bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytotoxic T cells in HIV2 seropositive Gambians. Identification of a virus-specific MHC-restricted peptide epitope.
Authors: Gotch F , McAdam S N , Allsopp C E , Gallimore A , Elvin J , Kieny M P , Hill A V , McMichael A J , Whittle H C 
Published: December 2022

Abstract
A preliminary study of gag-specific, MHC-restricted CD8+ CTL has been performed in nine Gambian patients infected with HIV2. Such CTL were present in at least 55% of patients in fresh peripheral blood mononuclear cells without the requirement for in vitro restimulation. We have identified a nonamer peptide from HIV2 gag that is recognized by CD8+ HLA-B53 CTL using an amino acid sequence motif predicted from analysis of endogenous peptides eluted from HLA-B53 molecules. This peptide, from an HIV2/SIV conserved sequence, has previously been reported to be recognized by CTL from non-human primates vaccinated with recombinant vaccinia virus expressing the gag protein of SIV or infected with SIV virus. HLA-B53-restricted, HIV2 gag-specific CTL did not recognize target cells expressing HIV1 gag proteins, indicating that no cellular cross protection to HIV1 could be expected in this case.
Regulation of apoptosis in vitro in mature murine spleen T cells.
Authors: Perandones C E , Illera V A , Peckham D , Stunz L L , Ashman R F 
Published: December 2022

Abstract
Previously it has been shown that thymocytes undergo apoptosis, a form of programmed cell death, in response to glucocorticoids. This classic form of apoptosis is prevented by inhibition of protein synthesis. The current paper demonstrates that mature T cells also undergo apoptosis, but that the regulation of apoptosis in spleen T cells differs from that of thymocytes. Mature mouse spleen T cells were shown to die by apoptosis, not necrosis, when cultured without an added stimulus. Assays for apoptosis included internucleosomal DNA cleavage by gel electrophoresis, percent fragmentation of DNA by the diphenylamine method, and percent of cells with hypodiploid DNA by flow cytometry. The percent of apoptotic cells was 2% in fresh spleen T cells, and increased at least until 16 h, when 21% were apoptotic. Dexamethasone caused apoptosis in both thymus and spleen T cells, but only thymocytes showed a requirement for protein synthesis in dexamethasone-induced death. Cycloheximide increased apoptosis in spleen T cells, indicating that apoptosis was controlled by newly synthesized protective proteins. Spontaneous apoptosis was decreased in spleen T cells by protein kinase C activation, and was increased by H7 and staurosporine, which inhibits protein kinases, in contrast with the behavior of thymocytes. The protein kinase A/G inhibitor HA1004 also decreased spleen T cell apoptosis. The contrasting effects of cycloheximide on thymocytes and spleen T cells occurred over the same concentration range, and the same was true for PMA. The dexamethasone dose-response curves were similar, except that a greater proportion of spleen T cells were dexamethasone-resistant. These data support the hypothesis that the apoptosis program in T cells undergoes a transition during their maturation, such that apoptosis in mature T cells is regulated more like that of mature B cells than that of thymocytes.
Apoptosis of activated CD8+/CD57+ T cells is induced by some combinations of anti-CD2 mAb.
Authors: Rouleau M , Bernard A , Lantz O , Vernant J P , Charpentier B , Senik A 
Published: December 2022

Abstract
Peripheral blood CD8+/CD57+ T cells display poor proliferative responses when stimulated with CD3 or CD2 in vitro, but can be induced to proliferate in the presence of exogenous IL-2. Although GT2+T11(1), a mitogenic anti-CD2 mAb pair, could synergize with IL-2 to induce sustained cell divisions in this population (as did immobilized OKT3), D66+T11(1), another anti-CD2 mAb pair, could only induce a small abortive proliferative response. All these antibodies were in contrast strongly mitogenic for CD8+/CD57- T cells. Assuming that D66+T11(1) were exerting inhibitory effects on CD8+/CD57+ T cells, we indeed found that such antibodies profoundly suppressed the anti-CD3 and IL-2-induced proliferation of those cells, but not that of CD8+/CD57- cells. CD2-mediated growth arrest was correlated with rapid cell death occurring within 2 h, once the cells had been submitted to D66+T11(1), and cells susceptible to the death signal were large cells committed in the cell cycle. D66+T11(1)-treated cells had the well-known ultrastructural form of apoptosis, and the DNA extracted from these cells showed the typical ladder pattern of DNA fragmentation accompanying this process. For apoptosis to occur, two anti-CD2 mAb had to be applied to the cells, one of them being D66, suggesting that the corresponding anti-CD2 mAb pairs were imposing on the CD2 molecule a particular conformational change appropriate to transduce a death signal. Notably, CD8+/CD57- T cells were largely resistant to apoptosis in the conditions just described. When exposed to anti-CD3 and IL-2 in primary and secondary cultures, CD8+/CD57+ T cells retained high viability, whereas in contrast, when exposed to D66+T11(1), important cell loss occurred, concomitant with apoptosis, illustrating the specificity of the CD2-derived death signal. Our results suggest that the expansion of CD8+/CD57+ T cells is critically dependent on the CD2 pathway which, according to the conformational change of the CD2 molecule and the activation state of the cells, will direct them either towards proliferation or towards cell death.
Activation of human neutrophils induces an interaction between the integrin beta 2-subunit (CD18) and the actin binding protein alpha-actinin.
Authors: Pavalko F M , LaRoche S M 
Published: December 2022

Abstract
Mac-1 and LFA-1, members of the leukocyte or CD18 integrin subfamily of adhesion molecules, rapidly change from a low avidity to a high avidity state on activation of neutrophils by various agonists. The control of CD18 integrin-dependent neutrophil adhesion and the mechanisms that regulate integrin avidity are poorly understood. Cytoplasmic domain deletion experiments indicate that the cytoplasmic domains of integrins are necessary for proper integrin function and suggest that interactions with intracellular proteins are involved. We have focused on identifying cytoskeletal proteins that interact with the cytoplasmic domain of the beta-subunit (beta 2 or CD18) common to the leukocyte subfamily of integrins, which include LFA-1, Mac-1, and p150,95. The actin binding protein alpha-actinin associates in vitro with a peptide corresponding to a portion of the CD18 cytoplasmic domain in solid phase binding assays and affinity chromatography experiments. The peptide sequence within the CD18 cytoplasmic domain that binds alpha-actinin is homologous with a region in the cytoplasmic domain of the integrin beta 1-subunit, which also binds alpha-actinin. We demonstrate that the association of alpha-actinin with CD18 is physiologically relevant by coimmunoprecipitating CD18 with alpha-actinin from stimulated human neutrophils under nondenaturing conditions. Using a mAb against CD18 to probe Western blots of immunoprecipitated complexes, CD18 was found to coprecipitate with alpha-actinin when cells were activated with the chemotactic peptide FMLP or with the cytokines leukotriene B4 or TNF-alpha. Very little CD18 coprecipitates with alpha-actinin from unactivated cells. FMLP concentrations as low as 10 nM were sufficient to induce the association of CD18 with alpha-actinin; very little association was detected in cells activated with 1 nM FMLP. The association between alpha-actinin and CD18 was transient, peaking 5-10 min after activation and decreasing to near resting levels by 20 min. CD18 did not coimmunoprecipitate with talin or vinculin in vivo. We conclude that activation of neutrophils results in an alpha-actinin-mediated association between CD18 integrins and actin filaments. In addition to its actin bundling activity, alpha-actinin has a major function as an actin membrane linker molecule, and integrin avidity may be affected by an association with the actin cytoskeleton involving alpha-actinin.
Clonal deletion of V beta 5+ T cells by transgenic I-E restricted to thymic medullary epithelium.
Authors: Burkly L C , Degermann S , Longley J , Hagman J , Brinster R L , Lo D , Flavell R A 
Published: December 2022

Abstract
A variety of cell types expressing MHC class II molecules is known to function as APC in vitro. We employed the Ig kappa gene enhancer and promoter to target the class II E alpha gene, and thereby I-E, exclusively to B cells to address their APC function in vivo. Although transgenic I-E was expressed on B lymphocytes, we unexpectedly obtained I-E on thymic medullary epithelium but not macrophages and at low frequency on dendritic cells. Using these transgenic mice, we constructed bone marrow irradiation chimeras with I-E expressed only on medullary epithelium, in order to determine the role of this cell type in tolerance by clonal deletion in the thymus. Although it is accepted that bm-derived cells play a primary role in deletion, and thymic epithelium can delete clones to a lesser degree, the role of cortical vs medullary thymic epithelium has not been directly dissected. We demonstrate that medullary epithelium alone can tolerize by partial deletion of I-E-reactive V beta 5+ T cells. These results indicate a role for medullary epithelium in deletion during the later stages of thymic development, and support the notion that positive and negative selection of developing T cells can occur in distinct temporal and anatomic compartments.
Production and characterization of soluble and transmembrane murine CD2. Demonstration that CD48 is a ligand for CD2 and that CD48 adhesion is regulated by CD2.
Authors: Kaplan A J , Chavin K D , Yagita H , Sandrin M S , Qin L H , Lin J , Lindenmayer G , Bromberg J S 
Published: December 2022

Abstract
The baculovirus expression vector was used to produce full length, two amino-terminal Ig-like extracellular domains, and one amino-terminal Ig-like extracellular domain soluble murine CD2 products. The products were monomeric, glycosylated, and of the correct predicted m.w. Sf9 insect cells infected with recombinant baculovirus encoding the full length construct display cell surface CD2 by flow cytometry and rosette with murine cell lines that express the ligand for CD2. Uninfected Sf9, wild-type baculovirus-infected Sf9, and Sf9 expressing truncated products do not display cell surface CD2 nor do these latter Sf9 bind to murine cell lines. Cell binding is inhibited by anti-CD2 mAb. All CD2 products possess ligand binding activity since purified preparations of these block cell adhesion. All CD2 antigenic epitopes are close to the ligand binding site because all mAb tested can inhibit cell adhesion. The ligand for CD2 is shown to be CD48. Only CD48+ cell lines can bind CD2+ Sf9 and this is inhibited by anti-CD48 mAb. Antibodies against the closely related cell surface Ag Ly-6A.2 and Ly-9.2 do not inhibit binding. Purified, soluble CD2 also inhibits the binding of anti-CD48 mAb to the cell surface. Unexpectedly, additional mAb blocking studies show that CD2 on the surface of CD48+ cell lines influences adhesion to CD2+ binding partners. The use of cells expressing CD2 and/or CD48 provides evidence for a cis CD2-CD48 interaction on the cell surface in which CD2 negatively regulates CD48 adhesion properties.
Distinct requirements of positive and negative selection for selecting cell type and CD8 interaction.
Authors: Schönrich G , Strauss G , Müller K P , Dustin L , Loh D Y , Auphan N , Schmitt-Verhulst A M , Arnold B , Hämmerling G J 
Published: December 2022

Abstract
We investigated the requirements of positive and negative selection in the thymus for CD8 interaction and the selecting cell type. Thymic epithelial cells are known to mediate positive selection, whereas thymocytes fail to do so. The reason for this failure could be either the low amount of MHC class I molecules on thymocytes or the lack of other properties required for positive selection. To address this question a CD2.Kb transgenic mouse was prepared in which the expression of the Kb gene is under control of the CD2 promoter. In these mice the thymocytes exhibited very high levels of Kb. The mice were crossed with two TCR transgenic mice expressing either the Des.TCR (anti-Kb), which is positively selected on Kk and negatively on Kb, and the 2C.TCR (anti-Ld) with positive selection on Kb and negative on Ld. Despite the high Kb expression on thymocytes in CD2.Kb x 2C.TCR mice no positive selection was observed, whereas efficient negative selection was found in CD2.Kb x Des.TCR F1 mice. Thus, although thymocytes can negatively select, even a strong increase of MHC class I expression cannot convert them into positively selecting cells. This is consistent with the notion that thymic epithelium is specialized for positive selection, but the respective difference between thymocytes and thymic epithelium is not clear. The influence of CD8 was investigated using transgenic mice expressing a Kk/A2 or a Kb/A2 hybrid gene in which the promoter, the alpha 1, alpha 2 domains were of mouse origin and the alpha 3 domain of human origin. Because the murine CD8 molecule does not efficiently bind to human HLA class I, in these mice the CD8 interaction was impaired. In Kb/A2 x 2C.TCR and Kk/A2 x Des.TCR mice no positive selection of the respective TCR was found, whereas in Kb/A2 x Des.TCR mice negative selection was still functional. Altogether, the results indicate that positive selection depends more strictly on CD8 interaction and cell type than negative selection.
Rapid activation of C-Raf-1 after stimulation of the T-cell receptor or the muscarinic receptor type 1 in resting T cells.
Authors: Siegel J N , June C H , Yamada H , Rapp U R , Samelson L E 
Published: December 2022

Abstract
The c-Raf-1 serine/threonine kinase is an important component of signal transduction pathways mediating the effects of a variety of growth factors. In activated T cells, IL-2 has been shown to induce activation of c-Raf-1, but c-Raf-1 has not previously been shown to be activated through the T-cell receptor (TCR) in resting G0 T cells. Using a sensitive immune complex kinase reaction, we show that cross-linking of the stimulatory and costimulatory receptors CD3, CD4, or CD28 induces c-Raf-1 activation in highly purified resting peripheral blood human T cells. In contrast, cross-linking the nonstimulatory receptor CD45 did not induce c-Raf-1. Surprisingly, although earlier studies had shown delayed kinetics in response to Thy-1 stimulation in murine cells, c-Raf-1 activation in response to CD3 cross-linking was one of the earliest measurable events. In spite of its early kinetics, c-Raf-1 activation was found to be downstream of several other early signal transduction events, including activation of a tyrosine kinase and a tyrosine phosphatase. Several lines of evidence suggest that activation of c-Raf-1 in response to TCR stimulation may be PKC-dependent: first, phorbol esters are extremely potent activators of c-Raf-1 in human T cells; second, the kinetics of accumulation of products of phosphatidylinositol hydrolysis coincides with the kinetics of c-Raf-1 activation; and third, physiologic activation of the PLC/PKC pathway through a transfected, G-protein-coupled receptor HM1 induced similar levels of c-Raf-1 activation with a similar time course. We conclude that c-Raf-1 activation is tightly coupled to TCR stimulation and may participate in signal transduction pathways in resting, G0 T cells. The observation that the HM1 receptor can also activate c-Raf-1 suggests that T cells have the capability to utilize both tyrosine kinase-dependent and tyrosine kinase-independent mechanisms of c-Raf-1 activation.
Xid-associated resistance to experimental Chagas' disease is IFN-gamma dependent.
Authors: Minoprio P , el Cheikh M C , Murphy E , Hontebeyrie-Joskowicz M , Coffman R , Coutinho A , O'Garra A 
Published: December 2022

Abstract
In contrast to normal Balb/c, Balb.Xid immunodeficient mice are naturally resistant to Trypanosoma cruzi infection. Thus, Balb.Xid mice control parasitemia, do not show the characteristic wasting in the acute infection and develop no tissue pathology in the skeletal or cardiac muscles in the chronic phase of disease. By in situ hybridization and semiquantitative polymerase chain reaction, the expression of IL genes in spleen cells from Balb/c and Balb.Xid mice were compared after T. cruzi infection. The results showed that Balb.Xid mice produce considerably higher levels of IFN-gamma, IL-2, and IL-4, but lower levels of IL-10, from as early as 4 days after parasite injection. By day 12 of the infection, although IFN-gamma, IL-2, and IL-4 expression was now comparable in both groups, IL-10 levels continue to be lower in Balb.Xid than in control Balb/c animals. The central role of IFN-gamma in the resistance to T. cruzi was confirmed by treatment of Balb.Xid mice with anti-IFN-gamma antibodies that reestablished susceptibility and lead to increased parasitemia and mortality.
Tumor-specific lysis of human renal cell carcinomas by tumor-infiltrating lymphocytes. I. HLA-A2-restricted recognition of autologous and allogeneic tumor lines.
Authors: Schendel D J , Gansbacher B , Oberneder R , Kriegmair M , Hofstetter A , Riethmüller G , Segurado O G 
Published: December 2022

Abstract
Metastatic renal cell carcinoma (RCC), like melanoma, belongs to the small group of human tumors in which partial or complete remission has been observed in some patients after treatment with various forms of immunotherapy. In contrast to melanoma, CTL showing MHC-restricted lysis of RCC have not been easily found among tumor-infiltrating lymphocytes (TIL). This has led to the suggestion by some that responses to immunotherapy are mediated predominantly by non-MHC-restricted effector cells. We have characterized an MHC-restricted, CD8+ CTL line obtained from an uncloned TIL population of a primary RCC using a low concentration of rIL-2; in fact, these CTL represented a majority of the short-term cultured TIL population. The CTL lysed autologous tumor cells but not normal kidney cells or target cells sensitive to non-MHC-restricted effector cells. In contrast, lymphokine-activated killer (LAK) cells grown in a high concentration of rIL-2 from the patient's PBL lysed autologous tumor and normal kidney cells in addition to several allogeneic tumors. The TIL could be expanded optimally using an autologous tumor line retrovirally transduced with the human cDNA encoding IL-2. TIL were 20-fold more potent than LAK cells in eliminating the IL-2 expressing tumor cells in vitro. The cultured TIL utilized a restricted number of V alpha gene families, suggesting that they may recognize only a limited number of MHC-peptide complexes presented by autologous tumor cells. HLA-A2 was identified as an MHC restriction molecule for presentation of one tumor-derived peptide to these CTL. Only some allogeneic HLA-A2 RCC tumors were lysed. Sequencing of the second and third exons of the HLA-A2 alleles of these cells revealed that both heterogeneity in MHC and peptide availability influenced CTL recognition. These studies demonstrate that some RCC express common antigenic determinants that can be recognized by MHC-restricted CTL and open the possibility of defining the nature of RCC-derived peptides, which, combined with HLA-A2, can generate specific immune responses.
Suppression of monocyte function and differential regulation of IL-1 and IL-1ra by IL-4 contribute to resolution of experimental arthritis.
Authors: Allen J B , Wong H L , Costa G L , Bienkowski M J , Wahl S M 
Published: December 2022

Abstract
IL-4 has diverse effects on hematopoietic cells, including the ability to suppress certain mononuclear cell functions. To evaluate the effect of IL-4 on the evolution of acute and chronic arthritis, murine recombinant IL-4 was administered systemically to animals receiving an arthropathic dose of group A streptococcal cell wall fragments. Daily treatment with IL-4 had a minimal effect on the acute phase, but significantly suppressed the chronic, destructive phase. By 4 wk after initiation of disease, the articular index of IL-4-treated animals was reduced &gt; 60% (articular index = 4 +/- 0.9) compared with the untreated rats (11.5 +/- 0.48, p &lt; 0.001). A substantial decrease in the influx of inflammatory cells and virtual elimination of pannus and erosions occurred after IL-4 therapy. Associated with the reduced accumulation of mononuclear leukocytes was a decrease in their proinflammatory functions including cytokine production and reactive oxygen intermediate metabolism. These observations are consistent with the selective effects of IL-4 on phagocytic cell function demonstrated in vitro. Furthermore, IL-4 induced gene expression for IL-1ra, a protein that antagonizes the action of IL-1 by binding to the IL-1 receptor without agonist activity. Through an expanding spectrum of effects on monocyte-macrophage phenotypic and functional parameters, IL-4 is emerging as an important inhibitor of cell-mediated immune responses and pathogenic processes.
CD40 expression in malignant plasma cells. Role in stimulation of autocrine IL-6 secretion by a human myeloma cell line.
Authors: Westendorf J J , Ahmann G J , Armitage R J , Spriggs M K , Lust J A , Greipp P R , Katzmann J A , Jelinek D F 
Published: December 2022

Abstract
Myeloma is a neoplasia characterized by the accumulation of malignant plasma cells in the bone marrow. In these studies, we have demonstrated that CD40 is expressed in human myeloma cells and have used a recently established IL-6-dependent myeloma cell line, ANBL-6, to examine the potential function of CD40 expression in myeloma cells. In addition to its expression on the ANBL-6 cells, we show that CD40 is expressed on freshly isolated myeloma cells from seven of seven patients tested. To address the role of CD40 expression in myeloma cells, we have examined the responsiveness of the ANBL-6 cell line to a CD40-specific mAb, G28-5. This cell line has previously been shown to proliferate only in response to IL-6. Of interest in this study, G28-5 also induced proliferation of the ANBL-6 cells. This proliferation was substantially inhibited by an IL-6-neutralizing mAb. Analysis of ANBL-6 cell culture supernatants by ELISA demonstrated that G28-5-stimulated cells secreted significant levels of IL-6, whereas unstimulated cell culture supernatants contained undetectable levels of IL-6. Furthermore, CV-1/EBNA cells expressing the human CD40 ligand also induced the proliferation of the ANBL-6 cell line, an effect that was inhibited by the anti-IL-6 mAb. Lastly, RNA blot analysis demonstrated an increase in IL-6 message in G28-5-stimulated ANBL-6 cells over unstimulated cells. These results indicate that the primary mechanism of anti-CD40-stimulated proliferation of the ANBL-6 cells is the induction of autocrine IL-6 production. Moreover, these data suggest that the expression of CD40 in malignant plasma cells may play a role in tumor cell expansion, possibly by stimulating the induction of autocrine IL-6 secretion.