Basis for fluctuations in lymphocyte counts in fingolimod-treated patients with MS

This study looked at the changes in total lymphocyte counts (TLCs) in the peripheral blood of 23 people with MS receiving fingolimod for four to seven years, as well as the association between TLCs and T-cell subsets including CD4+, CD8+ and CCR7+/-. The researchers found that all serially studied patients had mean TLCs <0.6 x 109 lymphocytes/L. They observed that in 30% of people with MS, 20-40% of TLCs were >0.6 x 109 lymphocytes/L versus mean 4% for nonfluctuator patients. TLCs of 0.2-0.6 x 109 lymphocytes/L correlated with numbers of CD8+ effector (CCR7-) cells. After stopping therapy, TLCs between 0.6 and 1.0 x 109 lymphocytes/L were associated with a relative increase of CD4 T-cells and a reappearance of CCR7+ T-cells. People with MS receiving treatment with TLCs of >0.6 x 109 lymphocytes/L showed no difference in total CD4 or CD8+ T-cells but there was increased proportion of CD4+CCR7+ T-cells compared to samples with TLCs <0.6 x 109 lymphocytes/L. Therefore, changes in TLCs within 0.2-0.6 × 109 lymphocytes/L in people with MS receiving fingolimod treatment is due to changes in total CCR7-CD8+ effector cells. When TLCs values are >0.6 × 109 lymphocytes/L, cells typically suppressed by this treatment may begin to re-emerge.

Authors: Henault D, Galleguillos L
Source: Neurology. 2013 Oct 16. [Epub ahead of print]

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