Cell-free antigens from precocious Paracoccidioides brasiliensis culture induce a typical delayed-type hypersensitivity reaction

Fecchio CJ (1), Dias-Melicio LA (2), Soares AMVC (3), Guimarães S (4), Peraçoli MTS (3), Sartori A (3)

(1) Postgraduate Program in Tropical Diseases, Botucatu Medical School, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil; (2) Department of Pathology, Botucatu Medical School, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil; (3) Department of Microbiology and Immunology, Botucatu Biosciences Institute, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil; (4) Department of Parasitology, Botucatu Biosciences Institute, São Paulo State University (UNESP - Univ Estadual Paulista), Botucatu, São Paulo State, Brazil.

Abstract: Cell-free antigens (CFAg) derived from Paracoccidioides brasiliensis have typically been used in immunodiffusion reactions for serodiagnosis or therapeutic follow-up of paracoccidioidomycosis patients. Thus, we investigated the usefulness of CFAg obtained from cultures at different ages, to evaluate cellular immunity by the footpad test, in experimental murine paracoccidioidomycosis. Male mice infected with P. brasiliensis 265 strain were challenged in the footpad with CFAg obtained from four- (4d CFAg) or 11-day-old cultures (11d CFAg). The increase in footpad swelling provoked by 4d CFAg and 11d CFAg was similar and showed significant difference in relation to control groups. However, the infiltrate pattern was strikingly different: 4d CFAg induced a predominant mononuclear infiltrate whereas 11d CFAg provoked a predominant polymophonuclear infiltrate. These different inflammatory patterns were associated with distinct electrophoretic characteristics. By comparison with 11d CFAg, 4d CFAg showed more numerous and intense bands, including a strong one of 43 kDa (gp43). These results suggest that CFAg derived from Pb 265 isolate can be used as a reagent to evaluate cellular immunity; however, the culture’s age is critical because only young cultures are able to induce a typical mononuclear infiltrate. The efficacy of this new paracoccidioidin to assay the cellular immunity in infections caused by other P. brasiliensis isolates is under investigation.

Key words: Paracoccidioides brasiliensis, cell-free antigens, delayed-type hypersensitivity reaction, gp43, murine paracoccidioidomycosis.

ACKNOWLEDGEMENTS

The grant of a fellowship by the Coordination for the Improvement of Higher Education Personnel (CAPES) to C. J. Fecchio (postgraduate program in Tropical Diseases, Botucatu Medical School, UNESP) is gratefully acknowledged.

COPYRIGHT

© CEVAP 2011

SUBMISSION STATUS

Received: February 28, 2011.

Accepted: June 8, 2011.

Abstract published online: June 14, 2011.

Full paper published online: August 31, 2011.

CONFLICTS OF INTEREST

There is no conflict.

FINANCIAL SOURCE

The Coordination for the Improvement of Higher Education Personnel (CAPES) provided the financial grants.

ETHICS COMMITTEE APPROVAL

The present study was approved by the Ethics Committee of the Botucatu Medical School, UNESP (protocol number 136/98).

CORRESPONDENCE TO

ALEXANDRINA SARTORI, Departamento de Microbiologia e Imunologia, Instituto de Biociências, UNESP, Rubião Júnior, Botucatu, SP, 18618-970, Brasil. Phone: + 55 14 3811 6058. Fax: + 55 14 3815 3744. Email: sartori@ibb.unesp.br.