Expression analysis of Js^a/Js^bpolymorphism. Flow cytometric analysis of 293T cells transiently transfected either with pRc/CMV-wt encoding the high incidence antigen Js^b or with the Kell cDNA encoding the T1910 to C mutation associated with Js^a antigen (pRc/CMV-Js^a). Alloimmune sera used were anti-Js^b (NM) and anti-Js^a (AM).