Microscopy and Microanalysis



Papers from the InterAmerican Congress on Electron Microscopy

A Morphological and Cytochemical Study of the Interaction between Paracoccidiodes brasiliensis and Neutrophils


Maria Fernanda R.G.  Dias  a1 , Absalom L.  Filgueira  a2 and Wanderley  de Souza  a1 c1
a1 Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS-Bloco G, 21949-900, Rio de Janeiro, RJ- Brasil
a2 Departamento de Dermatologia, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ- Brasil

Article author query
dias mfrg   [PubMed][Google Scholar] 
filgueira al   [PubMed][Google Scholar] 
de souza w   [PubMed][Google Scholar] 

Abstract

Paracoccidioidomycosis is a systemic granulomatous disease caused by the dimorphic fungus Paracoccidioides brasiliensis. It is the most prevalent systemic mycosis of Latin America and 80% of the reported cases are from Brazil. Because of the great number of neutrophils found in the P. brasiliensis granuloma, studies have been done to evaluate the role of these cells during the development of the infection. Scanning and transmission electron microscopy of thin sections showed that the neutrophils ingest yeast cells through a typical phagocytic process with the formation of pseudopodes. The pseudopodes even disrupt the connection established between the mother and the bud cells. Neutrophils also associate to each other, forming a kind of extracellular vacuole where large yeast cells are encapsulated. Cytochemical studies showed that once P. brasiliensis attaches to the neutrophil surface, it triggers a respiratory burst with release of oxygen-derived products. Attachment also triggers neutrophils' degranulation, with release of endogenous peroxidase localized in cytoplasmic granules. Together, these processes lead to killing of both ingested and extracellular P. brasiliensis.

(Received January 1 2003)
(Accepted May 6 2003)


Key Words: Paracoccidioides brasiliensis; oxidative burst; phagocytosis; endogenous peroxidase; NAD(P)H-oxidase; alkaline phosphatase; acid phosphatase.

Correspondence:
c1 Corresponding author. E-mail: wsouza@biof.ufrj.br