CD4 and osteoarthritis: For example, in inflammatory dental pain, women show a greater expression in the purinergic receptor, P2X 3, and CD39, a marker for chronic ATP release, than men, which was indicative of greater pain in women than men [327].Specific immune cells have also been implicated in osteoarthritis in females and males, with osteoarthritis females having a higher percentage of CD4+ T cells and macrophages, but a lower percentage of monocytes and CD8+ T cells in their synovial fluid compared to osteoarthritis males [328].