Current Status of the Vel Blood Group System

Abstract

A review of the Vel blood group system reveals that 19 thoroughly studied examples of anti‐Vel are known and at least 50 Vel negative persons are recorded. The frequency of the Vel negative person is 0.04 per cent. All cases to date have been in Caucasians. The antigen is poorly developed in cord blood, but retains reactivity in the aged, on storage at 4 C, as well as after freezing. An associated hemolysin is usually not reactivated by addition of complement after inactivation. Bromelin technics are best. Independence from most major blood groups is established. Clinical importance is in difficult crossmatching and transfusion reactions. No hemolytic disease of newborn has been reported (three examples of anti‐Vel present during pregnancy). Family studies are essential to discover compatible donors, since 25 per cent of the siblings of Vel negative persons must also be Vel negative. The American Association of Blood Banks Central File has a list of available donors. Awareness of the existence of anti‐Vel facilitates the transfusing of a patient with high frequency antibody.

Anti‐Vel reactivity diminished by adsorption with rabbit RBC stroma

“…Antibody to the Vel antigen is clinically significant because of its reported ability to cause hemolytic transfusion reactions. The antibody was first characterized in 1952 by Sussman and Miller, 2,3 who found that it reacted with all but 1 of 4000 samples tested. Other studies have estimated that the Vel‐negative phenotype occurs in only 2 of 10,000 individuals (i.e., Vel has an antigen frequency of 99.98%) 4 .…”

Molecular Screening for Vel- Blood Donors in Southwestern Germany

“…After further reports of acute hemolytic transfusion reactions and hemolytic disease of newborns of Vel- mothers, Vel was recognized as a clinically important blood group antigen [2,3]. The exact immunogenicity of the Vel antigen is not known but there are several requests and nation-wide searches for Vel- red cell concentrates every year in Germany.…”

High Frequency Antigens, including Vel

“…In the families of 11 Vel -propositi the sibling count, excluding propositi, approached very closely 3:1 Vel + :Vel -, the ratio expected if the Vel -phenotype results from Vel is generally expressed less strongly on cord red cells than on those of adults [3,16] . Vel has been detected on fetal red cells as early as 12 weeks ' gestation [17] .…”