Mx proteins in blood leukocytes for monitoring interferon beta-1b therapy in patients with MS

Objective: To correlate Mr protein (Mx) levels in lysed blood leukocytes wi th the clinical response to interferon (IFN) beta-1b (IFN beta-1b) in relap sing-remitting MS (RR-MS) patients for monitoring treatment. Background: In tracellular Mx expression is exclusively induced by the type I IFNs (IFN-al pha, -beta, and -omega) or by viruses and is strongly increased under IFN t reatment. Quantitative determination of Mr allows objective assessment of b iological effects of IFN. Methods: Mr protein levels were measured in blood leukocyte lysates from IFN beta-1b-treated RR-MS patients by ELISA and cor related to clinical parameters, including relapse rate and clinical deterio ration. Results: In stable IFN beta-1b-treated MS patients, Mr levels were significantly increased compared to patients with or without immunosuppress ive treatment. In IFN beta-1b-treated MS patients during relapse, Mr levels were significantly lower than during stable phases of the disease. Mean va lues of Mr (MVMx) over time of treatment in patients with a reduction of re lapse rate were significantly higher than in patients without response. Con clusion: Mr levels in lysed blood cells may represent a useful surrogate ma rker for IFN beta-1b activity corresponding to the clinical response during treatment of MS.