PTGER4 and infection: To investigate a potential link between post-resolution macrophage-derived PGE2 and EP4 with T cell numbers and phenotypes, minipumps loaded with the pan-COX inhibitor naproxen or the EP4 antagonist MF498 were implanted into mice following resolution of their lung inflammation (day 4) and the composition of the lung examined 6 weeks after initial infection, Fig. 6A.