Characteristics of RBC Alloimmunization Detected by Unexpected Antibody Screening Tests

Kim, Kyeong Hee; Kim, We Jong; Han, Jin Yeong; Kim, Jeong Man

Abstract

BACKGROUND: Alloimmunization to RBC antigens may cause delayed hemolytic transfusion reactions and delayed serological transfusion reactions. In the present study, the frequency of alloimmunization and its clinical significance were evaluated.
METHODS
Antibody screening tests for 17,365 samples from 11,372 patients were retrospectively analyzed during a 25-month period from February 2003 to March 2005. The records of transfusions and the clinical characteristics of the patients who had initially negative screening tests that converted to positive tests were evaluated. The unexpected antibody screening and identification tests were performed using the LISS/Coombs gel test with the DiaMed-ID system.
RESULTS
The positive rate of the antibody screening tests was 1.36% (155/11,372). Thirty-eight patients (0.63%, 38/5,993) showed positive antibody screening tests from an initially negative screening. The most common clinically significant alloantibodies were Rh group antibodies (52.6%). The mean transfused RBC units, mean interval and mean transfusion frequencies for patients with initially negative antibody screening tests that converted to positive findings were 3.7 units, 56 days and 1.7 times, respectively. Antibodies from nine patients became undetectable following the first detection assay.
CONCLUSION
RBC alloimmunization detected by unexpected antibody screening tests did not correlate with the quantity of transfusion and frequency of transfusion. One should be careful to recognize antibodies that are positive in an initial antibody screening test that subsequently become undetectable.