Humoral immunity in Nigerians with Schistosoma haematobium infection.

Circulating soluble immune complexes (CIC), immunoglobulin classes (IgG, IgA, and IgM), acute phase proteins (alpha-l-fetoprotein and alpha-1-acid glycoprotein) and complement factors (C4 and C3c) levels were determined in 52 Nigerian patients with urinary schistosomiasis (USS) and 39 healthy subjects by polyethylene glycol precipitation and single radial immunodiffusion methods respectively. A considerably higher proportion of USS patients than the controls had elevated levels of soluble immune complexes. IgM, IgA and C3c levels were significantly higher in USS patients than the controls. However, serum concentration of C4 was significantly reduced in USS patients than the controls while that of IgG was not significantly reduced in these patients. The mean levels of alpha-l-fetoprotein and alpha-l-acid glycoprotein were comparable in the USS subjects and the controls. Correlation analysis showed association between S. haematobium egg numbers with serum concentration of IgM, C3c and CIC. These observations could be the results of increased rate of CIC formation, and inflammatory responses to schistosome antigens. The study concluded that IgM associated-CIC may be responsible for the immunopathology of chronic schistosomiasis.