Resistance of melanized yeast cells of Paracoccidioides brasiliensis to antimicrobial oxidants and inhibition of phagocytosis using carbohydrates and monoclonal antibody to CD18

Marcelo Barbosa da Silva, Luciana Thomaz, Alexandre Ferreira Marques, Artur E. Svidzinski, Josh D. Nosanchuk, Arturo Casadevall, Luiz R. Travassos, Carlos P. Taborda

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23 Scopus citations


Paracoccidioides brasiliensis, a thermal dimorphic fungal pathogen, produces a melanin-like pigment in vitro and in vivo. We investigated the involvement of carbohydrates and monoclonal antibody to CD18, on phagocytosis inhibition, involving macrophage receptors and the resistance of melanized fungal cells to chemically generated nitric oxide (NO), reactive oxygen species (ROS), hypochlorite and H2O2. Our results demonstrate that melanized yeast cells were more resistant than nonmelanized yeast cells to chemically generated NO, ROS, hypochlorite and H2O2, in vitro. Phagocytosis of melanized yeast cells was virtually abolished when mannan, N-acetyl glucosamine and anti-CD18 antibody were added together in this system. Intratracheal infection of BALB/c mice, with melanized yeast cells, resulted in higher lung colony forming units, when compared to nonmelanized yeast cells. Therefore, melanin is a virulence factor of P. brasiliensis.

Original languageEnglish (US)
Pages (from-to)644-648
Number of pages5
JournalMemorias do Instituto Oswaldo Cruz
Issue number4
StatePublished - Jul 1 2009



  • Anti-CD18 antibody
  • Antimicrobial oxidants
  • Melanin
  • P. brasiliensis

ASJC Scopus subject areas

  • Microbiology (medical)

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