CD4 and coinfection: In terms of coinfection, a study comparing blood and pericardial fluid from TB patients with and without HIV found that a majority of CD4+ T cells from pericardial fluid of HIV-uninfected patients expressed CCR5 and were of effector memory and terminally differentiated phenotype while the Mtb-specific CD4+ T cells in the pericardial fluid from the coinfected group lacked the CCR5 receptor and were a less differentiated phenotype (69), suggesting that CCR5 positive cells are preferentially depleted.