Development of a leukocytopenic baby guinea pig model with azathioprine and cyclophosphamide

Immunosuppressive agents were given to baby guinea pigs to develop a leukocytopenic baby guinea pig model. Azathioprine in different doses, and cyclophosamide and methylprednisolone combinations did not result in predictable leukocytopenia without significant mortality. A combination of azathioprine 20 mg and cyclophosphamide 20 mg administered once daily for 5 days to 42 baby guinea pigs resulted in a mean white blood cell count of 2531/mm3 +/- 1198 (a reduction of 3931 +/- 1413 from pretreatment values). The mean counts for polymorphonuclear leukocytes and lymphocytes on day 6 were 398/mm3 and 2035/mm3, respectively. Only 7% mortality was seen in these animals. This model can be utilized to study a variety of bacterial and viral infections in "immunocompromised hosts".