Cluster Of Differentiation 7 (CD7)?is a member of the immunoglobulin superfamily. This protein is found on thymocytes and mature T cells. It plays an essential role in T-cell interactions and also in T-cell/B-cell interaction during early lymphoid development. SECTM1?has been proposed as a ligand for?CD7. Thus a functional binding ELISA assay was conducted to detect the interaction of recombinant human CD7 and recombinant human SECTM1. Briefly, biotin-linked CD7 were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 ul were then transferred to SECTM1-coated microtiter wells and incubated for 1h at 37℃. Wells were washed with PBST 3 times and incubation with Streptavidin-HRP for 30min, then 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 nm immediately. The binding activity of CD7 and SECTM1 was shown in Figure 1, and this effect was in a dose dependent manner.