V. Evaluation of Cross-Immunity against Type 1 Dengue Fever in Human Subjects Convalescent from Subclinical Natural Japanese Encephalitis Virus Infection and Vaccinated with 17D Strain Yellow Fever Vaccine
Murine resident peritoneal adherent cells bound and ingested Trypanosoma rhodesiense in the presence of specific rat or mouse antiserum. Serum which mediated this phenomenon was obtained as early as 3 days after mice were immunized with gamma-irradiated parasites, with peak levels of activity obtained on day 7. A second injection of gamma-irradiated trypanosomes resulted in a secondary elevation in activity. Fresh normal serum, as a source of complement, enhanced phagocytosis in the presence of otherwise suboptimal antiserum concentrations. P388D1 cells, which like peritoneal macrophages possess Fc and complement receptors, also bound trypanosomes in the presence of antiserum. This in vitro model reflects events that occur in vivo in hosts immunized against T. rhodesiense.
This work was performed while the senior author was a National Research Council Resident Research Associate at the Walter Reed Army Institute of Research.