Analysis of cytokine profiles in synovial T cell clones from chlamydial reactive arthritis patients: predominance of the Th1 subset

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Abstract
Subpopulations of human T cells (Th0, Th1 and Th2) can be distinguished by their cytokine-sceretion pattern. Evidence is increasing from other studies that the outcome of a human disease may depend on the subpopulation of T cells that predominates at the site of inflammation. Reactive arthritis serves as a useful model of chronic inflammatory diseases, because the triggering antigen can be identified. Using this triggering antigen we raised 33 Tcell clones reactive with Chlamydia trachomatis and 25 T cell clones that were not reactive, all from the synovial fluid of two patients suffering from Ohlamydia-induced arthritis. Their cylokine secretion patterns for inlcrferon-gamma (IFN-γ), IL-2 and IL-4 were analysed, as also were mRNAs for IFN-γ and IL-10 by in situ hybridization. Out of the 33 antigen-reactive clones 23 showed a Th1 pattern with IFN-γ but not IL-4 secretion, while the remaining 10 exhibited a ThO pattern. The clones that did not react with Chlaniydia expressed all patterns of cytokine secretion, including a Th2 pattern, thus providing a control population that excludes bias in the sampling procedure. CD4 and CD8 clones displayed a similar cytokine-secretion pattern. In addition this study demonstrates for the first time the expression of IL-10 mRNA in Tcell clones derived from synovial fluid, and ihis was not confined to the Th2 subset. The Th1 response that Chlamydia provoke can be regarded as appropriate for such an obligate intracellular pathogen.