Role of meningeal lymphoid follicle-like structures in the CNS inflammatory disorders

Abstract

cells with a naive phenotype decreased from baseline to Month 1 (36.7% to 2.3%), whereas the percentage of CD4 memory cells increased (62.5% to 97.4%). The percentages of both cell types then gradually returned toward baseline levels, but did not reach baseline levels by Month 12. The proportion of CD4 T cells with a regulatory phenotype increased from baseline to Month 1 (3.8% to 12.5%), and remained elevated at Month 12. A similar pattern was observed for CD8 T-cell subsets. The proportion of B cells with a mature naive phenotype decreased from 56.4% to 5.4% from baseline to Month 1, whereas the immature cell fraction increased from 4.7% to 36.8%; relative proportions then approached baseline levels by Month 6. Conclusions:Alemtuzumab-induced lymphocytedepletionwasselective andresulted inanincreasedproportionofmemoryandregulatoryTcells. A distinctive pattern of lymphocyte repopulation was observed within weeks. These effects may explain alemtuzumab's sustained benefit despite infrequent (yearly) administration. Study Supported by: Genzyme, a Sanofi Company, and Bayer Healthcare Pharmaceuticals.