Anti-Wj: an autoantibody that defines a high-incidence antigen modified by the In(Lu) gene.

An IgG autoantibody, named anti-Wj, reacts with all random and most selected red cell samples. It does not agglutinate cells of Lu(a-b-) type caused by the In(Lu) dominant inhibitor gene, but cells of recessive Lu(a-b-) type are reactive. These data establish that synthesis of the Wj antigen is suppressed by the In(Lu) gene, but it is not a part of the Lutheran blood group system. The Wj antigen is not well developed on fetal red cells. This example of auto anti-Wj is a non-complement-binding IgGl protein that did not appear to cause accelerated in vivo destruction of the patient's red cells.