Background: A polyspecific, intrathecal humoral immune response against neurotropic viruses such as measles, rubella, and varicella zoster virus (MRZ reac-tion, MRZR) is present in 80-100% of MS patients, but has not been evaluated in patients with neuromyelitis optica (NMO) so far.
Aim: To evaluate whether MRZR testing distinguishes NMO and MS.
Methods: Twenty patients with NMO and 42 with MS were included. The intrathe-cal synthesis of antibodies against measles, rubella, and varicella zoster virus was detected by calculation of the respective antibody indices (AI).
Results: A positive MRZ reaction as defined by a combination of at least two posi-tive AIs was found in 37/42 MS, but only in 1/20 NMO patients (p<0.0001). Median AI values differed significantly between groups (p<0.0005).
Conclusion: The polyspecific, antiviral humoral immune response characteristic for MS is widely missing in NMO, irrespective of the patients’ NMO-IgG status. Our findings further strengthen the case of NMO being pathologically distinct from MS.