Lack of evidence for superantigen activity of Toxoplasma gondii towards human T cells

Author(s)

A.L. Vallochi ^[1] ; J.H. Yamamoto ^[2] ; D. Schlesinger ^[3] ; M.A.C. Machado ; C. Silveira ^[5] ; M.C. Martins ^[6] ; R. Belfort Jr. ^[7] ; J. Kalil ; L.V. Rizzo

Affiliation

^[1] Universidade de São Paulo. Faculdade de Medicina. Instituto de Ciências Biomédicas

^[2] Universidade de São Paulo. Faculdade de Medicina. Divisão de Oftalmologia

^[3] Universidade de São Paulo. Faculdade de Medicina. Instituto de Ciências Biomédicas

^[5] Universidade Federal de São Paulo. Departamento de Oftalmologia - Brasil

^[6] Universidade Federal de São Paulo. Departamento de Oftalmologia - Brasil

^[7] Universidade Federal de São Paulo. Departamento de Oftalmologia - Brasil

• Document type: Journal article
• Source: Brazilian Journal of Medical and Biological Research; v. 34, n. 8, p. 1023-1031, 2001-08-00.

Abstract

Toxoplasma gondii is an obligatory intracellular parasite whose life cycle may include man as an intermediate host. More than 500 million people are infected with this parasite worldwide. It has been previously reported that T. gondii contains a superantigen activity. The purpose of the present study was to determine if the putative superantigen activity of T. gondii would manifest towards human T cells. Peripheral blood mononuclear cells (PBMC) from individuals with no previous contact with the parasite were evaluated for proliferation as well as specific Vß expansion after exposure to Toxoplasma antigens. Likewise, PBMC from individuals with the congenital infection were evaluated for putative Vß family deletions in their T cell repertoire. We also evaluated, over a period of one year, the PBMC proliferation pattern in response to Toxoplasma antigens in patients with recently acquired infection. Some degree of proliferation in response to T. gondii was observed in the PBMC from individuals never exposed to the parasite, accompanied by specific Vß expansion, suggesting a superantigen effect. However, we found no specific deletion of Vß (or Valpha) families in the blood of congenitally infected individuals. Furthermore, PBMC from recently infected individuals followed up over a period of one year did not present a reduction of the Vß families that were originally expanded in response to the parasite antigens. Taken together, our data suggest that T. gondii does not have a strong superantigen activity on human T cells. (AU)

• FAPESP's process: 98/11205-0 - Immunological evaluation in uveitis: study of the immune response and of inflammation in an immunoprivileged organ
• Grantee: Luiz Vicente Rizzo
• Support Opportunities: Research Projects - Thematic Grants