Changes in CD45 isoform expression accompany antigen-induced murine T-cell activation.
Leukocytes express a family of plasma membrane proteins called CD45 or the leukocyte common antigen. Isoforms of various molecular masses, 180-240 kDa, are produced by alternative splicing and usage of three exons, named A, B, and C, that encode the N-terminal portion of the external domain. By using monoclonal antibodies that precipitate B exon-dependent and B exon-independent isoforms we find that both murine CD4+ and murine CD8+ T cells selectively down-regulate the B exon-dependent forms of CD45 during an immune response. This change was monitored by using fluorescence-activated cell sorter (FACS) analysis and immunoprecipitation from surface radioiodinated and metabolically labeled cells. The loss of the 190-kDa B exon-dependent isoform during T-cell activation is accompanied by an increased production of a 180-kDa form, which does not contain the B exon-encoded sequence. This accounts for our observation that the overall expression of CD45, as assessed by FACS analysis, does not change.
Birkeland
M L
ML
Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, NY 10021.
Johnson
P
P
Trowbridge
I S
IS
Puré
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D000818:Animals; D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D005091:Exons; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006649:Histocompatibility Antigens / Q000032:analysis / Q000235:genetics / Q000276:immunology*; D017493:Leukocyte Common Antigens; D008198:Lymph Nodes / Q000276:immunology; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008815:Mice, Inbred Strains; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D017493:Leukocyte Common Antigens