Myelopeptide-2 recovers interleukin-2 synthesis and interleukin-2 receptor expression in human T lymphocytes depressed by tumor products or measles virus.

Myelopeptide-2 (MP-2; Leu-Val-Val-Tyr-Pro-Trp), originally isolated from the supernatant of porcine bone marrow cell culture, is able to restore the mitogen responsiveness of human T lymphocytes inhibited by conditioned medium from HL-60 leukemia cells or measles virus. This effect is based on the ability of MP-2 to recover the reduced interleukin (IL)-2 synthesis and IL-2 receptor (IL-2R) expression in human T lymphocytes treated with these harmful agents. The involvement of other cytokines in MP-2 restoration of the reduced IL-2 synthesis in T lymphocytes is experimentally studied. It is shown that T helper (TH) 1 and TH2 cytokines are acting in close interaction, the character of which depends on the immune status of the T-lymphocyte donors. The data obtained allow one to suggest that the MP-2 involvement in regulatory processes is directed to the maintenance of immune homeostasis. This peptide is perspective to be applied in antitumor and antivirus therapy.