Immunoregulatory effects of two bone-marrow hexapeptides (myelopeptides) in experimental models of immunodeficiency

Multiple anchoring of myelopeptides on sequential oligopeptide carriers (SOC(n)): synthesis, conformation and studies in human leukemia cells

Myelopeptides, MP-6 (Val-Asp-Pro-Pro) and MP-4 (Phe-Arg-Pro-Arg-Ile-Met-Thr-Pro), induce metabolic changes in human leukemia cells, HL-60, characteristic of the differentiation process, which should be regarded as a promising therapeutic approach in cancer and related diseases. With the aim to optimize the differentiation effect of MPs, they were coupled to the Lys-N(epsilon)H(2) groups of a sequential oligopeptide carrier Ac-(Lys-Aib-Gly)(4), SOC(4), and the constructs obtained were studied. The rigid 3(10) secondary structure of the carrier is preserved even after linkage of the MPs, which also maintain their initial conformations without interacting either with each other or with the carrier, as demonstrated by (1)H nuclear magnetic resonance (NMR) spectroscopy. It is concluded that the carrier accommodates the presentation of MPs, thus improving their differentiation effect on human leukemia cells.

Bone marrow immunoregulatory peptides (myelopeptides): isolation, structure, and functional activity

Myelopeptides (MPs) are bioregulatory mediators of bone marrow origin. Several individual MPs have been isolated from the supernatant of porcine bone marrow cell culture by successive solid phase extraction and reversed-phase high performance liquid chromatography. Two of them, MP-1 (Phe-Leu-Gly-Phe-Pro-Thr) and MP-2 (Leu-Val-Val-Tyr-Pro-Trp), were synthesized and their biological activities were comprehensively studied. Both hexapeptides display pronounced immunoregulatory activity but their final effects as well as mechanisms of action are different. Peptides MP-1 and MP-2 are identical to conservative fragments 33-38 alpha- and 31-36 beta-chains of hemoglobin, respectively. The sequences of other isolated MPs have no homology with any functional protein. The role of MPs in bioregulatory processes in vivo is discussed.

Immunostimulatory activity of Milife, a novel immunomodulator of fungus origin

Milife is a novel immunomodulator derived from the fungus Fusarium Sambucium. In this study we examined immunomodulatory properties of Milife in 10 months-old BLRB mice. Milife was given to mice orally in a daily dose of 1 mg per mouse, for 2 to 6 days. Groups of mice were sacrificed on days 2, 4, and 6 of treatment, and 3 weeks after completion of a 6 days treatment with Milife, and lymphoid organs were obtained for analysis. Milife administration led to rapid and significant increase in total leukocyte and lymphocyte numbers in peripheral blood that persisted for at least 3 weeks after a 6 days treatment. Cellularity of lymph nodes, bone marrow and thymus increased significantly at days 4 and 6 of treatment, but returned to pretreatment levels after Milife discontinuation. Though total splenocyte numbers did not change dramatically, there occurred delayed increase in CD4+ cells in the spleen 3 weeks following treatment. Preferential accumulation of CD4+ cells was also consistently found in peripheral blood, with the peak being observed at day 6 of treatment. As a result, CD4/CD8 ratio in blood and spleen was significantly higher in treated than in untreated mice. Splenocytes from treated mice proliferated more vigorously in response to Con A. When added in vitro, Milife also mildly costimulated Con A-induced proliferation of splenocytes from intact animals. In conclusion, we have found that Milife can stimulate leuko- and lymphopoesis in BLRB mice, in particular, accumulation of CD4+ T cells in peripheral lymphoid organs. We conclude that Milife may represent an immunomodulator with the potential to correct T cell dysfunction in patients with immunodeficiency.