CD195, also known as CCR5, is a 45 kD G protein-coupled seven transmembrane CC-chemokine receptor. It binds to MIP-1alpha, MIP-1beta, and RANTES and is expressed on a subset of T cells and monocytes. CD195 mediates an intracellular signal thought to induce differentiation and proliferation. CCR5 has also been shown to act as a co-receptor for R5 HIV-1 cell entry; modification of CCR5 by sulfation contributes to the efficiency of HIV-1 entry. The T21/8 monoclonal antibody has high affinity to CCR5 N-terminal epitope (Met1-Lys22) and is useful for flow cytometric analysis, immunoprecipitation, immunofluorescence microscopy, and ELISA assay of CCR5 expression.