Do Donors With Non-Deletional Blood Group O Allels Boost Anti-A and Anti-B Titers in Blood Group O Recipients? E. A. Scharberg, S. Seyboth, K. Panter, A. Ernst, J. Hagel, E. Richter, G. Rink, K. Janetzko, P. Bugert Institute for Medicine and Immunohematology Baden-Baden, Germany Institute for Medicine and Immunology Mannheim, Germany
Methods (1) Routine ABO, (RhD, RhCcEe, K) phenotyping of first and second time donors on Olympus PK 7200 with monoclonal anti-a, anti-b reagents and reverse typing (A1, A2, B, O red cells) Unclear results in ABO proved in tube test (incubation 30 minutes at room temperature) with monoclonal anti-a, anti-b reagents and reverse typing (A1, A2, B, O red cells) Since May 2004 Samples with weak or negative A and B antigens and missing or weak (< 2+) corresponding isoagglutinins Low resolution ABO genotyping for A, A2, B, O01, O03 alleles (PCR-SSP) If no correlation between phenotype and genotype ABO subtyping for 36 rare alleles (Ael, Ax, Aw, Bx, Bw, etc.) (PCR-SSP) If still no correlation between phenotype and genotype Exon amplification and sequencing of entire ABO gene from genomic DNA
Donors with aberrant ABO phenotypes May 2004 thru December 2007: 206,262 first and second time donors 412 samples with aberrant ABO phenotypes (0.20%) 45 samples with weak antigens Ax01 (646T>A): n=15 Aw06 (502C>G): n=5 Aw13 (2T>C): n=3 Ael01 (804insG): n=2 Ax03*, Aw04, Aw09, B(A)03: n=4 (one each) novel variant (Bw21): n=1 347 samples with negative antigens and weak or absent isoagglutinins non-deletional O alleles (O03, Aw08, O51): n=255 other alleles (Ax03, Ax01 # ): n=6 novel variants (Bw20, Aw15): n=3 molecular basis unknown: 123 molecular basis unknown: n=15 Ax03* (Ax03/O03) Ax01 # (Ax01/B101)
Variant ABO alleles in this study *O01 261delG *O03 *Aw08 53G>T 220C>T 297A>G 526C>G 802G>A *Ax03 220C>T 297A>G 526C>G 802G>A 488C>T *Bw20 646T>A 771C>T 681G>A 829G>A 297A>G 817insG 526C>G 703G>A 803G>C 657C>T 796C>A
Clinical significance of non-deletional O alleles in blood donors? practice: No deferral of donors with missing or weak isoagglutinins Red cell units with clear serological ABO antigen typing used for transfusions No transfusion reaction reported Do some of the non-deletional O alleles have low antigen expression that might boost the isoagglutinins of recipients?
Study Design Plasma or serum samples of all 6,387 patients tested in our laboratory from January 1 thru December 31, 2007 stored at -30 C. Look back procedure (January 2008) identifying patients who randomly received ABO variants with non-deletional O alleles In patients with follow up samples Titration of anti-a and anti-b in samples at the time of the cross-match of the ABO variant and in follow up samples in gel technique using A1 and B red cells: Neutral gel cards: incubation 15 minutes at room temperature Antiglobulin gel cards: incubation 15 minutes at 37 C
Results 20,566 red cell units cross-matched for 6,387 patients tested in our laboratory from January 1 thru December 31, 2007 stored at -30 C. 35 patients received red cell units with non-deletional O alleles 21 of them had follow up samples (6 to 286 days after transfusion) 17 patients (all group O) received units with O03 allele 2 patients (both group A) received units with Bw20 allele 1 patient (group O) received a unit with Aw08 allele 1 patient (group O) received a unit with Ax03 allele
Anti-A Titer before and after of Red Cell Units with O03 Allels 1000 100 Titer 10 1 1 2 3 4 5 6 7 8 9 Sample 10 11 12 13 14 15 16 17 IgG after IgG before IgM after IgM before
Anti-B Titer before and after of Red Cell Units with O03 Allels 100 10 Titer 1 1 2 3 4 5 6 7 8 9 Sample 10 11 12 13 14 15 16 17 IgG after IgG before IgM after IgM before
Anti-A Titer before and after of Red Cell Units with Aw08 and Ax03 Alleles 1000 100 10 Titer 1 IgG after Aw08 Ax03 IgM after IgG before IgM before
Anti-B Titer before and after of Red Cell Units with Aw08, Ax03 and Bw20 Alleles 100 10 Titer Aw08 1 Ax03 Bw20-1 Bw20-2 IgM before IgM after IgG before IgG after
Conclusions: The increasing number of known ABO variants with non-deletional alleles raises the question of their clinical significance especially in blood donors. of red cell units with the variant ABO alleles O03, Aw08, and Ax03 typed and transfused as group O, and Bw20 typed and transfused as group A did not boost anti-a and anti-b titers in blood group O/A recipients. For these variants no donor deferral because of missing or weak isoagglutinins seems to be necessary.