Autocrine IL-6 regulates GRO-α production in thymic epithelial cells

Thymic interleukin-6 (IL-6), which is produced primarily by thymic epithelial cells, is an important cytokine for T cell growth and differentiation in the thymus. In the present study, we investigated the effects of autocrine IL-6 on the cytokines in primary cultures of human thymic epithelial cells. Using an antibody array and ELISA, in addition to IL-8 and MCP-1, growth-related oncogene-α (GRO-α) was subsequently expressed after IL-6 production. Either IL-6 or GRO-α was time-dependently and strongly expressed in medium with and without serum. Neutralizing IL-6 significantly reduced GRO-α production. Inhibiting Janus kinase 2 (Jak2) spontaneously blocked GRO-α production with or without IL-6 stimulation. We conclude that primary human thymic epithelial cells produce GRO-α and that its expression is regulated primarily by autocrine IL-6 and IL-6-activated Jak2 signaling.