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-? when exposed to antigen in vitro. Conversely, lymph node cells of irradiated (550 rads) BALB/c mice produce IFN-?. Transfer experiments show that normal BALB/c mice contain cells which suppress IFN-? production. These downregulatory cells are CD4+??+and rearrange the invariant V?14-J?281 T cell receptor ? chain, thus belonging to the NK T cell subset. Downregulatory cells probably act by producing IL-4 as their effect is blocked by mAb to IL-4.