Humoral immunity in aged mice. I. Age-related decline in the secondary response to DNP of spleen cells propagated in diffusion chambers.

The secondary response of young-adult and old BC3F1 mice to DNP was assessed by boosting spleen cells from primed mice with DNP-KLH, propagating them in diffusion chambers implanted into irradiated recipient mice, and by counting the DNP-specific PFC. There was no difference between young-adult and old cells in the antigen dose response and in the kinetics of the immune response. There were marked differences in the magnitude of the peak response. The response of 2-year-old mice was significantly smaller than the response of young-adult mice. Two and one half-year-old mice had the smallest response. In the old mice, there was an inverse correlation between the number of nucleated cells in the spleen and the log of the number of PFC.