LONG-TERM FOLLOW-UP TESTING OF RED-CELL ALLOANTIBODIES

Background: In previous studies, 29 to 34 percent of potentially hemol ytic red cell antibodies were not detected after short-term follow-up. Study Design and Methods: To examine long-term detection, records wer e reviewed for 44 consecutive patients who were tested more than 5 yea rs after their potentially hemolytic red cell antibodies vi,ere first identified in this hospital. Results: After 5 to 10 years, 14 (39%) of 36 Rh, Kell, and Duffy system antibodies were not detected on at leas t one occasion. Twenty-two other such antibodies were sought again aft er more than 10 years; 10 (45%) were not detected. When restimulation by pregnancy was excluded, these rates were 42 and 48 percent, respect ively. Conclusion: Clinically significant red cell antibody formation is probably more common than previously realized, because nearly half of these antibodies are undetected after long-term follow-up.