Assessment of changes in immune measures of multiple sclerosis patients treated with laquinimod

• We assessed changes in PBMC phenotype and function in patients receiving laquinimod.
• No change was seen in the relative proportion of major circulating PBMC populations.
• Laquinimod did not alter the proliferative response or inflammatory bias of PBMC.
• Patients receiving 2 years of laquinimod retained full complement of functional PBMC.

Laquinimod is a novel orally active agent with immunomodulatory properties that was shown to be effective in suppressing disease activity in relapsing–remitting multiple sclerosis patients. Though many mechanisms of action of laquinimod have been described, little is known about the in vivo effects of laquinimod on the functionality of circulating human peripheral blood mononuclear cell populations. We assessed both phenotypical and functional measures of PBMC in a prospective longitudinal analysis comparing laquinimod and placebo treated cohorts. We determined that there were no significant changes in the relative proportion of T-cells, B-cells, monocytes & macrophages, NK-cells, dendritic cells or FoxP3+ CD25hi T-regs in laquinimod treated patients. There were also no significant differences in the proliferative response to PHA or tetanus antigen, or in the inflammatory cytokine bias of these responses. These data demonstrated that there were no significant changes in immune function of PBMC in patients receiving two years of continuous laquinimod therapy who retained a full complement of the major populations of circulating PBMC and retained their capacity to respond to immunologic stimuli.