An anti-B reagent prepared from the alpha-D-galactopyranosyl-binding isolectins from Bandeiraea simplicifolia seeds.

A method for the large scale preparation of the alpha-D-galactosyl binding isolectins from Bandeiraea simplicifolia seeds using an absorbent prepared by linking D-galactosamine to CH-Sepharose is described. The addition of N-acetyl-D-galactosamine (GalNAc) to these isolectins produced an anti-B reagent (BS I + GalNAc anti-B). Although BS I + GalNAc anti-B readily agglutinated red blood cells from the majority of group B and AB donor and patient blood samples tested, it reacted weakly with group B and AB cord red blood cells and failed to agglutinate five of 100 group AB donor blood samples when tested by an automated technique. The reagent did not agglutinate the red blood cells from seven acquired-B red blood cell samples and was strongly reactive with Tn-polyagglutinable red blood cells. These findings indicate that this lectin anti-B preparation may be of more value in investigative immunohematology, rather than as an alternative to human group A serum as a source of anti-B for blood-typing purposes. The results of tests on Tn-polyagglutinable red blood cells with BS I + GalNAc anti-B and the purified isolectins BS I(A4) and BS I(B4) are also presented, and discussed in relation to current concepts on the structure of the Tn receptor.