In vivo suppression of T-dependent antibody responses by treatment with a monoclonal anti-L3T4 antibody.

Minute amounts of the anti-L3T4 antibody designated GK1.5 were found to deeply suppress in vivo antibody responses to T-dependent antigens. Primary responses to sheep erythrocytes were completely inhibited even when GK1.5 was administered up to 6 days before or 4 days after the antigen. Secondary responses to potent immunogens like sheep erythrocytes or keyhole limpet hemocyanin were also completely abolished by a single injection of GK1.5 just before the boost. This treatment had no effect on T-independent reactions such as the polyclonal activation of B lymphocytes with lipopolysaccharide or the anti-2,4,6-trinitrophenyl (TNP) response elicited by injection of TNP-Ficoll.