Background: Mucormycosis is a severe disease that may affect susceptible people following the intake or inhalation of spores from fungi of the Mucorales order.
Objective: Research the ability of spores and yeasts of Mucor polymorphosporus in activate the complement system using human serum with or without chelators (EGTA or EDTA).
Methods: Complement consumption assays, ELISA to detect C3 and C4 fragments, MBL, CRP and IgG and Immunofluorescence tests for C3 fragments were carried out.
Results: We found full complement consumption when incubation occurred with EGTA-Mg2+ or without chelators, suggesting that this activation was mainly achieved by the alternative pathway. C3 and C4 fragments, MBL, CRP and IgG were present on both forms tested. The amount of C4, MBL, CRP and IgG was almost three folds higher on spores compared to yeast, suggesting that while spores may trigger more than one pathway of activation, yeasts exhibit mainly alternative pathway activation. Immunofluorescence tests verified the incidence of C3 fragments throughout the surface of all samples, which were evenly distributed, suggesting effective opsonization.
Conclusion: Complement system is part of innate immunity, and its activation by the spores of Mucor sp., which can be present at the earlier stages of mucormycosis, may prove to be essential for fungal clearance from the host.
Luiz Fernando Zmetek Granja, Lysianne Pinto, Jaqueline Souza Silvestre, Cátia Amancio Almeida, Daniela Sales Alviano, Galba Maria Campos Takaki, Maria Helena da Silva, Regina Ejzemberg and Celuta Sales Alviano