Doctoral defence: Marina Šunina "Flow cytometric analysis of T and B cell properties in healthy donors and subjects with vitiligo"

On October 25 Marina Šunina will defend her thesis "Flow cytometric analysis of T and B cell properties in healthy donors and subjects with vitiligo"

Supervisors:
Professor Raivo Uibo, University of Tartu
Professor Kai Kisand, University of Tartu

Opponent:
Professor Sirpa Jalkanen, University of Turku (Finland)

Summary:
Along with the endocrine and nervous systems, the immune system helps us to cope with various environmental stimuli and is crucial for human well-being and survival. Not only does it fight infection, but also eliminate damaged and tumour cells in addition to restraining inflammation and allergic reactions. Therefore, regulation of the immune response is a highly sophisticated multi-level process. Among other ways, the regulation can be exerted through expression of co-stimulatory and co-inhibitory cell surface molecules. If co-stimulatory signals outweigh, immune cells get activated. Co-inhibitory signals, in turn, hold back excessive activation. The regulation can be also exerted via specific cell subsets called regulatory cells, which are capable of directly suppressing unwanted inflammatory responses by cell–cell contacts or secretion of specific signalling molecules – cytokines. Disturbances in the regulation of the immune response may lead to development of various diseases. Hereby, we described the influence of cell stimulation on the surface expression of three particular molecules in major T-cell subsets: co-stimulatory CD28, co-stimulatory CD226 and co-inhibitory TIGIT. The balance of TIGIT and CD226 on the cell surface may influence differentiation, effector functions and acquisition of memory phenotype of immune cells. We also isolated and characterised circulatory regulatory B cells – a rare cell population with diverse phenotypes and a potent suppressive capacity. Additionally, we explored potential abnormalities in circulating subpopulations of immune cells in individuals with vitiligo. Vitiligo is an acquired chronic autoimmune disorder. During the disease, the immune system progressively destroys epidermal melanocytes, which results in the appearance of patchy depigmentation. This work suggests that B cells along with CD226 and TIGIT receptors may play a more profound role in the pathogenesis of vitiligo than suspected previously. 

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