Antibody response inPlasmodium vinckei malaria after treatment with chloroquine and adjuvant interferon-γ

Abstract

The antibody response of mice infected withPlasmodium vinckei after treatment with chloroquine either alone or in combination with interferon-γ (IFN-γ) was determined. Sequential serum samples were drawn from BALB/c mice receiving either 240 μg chloroquine on the day of infection or 120 μg chloroquine plus 10⁴ units IFN-γ daily for 11 days beginning on day 3 prior to infection. Mice treated with additional IFN-γ showed an early induction of IgG2a response and a reduction in IgG1 antibodies as detected by the immunofluorescence technique at between 10 and 16 days after infection as compared with mice treated with chloroquine alone. Thus, IFN-γ may partly exert its antimalarial activity via the induction of IgG2a antibody formation. At 4–6 weeks after infection, when mice from both groups resisted homologous re-infection, the predominant antibody isotypes found in both groups were IgG1 and IgG2a. Serum samples obtained from mice in both treatment groups at 6 weeks after infection were used for serum transfer experiments. When parasitised erythrocytes were preincubated with such immune serum, a retardation of the course of parasitaemia by 2 days was observed.