Another Kell-related antibody, anti-K19

A new high-frequency antigen related to the Kell system was defined by the serum of a patient, Mrs. Sub. The antigen was lacking from her cells and those of one of her three siblings. All random cells tested were incompatible with her serum as were bloods of other various "null" phenotypes, but Ko bloods were compatible suggesting that the antibody, subsequently called anti-K19, was related to the Kell blood group system.