• Methylprednisolone;
  • azathioprine;
  • opsonins;
  • leucocytes

Conventional rats were treated parenterally with high doses of methylprednisolone and/or azathioprine for 21 days. The influence on bactericidal and opsonic activities of serum against 32P-labelled E. coli as well as on the number of circulating PMN and lymphocytes was evaluated. Methylprednisolone induced neutrophilia, lymphocytopenia, and reduced the bactericidal activity of serum in one of two strains of rats investigated. Azathioprine induced neutropenia, but did not alter the serum activities studied, except when the dose approximated LD50. The combination of drugs neither altered the blood counts nor the serum activities studied.