Enhancement of B-cell stimulation by muramyl dipeptide through a mechanism not involving interleukin 1 or increased Ca2+ mobilization or protein kinase C activation.
Muramyl dipeptide (MDP) enhanced mitogenic stimulation of mouse lymphocytes by polyclonal B cell activators (peptidoglycan, lipopolysaccharide, Staphylococcus aureus Cowan I cells, and pokeweed mitogen), but not by T-cell mitogens (phytohemagglutinin and concanavalin A). Only adjuvant-active MDP analogs were effective, whereas adjuvant-inactive MDP analogs, muramic acid, peptidoglycan pentapeptide, and low Mr digests of peptidoglycan were not. The half-maximal enhancement was seen at 5-10 microM MDP and occurred at both optimal and suboptimal concentrations of B cell mitogens. The enhancing effect of MDP was exerted on the B cells, since it was T cell- and macrophage-independent and was not mediated by IL-1. MDP was effective during the first 12 hrs of culture, and most strongly enhanced the mitogen-induced DNA synthesis, although significant enhancement of RNA synthesis and B cell differentiation into antibody-secreting cells was also observed. The enhancement of mitogenic response was not due to changed requirements for extracellular or intracellular Ca2+ or to increased activation of protein kinase C. These results demonstrate a novel immunoenhancing effect of MDP that should be useful in the studies on the mechanism of B cell activation.
D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology*; D000917:Antibody Formation / Q000187:drug effects; D001402:B-Lymphocytes / Q000276:immunology*; D002118:Calcium / Q000502:physiology*; D004334:Drug Administration Schedule; D004357:Drug Synergism; D007375:Interleukin-1 / Q000502:physiology*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008264:Macrophages / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology*; D012313:RNA / Q000096:biosynthesis
D007375:Interleukin-1; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D012313:RNA; D011493:Protein Kinase C; D002118:Calcium