The effect of a single dose of cyclophosphamide on the kinetics of antibody production in the guinea pig.

Cyclophosphamide (CY) 250 mg/kg was given before, at the same time or after immunization with dinitrophenylated bovine gammaglobulin (DNP47-BGG) in Freund's incomplete adjuvant (FIA). CY, given on day +3 or +7 strongly suppressed both IgG subclasses. CY, on the day of immunization, reduced the IgG2 but not IgG1 anti-DNP antibody synthesis. Carrier BGG, injected 42 days after initial immunization, caused a secondary anti-hapten IgG1 response. This was not altered by CY treatment. The secondary anti-BGG response in animals pretreated with CY was also not affected. However, IgG1 anti-BGG in the other groups given CY on day 0, +3 or +7 was delayed and reduced. IgG2 anti-BGG was suppressed in guinea-pigs treated with CY, 3 or 7 days after primary immunization. DNP-BGG-specific IgE serum antibodies, not detectable in CY untreated animals, were found in guinea pigs given CY on days 0, +3 or +7. It is suggested that the kinetics of the IgG1 and IgG2 primary immune response differ, as does the development of IgG1 and IgG2 specific immunological memory.