Age-related enhancement of tumor necrosis factor (TNF) production in mice

We investigated age-related changes in the production of TNF at the cellular level using immunocompetent peritoneal and spleen cells from C3H/He mice of various ages. The density of cultured peritoneal macrophages and spleen cells required for TNF production was at least 5 x 10(5) cells/dish. The optimal concentration of OK-432 for 24-h culture of peritoneal macrophages (1 x 10(6) cells) and spleen cells (1 x 10(7) cells) was 0.5 and 0.1 KE/ml, respectively. Among peritoneal cells, adherent macrophages were the major TNF-producing cells, whilst nonadherent T or B cells alone did not produce TNF after stimulation with OK-432. In the case of spleen cells, T or B cells were involved in the production of TNF when cultured with a few adherent cells in the presence of OK-432. However, T or B cells alone failed to produce TNF. Production of TNF by peritoneal macrophages from both male and female mice increased significantly with aging. In contrast, although TNF production by spleen cells tended to increase with aging, no significant change was noted. The total number of peritoneal and spleen cells, respectively increased up to about 18 months after birth with B cells being principally responsible for this age-related increase. We previously reported that systemic production of TNF increases with aging. The present study of TNF production at the cellular level in mice indicated (1) that TNF production per macrophage increased with aging, and (2) that the number of T and B cells involved in the production of TNF in the presence of macrophages also increased at least up to middle age.