Humoral immune responses to mycetoma organisms: characterization of specific antibodies by the use of enzyme-linked immunosorbent assay and immunoblotting.

Levels of antibodies were determined by enzyme-linked immunosorbent assay (ELISA) in 13 patients with eumycetomas due to Madurella mycetomatis infections. Raised levels of specific IgM were observed in 12 patients, compared with normal human controls. By contrast, low levels of specific IgG were detected in some patients. Specific responses to separated protein antigens were investigated by immunoblotting. Of 10 patients' sera tested, IgM in 2 recognized up to 7 of the blotted antigens between 45 and 84 kDa. Gold-labelled protein A (which predominantly binds to IgG) indicated that sera from 2 patients reacted with at least 6 protein bands with relative molecular masses between 64 and 95. The demonstration of significant IgM levels by ELISA, but few antigenic bands in sera from the same patients by immunoblotting, may point to an antibody response against polysaccharide fungal antigens in mycetoma patients. The use of the ELISA to detect antibodies of different classes and the characterization of their antigenic specificities by immunoblotting may have both diagnostic and prognostic value.