Muramyl dipeptide-induced changes in murine splenocyte responses to concanavalin A

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.

Modulatory effect of mycobacterium cell wall extract (Regressin) on lymphocyte blastogenic activity and macrophage cytokine gene transcription in swine

Mycobacterium cell wall extract (MCWE) (Regressin) contains trehalose dimycolate and muramyl dipeptide, both of which have immunomodulatory properties. The goal of this study was to evaluate the effect of MCWE on the in vitro peripheral blood lymphocyte blastogenic activities to mitogens phytohemagglutinin (PHA) and concanavalin A (ConA) in 6- to 8-week-old piglets. The effect of MCWE on alveolar macrophage tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) gene transcription, as determined by a reverse transcription-PCR assay standardized with the endogenous glyceraldehyde-3-phosphate dehydrogenase gene, was also investigated. The results show enhanced blastogenic lymphocyte activities to mitogens PHA and ConA in MCWE-exposed cell cultures compared to those of control cell cultures. The enhanced blastogenic activity effect of MCWE was dose dependent. The cell background activity (spontaneous [3H]thymidine incorporation) of lymphocyte cultures was also significantly increased in the presence of MCWE, thereby demonstrating a lymphocyte mitogenic effect of MCWE. Cytokine gene transcription analysis showed that the TNF-alpha transcript levels in alveolar macrophage cell cultures stimulated with MCWE for 6 or 16 h were enhanced compared with those in control cell cultures. An enhancement of IL-1beta mRNA levels in cell cultures stimulated for 16 h with MCWE, compared with those in control cell cultures, was also observed. The overall results demonstrate that MCWE can stimulate lymphocyte functional activity and cytokine mRNA expression in swine, thereby indicating its potential use as a clinical immunotherapeutic agent.

Effects of retinoids on regulatory cellular interactions in primary mixed lymphocyte reaction (MLR)

The effects of two retinoids, all-trans-retinoic acid and 13-cis-retinoic acid on murine splenic lymphocyte proliferative response in mixed culture were evaluated. In contrast with previously reported absence of retinoic acid (RA) effect on mixed lymphocyte reaction (MLR) the conditions for a strong potentiation of proliferative response of murine lymphocytes with RA were obtained. Stimulatory cells were determined to be the main targets for RA. The data suggest that the RA potentiating effect is the result of an increase in stimulator cell immunogenicity after their pre-treatment with RA before use in MLR. Optimal potentiation by retinoids of proliferative response was found at non-optimal conditions of mixed culture.

Comparative study of immunomodulatory properties of muramyl peptides on immune system cells of young and old mice

The immunomodulatory effects of two synthetic muramyl peptides (MP): muramyl dipeptide and glucosaminyl- muramyl dipeptide have been compared. It was shown, that MP effects on immune response are a consequence of the alteration in T lymphocyte regulators balance. MP action on old mice immune response and lymphocyte function was stimulating only: increasing of T helper precursors frequency and IL-1 production by macrophages. In the latter both MPs acted as correctors, recovering the decreased IL-1 production by old mice macrophages to young control level.