Whole body irradiation induces IFN-gamma production in BALB/c mice by preventing the appearance of a V alpha 14(+) NK T downregulatory population

Lymph node cells from TNCB-immune BALB/c mice fail to produce IFN-gamma whe n exposed to antigen in vitro. Conversely, lymph node cells of irradiated ( 550 rads) BALB/c mice produce IFN-gamma, Transfer experiments show that nor mal BALB/c mice contain cells which suppress IFN-gamma production. These do wnregulatory cells are CD4(+) alpha beta(+) and rearrange the invariant V a lpha 14-J alpha 281 T cell receptor a chain, thus belonging to the NK T cel l subset. Downregulatory cells probably act by producing IL-4 as their effe ct is blocked by mAb to IL-4. (C) 2000 Academic Press.