Evaluation of Changes in New Calculated Panel Reactive Antibody Adopting HLA-Cw, DR51/52/53, and DQ Antigens in Koreans

Background: Calculated panel reactive antibody (cPRA) (%) is percentage of donors that would be incompatible with the candidate, based on the candidate's unacceptable HLA antigens. cPRA based on antigen frequencies of HLA-A, B, and DR has been used in Korea. We developed new cPRA including HLA-Cw, DR51/52/53, and DQ. Changes in new-cPRA were evaluated.

Methods: We analyzed the differences between cPRA based on HLA-A, -B, and -DR antigens (old-cPRA) from cPRA based on HLA-A, -B, -Cw, -DR, -DR51/52/53, and -DQ antigens (new-cPRA) on 125 waitlisted candidates for renal transplantation in Seoul National University Hospital. cPRA for unacceptable antigens was calculated according to 3 different cut-off values (MFI <1000, 3000, and 10000 for cPRAw, cPRAm, and cPRAs, respectively).

Results: For HLA class I, cPRAw and cPRAm were significantly increased in new-cPRA compared to old-cPRA (median 78.3% vs 71.7%, P < .001; 34.0% vs 23.5%, P = .029, respectively). For HLA class II, cPRAw, cPRAm, and cPRAs were significantly increased in new-cPRA compared to old-cPRA (median 86.8% vs 42.6%; 58.0% vs 0.0%; 0.0% vs 0.0%, P < .001 for all).

Conclusions: cPRA (%) including HLA-Cw, -DR51/52/53, and -DQ showed remarkable increase, especially in HLA class II antigens. The meaning of this should be carefully interpreted through further studies considering clinical outcomes.