EFFECTS OF THYMIC PEPTIDES, IN-VITRO, ON THE IMPAIRED IMMUNOCYTOTOXICITY OF PERIPHERAL-BLOOD MONONUCLEAR-CELLS FROM TUMOR PATIENTS

The effects of a thymic peptide preparation (TP) on the immunocytotoxi city and cytokine secretion of peripheral blood lymphocytes and monocy tes from patients with colorectal tumors, breast tumors and melanoma w ere studied in vitro. On average, breast tumor and melanoma patients s howed significantly lower natural killer (NK) cell activities than col orectal tumor patients and normal controls. In contrast, the generatio n of lymphokine (IL-2) activated killer (LAK) cells was found to be co mparable within the different tumor diseases (24% cytotoxicity), but l ower than in the group of normal controls. TP, being without any effec ts on NK cell activity in all groups, increased the deficient LAK cell activity of breast tumor and melanoma patients, as well as of normal controls? without significant effects on PBL from colorectal tumor pat ients. This increase was found to be associated with an increase of th e IL-2 induced IFN-gamma and, on a lower level, TNF-alpha secretion, e specially from breast tumor and melanoma patients. In addition, monocy tes from these patients showed a deranged tumoristatic activity, compa red to colorectal tumor patients and normal controls. The stimulation of monocytes by IFN-gamma greatly elevated the mean of the antitumor a ctivity in all groups studied. TP being slightly effective on monocyte s from melanoma patients, did not further enhance monocyte-mediated cy totoxicity when applied alone or in combination with IFN-gamma. Reduce d basal monocytic chemokine levels were only found in the groups of me lanoma (IL-8) and colorectal tumor patients (MCP-1), whereas RANTES se cretion was increased, compared to normal controls. TP was active only in reducing the IL-8 secretion of monocytes from colon tumor patients . The results indicate that selected functions of peripheral blood mon onuclear cells can be partially improved by the thymic peptide prepara tion.