Open AccessFalse negative single antigen bead assay: Is it always an effect of prozone?
Author(s) -
Jain Dharmendra,
Choudhuri Jui,
Chauhan Rajni,
Dorwal Pranav,
Sharma Deepak,
Tiwari Aseem K.,
Raina Vimarsh
Publication year - 2018
Publication title -
journal of clinical laboratory analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.536
H-Index - 50
eISSN - 1098-2825
pISSN - 0887-8013
DOI - 10.1002/jcla.22237
Subject(s) - panel reactive antibody , antibody , sensitization , flow cytometry , serial dilution , antigen , titer , immunology , human leukocyte antigen , medicine , chemistry , pathology , alternative medicine
Background Bead based flow cytometry and Luminex play a major role in identification of alloantibodies in renal transplant work‐up. Strong sensitization events may lead to prozone phenomenon that can affect single antigen bead ( SAB ) assay and result in false negativity. However, this can also be due to high titer of other blocking antibodies. While methods like, heat inactivation, C1 inhibitor, Ethylene diamine tetra‐acetic‐acid and Dithio threitol treatment can remove interfering antibodies of complement and IgM, these methods are not optimal if false negativity is due to prozone effect, which is high titer of antibodies alone. Methods We hereby present a case of a highly sensitized renal transplant recipient with 64% panel reactive antibody positivity ( PRA ) and a subsequent negative SAB assay. This paradoxical finding hinted at SAB being a false negative result and serial dilutions were used to perform further tests. Results Serum dilutions lead to positive flow based panel reactive antibody ( PRA ) and flow cytometry crossmatch ( FCXM ), with an increasing trend in FCXM . Conclusions In highly sensitized patients serial dilution should be considered during a transplant work‐up to avoid missing any underlying antibodies. Serum dilution can be used as first option to circumvent prozone. Also, interference of other antibodies should not be labeled as prozone effect.