Background Persistent inflammation as seen in patients with autoimmune disorders can potentially lead to the development of monoclonal B-cell disorders. The incidence of non-Hodgkin's lymphoma is more than 2-fold higher in RA patients compared to the general population . Monoclonal B-cell lymphocytosis (MBL) refers to the asymptomatic presence of monoclonal B-cells in the peripheral blood with a risk of progression to lymphoproliferative disease. MBL includes CLL-type (CD5 positive) MBL (5.1%), which is more common in the UK and less common non-CLL type (CD5 negative) MBL (1.8%) .
Objectives To assess whether the prevalence of monoclonal B-cell disorders is higher in autoimmune disorders compared to the native general population.
Methods Peripheral blood B-cells from patients with autoimmune disorders were analysed using a panel of CD19 PerCP-Cy5.5, CD20 APC-H7, Kappa BV421, Lambda FITC, CD45 BV510, CD305 PE and CD5 PE-Cy7. The presence of MBL was defined according to standard criteria , briefly the detection of a monoclonal B-cell population in the peripheral blood with an overall kappa:lambda ratio >3:1 or <0.3:1, or greater than 25% of B cells lacking or expressing low level surface immunoglobulin, or the presence of a disease-specific immunophenotype in the absence of any other feature diagnostic of a B-lymphoproliferative disorder.
Results Peripheral blood from a total of 128 patients with autoimmune disorders were analysed by flow cytometry for the presence of monoclonal B-cells. This included 101 RA patients, 11 patients with SLE, 7 patients with GPA and 8 patients with other autoimmune disorders. The patient group was predominantly females with female to male ratio of 2.7:1 (93:35). The median age of the patients was 57 years (18–85). 45 patients were between 40 – 60 years old and 55 patients were between 60 – 80 years old. 23 patients were less than 40 years old and 5 patients were more than 80.
The presence of a monoclonal B-cell population was detected in 10.1% (13/128) of the patients. One of these patients was already known to have CLL. The prevalence of CLL type MBL was 2.4% (3/127) and non-CLL type MBL was 7.1% (9/127). Of these 12 patients, 7 patients had RA, 2 patients had GPA, 2 patients had SLE and one patient had an overlap of RA and Sjogren's syndrome. Five patients were between 60–80 years old, three in their 30s, three in their 80s, and one in their 50s.
Conclusions Non-CLL type MBL may be more common in patients with autoimmune disorders compared to the general population in the UK. The apparent relative increase in CD5neg MBL could be associated with the effective control of the inflammatory disease process or the direct effect of therapies used for the treatment of autoimmune diseases on B-cells. More extensive studies are required to understand the implications of current treatment strategies on the selective pressure for expansion of monoclonal B-cell populations.
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Disclosure of Interest None declared