Natural killer cell subpopulations are associated with MRI activity in a relapsing-remitting multiple sclerosis patient cohort from Australia

Background: The importance of the innate immune system in multiple sclerosis (MS) is increasingly recognized and the role of natural killer (NK) cells in controlling autoimmunity may be an important modulator of disease activity. Objective: To examine NK subsets in MS patients on different treatments and to evaluate the role of NK subsets as indicators for disease activity. Methods: We measured NK subset levels in blood obtained from 110 relapsing-remitting MS patients. Patients were either off treatment or on treatment with natalizumab, fingolimod, glatiramer acetate or beta-interferon. Disease activity was defined according to No Evidence of Disease Activity' (NEDA) criteria within an observation period of up to 2.4years. The mean NK subset levels were compared among treatment groups using multivariate analysis of variance (ANOVA) and association analysis with disease activity performed using multi-factor logistic regression. Results: Our analysis revealed differences in NK cells and subsets on treatment compared to off treatment (p<0.0005). A high proportion of bright NK cells were significantly associated with stable magnetic resonance imaging (MRI) imaging after adjusting for treatment effects (p<0.05). Conclusion: The independent association of NK subsets with MRI stability needs to be confirmed in prospective studies to test their usefulness in predicting disease activity in MS patients.