The norepinephrine level is decreased in the lymphocytes of long-term interferon-beta-treated multiple sclerosis patients.

The mutual involvement of dopamine and its metabolites in the nervous and immune systems has the potential to provide information on the interaction of these two systems. During a 24-hour period, we used capillary electrophoresis with electrochemical detection to repeatedly measure the intracellular catecholamine concentrations in the peripheral blood lymphocytes of relapsing-remitting multiple sclerosis (RRMS) patients receiving interferon (IFN)-beta-1b (n = 13), and those of IFN-naïve RRMS patients receiving their first IFN-beta-1a injection (n = 19) during this study, and compared them with the levels in healthy controls (n = 12). At baseline, the norepinephrine level was significantly decreased (P =0.003) in the long-term IFN MS patients compared with the controls. The Time x Group interactions for dopamine (P=0.5854) and norepinephrine (P=0.6192) were not significant. The group effects for the individual drugs were P=0.3529 and 0.1282, respectively. The lower norepinephrine level at baseline in the long-term IFN MS group suggests an immunologically stable phase, in line with our previous findings. This is the first report of the effects of IFN-beta administration on intracellular catecholamines in MS patients. Further studies are necessary to elucidate the immune reactions affected by the catecholamines in MS and to evaluate the roles of these potential immunotransmitters.