ANTIGENIC MODULATION OF LYMPHOCYTIC SURFACE-IMMUNOGLOBULIN YIELDING RESISTANCE TO COMPLEMENT-MEDIATED LYSIS .2. RELATIONSHIP TO REDISTRIBUTION OF THE ANTIGEN

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 42  (1) , 13-17
Abstract
Experiments were carried out on guinea-pig L2C leukemic lymphocytes to investigate the mechanism of antigenic modulation of their surface Ig defined as the conferring by anti-Ig of resistance to lysis by anti-Ig plus complement [C]. The phenomenon reflects, and is probably a consequence of, Ig molecule redistribution by bivalent antibody. Fab fragments of the antibody were completely ineffective. Parallel studies by indirect immunofluorescence of surface antigen-antibody complex movement revealed that modulation for syngeneic C was apparent when the complexes were minimally aggregated: capping and extensive endocytosis were not necessary. Modulation for xenogeneic (rabbit) C required more extensive movement but was still appreciable while complexes persisted on the surface. NaN3 at 10 mM, which inhibits antibody-induced surface molecule redistribution, diminished modulation. In experiments omitting pre-incubation with antibody alone, the NaN3 presence during incubations with anti-Ig plus syngeneic C increased lysis from a low and variable to a consistently high level; there was no effect on the already high level of lysis occurring with the non-modulating anti-Ia plus syngeneic C. This NaN3 effect provides further evidence that antigenic modulation can be a major factor determining a cell''s survival when it is confronted simultaneously by antibody and C.