CCR5 blockade is well tolerated and induces changes in the tissue distribution of CCR5+ and CD25+ T cells in healthy, SIV-uninfected rhesus macaques.

Background: CCR5 is a main co-receptor for HIV, but also homes lymphocytes to sites of inflammation. We hypothesized that inhibition of CCR5 signaling would reduce HIV-associated chronic immune activation.

Methods: To test this hypothesis, we administered an antagonistic anti-CCR5 monoclonal antibody (HGS101) to five uninfected rhesus macaques (RMs) and monitored lymphocyte dynamics in blood and tissue.

Results: CCR5 blockade resulted in decreased levels of CCR5+ T cells in blood and, at later timepoints, in lymph nodes. Additionally, the levels of CD25+ T cells increased in lymph nodes, but decreased in blood, bone marrow, and rectal mucosa. Finally, a profile of gene expression from HGS101-treated RMs revealed a subtle, but consistent, in vivo signature of CCR5 blockade that suggests a mild immune-modulatory effect.

Conclusions: Treatment with anti-CCR5 antibody induces changes in the tissue distribution of CCR5+ and CD25+ T cells that may impact on the overall levels of immune activation during HIV and SIV infection.