bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of MHC-antigen complex formation on antigen-presenting cells.
Authors: Roosnek E , Demotz S , Corradin G , Lanzavecchia A 
Published: December 2022

Abstract
With the use of flow cytometry, we recorded changes in intracellular ionized calcium [Ca2+]i of Indo-1 loaded T cells that were triggered by contact with APC. This rapid readout of TCR perturbation enabled us to monitor the formation of stimulatory Ag-MHC complexes on EBV-transformed B cells that were either pulsed with native tetanus toxoid (TT) or with a 12-amino-acid fragment of this protein. Neither unpulsed APC nor Ag-specific APC that were pulsed with native Ag and kept at +4 degrees C were able to induce changes in basal T cell [Ca2+]i in TT-specific T cell clones. After 1 h at 37 degrees C, however, the Ag-pulsed APC were able to induce a three-to-fourfold increase in [Ca2+]i. This length of time appeared to be almost independent of the concentration of Ag with which the APC were pulsed, suggesting that the lag time was due more to intracellular transit than to association of the processed Ag with the MHC molecule. Furthermore, the same lag time and independence of Ag concentration were found when the EBV-transformed B cells were pulsed with a mouse-anti-transferrin receptor mAb and tested for their capacity to trigger a T cell clone specific for processed mouse Ig. This indicates that, in addition to surface Ig, other receptors that are internalized can function in the same fashion in the uptake and processing of a soluble Ag. In contrast to what was found with intact native Ag, no lag time was observed when the APC were pulsed with high concentrations of a 12-amino-acid peptide, containing the amino acid sequence recognized by a TT-specific T cell clone, suggesting that the formation of MHC-peptide complexes occurs instantly. Pulsing with a lower peptide concentration, however, caused the appearance of a time-dependent increase in efficacy of Ag presentation, suggesting a slow accumulation of MHC-peptide complexes on the B cell membrane.
Autoimmune CD4+ T cells interfere with immune tolerance to a thymic-independent antigen.
Authors: Miller M L , Chacko J A 
Published: December 2022

Abstract
The ability of autoimmune T cell subsets to interfere with tolerization of B cells can be studied by using thymic-independent Ag. We have defined an abnormality within the CD4+ T cell compartment in young NZB and MRL-lpr/lpr mice by studying tolerance of spleen and B cells to the thymic independent Ag, fluorescein-Brucella abortus. Tolerization of spleen cells is defective in MRL-lpr/lpr mice, but not MRL-+/+ or C3H.lpr mice, suggesting that the defect requires both the autosomal MRL background and the lpr gene to be present. T enriched cells from NZB mice and from MRL-lpr/lpr mice (but not MRL-+/+ or C3H.lpr mice) reverse tolerance in spleen cells from [NZB X DBA/2]F1 and C3H/HeJ mice, respectively. This interference is removed by treatment with anti-CD4 antibody and C. Supernatants from cultured T cells of NZB and MRL-lpr/lpr mice also prevent tolerance in spleen cells of [NZB X DBA/2]F1 and MRL-+/+ mice, respectively, unless CD4+ cells are removed prior to T cell culture. Removal of T cells from NZB and MRL-lpr/lpr spleen cells allows normal tolerization of B cells, which is abrogated by the addition of syngeneic T cells or cultured T cell supernatants. This effect also depends on the presence of CD4+ T cells. These studies show that in MRL-lpr/lpr mice, through interaction of the lpr and MRL background genes in a T cell subset, and in NZB mice, CD4+ T cells interfere with B cell tolerance to a thymic-independent Ag.
Altered expression of lymphocyte differentiation antigens on phorbol ester-activated CD4+8+ T cells.
Authors: Richie E R , McEntire B , Phillips J , Allison J P 
Published: December 2022

Abstract
Altered expression of cell surface Ag is an early event accompanying Ag-, mitogen-, or phorbol ester-induced activation of mature T cells. In this report, phorbol ester-induced changes in the expression of several functionally significant cell surface molecules are explored on immature thymocytes and lymphoma cells presenting a cortical CD4+8+ double-positive (DP) phenotype. Both CD4 and CD8 expressions are down-modulated on DP cells incubated with PMA. Cell-surface expression of CD4 and CD8 remains depressed for 72 h in the presence of PMA, but is restored after removal of PMA from the culture medium. The PMA-mediated loss of Ag expression is associated with a rapid down-regulation of steady state CD4 and CD8 mRNA transcript levels in treated cells. The sustained loss of CD4 and CD8 surface expression on DP cells is a selective event because CD5 expression is enhanced, H-2 expression is unchanged, and CD3 expression is only transiently diminished by PMA stimulation. Other T cell-activating agents, including Con A, ionomycin, and anti-CD3 mAb, induce selected surface antigenic changes on DP cells, but do not mimic the pattern of altered Ag expression observed after PMA stimulation. These data demonstrate that, similar to mature subsets, T cells in the DP nonmature compartment undergo alterations in expression of functionally important cell-surface molecules in response to activating agents. Nevertheless, distinctions between mature and nonmature T cells regarding specific alterations in differentiation Ag phenotype suggest that the effect of PMA on expression of these molecules depends, in part, on the maturation stage of the target cell population.
Human monoclonal rheumatoid factor-like antibodies from CD5 (Leu-1)+ B cells are polyreactive.
Authors: Nakamura M , Burastero S E , Notkins A L , Casal P 
Published: December 2022

Abstract
CD5+ lymphocytes constitute a major subset of the normal human B cell repertoire. We found here, by transformation with EBV and limiting dilution analysis, that the majority of CD5+ B cells from healthy subjects are committed to the production of antibodies with rheumatoid factor-like activity. By fusing the EBV-transformed cells generated from CD5+ B lymphocytes with human-mouse heterohybrid cells, we constructed continuous cell lines producing mAb. These mAb bound not only to the Fc fragment of IgG but also at varying degrees to other self-Ag, such as ssDNA, thyroglobulin, and insulin, as well as to exogenous Ag, such as tetanus toxoid, LPS from Gram-negative and polysaccharides from Gram-positive bacteria. Competitive inhibition studies revealed that although each of the mAb reacted with the Fc fragment of IgG, their functional affinities for other Ag varied by as much as 1000-fold. Our studies argue that broad polyreactivity is an inherent property of the antibodies produced by CD5+ B lymphocytes and that these antibodies may be what has been referred to as the "natural antibodies" of the serum.
Transforming growth factor-beta 1 modulates the expression of class II histocompatibility antigens on human cells.
Authors: Czarniecki C W , Chiu H H , Wong G H , McCabe S M , Palladino M A 
Published: December 2022

Abstract
We have examined the effects of transforming growth factor-beta (TGF-beta 1) on the expression of the class II histocompatibility Ag, HLA-DR: 1) induced by human rIFN-gamma (rHuIFN-gamma) in human melanoma, Hs294T cells and 2) constitutively expressed in a subclone Hs294T cell line. The expression of HLA-DR Ag on Hs294T cells was induced by rHuIFN-gamma in a dose- and time-dependent manner with maximal levels obtained with 10 ng/ml rHuIFN-gamma after 48 h exposure. Treatment of Hs294T cells with natural porcine platelet-derived or human rTGF-beta 1 (1 to 100 ng/ml) in the presence of rHuIFN-gamma (0.1 to 10 ng/ml) reduced the percentage of cells positive for this Ag by approximately 40 to 50%, as determined by flow cytometry. This suppressive effect of TGF-beta 1 was not restricted to Hs294T cells inasmuch as rHuIFN-gamma induced HLA-DR surface Ag expression on PBMC-derived adherent cells was also significantly inhibited by TGF-beta 1. Northern blot analysis of cytoplasmic RNA extracted from Hs294T cells indicated that the decreased levels of HLA-DR cell-surface Ag correlated with decreased levels of mRNA transcripts encoding this Ag. TGF-beta 1 also effectively reduced the levels of HLA-DR mRNA in 1) cells that had been pretreated with rHuIFN-gamma and were expressing maximal levels of HLA-DR surface antigen and 2) cells that constitutively expressed HLA-DR surface Ag without exogenous rHuIFN-gamma treatment.
C-reactive protein antigenicity on the surface of human peripheral blood lymphocytes. Characterization of lymphocytes reactive with anti-neo-CRP.
Authors: Bray R A , Samberg N L , Gewurz H , Potempa L A , Landay A L 
Published: December 2022

Abstract
Previously, we have shown that antibodies specific for C-reactive protein determinants, not present on the native molecule, termed neo-CRP, also react with a significant percentage of PBL. In the present study, cells were evaluated by flow cytometry using alpha-neo-CRP antisera and mAb specific for lymphocyte subsets. With use of either monocyte-depleted PBL or Percoll-enriched large granular lymphocytes, we observed an overlap between cells reactive with alpha-neo-CRP and cells bearing the surface markers CD16, CD11b, Leu-7, and/or Leu-19, which are expressed on NK cells. In addition, we showed co-expression of the neo-CRP antigen with CD19, CD20, and HLA-DR, cell surface markers which are expressed on B lymphocytes. The major proportion of CD3+ cells failed to exhibit co-expression of neo-CRP. Single parameter flow cytometric analyses demonstrated that cells reactive with alpha-neo-CRP exhibited a bimodal staining pattern based on fluorescence intensity: high intensity neo-CRPbright and low intensity neo-CRPdim. Two-color analysis revealed that neo-CRPbright cells co-expressed CD19, CD20, and HLA-DR, whereas neo-CRPdim cells co-expressed CD16, CD11b, Leu-7, and Leu-19. Anti-neo-CRP also reacted with PBL obtained from patients with CD16+ lymphoproliferative disorders and from patients with chronic lymphocytic leukemia of B cell origin, but not with cells from patients with T cell or myeloid leukemias. The alpha-neo-CRP cells from patients with NK cell expansions showed dim fluorescence, whereas patients with B cell expansions showed bright fluorescence, consistent with the staining patterns observed with normal PBL. In addition, cell lines of T cell, B cell, NK cell, myeloid, and erythroid origin were evaluated for reactivity with alpha-neo-CRP. The cloned NK cell line NK 3.3 reacted as neo-CRPdim, but the B cell lines BL41, BL41/95, T1, T2, and CESS all reacted as neo-CRPbright. The cell lines K562, Molt-4, Hut-78, HL-60, U-937, and THP-1-0, which lack characteristic NK and B cell markers, did not react with alpha-neo-CRP. Additional study of the two-color histograms revealed a distinct diagonal staining pattern that was observed only when cells were co-stained with alpha-neo-CRP and either alpha-CD16 (alpha-Fc gamma RIII) or antibody IV3 (alpha-CDw32; alpha-Fc gamma RII). This finding suggests a 1:1 relationship between Fc gamma R on both NK and B cells and determinants recognized by alpha-neo-CRP.(ABSTRACT TRUNCATED AT 400 WORDS)
Ig isotype switching in B lymphocytes. Isolation and characterization of clonal variants of the murine Ly-1+ B cell lymphoma, CH12, expressing isotypes other than IgM.
Authors: Arnold L W , Grdina T A , Whitmore A C , Haughton G 
Published: December 2022

Abstract
We have selected and cloned variant cells from the murine B cell lymphoma, CH12, that produce a variety of other Ig isotypes in addition to or in place of the original IgM and IgD. Variants were selected by flow cytometry and automated cloning and isotype production was analyzed by membrane immunofluorescence and ELISA of culture fluids. Variants have been isolated that produce the single isotypes IgA, IgG2b, and IgG3, as well as variants that produce more than one isotype simultaneously, i.e., IgM, IgD, and IgA; IgG2b and IgA; IgG3 and IgA. All isotypes have been seen as cell surface proteins and all except IgD have been found in culture supernatants. All isotypes display the same idiotype and Ag-binding specificity for phosphatidyl choline as the original IgM and all are translated from the same VDJH and VJ kappa gene assemblies. Production of more than one isotype by a variant clone is due to simultaneous production of all the isotypes by each cell within the clone. The finding that the variants producing more than one isotype are all tetraploid suggests the interesting possibility that each isotype is derived from an independently switching chromosome. All isotype variants can be stimulated by LPS to secrete the appropriate Ig isotype at an increased rate similar to the IgM expressing parent. The variants differ in stability; some have remained stable for more than 9 months in culture, whereas other have undergone further isotype switching. The facts that some isotypes have not been seen, that multistep switching has occurred, and that many variants produce IgA in addition to another isotype are discussed in relation to current notions of isotype switching mechanisms.
Antagonistic effects of calcium ionophores and phorbol esters on T cell receptor mRNA levels in human thymocytes.
Authors: Martinez-Valdez H , Doherty P J , Thompson E , Benedict S H , Gelfand E W , Cohen A 
Published: December 2022

Abstract
Levels of mRNA of the T cell antigen receptors (TcR) in human thymocytes are differentially regulated in response to distinct intracellular signals. Activation of protein kinase C by the phorbol ester, tetradecanoyl phorbol acetate or other phorbol esters increases the levels of the alpha and beta T cell receptor (TcR-alpha, TcR-beta) mRNA, whereas an increase in cytosolic free Ca2+, induced by ionomycin or other Ca2+ ionophores, results in a decrease of alpha and beta TcR mRNA levels. In contrast, ionomycin increases the expression TcR-gamma mRNA whereas tetradecanoyl phorbol acetate prevents this induction. Our results suggest the existence of two opposing intracellular pathways that control expression of TcR-alpha and TcR-beta mRNA levels, on the one hand and TcR-gamma mRNA, on the other. These results provide the first evidence for antagonistic actions of protein kinase C and cytosolic-free Ca2+ on gene expression.
Synergistic inhibition of human marrow granulocyte-macrophage progenitor cells by prostaglandin E and recombinant interferon-alpha, -beta, and -gamma and an effect mediated by tumor necrosis factor.
Authors: Pelus L M , Ottmann O G , Nocka K H 
Published: December 2022

Abstract
The effects of prostaglandin E (PGE) and recombinant human interferon-alpha, -beta, and -gamma alone and in combination were tested for their effects on the proliferation of human bone marrow granulocyte-macrophage colony-forming units (GM-CFU). When tested alone, both classes of cytokines inhibited GM-CFU proliferation. In combination, PGE and all three types of recombinant interferons synergized in their ability to inhibit GM-CFU proliferation. Progressive enrichment for marrow GM-CFU indicated that the synergistic effects of PGE and interferon were dependent upon the presence of marrow-adherent cells. Studies using conditioned media from marrow-adherent cells prepared in the presence of interferon-alpha, -beta, and -gamma indicated that adherent cells produced a soluble factor in the presence of interferons that subsequently synergized with PGE in inhibiting GM-CFU proliferation. Neutralization of this conditioned media with a monoclonal antibody to tumor necrosis factor abrogated the synergistic inhibition of GM-CFU observed in the presence of PGE. The addition of recombinant tumor necrosis factor and PGE to accessory cell-depleted bone marrow resulted in synergystic inhibition of GM-CFU proliferation.
B cell stimulatory factor-2 is involved in the differentiation of cytotoxic T lymphocytes.
Authors: Takai Y , Wong G G , Clark S C , Burakoff S J , Herrmann S H 
Published: December 2022

Abstract
The induction of cytotoxic T lymphocytes (CTL) from precursor T cells requires both antigen and lymphokine signals. Previous work from our laboratory has indicated that three lymphokines are required for the induction of CTL from murine thymocytes; interleukin 2, interferon-gamma (IFN-gamma), and a partially characterized factor referred to as cytotoxic differentiation factor (CDF). While attempting to clone CDF from the human T cell line C10-MJ2, we found that a gene encoding CDF-like activity is identical to the gene encoding the factor known variously as B cell stimulatory factor-2 (BSF-2), IFN-beta 2, and 26-kDa protein. We report here that BSF-2 can induce the differentiation of Ly-2+ CTL from murine thymocytes in the presence of interleukin 2 and that the level of cytotoxicity is augmented by the addition of murine IFN-gamma. Serine esterase, a marker for cytotoxic granules in CTL, was induced only in the presence of BSF-2, and the level of serine esterase activity correlated with the level of serine esterase activity correlated with the level of cytotoxicity. These data suggest that BSF-2 is a differentiation factor for CTL and that it functions in part by inducing proteins required for mediating target cell lysis.
Monoclonal autoantibodies with interleukin 3-like activity derived from a MRL/lpr mouse.
Authors: Sugawara M , Hattori C , Tezuka E , Tamura S , Ohta Y 
Published: December 2022

Abstract
Hybridomas that secrete monoclonal antibodies with interleukin 3 (IL-3)-like activity were established from spleen cells of a nonimmunized autoimmune MRL/lpr mouse. Five of the monoclonal antibodies thus obtained bound selectively to IL-3-dependent cells and supported their growth. These monoclonal antibodies inhibited the binding of IL-3 to FDC-P2 cells and vice versa. Thus, these antibodies were probably directed to IL-3 receptor sites, or at least to some cell surface proteins related to the growth of the IL-3-dependent cells. These MRL/lpr-derived monoclonal antibodies reacted strongly with cells from bone marrow, spleen, and lymph node of MRL/lpr mice, but minimally with such cells of MRL/+ or BALB/c mice. The findings were consistent with our earlier suggestion that the IL-3-like activity in MRL/lpr sera is not caused by IL-3 itself but is associated with IgG that is probably an autoantibody directed to the IL-3 receptor.
Antibody to Trypanosoma cruzi neuraminidase enhances infection in vitro and identifies a subpopulation of trypomastigotes.
Authors: Cavallesco R , Pereira M E 
Published: December 2022

Abstract
A rabbit antibody to the neuraminidase of the infective form of Trypanosoma cruzi identifies a subpopulation of trypomastigotes that expresses neuraminidase. Complement-mediated lysis by the antibody selectively destroys 30 to 40% of the trypomastigotes, supporting the conclusion that the immune antibody binds to a subset of parasites. The trypomastigotes that react with the immune antibody are the only ones expressing neuraminidase because the trypomastigotes that survive complement-mediated lysis are depleted of neuraminidase activity. The enzyme seems to negatively modulate infection in vitro, since infection of host cells by trypomastigotes is enhanced when neuraminidase activity is blocked by antineuraminidase antibody; infection is also enhanced when the infecting trypomastigotes have been depleted of parasites that express neuraminidase. Addition of exogenous neuraminidase (from Vibrio cholerae) to trypomastigotes treated with immune antibody, reverts the enhancement observed when infection takes place in the presence of antibody to T. cruzi neuraminidase only. Addition of V. cholerae neuraminidase in the absence of immune antibodies has no effect on infection. These results show that T. cruzi neuraminidase depresses infection and also suggest that sialic acid is involved in the parasite-host cell interaction. The antibody to T. cruzi neuraminidase recognizes on the surface of live trypomastigotes a set of proteins with high m.w. (165,000 to 200,000) and also two antigens of 79,000 to 82,000. The high m.w. proteins appear to be associated with neuraminidase activity as shown by renaturation experiments of released enzyme fractionated on a sodium dodecyl sulfate-polyacrylamide gel.
Proportion of antigenic variants induced by in vitro UV irradiation differs in clones derived from a single tumor.
Authors: Hostetler L W , Kripke M L 
Published: December 2022

Abstract
The purpose of this study was to examine the capacity of different clones derived from the same tumor to generate highly antigenic cells after in vitro exposure to UV radiation. Cells from the metastatic murine melanoma K1735 and clones of K1735 differing in metastatic potential were exposed to UV radiation in vitro, cloned, and tested for antigenic properties in vivo. Approximately half of the clones isolated after UV irradiation of parental K1735 melanoma cells were highly antigenic (five of nine). Similar treatment of cells of a nonmetastatic clone of K1735 generated clones that were all antigenic (nine of nine). In contrast, only one of nine clones derived from UV-irradiated cells of a highly metastatic clone of K1735 were antigenic. Clones derived from unirradiated cultures were not antigenic variants. The increased antigenicity of cells derived from UV-irradiated cultures did not correlate with an increase in expression of cell surface class I major histocompatibility complex antigens. These results demonstrate that the frequency of antigenic variant production after UV irradiation is an intrinsic property of the particular cell line used, and that even cloned cell lines derived from a single tumor differ in their ability to generate antigenic variants after UV irradiation. In addition, they indicate that the increased antigenicity is not necessarily due to a UV-induced increase in expression of cell surface class I histocompatibility antigens.
Nuclear disintegration induced by cytotoxic T lymphocytes. Evidence against damage to the nuclear envelope of the target cell.
Authors: Howell D M , Martz E 
Published: December 2022

Abstract
CTL and NK cells induce nuclear disintegration in their target cells. This phenomenon, which is seen as extensive fragmentation and solubilization of target cell DNA, is not seen with most other means of inducing cytolysis, including antibody- and complement-mediated cytolysis. We have previously shown that the degree of DNA solubilization is dependent upon the nature of the target cell. We here investigate the possibility that CTL induce, in all targets, damage to the nuclear envelope, which in turn leads to nuclear disintegration in only some of them. We reasoned that damage to the nuclear envelope would render nuclear DNA more accessible to exogenous DNase. Therefore, we determined the susceptibility of target DNA to exogenous DNase I after cytolysis by various means. We found no difference in DNA susceptibility for cells lysed by CTL vs methods (such as complement-mediated lysis or nonionic detergent) incapable of inducing nuclear disintegration. As a positive control, freezing and thawing dramatically enhanced susceptibility of the DNA. In conclusion, we found no evidence that the nuclear envelope is damaged by CTL in target cell types (or in the subpopulation of nuclei) that do not undergo nuclear disintegration.