Expression of HRF20, a regulatory molecule of complement activation, on peripheral blood mononuclear cells.
HRF20 is a homologous restriction factor of 20,000 MW that prevents cells from membrane attack by homologous complement. HRF20 has been identified by a monoclonal antibody (mAb), 1F5, and is one of the phosphatidylinositol(PI)-anchored cell-surface glycoproteins. We analysed the distribution of HRF20 expressed on subsets of peripheral blood lymphocytes using 1F5. HRF20 is expressed in relatively large amounts on T cells. In contrast, adherent cells possess smaller amounts of HRF20 while having large quantities of decay-accelerating factor (DAF). Although DAF was shown to be deficient or present at rather low levels on NK cells, HRF20 was detected in 95% of large granular lymphocytes (LGL), as described by FACS analysis. We also determined the effect of 1F5 on both mononuclear leucocytes and T cells in terms of their growth response. The results show that 1F5 induces T-cell proliferation when cells are stimulated with interleukin-2 (IL-2). In addition, induction of proliferation is facilitated by cross-linking 1F5 with a second antibody. These results suggest that HRF20 expressed on T cells not only protects them from cytotoxic attack by homologous complement, but also may initiate intracellular signals leading to cell activation when they happen to be cross-linked.
Department of Microbiology, Fukuoka University School of Medicine, Japan.
T
T
Hideshima
N
N
Okada
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H
Okada
D000911:Antibodies, Monoclonal / Q000276:immunology; D018957:CD59 Antigens; D002460:Cell Line; D003167:Complement Activation; D015938:Complement Membrane Attack Complex / Q000037:antagonists & inhibitors; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D008214:Lymphocytes / Q000032:analysis*; D008562:Membrane Glycoproteins / Q000097:blood* / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D018957:CD59 Antigens; D015938:Complement Membrane Attack Complex; D008562:Membrane Glycoproteins