[Changes caused by staphylococcal protein A and gamma interferon on the natural cytotoxic activity in patients with cancer].

The effects on natural killer (NK) activity of in vitro incubation of effector cells with staphylococcal Protein A (SPA) and gamma interferon (gamma IFN) in patients with different types of tumors have been compared. The modifications induced in NK activity by these two immunomodulators were assessed using the K-562 cell line and autologous tumoral cells as targets of natural cytotoxicity. The results obtained show that both SPA and gamma-IFN are good inducers of NK activity against the K-562 cell line. SPA always shows itself more efficient than gamma-IFN in increasing the basal level of NK activity. The cytotoxicity against autologous tumoral cells was also greatly increased by the two immunomodulators assayed, SPA being also in this type of assay more efficient than gamma-IFN. Taken the data as a whole the increases induced by SPA and gamma-IFN are parallel both against K-562 and autologous tumoral cells. However when the different types of tumours are considered separately some discrepancies between NK activity against K-562 and autologous tumoral cells appear. The effects of SPA as a modifier of NK activity against autologous tumoral cells looks clear. In our experiments incubation of effector cells with SPA behaves more effectively than the well established gamma-IFN model in the induction of this type of activity. The intimate mechanisms by which SPA exerts its action are quite interesting and merit further investigation.