Acquired B antigen and polyagglutination in a apparently healthy blood donor.

This work presents the second published report of an apparently healthy adult with an acquired B antigen. This case is unique because of the serial studies documenting the increase in strength of the B antigen, development of polyagglutinability, and absence of detectable gastrointestinal pathology. The cells of G.R., a 56-year-old caucasian female, came to our attention because of weak reactions with anti-B. Her cells were typed normal group A one year earlier. G.R.'s cells specifically absorbed an eluted anti-B. Her saliva contained A and H, but no B substance. The red cells were not polyagglutinable. Her cells did not react with the lectin Bandeiraea simplificolia. The cells reacted more strongly with anti-B from group A2 donors than A1. Her serum reacted with all normal group B cells, but was nonreactive with two other examples of acquired B cells. The autologous control and direct antiglobulin test were consistently negative. Samples examined three, six, and twelve months later showed the same serological results except that the acquired B antigen was stronger, although weaker than group B controls, and the cells were polyagglutinable. The cells failed to react with the following lectins Bandeiraea simplificolia I, Salvia sclarae, Salvia horminium and Soy bean lectin; but reacted with Arachis hypogea and Bandeiraea simplificolia II. Freezing and thawing the cells removed the polyagglutination but did not affect the B antigen. Normal A1 cells, but not O cells, became specifically agglutinable by anti-B after incubation with G.R.'s serum. G.R. is free from obvious pathology as determined by physical examination and gastrointestinal X-rays.