1986 Volume 46 Issue 3 Pages 383-389
The subcutaneous administration of muramyl dipeptide (MDP) and MDP-stearoyllysine [MDP-Lys (L18) ] proved to prolong the life-span of mice infected withMycobacterium tuberculosis. The time course for the change of viable number ofM. tuberculosisin lung revealed that the multiplication of the infected bacteria was more remarkably inhibited in MDP-Lys (L18) -treated mice than in control and MDP-treated mice. The lesions of lungs of MDP-Lys (L18) -treated mice showed tendency toward histopathological characteristics of proliferative-granulomatous type, while necrotic-exudative changes were predominant in control and MDP-treated groups. Marked enhancement of delayed-type hypersensitivity to PPD was observed in groups treated with MDP and MDP-Lys (L18) . Among bacteria other than M. tuberculosis, both substances were effective on infections ofStaphylococcus aureusand Escherichia coli. MDP and MDP-Lys (L18) were intraperitoneally injected into mice, and the opsonized zymosan-induced and luminol-amplified chemiluminescence (CL) of the peritoneal macrophages was measured. The CL values of macrophages collected 2-3 days after injection were 3-5 times higher than those of control group. Increase of candidastatic activity of peritoneal macrophages could also be demonstrated after intraperitoneal administration of MDP and MDP-Lys (L18) . The protective effect of MDP and MDP-Lys (L18) on bacterial infections is considered to be due to the activation of macrophages, as well as polymorphonu-clear leukocytes.
