Effect of immunosuppression on the clinicopathological changes in experimental zygomycosis in rabbits

A study was undertaken to investigate the effect of immunosuppression by cy clophosphamide or methylprednisolone on the clinicopathological alterations in respiratory absidiosis in rabbits. Infected rabbits showed respiratory distress that was more severe in immunosuppressed groups. Leukocytosis due to neutrophilia was observed in the non-immunosuppressed group in the initi al stages, whereas leukopenia was observed in both the immunosuppressed gro ups initially, owing to polymorphopenia in the cyclophosphamide-treated gro up and to lymphopenia in the methylprednisolone-treated group, followed by leukocytosis in both groups. Total serum proteins increased significantly i n the non-immunosuppressed group but were significantly decreased in the im munosuppressed groups. Serum creatinine increased significantly in all the infected groups from 20 days post inoculation (DPI) onwards. Blood urea nit rogen increased significantly in the initial stages only in the methylpredn isolone-treated group. AST and ALT also showed significant increases in the infected animals. Total serum immunoglobulins and circulating immune compl exes increased gradually in all three infected groups, except for an initia l significant drop in the immunosuppressed rabbits. Re-isolation of fungus was only achieved from the lungs of infected rabbits up to 15 DPI in the no n-immunosuppressed group and 30 DPI in the immunosuppressed groups. Patholo gical lesions in all the infected groups were found mainly in the lungs and consisted of pyogranulomas. The lesions were most severe in the cyclophosp hamide-treated group and least severe in the non-immunosuppressed group.