Experimental paracoccidioidomycosis: early immunosuppression occurs in susceptible mice after infection with pathogenic fungi.

The course of Paracoccidioides brasiliensis infection depends on the natural resistance of the host and on the virulence of the fungus isolate. In the present study the immune response to sheep red blood cells (SRBC) was investigated in susceptible (B10.A) and resistant (A/SN) mice after intraperitoneal (ip) infection with pathogenic (Pb18) and apathogenic (IVIC Pb267) P. brasiliensis isolates. Infection with Pb18 yeast cells quickly induces a state of immunodepression only in the susceptible mice. This immunosuppression was not observed when mice were inoculated with IVIC Pb267 yeast.