Candida albicans induces selective expansion of human T lymphocytes expressing the T-cell receptor variable region Vβ 5.1

Abstract Candida albicans is a common pathogen which can present major problems as an opportunistic skin pathogen in patients with immunodeficiency. The exact nature of the T cell responses to C. albicans is poorly understood. The purpose of this study was to determine whether C. albicans could stimulate the selective expansion of T lymphocytes expressing particular Vβ gene segments. Human T lymphocytes stimulated in vitro with an extract of C. albicans were analyzed for T cell receptor Vβ gene expression by using a quantitative PCR technique. We found that stimulation of peripheral blood mononuclear cells (PBMC) produced a selective increase in the expression of Vβ 5.1 and 5.2 gene transcripts. Using cytolluorographic analysis with available anti-Vβ monoclonal antibodies, we verified that there was a significant selective expansion ( P = 0.035) of Vβ 5.1 positive T lymphocytes in PBMC from six subjects stimulated in vitro with C. albicans . PCR analysis of Vβ 5.1 expansion in 10 subjects showed increases in Vβ 5.1 gene transcripts in 7 10 subjects. More importantly, analysis of the T cell infiltrate 48 h after intradermal injections with C. albicans also showed significant expression of Vβ 5.1 in the infiltrates, along with the infiltration of Vβ 8.1 + T cells. The selective expansion of Vβ 5.1 bearing T lymphocytes in PBMC stimulated with C. albicans and in skin test reactions to C. albicans suggests that a restricted population of T cells react to C. albicans . Furthermore, our present data raise the provocative possibility that one or more antigens in C. albicans can act as a superantigen, producing selective expansion of a population of T lymphocytes bearing a particular Vβ specificity.