Characterization of extrathymic T cells induced by recombinant murine interferon-beta in the peritoneal cavity of nude mice.

The effects of recombinant murine interferon-beta (rMuIFN-beta) on extrathymic lymphocyte formation in the peritoneal cavity of BALB/c athymic nude mice and tumor-bearing nude mice were examined for comparison with BALB/c normal euthymic mice. The 7 days of administration of 1 x 10(5) IU rMuIFN-beta caused the number of these cells to increase remarkably in the peritoneal cavity as a unique subset of asialoGM1+CD4+CD8-TcR alpha beta+ T cells. The asialoGM1+CD4+ T cells produced IL-2 and IFN-gamma in primary culture without stimulant but did not proliferate. Thus, extrathymic T cells can be induced easily in the peritoneal cavity in addition to the thymus for host defense systems.