Coreceptor expression on peripheral blood mononuclear cells. PHA-stimulated or nonstimulated cells were labeled with antibodies specific for GPR15, FPRL-1, APJ, CXCR4, and CCR5, and the percentage of positive cells was determined. Representative results from one of five blood donors are shown. The x axis indicates CD4+ T cells, while the y axis denotes cells expressing the tested coreceptors. No significant differences for expression of GPR15, FPRL-1, and APJ were noticed on PHA-stimulated and nonstimulated cells, and the results from nonstimulated cells are shown.