Interactions between CD3 and Thy1 T cell activation pathways: blockade of CD3-mediated T lymphocyte activation induced by immobilized anti-Thy1 antibodies.
Resting murine T cell activation induced by either CD3 complexes or Thy1 molecules was investigated in vitro, using surface-bound anti-CD3 mAb as the stimulus. One mitogenic anti-Thy 1 mAb (G7) lost mitogenicity when presented to T cells immobilized on a plastic surface, even in the presence of phorbol ester. Moreover, T cell activation induced by immobilized anti-CD3 was potently blocked by coimmobilized anti-Thy 1 mAb. Nonmitogenic anti-Thy 1 mAb also blocked CD3-induced activation when coimmobilized with anti-CD3. Control experiments showed that anti-Thy 1 specifically blocked T cell activation, even in the presence of measurable and functional concentrations of plastic-bound anti-CD3. Coimmobilized anti-Thy 1 potently blocked IL2 secretion stimulated by anti-CD3. Addition of exogenous rIL2 completely prevented anti-Thy 1-mediated blockade. On the other hand, while completely blocking T cell proliferation, immobilized anti-Thy 1 only partially blocked secretion of IL3-like activity by the T cells. One IgM anti-Thy 1 mAb (2A3) induced secretion of IL3-like activity by T cells when immobilized in the absence of bound anti-CD3. These results indicate that extensive aggregation of Thy 1 molecules delivers a potent negative signal which antagonizes CD3-mediated T cell activation and growth.
Bellio
M
M
Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Brazil.
Leal
L M
LM
Scharfstein
J
J
Dos Reis
G A
GA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D015703:Antigens, CD / Q000502:physiology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D000954:Antigens, Surface / Q000502:physiology*; D017252:CD3 Complex; D005260:Female; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology*; D018800:Thy-1 Antigens
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D017252:CD3 Complex; D007376:Interleukin-2; D011948:Receptors, Antigen, T-Cell; D018800:Thy-1 Antigens