For RA PB the percentage positive cells (mean ± SD) for CCR1, CCR2, CCR5 and CXCR4 was 94 ± 10, 94 ± 8, 55 ± 31, 72 ± 13, and for healthy PB 99 ± 1, 99 ± 1, 58 ± 22 and 46 ± 26 respectively. The gene discussed is CXCR4; the disease is rheumatoid arthritis.