Antibody-forming potential of lymph nodes in aged mice, with special reference to the influence of adjuvant

The secondary antibody-forming potential of non-splenic lymphatic tissues during senescence was investigated in NMRI/Han mice, both at the cellular and humoral levels. The mean life span of conventionally reared NMRI/Han mice amounts to 19.86 months. After primary immunization of aged (20-month-old) NMRI mice with 4 X 10(8) sheep erythrocytes (SE) by the intraperitoneal (i.p.) route, the primary antibody-forming potential of both spleen and lymph nodes was significantly reduced, as compared to young adult (3-month-old) controls. In contrast, the anamnestic response elicited by an i.p. booster injection of 4 X 10(8) SE at the 44th day after primary immunization was not significantly diminished in comparison to the controls. When killed cells of Bordetella pertussis were found to be significantly increased in young adult as well as in aged mice. These data obtained at the cellular level were in accordance with corresponding serological findings. The impressive restitution of the antibody-forming potential evident after secondary antigenic stimulation was associated with a remarkable restitution of the lymph node morphology. This was particularly pronounced in the pronounced in the parathymic lymph nodes which represent the draining nodes for the peritoneal cavity. These findings indicate that the lymph nodes of the senescent individual also possess remarkable reserves in immunocompetence.