ABSTRACT
Myelopeptides are immunoregulatory molecules originally isolated from porcine bone marrow cell culture. The influence of synthetic analogous of these peptides on IL-1 and IL-2 activities was studied. Myelopeptide-1 but not myelopeptide-2 replaced IL-1 activity in a test of costimulation of thymocyte proliferation in the presence of mitogen. Conversely, myelopeptide-2, but not myelopeptide-1, stimulated both production of IL-2 by murine splenocytes and IL-2-dependent proliferation of CTLL-2 cell line. The enhancing effect of myelopeptide-2 on IL-2-associated processes was the most pronounced at the early stages of cell activation. The resting T cells stimulated with suboptimum doses of concanavalin A and activated T cells, expressing low level of IL-2R, were sensitive to myelopeptide-2 action. The possible role of myelopeptides in differentiation of T0 helper into T1 helper and T2 helper is discussed.
