bluuebunny/crossref_metadata_2025 huggingface dataset:
A CD8 genomic fragment that directs subset-specific expression of CD8 in transgenic mice.
Authors: Hostert A , Tolaini M , Festenstein R , McNeill L , Malissen B , Williams O , Zamoyska R , Kioussis D
Published: December 2022

Helper and cytotoxic T cell subsets require the expression of different coreceptors (CD4 and CD8, respectively) for their development and function. We have cloned the CD8 gene locus from genomic cosmid and P1 libraries and analyzed the region around the CD8alpha and CD8beta genes for gene expression regulatory elements. DNase I (DNase I) hypersensitivity analysis of 80 kb in the CD8 locus identified four clusters of putative regulatory regions, three of which are thymocyte specific. Transgenic mice carrying the cloned CD8alphabeta genomic locus and containing the identified DNase I-hypersensitive site clusters express the transgenic CD8 in a developmentally regulated, tissue-specific, and CD8 T cell subset-specific manner.
Differential recruitment of leukocyte populations and alteration of airway hyperreactivity by C-C family chemokines in allergic airway inflammation.
Authors: Lukacs N W , Strieter R M , Warmington K , Lincoln P , Chensue S W , Kunkel S L
Published: December 2022

Allergic airway inflammation is characterized by peribronchial leukocyte accumulation within the airway. Subsequent tissue damage leading to airway hyperreactivity is a result of activation of multiple leukocyte populations. Using an established model of allergic airway inflammation induced by intratracheal challenge with parasite (Schistosoma mansoni) egg Ag in presensitized mice, we have examined differential leukocyte recruitment. These studies have identified key chemokines involved in the accumulation of specific subsets of cells and the induction of airway hyperreactivity. In this study we have examined three C-C family chemokines, MCP-1, MIP-1alpha, and RANTES, which promote mononuclear cell- and eosinophil-specific recruitment to the airway. The in vivo neutralization of either MIP-1alpha or RANTES, but not MCP-1, significantly reduced the intensity of the eosinophil recruitment to the lung and airway during the allergic airway response by >50 and >60%, respectively. In contrast, neutralization of MCP-1 significantly reduced total leukocyte migration (>50% reduction), whereas neutralization of RANTES and MIP-1alpha had no significant affect on the overall leukocyte migration. Further examination of the effect of MCP-1 depletion indicated that both CD4+ and CD8+ lymphocyte subsets were decreased. Depletion of MCP-1 significantly reduced the airway hyperreactivity to near control levels, whereas depletion of MIP-1alpha or RANTES did not affect the intensity of airway hyperreactivity. These data indicate that multiple C-C chemokines are involved in the recruitment of particular leukocyte populations and that neutralization of MCP-1, but not RANTES or MIP-1alpha, significantly reduced airway hyperreactivity.
Expression and regulation of the neural cell adhesion molecule L1 on human cells of myelomonocytic and lymphoid origin.
Authors: Pancook J D , Reisfeld R A , Varki N , Vitiello A , Fox R I , Montgomery A M
Published: December 2022

The neural cell adhesion molecule L1 has been implicated in a variety of neurologic processes, including neuritogenesis and cerebellar cell migration. Here we propose an expanded role for this cell adhesion molecule in the human immune system based on its expression on cells of myelomonocytic and lymphoid origin. Freshly isolated circulating monocytes had minimal L1 expression; however, activation of these effector cells by IFN-gamma, or as a result of density gradient isolation, resulted in a significant induction of L1 expression. Constitutive L1 expression was further evident on myelomonocytic cell lines but was absent on mature tissue macrophages. In further studies, positive selection with a L1-specific Ab enriched both B cells and dendritic precursor cells from peripheral blood. Significantly, L1 expression was not detected on mature dendritic cells but could be induced by treatment with LPS, PHA, and TNF-alpha. Immunohistochemical analysis further demonstrated significant L1 expression on follicular dendritic cells and on endothelial cells associated with the arterioles and red pulp of normal spleen. Based on these observations and known functions of L1, we propose that this cell adhesion molecule may contribute to cell-cell adhesion events associated with the effector function or extravasation of these immune effector cells. In support of the latter, we present evidence that L1 can be recognized by endothelial cells via the integrin alpha(v)beta3.
CD14-dependent and CD14-independent signaling pathways in murine macrophages from normal and CD14 knockout mice stimulated with lipopolysaccharide or taxol.
Authors: Perera P Y , Vogel S N , Detore G R , Haziot A , Goyert S M
Published: December 2022

The antitumor agent, Taxol, shares with bacterial LPS the ability to activate murine macrophages, and its LPS-mimetic effects are blocked by LPS analogue antagonists. Since CD14 is central to the recognition of LPS by macrophages, we sought to examine a role for CD14 in the response to Taxol vs LPS. A comparison of responses of macrophages from wild-type mice with those from mice lacking CD14 due to a targeted disruption of the CD14 gene (CD14-deficient knockout (CD14KO)) revealed that like LPS, Taxol induces both CD14-dependent and -independent pathways of gene activation, although the CD14 dependency of Taxol stimulation is much less striking than that observed with LPS. The macrophage interaction with low concentrations of LPS (< or = 10 ng/ml) is largely CD14 dependent, as evidenced by the lack of induction of TNF-alpha, IL-1beta, and interferon-inducible protein-10 (IP-10) genes by CD14KO macrophages cultured in the absence of soluble CD14 (i.e., in autologous CD14KO -/- mouse serum). However, at high concentrations of LPS or Taxol, a CD14-independent pathway of activation is observed: this pathway leads to minimal IP-10 gene induction, even though induction of TNF-alpha and IL-1beta occurs. Measurements of TNF secretion followed a similar pattern to that observed at the level of steady state mRNA. These data suggest the existence of two pathways of activation by both LPS and Taxol: one that is CD14 dependent and leads to induction of TNF-alpha, IL-1beta, and IP-10 gene induction, and a CD14-independent pathway that results in the induction of TNF-alpha and IL-1beta, with minimal induction of IP-10.
Effects of sleep and circadian rhythm on human circulating immune cells.
Authors: Born J , Lange T , Hansen K , Mölle M , Fehm H L
Published: December 2022

The role of nocturnal sleep for normal immune regulation and its relation to circadian rhythm was examined in 10 men participating in two 51-h sessions. One session included two regular wake-sleep cycles; the other included a night of sustained wakefulness followed by a night of recovery sleep. Blood was collected every 3 h to determine PBMC counts, including the enumeration of monocytes, NK cells, and lymphocyte subsets (CD19+, CD3+, CD4+, CD8+, HLA-DR+). Production of IL-1beta, TNF-alpha, IL-2, and IFN-gamma was determined after stimulation of whole blood samples with LPS and PHA, respectively. Concentrations of IL-6 and cortisol were assessed in plasma. Enumeration of cells indicated significant circadian rhythms for all PBMC subsets under conditions of sustained wakefulness. Compared with sustained wakefulness, nocturnal sleep acutely reduced the numbers of monocytes, NK cells, and counts of all lymphocyte subsets. However, in the afternoon and evening of the day following sleep, counts of NK cells and lymphocytes were significantly higher than after nocturnal wakefulness, indicating that effects of sleep interacted with those of the circadian pacemaker. Sleep markedly enhanced production of IL-2 by T cells (CD3+) but did not influence production of IL-1beta and TNF-alpha, or IL-6 concentrations. Effects of sleep were not mediated by changes in cortisol. The decrease in monocytes, NK cells, and lymphocytes, together with an increased production of IL-2 during sleep, may serve to support ongoing immune defense in extravascular lymphoid tissue during a time of diminished acute Ag challenge.
C-C chemokines, IL-16, and soluble antiviral factor activity are increased in cloned T cells from subjects with long-term nonprogressive HIV infection.
Authors: Scala E , D'Offizi G , Rosso R , Turriziani O , Ferrara R , Mazzone A M , Antonelli G , Aiuti F , Paganelli R
Published: December 2022

A combination of three beta, or C-C, chemokines, as well as IL-16, have been shown to inhibit HIV replication in vitro. Cellular antiviral factor is a more potent agent, and acts on all HIV strains. All are mainly, but not exclusively, produced by CD8+ T cells, both in HIV+ and healthy subjects. We studied the production of these HIV-suppressive factors in patients with HIV infection at different stages of disease. No difference in production by PBMC stimulated with PHA has been observed in asymptomatic HIV+, long-term nonprogressors (LTnP), and AIDS patients. When T cell line supernatants from these three groups were studied, no significant difference was found for C-C chemokines or IL-16 production, and viral suppression. However, T cell clones from LTnP secreted higher levels of all three chemokines, IL-16, and exerted a stronger inhibition on HIV replication. CD8+ clones showed a higher production than CD4+ clones. These clones were able to produce all antiviral factors irrespective of the secretion of type 1 or type 2 cytokines. The antiviral activities were not correlated, implying that viral suppression did not depend solely on C-C chemokines or IL-16. We postulate that all factors are needed to prevent HIV disease progression.
xid affects events leading to B cell cycle entry.
Authors: Brorson K , Brunswick M , Ezhevsky S , Wei D G , Berg R , Scott D , Stein K E
Published: December 2022

X-linked agammaglobulinemia patients and X-linked immunodeficient (xid) mice possess mutations in the Bruton's tyrosine kinase (Btk kinase) gene and display defects in B cell development and activation by sIg cross-linking. Btk is an early activation kinase in sIg-cross-linked B cells. xid does not ablate Btk protein kinase activity, and immediate signal transduction events, such as tyrosine phosphorylation, occur in sIg-activated xid B cells. These cells do not subsequently progress into cell division and have a high rate of apoptosis, which has been shown to correlate with an absence of sIg-mediated induction of the bcl-xL protein. To establish the point where Btk activity is critical for progression beyond immediate signaling, we examined early and late events in sIg-cross-linked xid B cells. Induction of proto-oncogenes and nuclear factors occurred normally in xid cells. However, induction of cyclins and increased GAPDH mRNA was not observed in xid cells. Degradation of the cyclin inhibitor p27Kip1 occurred normally in xid cells. After 24 h of culture with anti-mu, the remaining live, nonapoptotic xid cells were enlarged, viable, and primed for subsequent stimulation by LPS. Our data suggest that the Btk kinase is not essential for several G1 events and that the failure of sIg-activated xid B cells to enter cell cycle correlates with a defect of cyclin induction. Moreover, these data suggest that Btk is important not only for immediate events following B cell activation and control of apoptosis but also for subsequent events leading to cyclin activation.
CD38 ligation in human B cell progenitors triggers tyrosine phosphorylation of CD19 and association of CD19 with lyn and phosphatidylinositol 3-kinase.
Authors: Kitanaka A , Ito C , Coustan-Smith E , Campana D
Published: December 2022

CD38 is a 45-kDa transmembrane glycoprotein highly expressed in lymphoid progenitors. Ligation of CD38 with specific Abs inhibits growth and induces apoptosis in human immature B cells. CD38 ligation also triggers tyrosine phosphorylation of syk, c-cbl, and phospholipase C-gamma and activates phosphatidylinositol 3-kinase (PI3-K). In the present study, we investigated whether the cell surface membrane molecules used in B cell receptor-mediated signaling, such as Ig alpha, Ig beta, and CD19, could be involved in the CD38-mediated signaling cascade. In the B cell receptor-negative immature B cell lines RS4;11, 380, and REH, Ig alpha and Ig beta were expressed exclusively in the cytoplasm and were not tyrosine phosphorylated after CD38 ligation. By contrast, CD19 was markedly tyrosine phosphorylated and was associated with lyn and PI3-K. PI3-K activation appears to be directly linked to the growth-arresting effects of CD38 ligation, which are reduced by PI3-K inhibitors. Ligation of either CD38 or CD19 resulted in a similar pattern of protein tyrosine phosphorylation; both signaling pathways caused tyrosine phosphorylation of c-cbl. Levels of CD38 surface expression were not affected by prolonged incubation with anti-CD19 Ab, while CD19 expression markedly decreased. These results indicate that CD19 is a major component of the CD38 signaling cascade in B cell precursors, serving as a cell surface membrane docking site for cytoplasmic kinases. CD38 and CD19 are not physically linked, but activate an overlapping set of kinases in human immature B cells.
The immunosuppressive metabolite of leflunomide, A77 1726, affects murine T cells through two biochemical mechanisms.
Authors: Elder R T , Xu X , Williams J W , Gong H , Finnegan A , Chong A S
Published: December 2022

The immunosuppressive metabolite of leflunomide, A77 1726, inhibits the enzymatic activity of protein tyrosine kinases and of dihydro-orotic acid dehydrogenase, an enzyme involved in pyrimidine biosynthesis. Here murine CTLL cell lines were studied to determine which of the biochemical targets of A77 1726 was responsible for the observed inhibition of proliferation and cytotoxic activity. At low concentrations of A77 1726, pyrimidine biosynthesis is the target, since inhibition of proliferation correlates with a reduction in pyrimidine NTP levels and is reversed by uridine. At higher concentrations of A77 1726, uridine no longer reverses the inhibition of proliferation even though pyrimidine NTP levels are restored. This second mechanism for inhibiting proliferation is probably inhibition of protein tyrosine kinases, since these higher concentrations of A77 1726 inhibit IL-2-induced tyrosine phosphorylation of Jak1 and Jak3, the protein tyrosine kinases initiating signaling by the IL-2R. Tyrosine phosphorylation of the beta-chain of the IL-2R, which is required for IL-2-driven proliferation, is also inhibited by A77 1726. Cytotoxicity of a CTLL line that overexpresses the Lck protein tyrosine kinase is inhibited by A77 1726; this inhibition is not affected by uridine, but does correlate with inhibition of an Lck in vitro kinase reaction. These studies establish that inhibition of pyrimidine biosynthesis and that of protein tyrosine kinase both contribute to the effects of A77 1726 on CTLL cell lines.
Human alveolar T lymphocyte responses to Mycobacterium tuberculosis antigens: role for CD4+ and CD8+ cytotoxic T cells and relative resistance of alveolar macrophages to lysis.
Authors: Tan J S , Canaday D H , Boom W H , Balaji K N , Schwander S K , Rich E A
Published: December 2022

T cell-mediated cytotoxicity against Mycobacterium tuberculosis (MTB)-infected macrophages may be a major mechanism of specific host defense, but little is known about such activities in the lung. Thus, the capacity of alveolar lymphocyte MTB-specific cell lines (AL) and alveolar macrophages (AM) from tuberculin skin test-positive healthy subjects to serve as CTL and target cells, respectively, in response to MTB (H37Ra) or purified protein derivative (PPD) was investigated. Mycobacterial Ag-pulsed AM were targets of blood CTL activity at E:T ratios of > or = 30:1 (51Cr release assay), but were significantly more resistant to cytotoxicity than autologous blood monocytes. PPD- plus IL-2-expanded AL and blood lymphocytes were cytotoxic for autologous mycobacterium-stimulated monocytes at E:T ratios of > or = 10:1. The CTL activity of lymphocytes expanded with PPD was predominantly class II MHC restricted, whereas the CTL activity of lymphocytes expanded with PPD plus IL-2 was both class I and class II MHC restricted. Both CD4+ and CD8+ T cells were enriched in BL and AL expanded with PPD and IL-2, and both subsets had mycobacterium-specific CTL activity. Such novel cytotoxic responses by CD4+ and CD8+ T cells may be a major mechanism of defense against MTB at the site of disease activity.
Defective TCR stimulation in anergized type 2 T helper cells correlates with abrogated p56(lck) and ZAP-70 tyrosine kinase activities.
Authors: Faith A , Akdis C A , Akdis M , Simon H U , Blaser K
Published: December 2022

Development of IgE-mediated allergic conditions is dependent on the secretion of a Th2 cytokine pattern, including IL-4, IL-5, and IL-13. The induction of anergy would be one mechanism to abrogate cytokine secretion by Th2 cells, which may be pivotal to the allergic response. We demonstrate here that incubation of cloned human CD4+ phospholipase A2 (PLA)-specific Th2 cells with antigenic peptide, in the absence of professional APC, results in a state of nonresponsiveness. The anergic T cells failed to proliferate or secrete IL-4 in response to optimal stimulation with PLA and autologous, professional APC. Secretion of IL-5 and IL-13, however, was only partially inhibited. The anergic state of the Th2 cells was not associated with CD3 or CD28 down-regulation. However, anergy did appear to be closely related to alterations in signaling pathways, mediated through the TCR, of the cells. In contrast to untreated Th2 cells, anergized Th2 cells failed to respond to anti-CD3 mAb with either increased tyrosine kinase activity or increased levels of tyrosine phosphorylation of p56(lck) or ZAP70. A strong and sustained intracellular calcium flux, observed in untreated Th2 cells in response to anti-CD3 mAb, was absent in anergic Th2 cells. Furthermore, the induction of anergy seems to represent an active process, associated with increased levels of basal tyrosine kinase activity, cytokine production, and CD25 up-regulation in anergic Th2 cells. Together, our results indicate that anergy in Th2 cells is associated with defective transmembrane signaling through the TCR.
TNF-alpha bifunctionally induces proliferation in primary hepatocytes: role of cell anchorage and spreading.
Authors: Watanabe Y , Osaki H , Akaike T
Published: December 2022

In the absence of a growth factor or an appropriate extracellular matrix (ECM), cells are arrested in the G0/G1 phase. In this report, we demonstrate the evidence that TNF-alpha induced DNA synthesis of primary mouse hepatocytes in vitro by activating two distinct pathways. TNF-alpha induced drastic spreading of hepatocytes on hydrophobic plastic, while the adhesion was not influenced. The effect was time and dose dependent. The cell spreading was accompanied by the phosphorylation of paxillin, indicating the stimulation of focal adhesion molecules. TNF-alpha-induced spreading of hepatocytes was not transient, and kinetic analysis and morphologic observation suggest that the effect was different from epidermal growth factor- or hepatocyte growth factor-induced transient hepatocyte spreading. TNF-alpha-induced hepatocyte spreading was blocked by cytochalasin D, Arg-Gly-Asp peptides, cycloheximide, or anti-integrin beta1 Ab. Results of competitive PCR for ECM proteins demonstrated that TNF-alpha increased the expression of laminin alpha3 and gamma1 chains in hepatocytes. These data suggested that TNF-alpha induced cell anchorage for hepatocytes by up-regulating ECM production. More importantly, TNF-alpha, but neither epidermal growth factor nor hepatocyte growth factor, induced DNA synthesis following the spreading in primary hepatocytes on hydrophobic plastic, while mere cell spreading on collagen did not induce DNA synthesis. The DNA synthesis was blocked by the inhibition of either cell spreading or DNA polymerase, demonstrating that TNF-alpha induced DNA synthesis in primary hepatocytes by activating two distinct pathways, i.e., forming the scaffold and inducing growth signals. Taken together, TNF-alpha bifunctionally regulates the proliferation of primary hepatocytes, serving as both an ECM inducer and a growth factor.
Expansion of mature thymocyte subsets before emigration to the periphery.
Authors: Pénit C , Vasseur F
Published: December 2022

A small population of DNA-synthesizing mature thymocytes could be defined by analyzing cell surface markers and 5-bromo-2'-deoxyuridine (BrdUrd) labeling by four-color cytofluorometry. These cells have a completely mature phenotype (CD4- CD8+ or CD4+ CD8- TCR(high), HSA-, Qa-2(high)) and expand only weakly after BrdUrd incorporation. They recovered immediately in total number and in DNA synthesis rate after treatment with the antimitotic drug demecolcin, thus much faster than immature CD4+ CD8+ thymocytes. These data demonstrate the existence of a late intrathymic expansion phase, independent of that of developing CD4+ CD8+ immature cells, and involving phenotypically mature cells renewed each day. In mixed chimeras prepared by transfer of bone marrow and lymph node cells into RAG-2(-/-) mice, all cycling mature thymocytes were bone marrow derived. They are thus produced in situ and do not correspond to peripheral T cells reentering the thymus. Double FITC/BrdUrd detection showed that a high proportion (10-20%) of recent thymic emigrants were BrdUrd+ just postcycling cells and that around 50% of cycling mature thymocytes are just ready to emigrate to the periphery in the few hours after DNA synthesis. The late intrathymic expansion phase demonstrated here increases the daily thymic cell export by at least 30%. It could play a role in the adjustment of the T cell repertoire before emigration and in the regulation of the thymic cell output into the peripheral T cell pool.
Autoantigen recognition by human CD8 T cell clones: enhanced agonist response induced by altered peptide ligands.
Authors: Dressel A , Chin J L , Sette A , Gausling R , Höllsberg P , Hafler D A
Published: December 2022

Determination of immunodominant epitopes of MHC class I-restricted self-Ags and elucidation of TCR contact residues is of potential importance in providing a means of manipulating the immune response to self-Ags in human autoimmune diseases. A computer algorithm was used to examine the sequences of the two major encephalitogenic proteins of myelin, MBP and PLP, for HLA-A2 binding motifs. Thirty-eight peptides with HLA-A2.1 binding motifs were synthesized and their binding to HLA-A2.1 was measured. A panel of HLA-A2-restricted T cell clones directed against the PLPp80-88 epitope, which exceeded the binding affinity of the other myelin-peptides tested by at least one order of magnitude, was generated. Using a set of analogue peptides with single amino acid substitutions, we detected a distinct pattern of TCR contact residues for each clone. Surprisingly, modification of different presumed TCR contact residues generated superagonist peptides, which are defined as peptides with equal or lower MHC binding affinity to HLA-A2 that induce half-maximal effector responses at 100-fold lower concentrations than the original peptide. These agonist peptides could drive cytotoxic T cell clones to proliferate, secrete cytokines, and clonally expand at concentrations at which the native peptide induced only cytotoxic responses. The proliferation induced by the superagonist peptides gives additional evidence that the clonal expansion of CD8 T cell clones may in part be regulated on the level of Ag recognition by the TCR.
Costimulation provided by DNA immunization enhances antitumor immunity.
Authors: Corr M , Tighe H , Lee D , Dudler J , Trieu M , Brinson D C , Carson D A
Published: December 2022

The interaction of the TCR with MHC class I-bound Ag is insufficient for the priming of CTL unless secondary costimulatory signals are provided. To ascertain the minimum elements required to activate an Ag-specific CTL response in vivo, we injected mice intradermally or i.m. with plasmid DNA encoding a MHC class I-restricted peptide Ag (minigene) and different membrane-bound costimulatory ligands. The minigene-encoded epitope only primed a specific CTL response if injected in the vicinity of an ectopically expressed costimulatory ligand. Vector encoding B7-1 was repeatedly more potent at stimulating a cytolytic response than vector encoding B7-2. In contrast the B7-2-encoding plasmid preferentially enhanced Ag-specific Ab responses when injected with either protein or a cDNA expression vector. Gene vaccination with plasmids encoding OVA and B7-1, but not B7-2, prolonged survival in mice challenged with an OVA-transfected tumor. These results show that functional B7-1 transfection can be achieved in vivo and induces the selective induction of CTL. The data suggest that B7-1 plasmids should be coadministered with naked DNA vaccines that aim to induce tumor-specific cellular immunity.
SCID mice reconstituted with IL-4-deficient lymphocytes, but not immunocompetent lymphocytes, are resistant to cutaneous leishmaniasis.
Authors: Satoskar A , Brombacher F , Dai W J , McInnes I , Liew F Y , Alexander J , Walker W
Published: December 2022

To characterize the roles of lymphoid- and non-lymphoid-derived IL-4 during cutaneous infection with Leishmania mexicana, the disease was monitored in SCID mice reconstituted with splenocytes from either immunocompetent BALB/c mice or IL-4-deficient BALB/c mice. Whereas following s.c. infection with L. mexicana no lesion growth was observed in BALB/c IL-4(-/-) mice and lesion growth was significantly inhibited in SCID mice, rapid initial lesion growth occurred in both SCID IL-4(+/+) and SCID IL-4(-/-) reconstituted mice. However, after 3 to 4 wk of infection, lesions in SCID IL-4(-/-) but not SCID IL-4(+/+) reconstituted mice began to heal. This paralleled a developing Th1-like phenotype and parasite clearance in the former group and a developing Th2-like phenotype in the latter group. Lesion sites from the healing SCID IL-4(-/-) mice expressed the inducible nitric oxide synthase, whereas the SCID IL-4(+/+) mice with progressive disease did not. These findings indicate that non-lymphocyte-derived IL-4 may play a role in initiating lesion growth following cutaneous infection with L. mexicana, but the presence of lymphocyte-derived IL-4 is essential for disease progression, and in its absence, lesions heal due to a developing Th1 phenotype.
Lymphocytes mediate TNF-alpha-induced endothelial cell adhesion molecule expression: studies on SCID and RAG-1 mutant mice.
Authors: Horie Y , Chervenak R P , Wolf R , Gerritsen M E , Anderson D C , Komatsu S , Granger D N
Published: December 2022

TNF-alpha is known to elicit a rapid increase in the expression of specific endothelial cell adhesion molecules (ECAMs) within different vascular beds. The aim of this study was to determine whether lymphocytes contribute to the increased ECAM expression elicited by TNF-alpha. A dual radiolabeled mAb technique was used to quantify constitutive and TNF-alpha-induced expression of ICAM-1, VCAM-1, E-selectin, and P-selectin in different vascular beds (lung, heart, stomach, mesentery, small intestine, large intestine, and muscle) in wild-type and SCID mice. In reconstitution experiments, either whole splenocytes, T cell-enriched splenocytes, or B cell-enriched splenocytes were injected into SCID mice 48 h before TNF-alpha administration. Although the constitutive expression of ECAMs differed only slightly between wild-type and SCID mice, TNF-alpha-induced ECAM expression was markedly blunted in SCID mice compared with wild-type mice. This blunted response to TNF-alpha was also demonstrated for VCAM-1 in recombination activating gene (RAG)-1 mutant mice. Reconstitution studies revealed that administration of 50 x 10(6) splenocytes in SCID mice at 48 h before cytokine treatment restored the TNF-alpha-induced expression of VCAM-1 to levels normally observed in wild-type mice. Reconstitution with T cell- but not B cell-enriched splenocytes, also restored the TNF-alpha-induced expression of VCAM-1 in SCID mice to wild-type levels. These results implicate circulating T lymphocytes as modulators of the increased ECAM expression elicited by TNF-alpha.
CD28 costimulation increases CD8+ cell suppression of HIV replication.
Authors: Barker E , Bossart K N , Fujimura S H , Levy J A
Published: December 2022

A subset of CD8+ T lymphocytes that expresses CD28, a membrane receptor for B7 differentiation Ags found on APCs, is primarily responsible for the noncytotoxic suppression of HIV replication in CD4+ cells of HIV-infected individuals. Optimal inhibition of HIV production by CD8+ cells occurs after triggering the CD28 molecule on the cells with anti-CD28 Abs during stimulation. Blocking the interaction of the CD28 and B7 molecules with a CTLA4Ig fusion protein abrogates the ability of autologous macrophages to enhance this CD8+ cell antiviral activity. This blocking effect can be reversed by treating the CD8+ cells with anti-CD28 Ab. The increase in antiviral activity following CD28 costimulation correlates with enhanced IL-2 production and IL-2R expression by CD8+ cells. Prevention of IL-2 binding to its receptor, using anti-IL-2 or anti-IL-2R Abs, reduces the ability of CD8+ cells to suppress HIV replication following CD28 costimulation. Importantly, engagement of the CD28 molecule during stimulation of CD8+ cells from individuals with AIDS restored the ability of their cells to suppress HIV replication. Thus, triggering the CD28 molecule during stimulation of CD8+ cells could clinically benefit HIV-infected symptomatic patients.
T cell clonality in synovial fluid of a patient with rheumatoid arthritis: persistent but fluctuant oligoclonal T cell expansions.
Authors: Kato T , Kurokawa M , Masuko-Hongo K , Sasakawa H , Sekine T , Ueda S , Yamamoto K , Nishioka K
Published: December 2022

Recently, oligoclonal T cell accumulation has been reported in affected joints of patients with rheumatoid arthritis. To characterize such clonally accumulating T cells, we quantitatively monitored their frequency by analyzing TCR B chains. As a result, despite a similar TCR BV usage between synovial fluid (SF) and PBL, obviously skewed TCR BJ usage was detected in SF. Subsequent DNA sequencing demonstrated that the skewed BJ gene usage in SF resulted from clonal T cell accumulation. The complementarity-determining region 3 of TCR B chains of the detected clones appeared to have homologous amino acid sequences. Further, one of the predominant TCR B chains of the clones was identical with that reported previously. In the follow-up study, most of the accumulated clones persisted; however, in some, proportions were drastically decreased or increased during the time course. In particular, one of the clones expanded sixfold, from 11 to 67%, in the BV8-BJ2S3 TCR population of SF, even though the clone was not detected in PBL. In summary, oligoclonal T cell accumulation in SF was persistent, but it appeared to fluctuate independently of the clonality in PBL. The expansion of the clones in SF may occur by antigenic stimuli within the joint.
A dominant-negative mutant of the Rab5 GTPase enhances T cell signaling by interfering with TCR down-modulation in transgenic mice.
Authors: André P , Boretto J , Hueber A O , Régnier-Vigouroux A , Gorvel J P , Ferrier P , Chavrier P
Published: December 2022

TCR triggering results in the down-modulation of engaged receptors by endocytosis. As a result of this process, Ag-binding sites are depleted from the surface and signaling responses should be attenuated. To test the importance of TCR down-regulation on T cell signaling, we generated mice expressing a dominant-negative form of Rab5 (Rab5N133I) in T cells. Rab5, a monomeric GTPase of the Ras superfamily, has been implicated in the regulation of early steps in the endocytic pathway. In Rab5N133I mice, mature thymocytes developed, but the absolute number of CD4+CD8+ double positive thymocytes was reduced. Fluid phase endocytosis was severely impaired in the transgenic thymocytes. In peripheral T cells, the kinetics and rate of ligand-induced TCR down-modulation were delayed and reduced. These effects were correlated with enhanced early and late signaling responses. Analysis of thymocyte development in doubly transgenic mice for Rab5N133I and a lymphocytic choriomeningitis virus (LCMV) peptide-specific TCR demonstrated that TCR signaling was enhanced by dominant inhibition of Rab5 function, resulting in altered thymic selection. These findings suggest that TCR endocytosis is an important regulatory component of TCR signaling and that defects in this regulation can result in prolonged signaling and alter thymic development.
Role of Thy-1 in T cell development.
Authors: Page D M , Tokugawa Y , Silver J , Stewart C L
Published: December 2022

Tolerance to self proteins is accomplished in part by elimination of autoreactive immature T cells as they develop in the thymus. Although many investigators have studied the cellular interactions that regulate this important process, the specific molecules involved in negative selection are still not well understood. Thy-1 is a glycosyl-phosphatidylinositol-linked protein that is expressed at high levels on immature thymocytes, and recent evidence suggests that it is involved in thymocyte apoptosis. Correspondingly, we have found that Abs to Thy-1 block Ag-dependent thymocyte deletion in an in vitro culture system. Thus, we investigated the role of Thy-1 in T cell development by using Thy-1 -deficient mice containing a TCR transgene specific for a class II MHC-restricted Ag. With this system, the role of Thy-1 in Ag-specific self-restriction and self-tolerance could be analyzed. Thy-1-null mice were found to undergo normal negative selection in three different models: the in vitro culture system, anti-CD3-induced thymocyte deletion in vivo, and Ag-induced thymocyte deletion in vivo. Self-restriction to MHC class II also appeared to occur normally in Thy-1-null mice. These results therefore suggest that Thy-1 is not essential for either self-restriction or self-tolerance to MHC class II-restricted Ags. This finding is discussed in light of recent data regarding the role of other glycosyl-phosphatidylinositol-linked proteins in thymocyte development.
Structural requirements for beta1 integrin-mediated tyrosine phosphorylation in human T cells.
Authors: Finkelstein L D , Reynolds P J , Hunt S W , Shimizu Y
Published: December 2022

The beta1 integrin adhesion receptors activate signal transduction pathways that induce tyrosine phosphorylation of a variety of substrates. Increased tyrosine phosphorylation is mediated by the beta1 subunit cytoplasmic domain, which consists of 46 amino acids and contains no intrinsic kinase activity. In the H9 T cell line, beta1 integrin engagement leads to the increased tyrosine phosphorylation of three 105 to 115-kDa substrates that are distinct from focal adhesion kinase (FAK): HEF1 (human enhancer of filamentation 1), a protein with structural homology to p130Cas, and two novel substrates, pp105 and pp115. DNA-mediated gene transfer was used to explore the role of the beta1 cytoplasmic domain in integrin-mediated tyrosine phosphorylation of HEF1, pp105, and pp115 in human T cells. Using a chimeric receptor composed of the cytoplasmic domain of the beta1 integrin subunit and the extracellular and transmembrane domains of the CD2 Ag, we demonstrate that the beta1 cytoplasmic domain is necessary and sufficient for inducing tyrosine phosphorylation of each of these three substrates in H9 T cells. Analysis of a series of beta1 cytoplasmic domain truncations reveals that a truncation of only five amino acids from the carboxyl-terminal end of the beta1 cytoplasmic domain abrogates the ability of the CD2/beta1 chimera to activate tyrosine phosphorylation of HEF1, pp105, or pp115. Thus, the carboxyl-terminal five amino acids, Lys-Tyr-Glu-Gly-Lys (KYEGK), of the beta1 integrin cytoplasmic domain are critical for the coordinate tyrosine phosphorylation of three non-FAK substrates in human T cells.
Molecular analysis of V gene sequences encoding cytotoxic anti-streptococcal/anti-myosin monoclonal antibody 36.2.2 that recognizes the heart cell surface protein laminin.
Authors: Antone S M , Adderson E E , Mertens N M , Cunningham M W
Published: December 2022

Anti-streptococcal/anti-myosin mAb 36.2.2 is unique among the cross-reactive anti-streptococcal mAbs due to its cytotoxicity for rat heart cells and its ability to strongly label the surface of heart cells in indirect immunofluorescence assays. In this study, cytotoxic mAb 36.2.2 was found to react strongly with the extracellular matrix protein laminin in immunoblots and inhibition assays, while 11 other cross-reactive anti-streptococcal mAbs did not react with laminin and were not cytotoxic. Cytotoxicity appeared to correlate with the presence of laminin on the surface of cells. Heavy and light chain variable region genes encoding mAb 36.2.2 were highly homologous to other V genes encoding anti-carbohydrate and/or autoantibodies. VH, JH, and Jkappa segments of mAb 36.2.2 may be encoded by germline gene segments. The VH segment may be identical with an as yet unidentified VH7183 family germline sequence, and the 36.2.2 Vkappa region gene is encoded by a Vkappa8 family member.
Role of cyclic AMP response element-binding protein in cyclic AMP inhibition of NF-kappaB-mediated transcription.
Authors: Parry G C , Mackman N
Published: December 2022

The NF-kappaB family of transcription factors regulates the inducible expression of a variety of genes. Recently, we showed that elevation of intracellular cyclic AMP inhibits NF-kappaB-mediated transcription in human monocytes and endothelial cells without preventing nuclear translocation of NF-kappaB complexes. The present study examined the molecular mechanism of this inhibition. We hypothesized that activation of the protein kinase A signaling pathway may inhibit NF-kappaB-mediated transcription by phosphorylating proteins, such as cAMP response element-binding protein (CREB), which compete for limiting amounts of the coactivator CBP. Here, we show that the amino-terminal region (amino acids 1-450) of CBP specifically interacts with the carboxyl-terminal region (amino acids 286-551) of NF-kappaB p65 (RelA) both in vitro and in vivo. Functional studies using human endothelial cells demonstrated that overexpression of CBP rescued cAMP inhibition of NF-kappaB-mediated transcription and transcription mediated by a chimeric protein, GAL4-p65(286-551), which contained the GAL4 DNA binding domain fused to the carboxyl-terminal region of p65 (amino acids 286-551). In contrast, overexpression of CREB inhibited GAL4-p65(286-551)-mediated transcription. These results suggest that activation of the protein kinase A pathway inhibits NF-kappaB transcription by phosphorylating CREB, which competes with p65 for limiting amounts of CBP.
IgE from latex-allergic patients binds to cloned and expressed B cell epitopes of prohevein.
Authors: Banerjee B , Wang X , Kelly K J , Fink J N , Sussman G L , Kurup V P
Published: December 2022

Prohevein is one of the major allergens associated with latex allergy. In the present study, we identified IgE binding regions of prohevein, and expressed multiple IgE binding epitopes by selective cloning. These truncated polypeptides were then used to demonstrate IgE in the sera of patients. Decapeptides of prohevein were synthesized on derivatized cellulose membrane with an offset of one amino acid. The IgE reactivity of these linear peptides was evaluated separately using pooled sera from latex-allergic health care workers (HCW) and spina bifida (SB) patients. A total of 10 IgE binding epitopes representing unique as well as shared epitopes from both the N- and C-domains of the prohevein were identified. Recombinant polypeptides were constructed based on the identified epitopes, and clones carrying DNA fragments were overexpressed. These recombinant peptides were evaluated for IgE binding with sera from HCW, SB, and normal individuals. Recombinant prohevein, hevein, and the C-domain exhibited IgE binding in 84, 88, and 40% of HCW sera, respectively, as against reactivity of 84% with crude latex allergens. However, only 48% of the sera from SB patients showed IgE binding with recombinant prohevein, while 56 and 28% had reactivity with recombinant N- and C-domains, respectively. Among the three remaining recombinant peptides of the C-domain, only CA44-103 showed IgE binding with SB patients. The results of the present study suggest that linear IgE epitope analysis and construction of recombinant peptides increase the sensitivity and specificity of the immunodiagnosis of latex allergy and provide more information on the immunopathogenesis of hypersensitivity reaction mediated by type I allergy.
Ligation of cell surface CD4 inhibits activation-induced death of human T lymphocytes at the level of Fas ligand expression.
Authors: Oberg H H , Sanzenbacher R , Lengl-Janssen B , Dobmeyer T , Flindt S , Janssen O , Kabelitz D
Published: December 2022

Cross-linking of cell surface CD4 molecules by anti-CD4 mAb or HIV-1 gp120/anti-gp120 Ab primes resting T lymphocytes for activation-induced cell death (AICD) triggered via the CD3/TCR complex. In striking contrast, we demonstrate here that preincubation of activated human CD4+ T cells with anti-CD4 mAb consistently inhibited AICD triggered via anti-CD3 mAb or Staphylococcus aureus enterotoxin A superantigen. Inhibition of AICD of CD4+ T cell clones was also observed with F(ab')2, but not with Fab, of anti-CD4 mAb. Moreover, soluble HIV-1 gp120, but not rIL-16, inhibited AICD stimulated by S. aureus enterotoxin A. In susceptible clones, CD4 ligation prevented the up-regulation of Fas ligand mRNA and cell surface expression in response to anti-CD3 mAb or superantigen stimulation. CD3/TCR-dependent protein tyrosine phosphorylation and cytokine production were also prevented by preceding CD4 ligation. The inhibition of AICD due to the prevention of Fas ligand upregulation reveals a novel immunoregulatory consequence of CD4 ligation that might play a role in HIV infection and in the therapeutic application of anti-CD4 mAb.
Microtubule retraction into the uropod and its role in T cell polarization and motility.
Authors: Ratner S , Sherrod W S , Lichlyter D
Published: December 2022

Spherical circulating T cells must polarize to extravasate. We have found that the polarization process includes a drastic reconfiguration of the tubulin cytoskeleton. In spherical T cells, the nucleus is surrounded by microtubules radiating from the microtubule organizing center (MTOC). During polarization the uropod (a slender posterior appendage) forms at the site of the MTOC. As the uropod buds out, the MTOC is carried in its distal tip. The attached microtubules retract into the uropod lumen, collapsing like the spokes of an umbrella into a compact sheaf. Experiments with microtubule inhibitors show that the retracted microtubules do not support the uropod or produce motive force. Instead, the data suggest that retraction of the relatively rigid microtubules into the streamlined uropod increases T cell deformability, thereby facilitating migration through constricted spaces. Microtubule retraction, therefore, may prove to be a strategy for accelerating extravasation without disassembly of the microtubule-based transport system.
Cross-linking of the IgM receptor induces rapid translocation of IgM-associated Ig alpha, Lyn, and Syk tyrosine kinases to the membrane skeleton.
Authors: Jugloff L S , Jongstra-Bilen J
Published: December 2022

Cross-linking-induced association of membrane IgM (mIgM) with the cytoskeleton is well documented. However, its functional significance during B cell activation is not yet understood. One possible need for mIgM/cytoskeleton interactions may be to recruit the B cell receptor (BCR)-associated signaling molecules to the cytoskeletal matrix for the propagation of downstream signaling. We first verified whether BCR-associated Ig alpha translocates to the cytoskeleton together with mIgM in polyclonal anti-IgM-treated murine B lymphoma cell line, BAL17.7.1. Co-capping experiments and the purification of the membrane skeleton under conditions that preserve IgM-Ig alphabeta) interactions confirmed that Ig alpha translocates to the cytoskeleton as part of the BCR complex. Furthermore, two BCR-associated kinases that are known to play critical roles in anti-IgM-induced B cell signaling, the src family kinase Lyn and the non-src family kinase Syk, accumulate in the membrane skeleton shortly after BCR cross-linking, when most of IgM and Ig alpha accumulate in this fraction. The kinetics of recruitment of the bulk of Ig alpha, Lyn, and Syk into the membrane skeleton appeared to precede the accumulation of their hypertyrosine-phosphorylated forms, suggesting that activation of the BCR-associated signaling molecules occurs in this fraction. These data suggest that cross-linked mIgM translocating to the membrane skeleton serves as a vehicle for active signaling molecules to be recruited to this vicinity. This may promote B cell activation events by providing high affinity interactions between signaling molecules and their substrates supported by the cytoskeletal matrix.
The role of donor and recipient B7-1 (CD80) in allograft rejection.
Authors: Zheng X X , Sayegh M H , Zheng X G , Li Y , Linsley P S , Peach R , Borriello F , Strom T B , Sharpe A H , Turka L A
Published: December 2022

Blockade of CD28-mediated T cell costimulatory signals produces effective immunosuppression of a variety of T cell-dependent in vivo immune responses, including autoimmune disorders and transplant rejection. The soluble fusion protein CTLA4Ig, which competitively blocks CD28 ligands B7-1 and B7-2, can prevent allograft and xenograft rejection and in some circumstances induce transplantation tolerance. To determine the relative roles of B7-1 and B7-2 in graft rejection, we have performed islet and cardiac allografts with normal and B7-1(-/-) mice in conjunction with selective blocking reagents. We found that the absence of B7-1 on donor or recipient tissues leads to a slight prolongation of islet allograft survival, but has minimal or no effect on cardiac allograft survival. Allograft function is further prolonged in the islet model when both donor and recipient lack B7-1, although cardiac allograft survival is not prolonged. In the cardiac model, treatment with CTLA4Ig induces long term survival in B7-1(-/-) recipients regardless of donor status. In contrast, anti-B7-2 mAb leads to indefinite allograft survival only when the recipient and donor both lack B7-1, indicating that even in the absence of available B7-2, B7-1 molecules on the donor or recipient cells alone are sufficient to induce graft rejection. These data also indicate that B7-1 and B7-2 are the only CD28 ligands relevant to cardiac allograft rejection in mice.