Tuftsin stimulates the release of oxygen radicals and thromboxane from macrophages.

The physiologically occurring tetrapeptide, tuftsin (Thr-Lys-Pro-Arg), was examined for its effects on guinea pig peritoneal macrophages. Adherent macrophages (møo) were exposed to tuftsin at concentrations ranging from 10(8) to 10(6) M, and the release of oxygen radicals and the arachidonic acid cyclo-oxygenation product, thromboxane B2 (TXB2), was studied. Tuftsin causes both albumin-elicited and C. parvum-activated møo to set free superoxide anion (O2) and hydrogen peroxide (H2O2). It also stimulates the liberation of TXB2 from albumin-elicited møo. The demonstrated induction of the release of toxic oxygen species from møo by tuftsin may explain how tuftsin-augmented møo-mediated cytotoxicity is accomplished.