OBJECTIVEThis study was to investigate the influence of "dosage effect" on unexpected antibody identification and explore its condition, scope and regularity.

METHODSA total of 40 blood recipient samples containing definite unexpected antibodies were selected by column agglutination technology, then AB fresh plasma was used to dilute the samples to obtain different concentrate liquid. After selecting panel cells which show positive with corresponding unexpected antibody in the serum, "single dosage" antigens were distinguished from "double dosage" ones, and then the antigen-antibody reactions were observed between "single dosage" panel cells and respective diluted recipient samples (by column agglutination technology). It's believable that the highest concentration which retains a negative result was choose to evaluate the agglutination strength between "double dosage" panel cells and diluted unexpected antibody, and to observe the difference happened at different "dosage" antigens with unexpressed antibody.

RESULTSAmong 40 diluted recipient samples detected by column agglutination technology, the "dosage effect" appeared in 31 diluted samples. There were 30 samples in which the unexpected antibody agglutinated "double dosage" antigens ≤ 2+, while "single dosage" antigens negative. It appeared in another 1 diluted sample, in which the unexpected antibody agglutinated "double dosage" antigens 3+. There were 9 diluted samples in which the unexpected antibody agglutinated panel cells showing negative results (strength was between 1+-3+ before dilution).

CONCLUSIONSWhen the unexpected antibodies in Rh, MNS, Kidd, Duffy agglutinated "double dosage" antigens ≤ 2+ (by column agglutination technology) , "single dosage" antibody reaction maybe weaken, even be negative, and it may cause the "dosage effect" to interfere the unexpected antibody identification. The "dosage effect" appears in Rh, MNS, Kidd, Duffy blood system usually.