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

Abstract

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.