Clonal analysis of human T-cell responses to fractionated house dust mite antigens (Dermatophagoides pteronyssinus)

In the present study, we investigated the cellular basis of house dust mitedriven immune responsiveness in an atopic individual with perennial rhinitis. We established 40 human T-cell clones (CD3+, 4+, 8-) reactive to Dermatophagoides pteronyssinus (Dp) antigen under the restriction of HLA-DR. By using the crude Dp antigen and its 14 molecular weight (MW) fractions, we analyzed the distribution of T-cell-recognizing sites in the whole Dp extract. We tested T-cell-mediated immunity through two parameters; the identification of Dp fractions inducing T-cell proliferation, and the ability of T-cell clones to secrete IL-2, IL-4, and IFN-γ. According to a prominent peak among fraction-driven T-cell proliferation, we observed that T-cell clones that recognized 45,000-to 95,000-MW fractions were common, while clones reactive to 15,000-to 25,000-MW fractions were less frequent. Several clones were also reactive to antigens of Dermatophagoides farinae or other insects. Based on the responses of cloned T cells, we observed at least 9 distinct T epitopes in crude Dp antigen. These T-cell clones had a heterogenous secretory pattern of cytokines. T-cell clones showed no association between their ability to produce regulatory cytokine and their recognition of particular Dp fractions.