Human platelet alloantigens Bra/Brb are expressed on the very late activation antigen 2 (VLA-2) of T lymphocytes.
We report the molecular localization of the human platelet alloantigens Bra/Brb on activated T lymphocytes. By radioimmunoprecipitation anti-Bra precipitated two proteins from T lymphocytes of Br(a+) donors after long-term activation (24 days), but not from resting or short-term-activated T lymphocytes (4 days). No bands could be precipitated with anti-Bra from T lymphocytes of Br(a-) donors, but the same two bands were seen with anti-Brb. The apparent molecular weights of unreduced molecules were 155 and 130 kDa, respectively. Monoclonal antibody Gil4 directed against an epitope on the platelet membrane glycoprotein Ia/IIa complex precipitated the same two bands with long-term-activated T lymphocytes, whereas MoAb TS2/7 directed against very late antigen (VLA)-1 molecules precipitated two bands with Mr 180 and 130 kDa (alpha 1 beta heterodimer). The physicochemical properties of these two bands precipitated by anti-Bra, anti-Brb or monoclonal antibody Gil4 with molecular weights of 155 and 130 kDa, respectively, correspond to VLA alpha 2 and beta chains and fit defined criteria for the VLA-2 antigen. These results were corroborated by an assay employing monoclonal antibody for antigen immobilization showing that Bra and Brb antigens were present only on long-term activated T lymphocytes. Our results provide evidence for the expression of the Bra/Brb platelet alloantigen system on VLA-2 antigens of activated T lymphocytes and demonstrate a genetic polymorphism of VLA-2 molecules on both cell lines.
Santoso
S
S
Institute for Clinical Immunology and Transfusion Medicine, Justus-Liebig University, Giessen, Federal Republic of Germany.
Kiefel
V
V
Mueller-Eckhardt
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C
D000943:Antigens, Differentiation / Q000235:genetics; D016824:Antigens, Human Platelet; D001792:Blood Platelets / Q000276:immunology*; D002478:Cells, Cultured; D006801:Humans; D007519:Isoantigens; D008213:Lymphocyte Activation; D011110:Polymorphism, Genetic; D016029:Receptors, Very Late Antigen; D013601:T-Lymphocytes / Q000276:immunology*
C055973:5b alloantigen, human; D000943:Antigens, Differentiation; D016824:Antigens, Human Platelet; D007519:Isoantigens; D016029:Receptors, Very Late Antigen