Thymocytes stimulate metabolism of arachidonic acid in rat thymic epithelial cells.

Arachidonic acid metabolites play an important role in the development of T cells in the thymus. In the normal animal, prostaglandin levels in the thymus are significantly higher than in plasma. Herein, we have studied the regulation of arachidonic acid metabolism using the thymic endocrine epithelial cell line, TEA3A1, and thymocytes. We have found that TEA3A1 cells, but not thymocytes, produced prostaglandins and thromboxanes. We have also found that thymocytes could stimulate the production of arachidonic acid metabolites in TEA3A1 cells when both cells were cocultured. The strongest stimulation was observed when TEA3A1 cells were cocultured with thymocyte subpopulations either negative for OX8 or W3/25 functional surface markers (either double-negative or single-positive thymocytes). Furthermore, cell-cell contact seems to be absolutely required for the activation of arachidonic acid metabolism in TEA3A1 cells. The study presented here describes the existence of a novel regulatory mechanism of arachidonic acid metabolism which may play an important role in the development of T cells in the thymus.