Alternative complement pathway-mediated lysis of measles virus infected cells: induction by IgG antibody bound to individual viral glycoproteins and comparative efficacy of F (ab') 2 and Fab' fragments
Sissons, J.G.; Cooper, N.R.; Oldstone, M.B.
Journal of Immunology 123(5): 2144-2149
1979
ISSN/ISBN: 0022-1767 PMID: 489977 Document Number: 147958
Lysis of measles virus-infected cells by human serum is dependent on Ig pathway. The binding sites of IgG measles virus antibody or its fragments on the surface of measles virus-infected cells were determined by cell surface radioiodination and immunoprecipitation. IgG bound to either of the 2 measles virus surface glycoproteins was effective in inducing cell lysis by the alternative pathway. Thus, IgG bound only to the viral hemagglutinin (HA) or only to the fusion protein (F) could induce lysis in C4-depleted human serum; the same number of IgG molecules bound to HA or F induced equivalent dose-related lysis. Divalent antibody bound preferentially to HA on the surface of intact cells; this enabled antibody to F to be obtained free of antibody to HA by adsorption. Quantitative studies of binding and lysis showed that lysis of measles virus-infected cells by whole or C4-depleted serum required binding of at least 10 times more Fab' than F(ab')2 or IgG molecules per cell. C4-depleted serum was quantitatively and kinetically equivalent to whole serum in mediating lysis of measles-infected cells. Hence the binding of IgG to either of the 2 measles viral polypeptides (HA, F) expressed on the surface of infected cells induces lysis by the alternative pathway and there is a clear requirement for divalency for effective induction of lysis.