Immunogenic potency of human gamma-globulin in mice.

Heat-treated, but not untreated, human γ-globulin (HGG) is a potent antigen for the initiation of primary antibody response in mice. Thus a dose as low as 10 g of heat-treated HGG was sufficient to induce an excellent primary response in intact mice. However, the primary response was meagre and negative in the cell-transfer and diffusion-chamber culture systems of dispersed spleen cells, respectively. In contrast, no significant difference could be demonstrated between heat-treated and untreated HGG preparations in their capacity to induce a secondary response in intact mice. Furthermore, good secondary responses were obtained in both the cell-transfer and diffusion-chamber culture systems. This suggests differences between primed and non-primed spleen cells in their requirements of cellular organization for the initiation of antibody response. Both the primary and the secondary responses were found to be antigen—dose dependent, although the optimum antigen dose range was broad. Moreover, doses of heat-treated HGG (≤10 g) lower than that reported for the excellent immunogen, flagella, were sufficient to induce secondary responses, thereby emphasizing the utility of HGG for studying the role of antigen in the initiation of primary and secondary antibody responses.