Human Monoclonal Anti‐D with Reactivity against Category DVI Cells Used in Blood Grouping and Determination of the Incidence of the Category DVI Phenotype in the DU Population

B-lymphoblastoid cell lines transformed by Epstein-Barr virus were produced from cells obtained from a hyperimmunised donor with serum anti-D activity against category DVI red cells and enriched for this activity by rosetting with category DVI red cells. Three clones produced IgG1 anti-D and had stable cell growth and continuous secretion of antibody in prolonged culture. The monoclonal antibodies reacted with category DVI red cells, when assessed manually and in an automated blood grouping system, and are useful blood grouping reagents for the detection of the category DVI phenotype. Using a radiometric technique, the number of antibody molecules bound to category DVI red cells from 5 individuals was estimated to range from 2,800 to 11,200 per cell. Five percent of blood donors classed as Du in the south western region were found to have the category DVI phenotype.