Suppressor cells in normal immunisation as a basic homeostatic phenomenon

Abstract

WHEN guinea pigs are treated with one dose of cyclophosphamide (CY, 300 mg kg⁻¹) 3 d before sensitisation with either ovalbumin in Freund's incomplete adjuvant (OA/FIA) or 2,4 dinitrofluorobenzene (DNFB), the resultant Jones-Mote or contact skin reactions elicited 1 week later are increased in intensity and induration and prolonged as compared to control animals^1,2. We have postulated that CY pretreatment depletes a population of cells which normally modulate contact sensitivity and Jones-Mote reactions^1,2. If CY was depleting a population of suppressor cells normally present at the time of sensitisation, the passively transferred cells from these animals should be more reactive than if there was no CY given to the donors. Passive transfer of spleen or peritoneal exudate cells (PEC) from animals sensitised with OA/FIA 8 d earlier caused more intense and more indurated reactions in normal recipients when donors had been pretreated with CY 3 d before the OA/FIA sensitisation, when compared with those reactions transferred from sensitised animals which had not received CY (S. I. K., D. P., and J. L. T., unpublished) (Fig. 1). We used the following model for the assay of suppressor cells. Guinea pigs, treated with CY 3 d before immunisation with OA/FIA, served as cell recipients 8 d later. They were then potentially susceptible to the effect of suppressor cells which they were lacking.