Weak B antigen in a family.

A family is described in which six members were of a weak subgroup of B. Presence of the subgroup in each individual was first indicated by lack of anti-B in that person's serum. Additional tests showed that the B subgroup red blood cells would adsorb anti-B and yield that antibody on elution, and that the saliva of two B subgroup persons tested contained B and H substances. The blood of one of the family members with the weak B antigen was inadvertently transfused to a group O recipient but caused no ill effects.