Auto‐Anti‐Kp^b Associated with Weakened Antigenicity in the Kell Blood Group System: A Second Example

Abstract

An 84-year-old woman with intestinal bleeding had marked reduction of red blood cell antigenicity in the Kell system, and a positive direct antiglobulin test caused by auto-anti-Kpb. KX antigen activity of her cell was increased, an observation which supports the belief that KX marks a precursor structure utilized in the normal Kell biosynthetic pathway. It is postulated that reduced Kell antigenicity was an acquired change that resulted from enzymatic degradation, possibly of bacterial origin.