Immunostimulation with muramyl dipeptide and its desmethyl analogue: Studies of non-specific resistance to pulmonary blastomycosis in inbred mouse strains.

N-acetyl-muramyl-L-alanyl-D-isoglutamine (MDP) protected against pulmonary blastomycosis when given prophylactically to BALB/c mice. Its desmethyl analogue (DM-MDP) had a similar effect. In C3H/HeJ, the effect was less marked. Early treatment after infection, with MDP and DM-MDP, had a modest effect in C3H/HeJ and BALB/c respectively, whereas late treatment had no effect in any mouse strain. No effect could be demonstrated with challenge sizes producing too lethal a model or minimal lethality, or in DBA/2J or young BALB/c mice. The effects in various strains do not correlate with differing effects on nonspecific immunostimulation in these strains. Immunostimulation with glycopeptides deserves further study in prophylaxis or therapy of fungal infection.