.5 is not normally clonally deleted, there was a pronounced shift in the expression of this determinant between CD4 and CD8 single positive thymocytes, suggesting that CsA may inhibit normal positive selection processes for MHC class I and class II reactive T cells.
Expression of the Fas ligand in cells of T cell lineage.
Authors: Suda T , Okazaki T , Naito Y , Yokota T , Arai N , Ozaki S , Nakao K , Nagata S
Published: December 2022

Fas ligand (FasL) is a membrane-type cytokine belonging to the TNF family, and induces apoptosis through its cell-surface receptor, Fas. To determine the cell types that express FasL, various mouse tissues and cell lines were examined by Northern hybridization using a mouse FasL cDNA as a probe. Among tissues, lymphoid organs (thymus, lymph node, spleen), lung, and small intestine express low levels of FasL mRNA, suggesting the role of FasL in the general immune system and mucosal immunity. The testis expressed FasL mRNA most abundantly; however, the size of FasL mRNA in the testis was slightly shorter than those in other tissues. Distribution of FasL mRNA in a panel of cell lines indicated that the FasL expression is rather restricted to the cells of T cell lineage. Activation of the splenocytes with the T cell activators such as PMA and ionomycin, Con A, anti-CD3, or even IL-2 alone induced the expression of the FasL. CD8+ splenocytes expressed the FasL more abundantly than did the CD4+ splenocytes upon activation by Con A and IL-2. Among CD4+ CTL cell lines, the FasL was expressed in all Th1 and Th0, and some Th2 clones.
Compared TCR and CD3 epsilon expression on alpha beta and gamma delta T cells. Evidence for the association of two TCR heterodimers with three CD3 epsilon chains in the TCR/CD3 complex.
Authors: Thibault G , Bardos P
Published: December 2022

Current models for TCR/CD3 complex stoichiometry involve one or alternatively two TCR heterodimer(s) associated with two CD3 epsilon per complex. They mainly constructed on the basis of biochemical studies involving disruption of membrane complexes. The present study was undertaken to quantify the relative proportions of CD3 epsilon and TCR chains on alpha beta and gamma delta lymphocytes in nondenaturing conditions. Quantitative flow cytometry revealed that alpha beta and gamma delta PBL express on an average 1.56 and 1.52 more CD3 epsilon-chain than beta- and delta-chains, respectively. Accordingly, CD3 epsilon to TCR-alpha, TCR-beta, TCR-gamma, and TCR-delta ratios found on three polyclonal cell lines and on Jurkat cells were all very close to 1.50. These results clearly demonstrate that alpha beta as well as gamma delta T cells express approximately 1.50 more CD3 epsilon-chain than each of the TCR chains. They strongly suggest that alpha beta and gamma delta TCR/CD3 complexes involve two TCR heterodimers associated with three CD3 epsilon-chains (or a multiple of this combination). In addition, our results showed that gamma delta PBL expressed about 1.90 more TCR (-delta vs -beta) and CD3 epsilon-chains than alpha beta PBL. Furthermore, TCR-beta expression and CD3 epsilon expression were higher on CD4+ alpha beta PBL than on CD8+ alpha beta PBL, whereas TCR-delta expression and CD3 epsilon expression were both identical on CD8+ gamma delta PBL and on CD8- gamma delta PBL. These results demonstrate that CD8+ or CD8- gamma delta PBL, CD4+ alpha beta PBL and CD8+ alpha beta PBL express decreasing levels of the TCR/CD3 complex.
Representation of rearranged VH gene segments in the human adult antibody repertoire.
Authors: Suzuki I , Pfister L , Glas A , Nottenburg C , Milner E C
Published: December 2022

The heavy chain variable region composition of the human adult Ab repertoire is poorly defined, but recent evidence suggests that peripheral blood B cells may express a nonstochastic assortment of VH genes. In this study, the contribution of individual VH gene segments to the human Ab repertoire has been assessed. As a measure of VH gene utilization, the frequency of occurrence of eight individual VH3 gene segments contained in rearrangements was assessed in the peripheral blood B cells of two adult subjects. In addition, the frequency of occurrence of rearrangements containing nine individual VH4 gene segments was analyzed in one of the subjects. More than 2500 independent rearrangements were analyzed. For controls, amplifications and subsequent identification of nonrearranged VH3 and VH4 genes from the same individuals were also performed. The results of this germ-line analysis indicated that approximately 25 VH3 gene segments and nine VH4 gene segments could be amplified quantitatively. However, usage of elements was not uniform; one VH3 element, V3-23, and one VH4 element, V4-34, were represented among rearrangements more frequently than were other members of their respective families. This pattern of VH utilization was apparent in B cells isolated from the same subject after an 8-mo interval, indicating the relative stability of the repertoire over time. These results indicate that the adult human Ab repertoire is dominated by a few VH genes demonstrating a pattern of nonrandom utilization that could involve preferential rearrangement and/or receptor-dependent selection.
Activation of serine/threonine protein kinases and early growth response 1 gene expression by tumor necrosis factor in human myeloid leukemia cells.
Authors: Saleem A , Yuan Z M , Taneja N , Rubin E , Kufe D W , Kharbanda S M
Published: December 2022

The early growth response 1 (EGR-1) gene is induced by mitogenic and differentiating signals in diverse cell types. The present studies have examined the effects of TNF-alpha on the induction of EGR-1 expression in human myeloid leukemia cells and the potential cytoplasmic signaling cascades that transduce TNF-induced signals to the nucleus. The results demonstrate that treatment of HL-60 cells with TNF is associated with the transient induction of the EGR-1 gene. The results also demonstrate that TNF treatment is associated with activation of the serine/threonine kinase, pp90rsk, which acts upstream to EGR-1 gene induction. Partial purification of pp90rsk by affinity chromatography demonstrated an increase in S6 peptide phosphorylation in response to TNF treatment. Because TNF activates sphingomyelin hydrolysis, we also studied the effects of sphingomyelinase (SMase) on induction of EGR-1 and pp90rsk. The results demonstrate that SMase also activates pp90rsk and induces EGR-1 gene expression. Previous work has demonstrated that mitogen-activated protein (MAP) kinase activates pp90rsk. The present studies further show that treatment with TNF or SMase is associated with induction of both the pp42/44 MAP and the related Jun kinases. Induction of pp42/44 MAP kinase activity is temporally related to activation of pp90rsk and the EGR-1 gene. These findings support the involvement of an MAP kinase/pp90rsk/EGR-1 cascade in the response of myeloid leukemia cells to TNF.
Autoantibody germ-line gene segment encodes VH and VL regions of a human anti-streptococcal monoclonal antibody recognizing streptococcal M protein and human cardiac myosin epitopes.
Authors: Quinn A , Adderson E E , Shackelford P G , Carroll W L , Cunningham M W
Published: December 2022

Cross-reactivity of anti-streptococcal Abs with human cardiac myosin may result in sequelae following group A streptococcal infections. Molecular mimicry between group A streptococcal M protein and cardiac myosin may be the basis for the immunologic cross-reactivity. In this study, a cross-reactive human anti-streptococcal/anti-myosin mAb (10.2.3) was characterized, and the myosin epitopes were recognized by the Ab identified. mAb 10.2.3 reacted with four peptides from the light meromyosin (LMM) tail fragment of human cardiac myosin, including LMM-10 (1411-1428), LMM-23 (1580-1597), LMM-27 (1632-1649), and LMM-30 (1671-1687). Only LMM-30 inhibited binding of mAb 10.2.3 to streptococcal M protein and human cardiac myosin. Human mAb 10.2.3 labeled cytoskeletal structures within rat heart cells in indirect immunofluorescence, and reacted with group A streptococci expressing various M protein serotypes, PepM5, and recombinant M protein. The nucleotide sequence of gene segments encoding the Ig heavy and light chain V region of mAb 10.2.3 was determined. The light chain V segment was encoded by a V kappa 1 gene segment that was 98.5% identical with germ-line gene humig kappa Vi5. The V segment of the heavy chain was encoded by a VH3a gene segment that differed from the VH26 germ-line gene by a single base change. VH26 is expressed preferentially in early development and encodes autoantibodies with anti-DNA and rheumatoid factor specificities. Anti-streptococcal mAb 10.2.3 is an autoantibody encoded by VH and VL genes, with little or no somatic mutation.
Hyperinducibility of HLA class II expression of thyroid follicular cells from Graves' disease. A primary defect?
Authors: Sospedra M , Obiols G , Babi L F , Tolosa E , Vargas F , Roura-Mir C , Lucas-Martin A , Ercilla G , Pujol-Borrell R
Published: December 2022

Thyroid follicular cells (thyrocytes) from Graves' disease (GD) patients' thyroid glands express HLA class II molecules "ectopically." This phenomenon has been attributed to induction by locally produced cytokines and may be relevant to disease pathogenesis. We have compared IFN-gamma-mediated induction of HLA class II in thyrocytes from glands affected with GD and a nonautoimmune disease (MNG), to investigate a possible differential regulation of HLA expression between these two pathologies. HLA induction has been measured in primary thyrocyte cultures and control autologous macrophages stimulated or not stimulated with IFN-gamma. Comparison of flow cytometric data using an improved algorithm demonstrated that expression of HLA class II molecules is more readily induced in thyrocytes from GD than from MNG thyroid glands. This higher inducibility was parallel to a faster and stronger induction of HLA class II message in GD thyrocytes but did not correlate with the levels of HLA class II or class I originally expressed by thyrocytes in the tissue or with the degree of lymphocytic infiltration of the gland. There was no association with a particular HLA class II allele or with the presence of IFN-gamma and IL-2 in the tissue, as assessed by reverse transcription-PCR. No differences in the induction of class II were found in macrophages from each group of patients. These results suggest that an intrinsic feature of thyrocytes from GD patients is an up-regulation of HLA class II expression and that this is a characteristic that may facilitate the triggering of autoimmunity to "hyperinducible" thyroid glands.
CD40 signaling-mediated induction of Bcl-XL, Cdk4, and Cdk6. Implication of their cooperation in selective B cell growth.
Authors: Ishida T , Kobayashi N , Tojo T , Ishida S , Yamamoto T , Inoue J
Published: December 2022

Signals sent through CD40 play crucial roles in B cell differentiation, including blocking apoptosis of germinal center B cells. In this study, using a murine B cell WEHI-231 line that undergoes apoptosis by the cross-linking of surface Ag receptors (sIgM), we have demonstrated that CD40 signalings are linked to induction of the Bcl-xL, Cdk4, and Cdk6 proteins whose expression was significantly suppressed by the apoptotic signal through sIgM. Mutational analyses of CD40 revealed that the domain of human CD40 required for blocking apoptosis of WEHI-231 cells coincides with that required for Bcl-xL induction. Signals through sIgM arrest cells in the G1 phase of the cell cycle, which is followed by apoptosis. However, while constitutive expression of Bcl-XL leads to the inhibition of apoptosis. Nevertheless, Bcl-xL fails to induce S phase entry. By CD40 signalings, both Cdk4 and Cdk6 resume their normal expression levels, which are sufficient for passing the restriction point in G1 even in the presence of the apoptotic signals mediated by sIgM. These results suggest that cooperation of Bcl-xL, Cdk4, and Cdk6 induced by CD40 signaling plays a key role in CD40-mediated selective growth of B cells.
Sex hormone and IL-6 regulation of antigen presentation in the female reproductive tract mucosal tissues.
Authors: Prabhala R H , Wira C R
Published: December 2022

The purpose of this study was to determine whether Ag presentation takes place in the female reproductive tract and if the stage of the reproductive cycle, sex hormones, and IL-6 regulate uterine Ag presentation. Purified epithelial and mixed stromal cells were incubated with sensitized lymph node T lymphocytes in the presence of OVA. Ag presentation was highest at proestrus, the stage of the reproductive cycle that immediately precedes ovulation when estradiol levels peak, and lowest at estrus, when sperm enter the uterus in preparation for fertilization. Further, these studies demonstrate that estradiol given to ovariectomized rats increases uterine cell Ag presentation relative to that in controls. In the presence of mouse anti-rat Ia Ab, Ag presentation was blocked, indicating that Ag presentation by uterine cells is MHC class II restricted. In studies to analyze Ag presentation at sites distal to the female reproductive tract, we found that Ag presentation by adherent cells from the spleen is elevated at proestrus relative to that at other stages of the estrous cycle. When IL-6 was placed in the uterine lumen of ovariectomized rats, Ag presentation by epithelial and mixed stromal cells as well as mitogenesis by spleen cells were increased significantly relative to those in controls. These studies demonstrate that the female reproductive tract is an inductive site for immune responses and that mucosal immune protection may be either enhanced or suppressed depending on the endocrine balance when the female reproductive tract is exposed to pathogens.
Suppressor T cell-activating macrophages in ultraviolet-irradiated human skin induce a novel, TGF-beta-dependent form of T cell activation characterized by deficient IL-2r alpha expression.
Authors: Stevens S R , Shibaki A , Meunier L , Cooper K D
Published: December 2022

Because UV-induced epidermal macrophages (UV-Mph) preferentially activate CD4+ T suppressor-inducer cells and induce tolerance, we hypothesized that they differentially up-regulate T cell early activation genes compared with constitutive epidermal APC, Langerhans cells. We used epidermal cells from UV-exposed (UV-EC) and control (C-EC) human skin to stimulate allogeneic CD4+ T lymphocytes. Reverse transcriptase-PCR revealed that both C-EC (Langerhans cells) and UV-EC (UV-Mph) induced 10(3)- to 10(6)-fold increases in IL-2 mRNA. However, while T cells stimulated by C-EC for 48 h showed a greater than 10(3)-fold increase in IL-2R alpha mRNA, those stimulated by UV-EC did not (n = 5, p = 0.004). Flow cytometry demonstrated that 4.1 +/- 2.3% of unstimulated CD4+ lymphocytes expressed cell surface IL-2R alpha, which increased to 15.7 +/- 1.8% upon stimulation by C-EC for 48 h, but stimulation by UV-EC failed to increase the IL-2R alpha+ population (n = 3, p = 0.038). The addition of neutralizing anti-TGF-beta Abs to UV-EC-stimulated cultures restored CD4+ cell surface IL-2R alpha expression to 12.9 +/- 0.2%. CD4+ T cell activation by UV-Mph is distinct from previously described models of tolerance such as Th2 activation (IFN-gamma mRNA was induced and IL-4 mRNA was not) and Th1 anergy (IL-2 mRNA levels induced by UV-EC and C-EC were similar). Furthermore, costimulatory signals were provided by UV-Mph; CTLA4-Ig and LFA-3-Ig fusion proteins and Abs to CD2, LFA-3, LFA-1, and ICAM-1 inhibited UV-Mph-induced T cell proliferation. Thus, the altered immune outcome induced by UV-Mph (tolerization) compared with Langerhans cells (sensitization) is reflected as a novel mechanism of initial CD4+ T cell early activation gene expression characterized by TGF-beta-dependent deficient IL-2R alpha expression.
Durable elimination of high affinity, T cell-dependent antibodies by low molecular weight antigen arrays in vivo.
Authors: Symer D E , Reim J , Dintzis R Z , Voss E W , Dintzis H M
Published: December 2022

Ongoing Ab responses to a T cell-dependent Ag can be suppressed in hyperimmune animals by exogenous, multivalent Ag arrays. The pharmacologic basis for this suppression was studied by varying the molecular mass, ligand valence, and dose of Ag arrays, and then determining their efficacy, pharmacokinetics, and tissue distribution. Arrays ranging in molecular mass from 30 to 500 kDa caused initial clearance of specific serum Abs, but only the smaller arrays caused persistent suppression despite their relatively lower binding avidity and shorter retention in vivo. Suppression by the smaller arrays at lower doses was biphasic, implying two distinct modes of Ab elimination. High affinity IgG was eliminated preferentially, as shown by calibrated variable ligand-density ELISA. Suppressive arrays were localized discretely in the splenic germinal centers of hyperimmune animals. These results indicate that Ag array mass, ligand valence, and dose all play critical roles, and histologic compartmentalization may also be a pertinent parameter, in determining suppressive efficacy in vivo.
Induction of germ-line gamma 1 and epsilon Ig gene expression in murine B cells. IL-4 and the CD40 ligand-CD40 interaction provide distinct but synergistic signals.
Authors: Warren W D , Berton M T
Published: December 2022

The interaction between B cell CD40 and its ligand (CD40L) on activated Th cells provides a critical signal necessary for T cell-dependent isotype switching. Previous studies suggest that this signal might be important in regulating isotype switching at the level of germ-line Ig transcription. To assess the effects of the CD40L-CD40 interaction on germ-line Ig transcript expression in murine B cells, a membrane-bound form of mouse CD40L was expressed in the baculovirus system. We show that stimulation of resting splenic B cells with CD40L-expressing Sf9 cells induces germ-line gamma 1 and epsilon transcripts independently of cytokines. The CD40-mediated induction cannot be blocked by anti-IL-4 Ab and is not mediated by other cytokines secreted endogenously in response to CD40 stimulation. Importantly, stimulation with CD40L and IL-4 together has a significant synergistic effect on germ-line transcript expression. Stimulation of CD40 does not activate the NF-IL-4-gamma 1 DNA binding factor believed to be required for IL-4-dependent germ-line gamma 1 transcription. Moreover, mutation of the NF-IL-4-gamma 1 DNA binding site in a germ-line gamma 1 promoter-luciferase reporter gene construct completely ablates IL-4 responsiveness but has no effect on responsiveness to CD40L in transient transfection assays. These results demonstrate that the CD40L-CD40 interaction and IL-4 activate germ-line Ig gene transcription by distinct but synergistic mechanisms and suggest that multiple signals may be required to induce sufficient germ-line transcription and/or germ-line transcript levels necessary to target switch recombination.
Naturally processed peptides from rheumatoid arthritis associated and non-associated HLA-DR alleles.
Authors: Kirschmann D A , Duffin K L , Smith C E , Welply J K , Howard S C , Schwartz B D , Woulfe S L
Published: December 2022

Naturally processed peptides from immunoaffinity-purified HLA-DRB1*0401, -DRB1*0404 (rheumatoid arthritis (RA)-associated), and -DRB1*0402 (non-RA-associated) molecules were analyzed by capillary liquid chromatography and mass spectrometry. The molecular weights observed for more than 60 eluted peptides from each HLA-DR protein ranged from 788 to 3535 atomic mass units, corresponding to peptides 7 to 32 amino acids in length. Sequencing of more than 60 of the abundant peptides revealed nested sets of peptides that were derived from only 12 different proteins. The majority of these proteins were membrane-associated (HLA class I, class II, and Ig molecules). Synthetic peptides, corresponding to endogenous peptide sequences, bound with high affinity (5 to 80 nM) to the HLA-DR molecules from which they were eluted. In addition, most were promiscuous binding peptides in that they also bound to other HLA-DR molecules. Truncations of eluted peptide sequences and alanine scanning mutational analysis of a Mycobacterium leprae peptide were used to identify the peptide residues involved in binding to DRB1*0404 and DRB1*0402 molecules. Furthermore, an invariant chain peptide was eluted from the DRB1*0402 molecules but not from the RA-associated molecules. The lack of invariant chain peptides from DRB1*0401 and DRB1*0404 molecules may contribute to the loading of autoantigen peptides into these molecules and to their association with disease.
Targeted removal of the mu switch region from mouse hybridoma cells. A test of its role in gene expression in the endogenous IgH locus.
Authors: Oancea A E , Tsui F W , Shulman M J
Published: December 2022

The switch regions adjoining the DNA encoding the Ig heavy chain constant regions have been implicated in gene expression as well as isotype switching, in that transgenic mice express switch-containing transgenes at a level 100- to 1000-fold higher than the corresponding switch-deleted transgenes. To test whether the switch region of the natural IgH locus is also required for high level expression we have used homologous recombination to generate targeted recombinant hybridoma cell lines that lack the switch region sequences from the major intron of the mu gene. The expression pattern of these switch knock-out cell lines was compared with that of the parental cell line as well as to that of control recombinants using both steady-state mRNA level and nuclear run-on activity to assess heavy chain gene expression. In striking contrast with the results reported for transgenic animals, we have found only a minimal effect, if any, of deleting the switch element from the natural chromosomal location.
Endogenous IL-2 contributes to T cell expansion and IFN-gamma production during lymphocytic choriomeningitis virus infection.
Authors: Cousens L P , Orange J S , Biron C A
Published: December 2022

IL-2-deficient mice were used to examine the role of endogenous IL-2 for supporting T cell proliferative responses during infection with lymphocytic choriomeningitis virus (LCMV). The studies showed that, although virus-specific CTL activity was induced in the absence of IL-2, the overall magnitude of the response was profoundly inhibited. Examination of proportions and numbers of CD8+ T cells demonstrated that the normal virus-induced expansion of these cells was virtually eliminated in spleens and dramatically decreased in lymph nodes from IL-2-negative mice. Absence of endogenous IL-2 also significantly inhibited virus-induced activated T cell production of IFN-gamma, as well as increases in frequencies and numbers of IFN-gamma-producing cells. Reductions in immune responses were accompanied by impaired viral clearance. Although T cell responses were dramatically reduced in IL-2-deficient, as compared with IL-2-containing mice, activation signals were being delivered in vivo because induced CTLs were sensitive to the cell cycle-specific toxin, hydroxyurea (HU), and CD8+ T cells had induced expression of the IL-2R alpha- and beta-chains. These studies demonstrated that, although low levels of T cell responses can be induced in the absence of IL-2, the factor plays a unique and critical role in supporting T cell proliferative responses in vivo and in optimizing induction of the biologic functions mediated by these cells. Furthermore, the results identify a role for IL-2 in promoting IFN-gamma production in vivo.
Protective immunity induced by B7/CD28-costimulated gamma delta T cells to the EL-4 lymphoma in allogenic athymic mice.
Authors: Li Y , Newby S A , Johnston J V , Hellström K E , Chen L
Published: December 2022

We previously reported that the murine EL-4 lymphoma (H-2b) transduced with a retrovirus containing the murine B7-1 gene (B7+ EL-4) grew transiently for several weeks and subsequently regressed in allogenic BALB/c (nu/nu) athymic mice (H-2d). We now show that, in contrast, B7+ EL-4 cells grow progressively in several combined immunodeficiency mice, including SCID and NIH III mice, which lack T cells expressing either TCR-alpha beta or -gamma delta. Furthermore, depletion of gamma delta T cells with a specific mAb made possible the progressive growth of B7+ EL-4 cells in 90% of athymic mice while depletion of alpha beta T cells allowed tumor growth in 50% of these mice. Immunization of athymic mice with B7+ EL-4 cells prevented the outgrowth of wild-type B7- EL-4 cells. This protective immunity was abrogated by in vivo treatment with an anti-TCR-gamma delta mAb, further indicating that gamma delta T cells play an important role in tumor rejection by athymic mice. A gamma delta T cell line, Tc1, was established from B7+ EL-4-immunized athymic mice by repeated restimulation in vitro with irradiated B7+ EL-4 cells. When tested against a broad spectrum of target cells, Tc1 lysed several murine lymphoma lines, but did not lyse other tumor lines, suggesting that the Ag recognized by Tc1 has a limited distribution. Our data demonstrate that gamma delta T cells, and, to a less extent, extrathymic alpha beta T cells, mediate an immune response against B7+ EL-4 cells in allogeneic athymic mice.
Inhibition of vaccinia virus DNA replication by inducible expression of nitric oxide synthase.
Authors: Mĕlková Z , Esteban M
Published: December 2022

Nitric oxide (NO) exerts multiple biologic roles in animal cells through differential regulation of three distinct forms of NO synthase encoded by separate genes. Macrophage-inducible nitric oxide synthase (iNOS) has been correlated with inhibition of viral growth, but little is known about the mechanism of this effect. To study the antiviral role of NO, we have generated a vaccinia virus (VV) recombinant expressing iNOS under the control of Escherichia coli LacI operator/repressor elements. When cultured cells of various origins are infected with this recombinant virus, there is inducible expression of iNOS in the presence of isopropylthio-beta-galactoside, as determined by Western blot and by detection of nitrite, a NO oxidation product. The levels of nitrite increase with time after infection, correlating with marked inhibition of VV DNA and late protein synthesis. Expression of VV early proteins is not affected by NO. Inhibition of VV DNA synthesis is likely to be in part a consequence of NO-mediated inhibition of viral ribonucleotide reductase, as this inhibition can be partially overcome by addition of deoxyribonucleosides. Inhibition of the essential viral functions by NO results in a reduction of virus yields by 50 to 90%, depending on the cell line. Thus, our results demonstrate a direct antiviral effect of NO, with inhibition of VV replication occurring at the level of DNA synthesis.
Clearance pathways of soluble immune complexes in the pig. Insights into the adaptive nature of antigen clearance in humans.
Authors: Davies K A , Chapman P T , Norsworthy P J , Jamar F , Athanassiou P , Keelan E T , Harrison A A , Binns R M , Haskard D O , Walport M J
Published: December 2022

Efficient delivery of immune complexes (ICs) to the mononuclear phagocytic system, and subsequent IC processing, may prevent their potentially harmful effects in other tissues and may also be important in the development of humoral immune responses. In mice, rabbits, and primates, the liver and spleen are the main sites of IC clearance. It has been demonstrated previously that the pulmonary capillaries in the pig are lined with macrophages and that certain particulates, including bacteria, localize to this organ. In this study, we used gamma scintigraphy to explore the sites and kinetics of clearance of soluble IC comprising 123I-labeled hepatitis B surface Ag (HBsAg):porcine anti-HBsAg in the Large White pig. At t = 10 min after i.v. injection, 43 +/- 5% (mean +/- SE) IC localized in the lungs, and 36 +/- 6% counts in the liver. At t = 85 min, values were: lungs, 15 +/- 4% and liver, 29 +/- 2%. Findings were similar following intraarterial injection. Complement depletion resulted in more rapid initial IC clearance (t1/2 = 5 min), reduced lung uptake (23 +/- 3% at 10 min), and impaired IC catabolism. In normal animals, 5 to 7% injected IC bound to PBMCs, but no E binding was seen. A fall in PBMC numbers (46 to 59% of baseline), was observed following IC injection. These findings contrast with our previous observations using analogous IC in humans, in which we did not observe any change in peripheral blood leukocyte counts consequent upon complex processing, suggesting that in humans, Es may function as a buffering system for complement-bearing IC in the circulation, preventing their interaction with leukocytes bearing complement and FcR, and the potential activation of these cells.
Collagen-like complement component C1q is a membrane protein of human monocyte-derived macrophages that mediates endocytosis.
Authors: Kaul M , Loos M
Published: December 2022

The collagen-like C1q molecule, a subcomponent of the first component of complement, C1, is synthesized by macrophages (M phi). Previously, we have demonstrated that C1q is a membrane protein of guinea pig peritoneal macrophages (M phi). To extend this observation as a general biologic characteristic of M phi, we investigated human (hu) monocyte-derived M phi. Interestingly, surface labeling with the biotin derivative sulfosuccinimidyl-6-(biotinamido)-hexanoate of M phi, freshly isolated monocytes, lymphocytes, granulocytes, and myelomonocytic U937 cells revealed that C1q occurs only on the surface of M phi and not on the surface of the other cells types. Therefore, C1q appears to be a marker for differentiation into M phi. FITC-labeled, fixed Staphylococcus aureus coupled to membrane C1q via a monoclonal alpha-hu-C1q Ab were used to demonstrate that membrane C1q is capable of mediating phagocytosis. Various detergents (Nonidet P-40, digitonin, lubrol, and Triton X-114) were used to solubilize membrane C1q. Membrane C1q of hu M phi is tightly bound to or located in the intact membrane, since treatment of cells with acidic buffers ("acid strip") failed to remove C1q from the cell surface. However, repeated freezing and thawing of cells and washing of segregated membranes with buffer containing 1 M KCl and 3 M urea brought about a marked release of membrane C1q.
Insertional mutagenesis affecting programmed cell death leads to thymic hyperplasia and altered thymopoiesis.
Authors: Volkmann A , Döffinger R , Rüther U , Kyewski B A
Published: December 2022

The mouse mutant Ft displays thymic hyperplasia and fused toes (Ft) of the forelimbs. Both phenotypic abnormalities are caused by transgene insertion in the D region of chromosome 8. While the forelimb defect is probably caused by developmentally dysregulated programmed cell death, the mechanism underlying thymic hyperplasia has not been characterized. In this work, we show that expansion of the thymocyte compartment progresses with time, is polyclonal, and affects all major thymocyte subsets, including the earliest CD4-8- subset, i.e., CD44+ CD25- cells; hyperplasia is not an autonomous property of mutant T cells, but is caused indirectly by a primary defect in thymic stromal. The rate of cell division and the cell turnover of immature CD4-8- and CD4+8+ thymocytes under steady state conditions are not altered in hyperplastic Ft thymi. Immature CD4+8+ thymocytes of mutant mice, however, are less susceptible to induction in vitro of programmed cell death by different modes (TCR cross-linking, cortisone, or radiation). Increased production of thymocytes results in increased export of T cells, yet the size and composition of the peripheral T cell pool are normal. Overproduction of immature CD4+8+ thymocytes is offset partly by a reduced conversion rate of CD4+8+ double positive to single positive thymocyte growth control by epithelial cells, and may serve as a model to study the regulation of early thymopoiesis.
Stimulus specificity of matrix metalloproteinase dependence of human T cell migration through a model basement membrane.
Authors: Xia M , Leppert D , Hauser S L , Sreedharan S P , Nelson P J , Krensky A M , Goetzl E J
Published: December 2022

Chemotaxis of human T lymphoblastoma cells of the Tsup-1 line, which migrate similarly to blood T cells, through a layer of basement membrane-like Matrigel on a polycarbonate micropore filter was evoked by vasoactive intestinal peptide (VIP; concentration for a maximal response, 10(-7)M), IL-2 (10(-9)M), and the chemokines RANTES (10(-10)M) and macrophage inflammatory protein-1 alpha (10(-10)M). Chemotactic concentrations of each factor increased Tsup-1 cell secretion of matrix metalloproteinase-9 (MMP-9), with significant responses by 4 h for VIP, IL-2, and IL-4, but only after 24 h for macrophage inflammatory protein-1 alpha and RANTES, as quantified by Western blots and zymography. 3H-Labeled type IV human collagen incorporated in the Matrigel layer was degraded by migrating Tsup-1 cells, as assessed by release of radioactive fragments of the collagen. The in situ degradation of type IV collagen in Matrigel by migrating Tsup-1 cells was enhanced most significantly by VIP, IL-2, and IL-4 after 4 h at concentrations that increased the secretion of MMP-9 optimally, but only after 24 h by macrophage inflammatory protein-1 alpha and RANTES. The specific MMP inhibitor GM6001 suppressed Tsup-1 cell MMP activity evoked by all stimuli, as determined by zymography and in situ degradation of 3H-Labeled type IV human collagen. The chemotactic migration of Tsup-1 cells through Matrigel, but not through a filter alone, in response to optimal concentrations of VIP, IL-2, and IL-4, but not the chemokines, was inhibited by GM6001, with a concentration dependence similar to that for suppression of MMP activity. Thus elicitation of T cell chemotactic migration through a model basement membrane by stimuli that increase MMP activity early in the response depends on degradation of matrix proteins by MMP, whereas stimuli that recruit MMP late may rely on early activation of other proteases.
Amino acid residues on the I-Ak alpha-chain required for the binding and stability of two antigenic peptides.
Authors: Nelson C A , Viner N , Young S , Petzold S , Benoist C , Mathis D , Unanue E R
Published: December 2022

The class II molecules of the MHC bind processed Ag fragments (peptides) for presentation to T cells, but the role of individual MHC residues in binding these peptides has not been entirely defined. A panel of 27 mutant I-Ak transfectants was analyzed for the capacity to bind 2 unrelated peptides. The main peptides examined were hen egg lysozyme residues 48-62 and heat shock protein (hsp70) to residues 28-41. Alanine substitutions of sites in the alpha-helical region of the I-Ak alpha-chain altered the ability of this class II protein to bind both peptides. Of the 27 substitutions tested, nine caused a decrease in peptide binding while only three caused an increase in peptide binding. The stabilities of these altered I-Ak-peptide complexes were also examined on SDS-Page. Complexes with lowered stabilities were observed after only four substitutions, and in all four cases this loss of stability was accompanied by a loss in hen egg lysozyme or hsp70 peptide-binding ability. Further, three of these residues lie in the short extended strand at the N terminus of the alpha-helix of the alpha 1 domain, suggesting that this region of I-Ak molecule may be critical for the formation of stable peptide-MHC complexes.
Cytokine enhancement of DNA immunization leads to effective treatment of established pulmonary metastases.
Authors: Irvine K R , Rao J B , Rosenberg S A , Restifo N P
Published: December 2022

DNA immunization can result in the induction of Ag-specific cellular and humoral immune responses and in protective immunity in several Ag systems. To evaluate the utility of DNA-based immunization as a potential cancer treatment strategy, we employed an experimental murine tumor, CT26, expressing the model tumor-associated Ag, beta-galactosidase (beta-gal), designated CT26.CL25. A plasmid expressing beta-gal (pCMV/beta-gal) administered by particle-mediated gene delivery to the epidermis using a hand-held, helium-driven "gene gun" induced beta-gal-specific Ab and lytic responses. Immunization with this construct prevented the growth of pulmonary metastatic tumor, and the adoptive transfer of splenocytes generated by pCMV/beta-gal in vivo immunization and cultured in vitro with the beta-gal876-884 immunodominant peptide reduced the number of established pulmonary nodules. DNA immunization alone had little or no impact on the growth of established lung metastases. To enhance the function of DNA immunization for active immunotherapy, a panel of cytokines was added as adjuvants following DNA administration. Significant reduction in the number of established metastases was observed when human rIL-2, mouse rIL-6, human rIL-7, or mouse rIL-12 were given after DNA inoculation; mouse rIL-12 as an adjuvant had the most profound effect. These findings suggest that the cytokines involved in the activation and expansion of lymphocyte populations may improve the therapeutic effects of DNA immunization. Given the ease with which plasmid DNA can be prepared to high purity for safe use in humans with infectious diseases and cancers, DNA immunization administered together with cytokine adjuvant may be an attractive alternative to recombinant viral vaccines.
Involvement of bradykinin B1 receptors in the polymorphonuclear leukocyte accumulation induced by IL-1 beta in vivo in the mouse.
Authors: Ahluwalia A , Perretti M
Published: December 2022

Local application of the bradykinin B1 receptor antagonist desArg9[Leu8]BK, but not the B2 receptor antagonist Hoe 140, attenuated by approximately 50% the polymorphonuclear leukocyte accumulation into 6-day-old air pouches observed in response to application of murine IL-1 beta (5 ng). The selective appearance of a chemotactic response to the bradykinin B1 receptor agonist desArg9BK only in air pouches pretreated (4 h) with IL-1 beta indicated the involvement of this receptor type during this acute inflammation model. The pro-migratory action of desArg9BK was magnified when the effect of IL-1 on polymorphonuclear leukocyte accumulation had subsided (i.e., 24 h post-IL-1). desArg9[Leu8]BK, but not Hoe 140, antagonized the effect of desArg9BK, indicating an action on B1 receptors, but not B2 receptors. The cellular infiltration observed following application of desArg9BK in IL-1-sensitized air pouches was due to the release of neuropeptides from C fibers, as indicated by the inhibitory action of the substance P antagonist, RP 67,580, and the calcitonin-gene related peptide antagonist, CGRP-(8-37). In conclusion, this study provides evidence that activation of C fibers, which is necessary for the achievement of a full chemotactic action of IL-1, is due to up-regulation (or induction) of bradykinin B1 receptors and describes, for the first time, a relationship between these receptors and polymorphonuclear leukocyte recruitment.
Analysis of bovine gamma delta T cell interactions with E-, P-, and L-selectin. Characterization of lymphocyte on lymphocyte rolling and the effects of O-glycoprotease.
Authors: Jutila M A , Kurk S
Published: December 2022

In earlier studies, we found that bovine gamma delta T cells avidly bind and roll under physiologic flow on E- and P-selection. In this study, we have extended our analyses of shear interactions of gamma delta T cells and have found that once gamma delta T cells permanently bind to endothelial cell monolayers they can support continued rolling of newly arriving gamma delta T cells. Anti-L-selection Abs blocked gamma delta T cell rolling on immobilized gamma delta T cells, and it was L-selection on the rolling cell, not the bound cell, that mediated the interaction. We propose, as we have for neutrophils, that lymphocyte/lymphocyte rolling represents a mechanism for amplification of the extravasation process. Having defined P-, E-, and L-selectin interactions with gamma delta T cells, we tested the susceptibility of the ligands for these selectins to treatment with O-glycoprotease, a compound that selectively cleaves mucin-like selectin ligands. O-glycoprotease treatment of gamma delta T cells blocked their interaction with P-selectin, but not E-selectin. Rolling of O-glycoprotease-treated cells on bound untreated gamma delta T cells was unaffected; however, O-glycoprotease treatment of the bound gamma delta T cells blocked their capacity to support rolling interactions. These results define a new lymphocyte/selectin interaction that may be important in amplifying lymphocyte extravasation and suggest that gamma delta T cell ligands for P- and E-selectin are distinct, whereas ligands for P- and L-selectin may be similar.