Long‐term follow‐up testing of red cell alloantibodies

Background: In previous studies, 29 to 34 percent of potentially hemolytic red cell antibodies were not detected after short‐term follow‐ up. Study Design and Methods: To examine long‐term detection, records were reviewed for 44 consecutive patients who were tested more than 5 years after their potentially hemolytic red cell antibodies were 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 least one occasion. Twenty‐two other such antibodies were sought again after more than 10 years; 10 (45%) were not detected. When restimulation by pregnancy was excluded, these rates were 42 and 48 percent, respectively. 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. 1994 AABB