Effect of treatment with cyclophosphamide on the electrophoretic mobility and mitogen responsiveness of mouse thymus cells.

Two days after a single intraperitoneal injection of cyclophosphamide (CY) in a dose of 300 mg/kg of body weight, the cellularity of the thymus from adult female CBA mice was reduced to 17% of its normal value. The electrophoretic mobility (EPM) analysis of the surviving cells revealed a decrease in the proportion of the slow-moving cells together with a significant diminution of their mean EPM. The proportion of fast-moving cells, which were shown to correspond to the hydrocortisone-resistant and mitogen-responsive pool of mature thymocytes, was correlatively increased by 2-3 fold. Despite this enrichment in cells with a high surface charge, the thymocytes from CY-treated mice exhibited a diminished reactivity "in vitro" to both concanavalin A and phytohemagglutinin. The possible significance of theses results is discussed with reference to the known mitostatic properties of CY.