Regulation of Homocytotropic Antibody Formation in the Rat

Abstract

Abstract The effects of four representative immunosuppressants, i.e., 5-bromouridine deoxyriboside (BUDR), actinomycin D, cyclophosphamide and cortisone, on the formation of homocytotropic antibody (HTA) were observed in rats immunized with dinitrophenylated ascaris extracts (DNP-As) and killed Bordetella pertussis, with the following results. 1) A single injection of 35 mg/kg of BUDR given simultaneously with or shortly after the start of immunization caused enhancement and prolongation, after some delay, of HTA formation, as measured by the mean of reciprocal PCA titers. 2) Pretreatment with 0.3 mg/kg of actinomycin D caused a delayed response of HTA, but the subsequent mean peak titer was about the same as that of the control untreated rats. Such treatment after immunization was started caused an absolute stimulation of HTA, as judged by high peak titers and prolonged production of the antibody. 3) Pretreatment with a single injection of 150 mg/kg of cyclophosphamide caused delayed but enhanced formation of HTA which lastedo lnger than the normal period of time, whereas the same treatment started 2 days after the antigen was given caused suppression. 4) Pretreatment with 200 mg/kg of cortisone caused temporary enhancement, whereas treatment during immunization was moderately suppressive. The enhancement or suppression of HTA formation did not correlate with γM and γG antibodies in the serum, as measured by passive hemagglutination titers before and after 2-mercaptoethanol treatment.