Anti-CD72 monoclonal antibody, clone 5E20

Systemic lupus erythematosus (SLE) is a severe and heterogeneous autoimmune disease with a complex genetic etiology, characterized by the production of various pathogenic autoantibodies, which participate in end-organ damages. The majority of human SLE occurs in adults as a polygenic disease, and clinical flares interspersed with silent phases of various lengths characterize the usual evolution of the disease in time. Trying to understand the mechanism of the different phenotypic traits of the disease, and considering the central role of B cells in SLE, we previously performed a detailed wide analysis of gene expression variation in B cells from quiescent SLE patients. This analysis pointed out an overexpression of TRIB1. TRIB1 is a pseudokinase that has been implicated in the development of leukemia and also metabolic disorders. It is hypothesized that Trib1 plays an adapter or scaffold function in signaling pathways, notably in MAPK pathways. Therefore, we planned to understand the functional significance of TRIB1 overexpression in B cells in SLE. We produced a new knock-in model with B-cell-specific overexpression of Trib1. We showed that overexpression of Trib1 specifically in B cells does not impact B cell development nor induce any development of SLE symptoms in the mice. By contrast, Trib1 has a negative regulatory function on the production of immunoglobulins, notably IgG1, but also on the production of autoantibodies in an induced model. We observed a decrease of Erk activation in BCR-stimulated Trib1 overexpressing B cells. Finally, we searched for Trib1 partners in B cells by proteomic analysis in order to explore the regulatory function of Trib1 in B cells. Interestingly, we find an interaction between Trib1 and CD72, a negative regulator of B cells whose deficiency in mice leads to the development of autoimmunity. In conclusion, the overexpression of Trib1 could be one of the molecular pathways implicated in the negative regulation of B cells during SLE.

The aim of this investigation is the comparative study of changes in the surface phenotype of lymphocyte in patients with different forms of atopic diseases and latent sensitization. Materials and methods. The study was conducted on peripheral blood lymphocytes from 22 latent sensitization patients, 30 pollinosis patients, 44 atopic bronchial asthma patients and 36 atopic dermatitis patients. The control group consisted of 26 healthy people. The results of our studies demonstrate that atopic diseases are different not only in clinical manifestations, but also in mechanisms of disturbances in the functions of the immune system. Comparative study of surface markers of lymphocytes in patients with different forms of atopic diseases revealed a significant increase of surface changes of lymphocyte phenotype according to the severity of the clinical manifestations of the disease. All patients with studied forms of atopy had an increase in content of B-lymphocytes expressing CD72 marker in the peripheral blood and of lymphocytes expressing early activation antigens CD23, CD25, CD71 and adhesion receptor CD54. The developments of pollinosis, atopic bronchial asthma and atopic dermatitis are accompanied by an additional increase levels of lymphocytes expressing the late activation marker HLADR, the CD38(+) precursors of plasma cells, and of lymphocytes carrying surface immunoglobulins in peripheral blood. In the blood of patients with atopic disease during exacerbation with evident clinical symptoms revealed a significant increase in all the studied populations and subpopulations of B-lymphocytes. Patients with latent sensitization had increasing blood lymphocytes expressing the CD95 receptor of Fas inducing apoptosis and low content of cells expressing its ligand CD178. Content of CD95(+) lymphocytes in peripheral blood at atopic bronchial asthma and atopic dermatitis patients is reduced, and CD178(+) lymphocytes increased, reflecting infringement of Fas-dependent apoptosis in severe atopic diseases.