Activation signal induces the expression of B cell-specific CD45R epitope (6B2) on murine T cells.
T lymphocytes express multiple forms of the leukocyte-common antigen CD45, transcribed by alternative usage of leukocyte-common antigen exon 4-6. The various isoforms of CD45R expressed differentially on T cells are involved in different stages of development and activation. The monoclonal antibody (MoAb) RA3-6B2 is established as a B cell-type isoform (B220)-specific marker. However, it reacts with certain activated T cells although the relationship between 6B2 expression and T-cell activation is unclear. We have examined the 6B2 expression on activated T cells and found that concanavalin A, anti-CD3 antibody and staphylococcal enterotoxin B (SEB) induced 6B2 expression on T cells. The expression was found on both CD4+ and CD8+ T cells and also was induced by SEB in vivo predominantly on CD8+ T cells. The 6B2+ T cells are IL-2R+ and blasted cells according to flow cytometry analysis. Therefore, the 6B2+ T cells are supposed to be in an activated stage. Enzymatic analysis demonstrated that trypsin treatment decreased the 6B2 expression, whereas neuraminidase increased the intensity on activated T cells. Neither endo-D or endo-H have any effect on the expression and there are no differences, in the results of immunoprecipitation and RT-PCR analysis, between control T cells and activated T cells. Taken together, the 6B2 epitope is presumed to be the product of CD45R modification and is expressed on activated T cells. These results illustrate a novel classification of a T-cell subpopulation bearing a 6B2 epitope.
Watanabe
Y
Y
Department of Biomolecular Engineering, Tokyo Institute of Technology, Yokohama, Japan.
Akaike
T
T
D000818:Animals; D000954:Antigens, Surface / Q000096:biosynthesis*; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D000939:Epitopes / Q000096:biosynthesis* / Q000276:immunology; D005434:Flow Cytometry; D017493:Leukocyte Common Antigens / Q000096:biosynthesis*; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011233:Precipitin Tests; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D000954:Antigens, Surface; D000939:Epitopes; D017493:Leukocyte Common Antigens