Isotope dilution method for assay of inagglutinable erythrocytes

The number of cells that remain free in the presence of agglutinin is usually much larger than the number of inagglutinable cells. The true inagglutinable proportion can be found by successive agglutinations of a labeled population in the presence of unlabeled carrier cells. By this means it is shown that group A persons possess non-A erythrocytes in proportions of the order of 10(-3).