B cell expression of the inhibitory Fcγ receptor is unchanged in early MS

• Published in: Journal of neuroimmunology 2010-06, Vol.223 (1), p.135-137
• Main Authors: Comabella, Manuel, Montalban, Xavier, Kakalacheva, Kristina, Osman, Deeqa, Nimmerjahn, Falk, Tintoré, Mar, Lünemann, Jan D
• Format: Article
• Language: English
• Subjects: Adult; Allergy and Immunology; Autoimmunity; B cell; B-Lymphocyte Subsets - immunology; B-Lymphocyte Subsets - metabolism; Clinically isolated syndrome; Cohort Studies; Disease Progression; Fc receptor; Female; Follow-Up Studies; Gene Expression Regulation - immunology; Growth Inhibitors - biosynthesis; Growth Inhibitors - genetics; Growth Inhibitors - physiology; Humans; Immune Tolerance - genetics; Male; Multiple sclerosis; Multiple Sclerosis - immunology; Multiple Sclerosis - metabolism; Neurology; Receptors, IgG - biosynthesis; Receptors, IgG - genetics; Receptors, IgG - physiology; Syndrome; Time Factors; Young Adult
• ISSN: 0165-5728; 1872-8421
• DOI: 10.1016/j.jneuroim.2010.03.015

Abstract Expression of the inhibitory Fcγ receptor IIB (FcγRIIB) has emerged as a late checkpoint during peripheral B cell development which prevents autoreactive memory B lymphocytes from becoming long-lived plasma cells. Decreased expression of FcγRIIB or non-functional FcγRIIB variants are associated with the development of autoimmune tissue inflammation. We determined the expression profile of FcγRIIB in peripheral blood cells in treatment-naïve patients with early MS. Twenty-five patients with clinically isolated syndrome (CIS) who converted to clinically definite MS (CDMS) and 25 demographically matched healthy donors were included in the study. Frequencies of peripheral blood monocytes and B cell subsets as well as FcγRIIB expression profile was determined by flow cytometry. FcγRIIB expression levels were higher in B cells compared to monocytes ( p < 0.0001) and higher in memory B cells compared to their naïve counterparts ( p < 0.0001). However, FcγRIIB expression in naïve and memory B cells as well as monocytes was unchanged in patients with early MS at onset of symptoms as well as after conversion to CDMS compared to controls. No significant correlations were found between FcγRIIB expression levels and brain MRI-derived metrics or EDSS progression during follow-up. These data indicate that FcγRIIB expression, a critical late B cell differentiation checkpoint preventing the occurrence of autoreactive long-lived plasma cells, is not impaired in treatment-naïve patients with MS, at least in the early phases of the disease.