QUANTITATIVE AND QUALITATIVE EFFECTS OF CYCLOPHOSPHAMIDE ADMINISTRATION ON CIRCULATING POLYMORPHONUCLEAR LEUKOCYTES

  • 1 January 1976
    • journal article
    • research article
    • Vol. 31  (1) , 139-144
Abstract
The effect of cyclophosphamide (CY) on the absolute numbers and function of polymorphonuclear leukocytes (PMN) surviving in the circulation following either a single dose (100 mg/kg, i.p.) or daily administration (20 mg/kg, i.p., for 5 days) was studied in the guinea-pig. The quantitative effect of CY on peripheral blood leukocytes was assessed by measuring the absolute numbers of neutrophils, lymphocytes and monocytes daily for 5 days following the initial injection of CY. The qualitative effects of CY on PMN function were determined by measuring the ability of these cells to function as killer cells. The 2 functional assays employed were the PMN-mediated PHA[phytohemagglutinin]-induced cellular cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC) assays against chicken erythrocyte targets. Both regimens of CY administration produced an equivalent degree of leukopenia 5 days after the initial injection with disproportionately severe neutropenia (< 300 PMN/mm3). Neither regimen of CY administration produced a significant decrease in cytotoxic effector function as measured through a wide range of effector to target cell ratios, PHA concentrations and antiserum dilutions. These findings have clinical relevance in that they demonstrate the dichotomy between the quantitative and qualitative effects of (CY) on PMN in that CY administration can dramatically decrease the absolute numbers of circulating polymorphonuclear leukocytes while leaving intact certain effector cell functional capabilities of those PMN surviving in the circulation during drug administration.