Immunomodulatory activity of a potent thymopentin analog: disulphide bridged beta-mercaptopropionyl-arginyl-lysyl-aspartyl-valyl-tyrosyl-cysteine amide.

The immunomodulatory activity of the disulphide bridged heptapeptide Mpa-Arg-Lys-Asp-Val-Tyr-Cys-NH2 (CTP-1), containing the thymopentin (TP5) sequence (Arg-Lys-Asp-Val-Tyr), was investigated by different immunological tests. The activity of CTP-1 was compared with the activities of two other disulphide bridged TP5 analogs: Mpa-Arg-Lys-D-Pro-Val-Tyr-Cys-NH2 (CTP-2) and Mpa-Arg-Lys-Asp-Val-Pro-Cys-NH2 (CTP3). The results obtained indicate that from the whole series of TP5 analogs CTP-1 may be of interest from the point of view of its prospective medical use. The results of autologous rosette forming cells (ARFC-test), as well as the direct examination of the influence of CTP-1 on the interleukin-1 (IL-1) production by P-388 D1 cell line evidence that the mechanism of CTP-1 action involves stimulation of IL-1 production. The results of E-rosette assay, ARFC test, and imuran test show that the activity of CTP-1 is stronger than that of TP5.