Evaluation of the immunosuppressive effect of cyclophosphamide and dexamethasone in mice with visceral toxocariasis.

Visceral toxocariasis is a serious public health problem with a cosmopolitan distribution. Children are susceptible due to their immature immune system and high risks of infection. Nevertheless, the few completed studies about immunosuppression have had controversial results. To evaluate the effect of two immunosuppressive drugs on the larval burden of Toxocara canis, four groups of ten Swiss strain mice each were inoculated on day 0 with 1,200 embryonated T. canis eggs. Fifteen days before the experimental infection, group 1 (control) was treated via intraperitoneal injection (IP) with sterile distilled water and groups 2 and 3 were treated with dexamethasone (DEX) at 1 and 5 mg/kg/day, respectively. Additionally, group 4 was treated IP with cyclophosphamide (CY) at 50 mg/kg at two times per week for 2 weeks. Sixty days following infection, the mice were euthanised to recover the larvae by means of the tissue digestion technique. The levels of antibodies detected by indirect ELISA were not associated with the larval burden. Administration of CY (50 mg/kg) and DEX (5 mg/kg) resulted in an increase of the larval burden of 162.1% and 50.8%, respectively, in relation to the control group. These two treatments, especially CY (50 mg/kg), promoted immunosuppression and the establishment of a significant larval burden, supporting its further utilisation in studies related to immunosuppression in visceral toxocariasis.