Antibodies recognizing CD24 LAP epitope on human T cells enhance CD28 and IL-2 T cell proliferation.
Membrane expression of the CD24 molecule on activated T lymphocytes is not elucidated fully. We previously described the intracellular and cell-surface expression of the CD24 sialic acid-dependent epitope(s) on phytohemagglutinin-activated peripheral blood mononuclear cells. However, the CD24 core protein was not detected previously on human T cells. This study reinvestigated the expression and role of CD24 in T cell subsets. We analyzed binding of anti-CD24 monoclonal antibodies (mAbs) to sialic and leucine-alanine-proline (LAP) epitopes in resting and activated, normal T lymphocytes. CD24 LAP and CD24 sialic epitopes were detected on activated CD4- and CD8-positive cells. Although expression of CD24 sialic epitopes remained stably expressed in interleukin (IL)-2-dependent cultures, T cell expression of the LAP epitope was transient. Anti-LAP antibodies strongly enhanced the response of T cells to a combination of anti-CD3/CD28 mAbs and enhanced proliferative response induced by recombinant IL-2. We found similarities in the tissue distribution and function of the human CD24 LAP molecule and the murine, heat-stable antigen, which suggests that CD24 might function as a signaling molecule on human T cells.
Immunogenetic Division, University Hospital, School of Medicine, University of Buenos Aires, Argentina. marysasinectis@com.ar
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Salamone
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Rosselot
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Salamone
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Barboza
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Kado
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Fainboim
D000276:Adjuvants, Immunologic / Q000378:metabolism / Q000494:pharmacology*; D000409:Alanine; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology*; D015703:Antigens, CD / Q000276:immunology*; D051927:CD24 Antigen; D018106:CD28 Antigens / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D018984:Epitopes, T-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology*; D007399:Interphase / Q000276:immunology; D007930:Leucine; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology*; D008562:Membrane Glycoproteins; D009842:Oligopeptides / Q000276:immunology / Q000378:metabolism; D011392:Proline; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism
D000276:Adjuvants, Immunologic; D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D051927:CD24 Antigen; C497889:CD24 protein, human; D018106:CD28 Antigens; D018984:Epitopes, T-Lymphocyte; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D009842:Oligopeptides; D011392:Proline; D007930:Leucine; D000409:Alanine