The chemokine receptor CCR 5 Δ32 allele in natalizumab‐treated multiple sclerosis

Objective The chemokine receptor CCR 5 may be important for the recruitment of pathogenic T cells to the CNS in multiple sclerosis ( MS ). We hypothesized that this chemokine receptor might still be important for T‐cell migration during treatment with anti‐very late antigen ( VLA )‐4 antibody. We therefore analysed whether natalizumab‐treated MS patients carrying the CCR 5 Δ32 deletion allele, which results in reduced expression of CCR 5 on the cell surface, had lower disease activity. Methods CCR 5 Δ32 was analysed in 212 natalizumab‐treated MS patients. Results CCR 5 Δ32 status had no significant impact on the frequency of relapses 1 year prior to natalizumab treatment or during the first 48 weeks of treatment. The multiple sclerosis severity score ( MSSS ) was significantly lower at baseline in patients carrying CCR 5 Δ32 ( P  = 0.031). Conclusions CCR 5 Δ32 is not associated with lower disease activity in MS patients treated with natalizumab. We found lower MSSS scores in patients carrying CCR 5 Δ32 compared with the remaining patients, which is consistent with previous studies reporting an association with a more favourable disease course. Further studies are, however, needed before the relationship between CCR 5 Δ32 and disease activity in MS can be definitely established.