Humoral immune response to Malassezia furfur in patients with pityriasis versicolor and seborrheic dermatitis.

Humoral immune responses against exoantigen components of oval, elliptic and round yeast forms of Malassezia furfur were analysed by ELISA and Western blotting assays, using sera from patients with pityriasis versicolor (PV), seborrheic dermatitis (SD) and healthy adults (HA), as control. Sera from patients with SD showed IgG anti-oval M. furfur titers ranging from 1/400 to 1/6400 showing geometric mean (GM) of 1/1472, higher than those obtained with sera from patients with PV (1/200 to 1/6400, GM = 1/1239). Both patient groups showed mean titres statistically superior (P < 0.05) than those obtained form HA (GM = 1/229). Similar data were also obtained with the elliptic and round antigens. However, the anti-oval IgG mean titers from patients' sera were much higher than those obtained with elliptic or round antigenic components (p < 0.05) Anti-M furfur IgM titers obtained from patient's sera with PV against all three exoantigens were statistically superior (p < 0.05) than HA group. Patients with SD showed IgM titers statistically superior (p < 0.05) only to oval yeasts of M. furfur. The IgA mean titers from patients' groups against the different morphological antigens were shown be slightly higher than those HA group. By Western blot, using rabbit anti-sera, the different antigenic components of M.furfur showed a close relationship mainly between oval and elliptic yeast cells antigens. The 70 kDa component of the M. furfur exoantigen of oval morphology was recognized by 84% of the PV patients' sera. On the other hand, SD patients' sera recognized 3 principal components of 70 kDa (100%), 65 kDa (67%) and 84 kDa (53%). These components may be considered immunological markers for PV and SD. Twenty-five percent of HA sera recognized the components of 65, 70 and 94 kDa. This investigation shows that M. furfur antigens can sensitize the host, mainly the oval yeast form of M. furfur with a very important specific IgG response in patients with SD and PV.