Suppression of spontaneous in vitro transformation of autologous leukocytes by plasma from convalescent and postconvalescent infectious mononucleosis patients.

All 14 plasma samples from 13 convalescent and postconvalescent infectious mononucleosis (IM) patients suppressed the spontaneous in vitro transformation of autologous leukocytes. In contrast, only 2 of 8 plasma samples from patients with acute IM suppressed this transformation. All 7 patients whose blood was tested both in the acute and convalescent or postconvalescent phases of IM showed either a conversion in transformation suppression status from negative to positive or an increase in the strength of transformation suppression. Thus recovery from IM appeared to be associated with the ability of plasma to suppress the in vitro spontaneous transformation of autologous leukocytes.