Chronic dermatophyte infection: evaluation of the Ig class-specific antibody response reactive with polysaccharide and peptide antigens derived from Trichophyton mentagrophytes.

An enzyme-linked immunosorbent assay was used to detect serum antibodies within Ig classes IgG, IgM, IgA, and IgE against two partially purified Trichophyton mentagrophytes-derived antigens: polysaccharide (SAC) and peptide (PEP). Sera from 27 chronically infected adults, 16 normal noninfected adults, and 17 noninfected children were evaluated. All sera were reactive, indicating that circulating antibody reactive to PEP and SAC is a feature common to most people, regardless of age and the presence of active infection. The reactivity to SAC was much greater than to PEP. Inhibition assays revealed that components of PEP are found in SAC. Chronically infected adults showed slightly elevated IgG and IgA reactivity to both SAC and PEP compared with noninfected normal adults. This elevated reactivity correlated with the extent (% surface affected) of cutaneous infection. IgE antibody reactivity was detected only against SAC and was somewhat elevated in chronically infected adults. There was no association between antibody reactivity and immunoglobulin level or between the individual subject's level of antibody reactivity to PEP and SAC.