Thymic eicosanoid profiles and cyclooxygenase localization in prenatal and postnatal CBA/J mice

Previous work in our laboratory has implicated arachidonic acid metabolites as modulators of fetal murine thymocyte development in vitro. Therefore, we determined whether distinct temporal patterns existed with regard to the capacity for eicosanoid synthesis by fetal and postnatal thymic lobes which might relate to early proliferative and differentiation events within the thymus. Thin layer chromatography was used to demonstrate differential synthesis of 15-HETE, 5-HETE, PGD2, 6-keto PGF1 alpha, and PGF2 alpha by both fetal and postnatal thymic lobes. In contrast, PGE2 and TXB2 were synthesized at a constant level. These findings were in part substantiated by radioimmunoassay of culture media for PGE2 and 6-keto PGF1 alpha following fetal thymic organ culture for 7 or 8 days. In addition, we were able to demonstrate immunoreactive cells for cyclooxygenase in early embryonic and postnatal thymic lobes. Taken together, the above findings permit the suggestion that metabolites of arachidonic acid modulate development of thymocytes and, in turn, their capacity for synthesis is modulated as the thymus develops.