Induction of an immune response through interaction of helper cells with an immune complex bound to the surface of B cells

Abstract Adoptive anti-trinitrophenyl (Tnp) responses were elicited from Tnp-hemocyanin (Tnp-KLH)-primed cells by challenge with an immune complex of KLH and a Tnp conjugate of the Fab fragment of rabbit anti-KLH. Removal of T cells by treatment with anti-Thy 1.2 (phi C3H) + complement abolished this effect. Tnp-KLH primed cells that had been incubated with a Tnp conjugate of pneumococcal polysaccharide type III (Tnp-SIII), and which were then unable to respond to Tnp-KLH, made an anti-Tnp response upon incubation with rabbit anti-Dnp when transferred together with cells primed with rabbit gamma globulin. Since Tnp-KLH was not added in these experiments, it would appear that the cells were triggered by immune complexes on their surfaces consisting of Tnp-SIII and rabbit anti-Dnp with the help of T cells primed with rabbit gamma globulin; the presence of free antigen was evidently not required. Therefore, antigen-antibody complexes, when bound to the surface of B cells, may mediate T-B cell cooperation in the humoral immune response.