TCR is a heterodimer composed of alpha and beta chains or gamma and delta chains. TCR Valpha elements expression is largely independent of MHC haplotype. It is likely that the Valphas interact preferentially with conserved region of class I or class II molecules. RR3-16 antibody reacts with the Valpha3.2 T-cell receptor (TCR) of mice having the b (e.g., C57BL/6) and c (e.g.,SJL, NOD) haplotypes, but not with the strains having the a ( Balb/c) or d (DBA/2) haplotype. Valpha3.2 TCR is preferentially expressed by CD8+ T cells.