The role of Vδ1 and Vδ2 γδT subsets in immune responses to Mycobaqterium tuberculosis in Georgian population

Author: Lana Sajaia
Keywords: Tuberculosis, T lymphocytes, γδT cell
Annotation:

Georgia belongs to the high tuberculosis (TB) incidence countries with high proportion of multiple drug resistance cases. Hence studying immune responses to Mycobacterium tuberculosis (MTb) in Georgian population is of a paramount importance. Recent data suggest an important role for γδT cells, particularly Vδ2 γδT subset in the in vivo responses to MTb. The T cell population comprises between 1 and 10% of the peripheral T cell pool, of these cells approximately 70%express the Vδ2 chain of the T cell receptor and 30% Vδ1 (Fahl et al., 2014). The cells expressing Vδ2 have been shown to recognise small phospholipid antigens (PAg) which are overexpressed in some tumour cells and some infectious diseases. Of importance here is the over-expression of the molecule (E)-4-hydroxy-3-methyl- but-2-enyl pyrophosphate(HMBPP) in cells infected with Mycobacterium tuberculosis (MTb, Chen et al., 2013). The mechanism by which the γδ T cell recognises this PAg is currently under much investigation but is thought to involve the B7 superfamily member Butyrophilin 3A (specifically BTN3A1). What is becoming clear is that the binding of PAg to BTN occurs within the cells, to the intracellular component of the BTN molecule. This appears to change the conformation of the molecule which is then recognised by the Vδ2 γδT cell (Sandstrom et al., 2014, Adams et al., 2015). Of interest in TB is that the HMBPP molecule is thought of as being 1000 times more effective than the endogenous isopentenyl pyrophosphate (IPP) molecule expressed in some tumour cells. This implicates the recognition of MTb infected cells by V γ2 δγT cells of being of particular importance. The aim of this research was to assess the frequency and phenotype of the subsets of γδTcells and their role in the immunopathogenesis of active form of the thepulmonary TB in Georgian population.This study conducted in Georgia for the first timein patients with an active form of pulmonary TB includes those receptors on γδT Vδ1 and Vδ2 cell subsets which are associated with activation, expansion, homing and memory phenotype. According our results, and in their latent TB family members in Georgia. in patients with active. We anticipate that the results of this investigation will allow us to understand possible correlation between the assessed features of γδT cells and transition of the latent form of TB to the active TB form.