The residual effect of cyclophosphamide is not required to evoke the conditioned immune response

Abstract

The goal is to find out if the residual immunodepressant effect of cyclophosphamide is necessary for the conditioned antibody response to take place. Random-bred male mice were conditioned with a 0.15% saccharin solution as the conditioned stimulus, and with the immunosuppressant drug cyclophosphamide, at 50 and 250 mg/kg, as the unconditioned stimulus. Four days after conditioning with 50 mg/kg of cyclophosphamide, or 14 days after conditioning with 250 mg/kg thereof, mice were immunized with rat erythrocytes and thereafter drank a saccharin solution. The results were: (i) the higher dose of cyclophosphamide left a residual effect, whereas the lower dose did not, and (ii) presentation of a saccharin solution did not impair the antibody response to rat erythrocytes in any case. It was concluded that, regardless of the residual effect of cyclophosphamide, conditioning of the antibody response did not occur.