Impact of MD1 on the degree of expression of CD180 in chronic lymphocytic leukemia cells

Author: Ana-Mariam Kvachadze
Keywords: Chronic lymphocytic leukemia, MEC1 cell culture, CD180, MD1
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Chronic lymphocytic leukemia (CLL) is the most common leukaemia in the Western world and represents expansion of CD19+CD5+CD23+ cells. CLL cell proliferation and expansion is driven by B cell receptor ligation with (auto)antigens and by interaction with the microenvironment through a variety of receptors. One of these receptors is the CD180 toll-like receptor. Our team has shown, that it is expressed on about 60% of CLL cells, is involved in the regulation of CLL cell proliferation and apoptosis and correlates with overall patients survival. Since all normal B cells express CD180, its absence from 30% of the CLL samples is puzzling. CD180 is structurally associated with the satellite molecule MD1. In this project we will investigate whether MD1 expression patterns would affect CD180 expression and pro-apoptotic and pro-survival signaling mediated by CD180. For this purpose MEC1 CLL-based cell line was used. Cell phenotype in cell culture dynamics, CD180 and MD1 expression patterns and signaling pathways will be studied with the use of flow cytometry and appropriately labeled monoclonal antibodies. We anticipate better understanding of the role of MD1 in CD180 expression and signaling. Our research goal was to understand the role of MD1 towards CD180 and other signaling molecules in the different time spots in the proliferative cell line – MEC1. In order to understand the impact of MD1 on the degree of expression of CD180 in MEC1 cells, we studied the immunophenotype of cells in the different time spots, the CD19+/MD1+//CD180+ immunophenotype percentage alteration of 24-72h cells after 24 hour stimulation of these cells with IgM or/and IgD. As a result of our research, it was concluded that MD1 in MEC1 cell culture is a positive regulator of CD180 receptor; MEC1 72-hour cell culture is anergic to IgM, IgD and joint binding of B cell receptor. MEC1 in 72-hour cell culture, IgD stimulation in 48-hour culture may cause an increase in CD180 expression. This is evidenced by a small level of CD19+CD180+ population in a 48-hour culture, the invariance of apoptosis in IgD-stimulated cells compared to non-stimulating cells and at the same time a sharp increase in MD1 expression in none CD19+CD180+ cells of a 48-hour cell culture. In result, the impact of MD1 expression was determined on the expression of CD180 and its functions, which modulation is followed by leukemic cell apoptosis. This research will allow us to determine new approaches to CLL immunotherapy.This work was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) [grant number MR-21-255].

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