CD3 epsilon (T-Cell Surface Glycoprotein CD3 Epsilon) is a 104-kD glycoprotein of the immunoglobulin (Ig) superfamily expressed in lymph node (RPKM 92.6), appendix (RPKM 45.9) and 9 other tissues. CD3 epsilon plays essential role in adaptive immune response. Mutations in CD3 epsilon lead to SCID (severe combined immunodeficiency). CD3E and CD247 can form two heterodimers flanking either side of the TCR. Thus a functional ELISA assay was conducted to detect the interaction of recombinant human CD3e and recombinant human CD247. Briefly, CD3e was diluted serially in PBS with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to CD247-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST and incubated for 1h with anti-CD3e pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody for 1h at 37℃, wells were aspirated and washed 5 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37℃. Finally, add 50 µL stop solution to the wells and read at 450/630 nm immediately. The binding activity of recombinant human CD3e and recombinant human CD247 was shown in Figure 1, the EC50 for this effect is 0.68 ug/mL.