Effect of rheumatoid factor and anti-immunoglobulin G antibodies on complement-mediated lysis of herpes simplex virus-infected human fibroblasts.

The effect of various anti-immunoglobulin G (IgG) antibodies on the complement-mediated lysis of herpes simplex virus-infected human fibroblasts was determined. IgM rheumatoid factor, a naturally occurring anti-human Fc, inhibited lysis, whereas rabbit anti-human IgG serum potentiated immune cytolysis. We attempted to explain this disparity by determining the effect various classess of anti-IgG's with differing specificities had on complement-mediated lysis. Inhibition of cytolysis occurred with IgM anti-Fc and all of the IgG antiglobulins (anti-IgG, Fab, and Fc). In contrast, IgM anti-Fab enhanced lysis. IgM anti-IgG suppressed immune cytolysis when high concentrations of antiviral serum were incubated with the virus-infected cell, but augmented lysis when low concentrations of anti-herpes simplex virus antibody were exposed to the fibroblasts. The experiments indicated that whether a particular antiglobulin potentiates or inhibits lysis depends on the concentration of antibody bound to the target cells as well as the class and specificity of the antiglobulin exposed to the antibody-coated cell.