Human γδ-T Lymphocytes Express and Synthesize Connective Tissue Growth Factor: Effect of IL-15 and TGF-β1 and Comparison with αβ-T Lymphocytes

T lymphocytes bearing the gammadelta-TCR accumulate during wound healing and inflammation. However, the role of gammadelta-T lymphocytes in fibrogenic tissue reactions is not well understood. Therefore, we addressed the question of whether human gammadelta-T cells express and synthesize connective tissue growth factor (CTGF), a factor known to regulate fibrogenesis and wound healing. In addition, the lymphoblastic leukemia T cell line (Loucy) that possesses characteristics typical of gammadelta-T cells was used as a model to evaluate the regulation of CTGF gene expression. Blood gammadelta-T cells isolated from healthy donors were grown in the presence of IL-15/TGF-beta1 for 48 h and assessed for the expression and synthesis of CTGF. Nonstimulated human blood gammadelta-T cells and Loucy gammadelta-T cells expressed low levels of CTGF mRNA. Costimulation of the cells with IL-15 and TGF-beta1 resulted in a substantially increased level of CTGF mRNA expression within 4-8 h, and it remained elevated for at least 48 h. In contrast, no CTGF mRNA was detected when nonstimulated and stimulated human CD4+ alphabeta-T cells were analyzed. In addition, Western blot analysis of human gammadelta-T cell lysates prepared 4 days following stimulation with IL-15 and TGF-beta1 revealed a 38-kDa CTGF protein in cell lysates of human gammadelta-T cells. Detection was confirmed using Colo 849 fibroblasts, which can constitutively express high levels of CTGF. In conclusion, we herein present novel evidence that in contrast to CD4+ alphabeta-T cells human gammadelta-T cells are capable of expressing CTGF mRNA and synthesizing its corresponding protein, which supports the concept that gammadelta-T cells may contribute to wound healing or tissue fibrotic processes.