Autoantibodies in sera of Thai patients with Plasmodium falciparum infection.

Serum from 98 Thai adults infected with Plasmodium falciparum were examined for the presence of autoantibodies. Malarial containing antibodies sera were also revealed positive for anti-nuclear antibodies with fluorescence speckled pattern, anti-smooth muscle antibodies, anti-mitochondria antibodies and rheumatoid factor. There was no detectable antibody to double stranded DNA. There was a significant relationship between high titre of malarial antibody and high frequency of speckled pattern of anti-nuclear factor or anti-nuclear antibodies. By the ELISA technique determination of serum antibodies against an extractable nuclear antigen (ENA) in patients with P. falciparum infection gave 43.8% (43 of 98) positive result. In addition, sera contained malarial antibodies gave positive antibodies to ENA in 50% (49 of 98) by tanned red cell haemagglutination. Among the positive sera with antibodies to ENA, they showed the presence of antibodies to both ribonucleoprotein RNAase sensitive (RNP) and ribonucleoprotein RNAase resistance (Sm). Also both of antibodies exhibited positive staining of speckled pattern of antinuclear factor. This observation indicated that malaria infection induces autoantibodies which were predominantly anti-nuclear antibodies.