Expression analysis of Kp^a/ Kp^bpolymorphism. Flow cytometric analysis of 293T cells transiently transfected either with pRc/CMV-wt encoding the high incidence antigen Kp^b or with the Kell cDNA encoding the C961 to T mutation associated with Kp^a antigen (pRc/CMV-Kp^a). Alloimmune sera used were anti-Kp^b (RAU) and anti-Kp^a (JH).