Monocyte pre-incubation with anti-CCR2 antibodies resulted in blockade of CCL2/MCP-1-induced migration of cells derived from both HD (Fig. 1A; 5 or 25 μg/ml, P = 0.0147 and P = 0.0035, respectively) and RA patients (Fig. 1B; 5 and 25 μg/ml, P = 0.0226 and P = 0.0009, respectively). The gene discussed is CCL2; the disease is Huntington disease.