Demonstration of antigen-specific immune response against Streptococcus sanguis

The genetic control of Streptococcus sanguis antigen response was studied. Mice sensitized with inactivated S. sanguis organisms antigen-injected at the base of the tail developed footpad swelling. Those with an I-Ak,q,r region of H-2 showed a strong footpad response, whereas those with an I-Ab,d,s region showed a weak response to S. sanguis cell wall antigen. Footpad response was mediated by CD4+,8- T cells by using in vitro monoclonal antibody treatment. Similar evidence of genetic control was obtained with an in vitro T cell proliferation assay. However, quantitation of antibodies against S. sanguis showed that antibody production was not controlled by H-2. These results indicated that both in vivo footpad swelling and in vitro T cell proliferation responses were functions of helper (CD3+,4+,8-) T cells and controlled by the I-A region of H-2.