Strain differences in resistance to infection reversed by route of challenge: studies in blastomycosis.

The inbred mouse strains C3H/HeJ and DBA/1J have been shown to represent the extremes of susceptibility and resistance, respectively, to pulmonary blastomycosis. This pattern was completely reversed when challenge was performed by the intraperitoneal route, whether a virulent or an attenuated strain of Blastomyces dermatitidis was utilized. By a third route (subcutaneous), the differences were insignificant. Inhibition of replication of blastomyces in vitro by macrophages from both strains, before or after activation by subcutaneous infection, was similar.