Peripheral blood B cell subsets from patients with various activity of chronic sarcoidosis

Abstract

Sarcoidosis is an inflammatory disease of unknown etiology, characterized by development of necrosis-free epithelioid cell granulomas, resulting in hyperactivation of various cells of the immune system. The role of humoral mechanisms in the pathogenesis of sarcoidosis is less studied than cell-mediated. It is necessary to study the role of activation or the anergy of the B cell development of immunity in sarcoidosis, the degree of its activity and the characteristics of the clinical course of the disease. Our study was aimed at investigating the characteristics of the B cells subsets in the peripheral blood of patients with chronic sarcoidosis (n = 41), depending on the activity of the disease. The control was peripheral blood samples from healthy volunteers (n = 43). Objective clinical and instrumental criteria, angiotensin converting enzyme (ACE) were used to determine the activity of the disease. Using flow cytometry analysis of peripheral blood cell B cells were determined based on two approaches: expression of IgD/CD38 (“Bm1-Bm5” classification) and IgD/CD27. In patients with sarcoidosis there was a significantly higher relative number of Bm2 "activated" naive cells" (IgD+CD38+) than in conditionally healthy volunteers, 65.38% versus 55,66% (p < 0.001). The relative and absolute contents of eBm5 (IgD-CD38+) and Bm5 (IgD-CD38+) memory cells were significantly lower in the group of patients with sarcoidosis relative to the control group. Relative values: 6.59% versus 13.31%, (p < 0.001), and 3.43% versus 8.49%, (p < 0.001), respectively. It was shown that with an increased level of ACE in the peripheral blood of patients, the number of naive Bm1 cells (IgD+CD38-) was significantly reduced, r = -0.557, p < 0.001. The relative content of memory B cells that did not switch the class of synthesized antibodies (IgD+CD27+) in the group of patients was reduced to 6,25%, and in the control group — 12,95% (p<0.001). The number of memory cells that switched the class of synthesized antibodies (IgD-CD27+) was also significantly reduced in patients with sarcoidosis and amounted to 6.75% versus 16.50% in the control group (p < 0.001). In patients with high levels of ACE, there was an increase in the relative content of naive B cells (IgD+CD27-), r = 0.532, p < 0.001. An inverse relationship was established between the number of memory B cells (IgD+CD27+) and ACE levels, r = -0.565, p < 0.001. These results indicate the important role of the B cell immune response in the pathogenesis of sarcoidosis and make it possible to evaluate the characteristics of the humoral response with various degrees of disease activity.

Keywords

• sarcoidosis
• disease activity
• b cells
• flow cytometry
• multicolor immunophenotyping