Comparison of antibody titers in donor specimens and associated AS-1 leukoreduced donor units

Impact of Uniform Methods on Interlaboratory Antibody Titration Variability: Antibody Titration and Uniform Methods

Context.—Substantial variability between different antibody titration methods prompted development and introduction of uniform methods in 2008.

Objective.—To determine whether uniform methods consistently decrease interlaboratory variation in proficiency testing.

Design.—Proficiency testing data for antibody titration between 2009 and 2013 were obtained from the College of American Pathologists. Each laboratory was supplied plasma and red cells to determine anti-A and anti-D antibody titers by their standard method: gel or tube by uniform or other methods at different testing phases (immediate spin and/or room temperature [anti-A], and/or anti-human globulin [AHG: anti-A and anti-D]) with different additives. Interlaboratory variations were compared by analyzing the distribution of titer results by method and phase.

Results.—A median of 574 and 1100 responses were reported for anti-A and anti-D antibody titers, respectively, during a 5-year period. The 3 most frequent (median) methods performed for anti-A antibody were uniform tube room temperature (147.5; range, 119–159), uniform tube AHG (143.5; range, 134–150), and other tube AHG (97; range, 82–116); for anti-D antibody, the methods were other tube (451; range, 431–465), uniform tube (404; range, 382–462), and uniform gel (137; range, 121–153). Of the larger reported methods, uniform gel AHG phase for anti-A and anti-D antibodies had the most participants with the same result (mode). For anti-A antibody, 0 of 8 (uniform versus other tube room temperature) and 1 of 8 (uniform versus other tube AHG), and for anti-D antibody, 0 of 8 (uniform versus other tube) and 0 of 8 (uniform versus other gel) proficiency tests showed significant titer variability reduction.

Conclusion.—Uniform methods harmonize laboratory techniques but rarely reduce interlaboratory titer variance in comparison with other methods.

Pathogenesis and mechanisms of antibody-mediated hemolysis

BACKGROUND

The clinical consequences of antibodies to red blood cells (RBCs) have been studied for a century. Most clinically relevant antibodies can be detected by sensitive in vitro assays. Several mechanisms of antibody-mediated hemolysis are well understood. Such hemolysis after transfusion is reliably avoided in a donor-recipient pair, if one individual is negative for the cognate antigen to which the other has the antibody.

STUDY DESIGN AND RESULTS

Mechanisms of antibody-mediated hemolysis were reviewed based on a presentation at the Strategies to Address Hemolytic Complications of Immune Globulin Infusions Workshop addressing intravenous immunoglobulin (IVIG) and ABO antibodies. The presented topics included the rates of intravascular and extravascular hemolysis; immunoglobulin (Ig)M and IgG isoagglutinins; auto- and alloantibodies; antibody specificity; A, B, A,B, and A1 antigens; A1 versus A2 phenotypes; monocytes-macrophages, other immune cells, and complement; monocyte monolayer assay; antibody-dependent cell-mediated cytotoxicity; and transfusion reactions due to ABO and other antibodies.

CONCLUSION

Several clinically relevant questions remained unresolved, and diagnostic tools were lacking to routinely and reliably predict the clinical consequences of RBC antibodies. Most hemolytic transfusion reactions associated with IVIG were due to ABO antibodies. Reducing the titers of such antibodies in IVIG may lower the frequency of this kind of adverse event. The only way to stop these events is to have no anti-A or anti-B in the IVIG products.