Activation of the human complement system by pigmented and hypopigmented mycelia of the fungus Fonsecaea pedrosoi.

Summary The action of the complement system on pigmented and hypopigmented mycelia of the fungus Fonsecaea pedrosoi, the major aetiological pathogen of the chromoblastomycosis is herein discussed. Fungi were grown in medium Czapeck-Dox at 37 °C, for 14 days, without shaking to obtain pigmented mycelium. To obtain hypopigmented mycelium, the fungus was grown at the same conditions, but in the dark and with low oxygenation. Activation was measured by complement consumption and enzyme-linked immunosorbent assay. We also observed by immunofluorescence the deposition of C3, C4 fragments and C9 on the surface of the different forms studied. The results indicate that both forms were able to activate the complement system mainly by the alternative pathway. Pigmented mycelia had the highest consumption results, indicating that the pigment, melanin, may have influence in activation.