Induction of a marked eosinophilia by cyclophosphamide in Toxocara canis infected SJL mice.

Cyclophosphamide (Cy) is known to produce a marked eosinophilia in mice after antigen challenge. In this study, we studied the effect of Cy on eosinophilia in helminthic infection. Peripheral blood eosinophils were counted in SJL mice following a large dose of Cy injection, infection with Toxocara canis, and both Cy injection and T. canis infection simultaneously. Following the injection with Cy (150 mg/kg), the eosinophil counts fell sharply, then rose abruptly to six times the normal level followed by a decrease. Infection with T. canis induced eosinophilia in mice. However, when mice were both infected with T. canis and given Cy injection, the eosinophilia was markedly enhanced. The results suggest that the marked eosinophilia in mice induced by Cy is not only observed in antigen challenge but also in helminthic infection.