The effect of TP-3 (Arg-Lys-Asp), TP-4 (Arg-Lys-Asp-Val), and TP-5 on the metastatic capacity of intravenously injected Lewis lung tumor cells.

The oligopeptides Arg-Lys-Asp (TP-3), Arg-Lys-Asp-Val (TP-4), and Arg-Lys-Asp-Val-Tyr (TP-5) considered as the active short fragments of thymopoietin were administered (lo mg/kg) to C57B1 mice 24 hours before the intravenous inoculation of Lewis lung tumor (LLT) cells. A substantial decrease in lung metastasis number was observed as a result of treatment with all of the three oligopeptides. TP-3, TP-4, and TP-5 treatment decreased the immunosuppressive activity of Cyclophosphamid (240 mg/kg) given 96 hours before the inoculation of LLT cells. After thymectomy, performed eight days before the LLT inoculation, only TP-3 treatment resulted in the decrease of Cyclophosphamid immunotoxicity. A stimulating effect of TP-3 on T helper cell activity is assumed. The oligopeptides TP-3, TP-4, and TP-5 are recommended for clinical trial in case of malignant tumors and immunodeficiency.