CD4 and infection: In agreement with histological findings, infection in COX-2-/- mice compared to COX-2+/+ mice, led to lower expression of the common leukocyte marker Ptprc (CD45) as well as of Cd4, Cd8, Cd68, and Itgax (CD11c) as markers of T helper cells, cytotoxic T cells, macrophages and dendritic cells, respectively (Fig 4A).