NK1(-) CD8(-) ALPHA-BETA T-CELLS IN THE PERITONEAL-CAVITY - SPECIFIC T-CELL RECEPTOR-MEDIATED CYTOTOXICITY AND SELECTIVE IFN-GAMMA PRODUCTION AGAINST B-CELL LEUKEMIA AND MYELOMA CELLS() CD4()

NK1(+) double negative (DN) alpha beta T cells were present in the per itoneal exudate cells (PEC) of both normal and athymic B6 mice, accoun ting for as much as 25% of the total T cells, while their numbers were far less in the PEC of BALB/c and (BALB/c x B6)F-1 mice. IL-2-depende nt clones established from the DN alpha beta T cell population in the PEC of IL-2 receptor alpha-chain transgenic B6 mice exhibited potent c ytotoxicity against a series of B cell lineage leukemias and myelomas, such as CD5(+)BCL1 and MOPC, without affecting NK-susceptible targets . The cytotoxicity of the clones against BCL1 and MOPC was specificall y inhibited by anti-CD3, anti-alpha beta TCR, or anti-relevant V beta (V beta 8) Ab, but not by control Abs, indicating that it was mediated by the specific alpha beta TCR/CD3. Other BALB/c-derived target cells expressing both MHC class I and class II were not affected, and neith er Ab against them affected the cytotoxicity, strongly suggesting that the cytotoxicity of NK1(+) DN ap T cell clones was independent of the particular MHC Ags. The clones produced IFN-gamma, but little IL-2 or IL-4, in response to anti-CD3 stimulation, to the susceptible, but no t resistant, targets, and to IL-12. The clones exhibited TCR alpha (V alpha 8) distinct from an invariant TCR alpha (V alpha 14) reported to dominate in thymic NK1(+) ap T cells. The presence of DN alpha beta T cells with similar functional features in the normal PEC was confirme d by the short term stimulation in vitro. The present results along wi th other recent reports strongly suggested that, like the mainstream a lpha beta T cells, the NK1(+) DN alpha beta T cell population consiste d of functionally heterogeneous subsets.