The Clinical Significance of Anti‐H in an Individual with the Oh (Bombay) Phenotype

To evaluate the clinical significance of anti-H present in individuals with the Oh (Bombay) phenotype, red blood cell 51chromium survival studies and related serological tests were undertaken in an Oh (Bombay) individual. A small sample of group O donor red blood cells was labeled with 51chromium and infused into the patient. The T 1/2 of the infused cells was six minutes, with two percent of the cells surviving at 24 hours. A similar study using the patient's own labeled red blood cells demonstrated 100 per cent survival at 24 hours. Initial laboratory studies indicated that the anti-H was active in saline at 4, 22 and 37 C and by the indirect antiglobulin test. Analysis of the antibody in both preand posttransfusion specimens showed it to have both IgM and IgG components. The anti-H titer at 37 C rose from 1:4 prior to the infusion of the O cells to 1:32 one week postinfusion, and a partial hemolysin appeared. Saliva inhibition studies demonstrated that the antibody was neutralizable prior to the group O exposure but was not neutralizable one week post exposure. We conclude that the anti-H present in this individual rapidly destroyed infused group O red blood cells. Individuals with the Oh (Bombay) phenotype should be transfused only with Oh (Bombay) blood.