Strain differences of age-dependent changes in the responsiveness to a T-independent type-2 antigen in mice

We have assessed age-associated early changes in antibody response to a T-independent type-2 (TI-2) antigen, dinitrophenylated ficoll (DNP-Ficoll). Mice of most strains, including long-lived and autoimmune-prone strains, give a high response when approximately 2 months old; thereafter the response declines sharply to the 3rd-4th month of age and continues to do so, more gradually, up to the age of 6 months. Age-related changes in the response of C57BL/6 mice follows a different course: the response remains unchanged up to the first year of life, i.e. to middle age. The in vitro anti-DNP-Ficoll antibody response of B cells could be increased by the addition of young syngeneic T cells. The augmenting activity of splenic T cells of C3H/He mice declines clearly as a function of age. In contrast, splenic T cells of C57BL/6 mice have low augmenting activity whether the T cells are obtained from young or middle-aged donors. Unlike the augmenting capacity of T cells, B-cell responsiveness to DNP-Ficoll increases until middle age in all strains examined. We conclude that early age-associated changes in antibody response to the TI-2 antigen is polymorphic and that the early age-related decline in in vivo responsiveness is attributable to an age-associated decline in augmenting T helper cell activity.