The procedure used with this reagent is based on the principle of agglutination described by Landsteiner. Normal human red blood cells possessing antigens will clump in the presence of antibody directed towards the antigens. Renkonen showed that some extracts of seeds (lectin) contain powerful agglutinins with human blood group specificity. The extract of the seeds from Dolichos biflorus is virtually specific for A1 antigen on red blood cells.
