Anti-Vel reactivity diminished by adsorption with rabbit RBC stroma.

Background: An anti-Vel, nearly missed in antibody identification studies, and the effect of a commercially available rabbit RBC stroma (RESt, Immucor) adsorptions on eight anti-Vel sera are reported. Anti-Vel is an antibody to an antigen of high prevalence.

Case Report: A 48-year-old woman with chronic vaginal bleeding presented with a Hct of 14.7 percent. The transfusion service was not informed of her history of anti-Vel when she was transferred from another institution. Studies performed on an emergency request for transfusion were interpreted as a cold autoantibody as adsorption with a commercial source of RESt eliminated the reactivity. Stored anti-Vel sera were tested by titration studies before and after adsorption with commercial RESt.

Results: Serum from the index case did not react after adsorption with RESt at the transfusion service. Studies with the stored anti-Vel indicated antibody adsorption with four of four samples at immediate spin (IS) and room temperature (RT) phases, four of eight samples at 37 degrees C in albumin (ALB) phase, and four of eight samples at ALB-IgG-AGT phase. Variations in antibody reactivity were observed in the samples tested, but RESt adsorption diminished antibody reactivity in most samples. All eight stored sera demonstrated some reactivity in at least one phase after adsorption with RESt.

Conclusion: Anti-Vel was completely or partially adsorbed by RESt. Caution should be used when interpreting cold agglutinins with this method. The manufacturer warns that uncommon alloantibodies may be adsorbed.