The role of complement in Ascaris suum induced histopathology

The role of complement in the histopathology of primary and challenge re-infection by Ascaris suum was assessed. Guinea-pigs deficient in C4 or depleted of the terminal components C3 to C9 by cobra venom factor (CVF) were employed. Pathological changes in the livers of complement-deficient guinea-pigs differed slightly from controls. The most striking findings were in the lungs of CVF-treated infected animals, where marked eosinophilic abscesses were observed following either a primary or repeat infection with Ascaris suum. Additionally, greater numbers of larvae were harvested from the lungs of both CVF-treated and C4-deficient infected guinea-pigs as compared with controls. Serum C4 levels varied over the first 7 days after primary infection, declining in several of the normal and CVF-treated animals, but remaining stable in others. The C4 levels remained unchanged in re-infected animals. The C3 to C9 levels remained within the normal range in both primary and re-infected guinea-pigs. The data suggests that complement is involved in the host responses to infection with Ascaris suum. In the absence of complement (C3 to C9), enhanced pulmonary eosinophilic infiltration and eosinophilic granuloma formation occur in both primary and re-infected animals.