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

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 V beta gene segments. Human T lymphocytes stimulated in vitro with an extract of C. albicans were analyzed for T cell receptor V beta 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 V beta 5.1 and 5.2 gene transcripts. Using cytofluorographic analysis with available anti-V beta monoclonal antibodies, we verified that there was a significant selective expansion (P = 0.035) of V beta 5.1 positive T lymphocytes in PBMC from six subjects stimulated in vitro with C. albicans. PCR analysis of V beta 5.1 expansion in 10 subjects showed increases in V beta 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 V beta 5.1 in the infiltrates, along with the infiltration of V beta 8.1 + T cells. The selective expansion of V beta 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 V beta specificity.