Correlation of serum IL-13 and IL-5 levels with clinical response to Glatiramer acetate in patients with multiple sclerosis.

Glatiramer acetate (GA) is effective in the treatment of Multiple Sclerosis (MS) presumably by the induction of an immunoregulatory T-cell response. We have previously shown that GA directly induces the Th2 cytokines IL-13 and IL-5 in T-cells in vitro. In the present study we compared the in vitro response to GA in healthy controls, untreated and GA-treated MS patients and tested whether the induction of IL-13 and IL-5 secretion is also detectable in the serum of 25 MS patients treated with GA. Patients were grouped into clinical responders and nonresponders in order to determine a possible correlation with the immunological response. As a result we found a significant increase of IL-13 in the serum of clinical GA-responders whereas IL-13 was not detectable in controls, untreated MS (P < 0.001) and nonresponders (P = 0.015). Similarly, GA-treatment increased serum levels of IL-5 (P = 0.001). The correlation of serum IL-5 and clinical response was also significant (P = 0.039), however, there was an overlap between the different groups. The selective induction of IL-13 and IL-5 but not IL-4 by GA treatment suggests that the specific biological functions of these cytokines might be important for the therapeutic mechanism of GA. Measurement of serum IL-13 and IL-5 levels is a simple and inexpensive tool for monitoring the response to GA in MS patients.