Interrelationship of the Various Subgroups of the Blood Group A: Study with Immunofluorescence

The various subgroups of A studied with immunofluorescence seemed to form a single antigenic continuum with the A1 bloods at one end, and the “weak” A bloods at the other. Within this continuum each blood except the strongest samples of A1 was characterized by its own individual spectrum of reactivity, which ranged frcm 4+ to no fluorescence. These findings support a quantitative basis for the differences between the various subgroups of A. It is suggested that “weak” or Aw be used for the various bloods comprising the weak end of the continuum, rather than the numerous designations currently used, since with the fluorescent antibody technic, the differences within this group were no greater than those within the single category of A1 bloods.