NATURALLY-OCCURRING PLASMODIUM-SPECIFIC IGA ANTIBODY IN HUMANS FROM AMALARIA ENDEMIC AREA

Blood samples collected from individuals belonging to an endemic area in Uttar Pradesh, were tested for plasmodial antigen specific immunogl obulin A (IgA) by enzyme immune assay using soluble extract of Plasmod ium falciparum from culture. Among 773 (20.18%, P < 0.0001) samples 15 6 sera demonstrated a detectable seropositivity for antigen specific I gA. IgA levels were higher among individuals who experienced repeated attacks of malaria compared to acute infected patients. Among seroposi tive individuals the IgA titers were found increased with the age. Imm unoglobulin isolated from sera having high level of IgA showed growth inhibitory effect in Plasmodium falciparum in vitro. A group of sera w ith high IgA antibody against Plasmodium falciparum crude antigen show ed seronegativity with specific peptides. Statistically, no positive o r negative correlations were observed between antigen specific IgG and IgA. However, there was a tendency towards negative correlation betwe en IgA and IgM. Mechanisms for the parasite specific IgA production re main to be established.