Suppression of antibody response to an unrelated antigen in experimental murine paracoccidioidomycosis: effect of cyclophosphamide and indomethacin.

A suppressive effect of experimental paracoccidioidomycosis on the IgE antibody response to an unrelated antigen (ovalbumin) has been previously observed in mice. This effect was restricted to a short period, reaching maximum levels when OA was administered on the third day of Pb-infection. In order to study possible mechanisms involved in the establishment of this suppression, resistant (A/SN) and susceptible (B10.A) mice were treated with either a low dose of cyclophosphamide (CY) or indomethacin (INDO), a potent inhibitor of prostaglandin synthesis. While treatment with the first drug in A/SN mice induced only a recovery of the IgE anti-OA antibody response, in B10.A mice this effect was extended to IgG1, IgG2a and total levels of anti-OA antibodies. On the other hand, treatment with INDO reverted the anti-OA antibody suppression regarding each antibody class tested and in both strains of mice. These results suggest the participation of prostaglandins and of a cyclophosphamide-sensitive mechanism in the induction of the suppressive phenomenon in the human system.