Brief introduction to TCR sequencing and analysis: immune repertoire sequencing (Rep-seq) Part One
1. Introduction T cell-mediated antigen recognition depends on the interaction of the T cell receptor (TCR) with the antigen major histocompatibility complex (MHC) molecule. TCR is a highly diverse heterodimer composed of the alpha and beta chains (αβ TCR) expressed by most T cells, or from T cells (1-5%) in peripheral blood or T-cell expressed γδ chain (γδ TCR) in mucosal sites. Similar to immunoglobulins expressed by B cells, membrane-bound immunoglobulins are commonly referred to as B cell receptors (BCRs), which consist of variable and constant regions recognized by the antigen. The variable regions of the TCR alpha and delta chains are encoded by a plurality of variable (V) and ligation (J) genes, while the TCR beta and gamma chains are encoded by a diversity (D) gene. During VDJ recombination, one random allele of each gene fragment is recombined with other gene segments to form a functional variable region. A functional TCR strand transcript is produced by recombining t
