Antibody and cellular immune responses to Plasmodium falciparum histidine-rich protein II in malaria-exposed individuals in Orissa, India.

The precise function of Plasmodium falciparum histidine-rich protein II (HRPII) is not known, but in vitro studies have indicated its immunomodulatory function. The host immune response to HRPII was measured and compared with the response to P. falciparum merozoite surface protein 1 (MSP1) in four groups of study subjects (healthy malaria-naïve adults, uncomplicated malaria patients, asymptomatic parasite carriers and aparasitemic endemic adults; n=15 in each group). Serum antibody concentrations, lymphocyte proliferation and IFN-( and IL-4 responses were significantly higher with MSP1 than with HRPII stimulation in all three malaria-exposed groups (P<0.001), suggesting a strong immunomodulatory role for HRPII.