Several commercially available anti-CCR5 monoclonal antibodies lack specificity and should be used with caution

CCR5 (CD195) is a receptor for the chemokines RANTES, MIP-1α, and MIP-1β and is used by HIV-1 as a co-receptor for entry into macrophages and CD4+ T cells. CCR5 exists in multiple conformations in the membrane and is present at low levels on human macrophages, making it difficult to detect. Nine commercially available anti-CCR5 monoclonal antibodies were evaluated for their specificity and their recognition of CCR5 expressed by macrophages. Unexpectedly, we found that three of the nine clones tested displayed substantial background binding to CCR5 negative cells, suggesting that these antibodies may give unreliable results. We recommend the use of clones CTC8, 45531 (PE conjugated), and 45523 and advise that data obtained using CTC5, 45531 (unconjugated), and 45549 anti-CCR5 antibody clones should be interpreted with care.