The influence of cyclophosphamide and 6-mercaptopurine on the IgG1 and IgG2 immune response in guinea-pigs.

The purpose of this study was to investigate the effect of cyclophosphamide (CY) and 6-mercaptopurine (6-MP) on the production of the two IgG antibody subclasses in guinea-pigs. Following the intradermal application of dinitrophenylated bovine gamma globulin (DNP20-BGG) emulsified in Freund's incomplete adjuvant (FIA) each animal was given CY or 6-MP, 10 mg per kg of body weight per day on days 1--7, and the DNP- and BGG-specific anaphylactic (IgG1) and lytic (IgG2) antibodies were determined. Only treatment with CY resulted in a significantly-depressed IgG2 anti-DNP immune response; 6-MP was not suppressive and caused a prolonged IgG2 anti-DNP production. Both substances showed a stimulatory effect on IgG1 anti-DNP antibody formation. The carrier-specific IgG1 and IgG2 antibody levels were suppressed completely by CY but unaffected by 6-MP. After a booster injection of 1 mg BGG on day 86 the animals in the CY-treated group were not able to mount a secondary IgG2 anti-BGG immune response. In contrast, IgG1 anti-BGG production was strong and uninfluenced by CY treatment.