Differential effect of aging on the heterogeneity of the immune response to a T-dependent antigen in systemic and mucosal-associated lymphoid tissues.

The heterogeneity of the immune response in various lymphatic sites to trinitrophenylated bovine gamma-globulin was measured in old and young mice at a cellular level using inhibition of plaque-forming cell assay. The primary splenic PFC response of old C57BL/6J male mice was found to be markedly restricted in heterogeneity, with a preferential loss of IgM, IgG, and IgA high avidity PFC. The draining peripheral lymph node IgG PFC response of old mice exhibited similar restriction in heterogeneity, with a preferential loss of high avidity PFC. In contrast, mesenteric and mediastinal lymph node PFC response of old mice remained highly heterogeneous with respect to antibody affinity in the 3 isotypes studied. These results support the hypothesis that the mucosal-associated lymphoid system differs from the systemic system with regard to its immune competence with age. Furthermore, the results imply that the T cell helper activity is unimpaired in the mucosal-associated lymphoid apparatus in aged animals.