IgG-subclass expression of anti-DNA and anti-ribonucleoprotein autoantibodies in human malaria

To understand further the autoimmune phenomena associated with human malaria, we examined the IgG-subclass expression of antibodies to DNA and to ribonucleoproteins (RNP) in the serum of 99 patients with acute malaria. Of the sera, 22% were positive for single-stranded DNA (ssDNA), 18% for double stranded DNA (dsDNA) and 32% for RNP. Using a set of human IgG-subclass-specific murine monoclonal antibodies, we found that autoantibodies to dsDNA were predominantly expressed in the IgG1 subclass. In contrast, anti-ssDNA antibodies were more evenly distributed among the three other isotypes. Antibodies to RNP were essentially of the IgG1 and IgG2 isotypes. However, there was no correlation between these restricted IgG-subclass in the sera. These results are discussed in the context of previous findings of isotype expression of these autoantibodies in patients with the autoimmune disease systemic lupus erythematosus.