Fig. 1

Interaction between an antigen presenting cell (APC) and a T cell, and V(D)J recombination. a Interaction between the antigen–major histocompatibility complex (MHC) and the αβ T-cell receptor (TCR). b V(D)J recombination: During T cell development, the loci that encode T-cell receptor α and β-chains are rearranged. For both loci, variable (V) and joining (J) gene segments, and an additional diversity (D) gene segment for the β-chain, are recombined to form the final rearranged TCR DNA sequence. This process also involves the deletion and insertion of nucleotides at the V-D, D-J and V-J junctions (not shown). Following transcription, the sequence between the recombined V (D)J regions and the gene encoding the constant (C) region is removed by splicing. The complementarity-determining region (CDR) 3 is encoded by the V (D) J junction, whereas the CDR1 and CDR2 loops are encoded within the germline V gene