Differential expression of CD300a/c on human TH1 and TH17 cells

Extensive phenotypical and functional characterization showed that in both TCM and TEM cells, the CD300a/c+ subset contained a higher number of TH1 (IFN-γ producing) cells. Alternatively, TH17 (IL-17a producing) cells tend to be CD300a/c-, especially in the TEM subset. Further characterization of the IL-17a+ cells showed that cells that produce only this cytokine are mostly CD300a/c-, while cells that produce IL-17a in combination with other cytokines, especially IFN-γ, are mostly CD300a/c+, indicating that the expression of this receptor is associated with cells that produce IFN-γ. Co-ligation of the TCR and CD300a/c in CD4+ T cells inhibited Ca2+ mobilization evoked by TCR ligation alone and modulated IFN-γ production on TH1 polarized cells.We conclude that the CD300a/c receptors are differentially expressed on human TH1 and TH17 cells and that their ligation is capable of modulating TCR mediated signals.Upon encounter with the antigen in secondary lymphoid tissues, na？ve CD4+ T cells initiate a vigorous clonal expansion. This expansion leads to the differentiation and specialization into functionally distinct T helper (TH) cell subsets or lineages. Each TH subset is involved in tailoring immune responses specific to a wide range of antigens. They are characterized by the expression of specific cell surface receptors, and distinct transcription factors that lead to the secretion of a particular set of cytokines [1]. For example, TH1 cells express the transcription factor T-bet and secrete IFN-γ, TNF-α and IL-2. They also express the chemokine receptors CCR5 and CXCR3 and the cytokine receptors IL-12Rβ2 and IL-18Rα. TH1 cells play an important role in the resistance against intracellular pathogens and in the pathogenesis and maintenance of certain autoimmune diseases [2-13]. Another TH subset, TH17 cells, express the transcription factor RORγt, secrete IL-17a, IL-17f and IL-22 and are characterized by the expression of the chemokine receptor CCR6, the cytokine rece