Treg Cell Function and Related Cytokines and Chemokines Changes during Alemtuzumab Treatment: A 24 Months Immunological Study (P05.148)

OBJECTIVE: T cell phenotypic and functional analysis.Cytokine, chemokine, and chemokine receptor mRNA levels after Alemtuzumab in RRMS:2-year follow-up. BACKGROUND: Alemtuzumab is associated with a long-standing reduction of T CD4+ subset. DESIGN/METHODS: Multicenter follow-up of alemtuzumab-treated relapsing-remitting multiple sclerosis(RRMS)patients in CAMMS323 or 324 trials.FACS analysis of Treg, Th1 and Th17 cells. Immunological molecule mRNA levels (chemokines:CCL-11,CXCL-10;chemokine receptors:CCR-4,CCR-6; cytokines:IFNγ,TGFβ,TNFα,IL-1β,IL-2,IL-6,IL-10,IL-12p35,IL-17A,IL-17F,IL22,IL-23,IL-26,IL-27;and T-bet,RORγt,Foxp3) quantified by TaqMan® low density array (TLDA) real-time polymerase chain reaction in whole blood.Treg suppressor activity assessed at M12 and M24 by ELISPOT on PBMC depleted of CD25highT cells and activated with myelin basic protein (MBP) or anti-CD3-CD28. Timepoints:Baseline(before first alemtuzumab course);Month (M)6,M12,M18,M24:6,12,18,24 months after first course.M12 was before second Alemtuzumab course. The relative mean difference between baseline and subsequent timepoints estimated through the formula:(Timepoint-Baseline)/Baseline, and significance of the differences tested. RESULTS: Twenty-nine patients from 6 European sites.After alemtuzumab, CD4+ lymphocytes decreased from 45 to 14%.Th17 increased at M18; no significant variation were observed in Th1 cells. T-bet and IL-23 decreased; Foxp3, TGFβ, IL-10 and IL-27 increased from M6 to M24. Treg cell specific suppressive function on MBP auto-reactive Th1 and Th17 cell increased only at M24, whereas the number of Treg cells and their overall suppressor function did not significantly change during the follow-up. Four Relapses were observed in 3 patients. No occurrence of severe autoimmune disease or changes of thyroid function. CONCLUSIONS: The overall alemtuzumab-induced CD4+ lymphocyte depletion might relate to the reduction of MS disease activity.The increase of suppressor cytokines IL-27,IL-10,TGFβ and of MBP-specific Treg suppressor function could have resulted in the decrease of T-bet, modulating the anti-CNS pathogenicity of Th1 and Th17 cells. The lack of an increase of the overall Treg suppressor function might allow the development in some patient of non MBP-specific autoimmunity.The further long-term follow-up could provide information on the timing of subsequent courses of Alemtuzumab in individual patients. Supported by: Genzyme Corporation. Disclosure: Dr. De Mercanti has nothing to disclose. Dr. Clerico has nothing to disclose. Dr. Rolla has nothing to disclose. Dr. Cucci has nothing to disclose. Dr. Novelli has nothing to disclose. Dr. Taverna has nothing to disclose. Dr. Bardina has nothing to disclose. Dr. Piazza has nothing to disclose. Dr. Gibbin has nothing to disclose. Dr. Vargas has nothing to disclose. Dr. Vladic has nothing to disclose. Dr. Habek has nothing to disclose. Dr. Adamec has nothing to disclose. Dr. Brinar has nothing to disclose. Dr. Cocco has nothing to disclose. Dr. Frau has nothing to disclose. Dr. Annovazzi has nothing to disclose. Dr. Horakova has received personal compensation for activities with Biogen Idec, Novartis, Merck Serono, Teva Neuroscience, and Bayer. Dr. Horakova has received research support from Biogen Idec. Dr. Kovarova has nothing to disclose. Dr. Durelli has received personal compensation for activities with Bayer, Genzyme Corporation, and Merck Serono.