T cell involvement in production of tumor necrosis factor: reconstitution experiments with nude mice.

In order to investigate the role of T cells in the production of tumor necrosis factor (TNF), a reconstitution experiment was performed with nude mice (Balb/c, nu/nu). The results obtained were as follows: 1) The cytotoxic activity of tumor necrosis serum (TNS) from Balb/c, nu/nu mice treated with Propionibacterium acnes-LPS was 1/22 of that from Balb/c, nu/+ mice. 2) TNF activity increased 14 times in reconstituted nude mice as compared to Balb/c, nu/nu mice. 3) The production of the cytotoxic activity per cell was investigated using T cell and macrophage fractions separated from the spleens of both Balb/c, nu/nu and Balb/c, nu/+ mice treated with P. acnes as a priming agent. Elicitation with LPS was done in vitro. Release of cytotoxic activity into the culture medium was observed in the macrophage fraction, but not in the T cell fraction. However, no significant species difference was found. 4) With P. acnes treatment, the population of macrophages in the spleens from Balb/c, nu/+ mice increased 25.5 times, whereas that from Balb/c, nu/nu mice only increased 6.8 times. The above results suggest that the mechanism of the incremental effect of T cells on TNF production was due to the promotion of macrophage proliferation during the priming period after injection of P. acnes.