Flow cytometry analysis of CD9 cDNA-transfected CHO cells using anti-CD9 EC1 and EC2 antibodies.

Cell suspensions were incubated with rabbit IgG (rIgG), anti-CD9 EC2 antibodies mAb7 or RAP5a, or anti-CD9 EC1 RAP2. Bound antibody was detected by a species-specific FITC-conjugated antibody. The measured mean fluorescence intensity of anti-CD9 EC1 RAP2 suggested that each CD9 clone had equivalent CD9 surface density. The lack of anti-CD9 mAb7 binding on all CD9 EC2 deletion mutants suggests that the mAb7 epitope is located on CD9 EC2.