Стимуляция В-клеток в системе ИЛ-21/CD40L в норме и у пациентов с общей вариабельной иммунной недостаточностью

Stimulation of B cells in the IL-21/CD40L system in healthy donors and in patients with common variable immunodeficiency

Introduction. Common variable immunodeficiency (CVID) refers to primary immunode-ficiencies. To date, a number of genes have been identified, mutations in which lead to the development of CVID. However, monogenic defects underlie no more than 10 % of CVID cases, and the bulk of CVID is associated with the participation of many genes. Under these conditions, to search for and decipher possible pathogenetic factors, it is effective to use the analysis of functional defects in the activation of B-lymphocytes. The aim of the study - to search for functional defects in the activation of B-lymphocytes in patients with CVID when stimulated in vitro in the IL-21/CD40L system. Material and methods. The study involved 14 patients with CVID. The group of comparison consisted of 10 healthy volunteers. Samples of blood mononuclear cells were obtained from peripheral blood and used to activate T cells. Phytohemagglutinin (PHA) or a combination of phorbol myristate acetate (PMA) and ionomycin (Io) were used as activators. CD40L induction on CD4+-cells was assessed using flow cytometry. B cells were isolated from the mononuclear cells by the method of immunomagnetic separation and B cell activation in the IL-21/CD40L system was carried out. Recombinant IL-21 and A549 feeder cells stably transfected with the CD40L gene were used as activating stimuli. The differentiation of B cells into plasmablasts was determined by the proportion of cells with the CD19+CD27+CD38+CD20low phenotype. Subpopulations of naive (IgM+IgD+), unswitched (IgM+CD27+) and switched (IgG+CD27+) B cells were isolated using a flow sorter. The secretion of IgG and IgM was determined using an enzyme immunoassay, and the number of IgG-secreting cells was estimated using the ELISpot method (Enzyme-Linked ImmunoSpot Analysis). Results. When T cells were activated by polyclonal stimulants, some of the CD4+-cells began to express CD40L. In T cells of healthy volunteers, stimulation with PHA or a combination of PMA and Io resulted in CD40L expression on 10 and 80 % of CD4+-cells, respectively. T cells from patients with CVID showed comparable activation and the proportion of CD4+CD40L+-cells was close to normal. When stimulated in the IL-21/CD40L system, B cells of patients with CVID retained the ability to differentiate into plasmablasts with the CD19+CD27+CD38+CD20low phenotype, but secreted IgG 10 times less than B cells from healthy volunteers. Сonclusion. In CVID patients the B cell activation pathways associated with IL-21 and CD40L remain intact, and the functional defects observed in CVID are obviously associated with other molecules. © 2021 Meditsina Publishers. All rights reserved.