Cloned murine T lymphocytes synthesize a molecule with the biological characteristics of nitric oxide

Recently, activated neutrophils and macrophages have been shown to synthesize nitric oxide (NO) exclusively from L-arginine. We searched for the presence of this pathway in murine T cell clones. Using a platelet aggregation bioassay sensitive to NO, we demonstrate that IL2-stimulated CTLL and HT2 cells inhibit platelet aggregation, whereas unstimulated lymphocytes do not. This action can be inhibited by the specific NO synthase competitor NG-mono-methyl arginine, and only the L form of arginine or its analogue L-homoarginine are capable of providing substrate for NO synthesis.