Expression and synthesis of fibroblast growth factor-9 in human γδ T-lymphocytes. Response to isopentenyl pyrophosphate and TGF-β1/IL-15

γδ T-lymphocytes are believed to play a role in maintaining the normal configuration of epithelial tissue. As little is known about the factors mediating this function, we addressed the question of whether γδ T-lymphocytes produce fibroblast growth factor (FGF)-9 as well as two other growth factors associated with epithelial tissue reconstitution. Blood γδ T cells isolated from healthy donors were grown in the presence of isopentenyl pyrophosphate (IPP) or transforming growth factor-β1 (TGF-β1)/interleukin-15 (IL-15) for 24 h and were assessed for the expression and synthesis of FGF-9, keratinocyte growth factor (KGF), and epidermal growth factor (EGF). Resting human γδ T cells constitutively expressed KGF and FGF-9 mRNA but no EGF mRNA. In the presence of IPP, FGF-9 mRNA expression significantly increased in a dose-dependent manner, expression of KGF remained unaltered, and EGF mRNA could not be detected. In contrast to IPP, stimulation of the cells with TGF-β1/IL-15 did not alter FGF-9 expression. Moreover, stimulation with anti-CD3 does not induce FGF-9 expression but triggers a high signal of interferon-γ mRNA. Western blot analysis of γδ T cell lysates, prepared 4 days following stimulation with IPP, showed an increase of FGF-9 protein as compared with control cells. In conclusion, the results demonstrate for the first time that human blood and bronchoalveolar lavage γδ T-lymphocytes are capable of expressing FGF-9. The data also provide novel evidence that immunoregulatory cells can synthesize FGF-9.