Background: A formal quality assurance (QA) scheme has been established to facilitate proficiency testing for granulocyte antibodies and antigens.
Study design and methods: Fifteen laboratories participated in the Fourth International Granulocyte Immunology Workshop. The main objective of the workshop was to establish a formal QA scheme for granulocyte serology and molecular typing methods. A secondary objective was to determine the relative sensitivities of the granulocyte immunofluorescence test, granulocyte agglutination test, and MoAb immobilization assays using defined antisera and protocols.
Results: Laboratories scored between 16.7 and 100 percent (mean, 57.5%) of the maximum available in the serologic part of this QA exercise. There were particular problems in detecting granulocyte-specific human neutrophil antigen-1 (HNA-1a) IgM antibodies and HNA-2a antibodies in the presence of HNA-1b antibodies. The granulocyte immunofluorescence test was more sensitive than the granulocyte agglutination test in titration studies, but the latter method more readily identified the presence of HNA-3a antibodies. HNA genotyping was generally well performed, with nine laboratories obtaining 100-percent correct results for HNA-1a, HNA-1b, and HNA-1c.
Conclusions: There is a need to standardize the detection of granulocyte-specific antibodies. Laboratories with good performance tended to use two methods for detecting granulocyte-specific antibodies and an HNA-typed panel of granulocytes. The use of a method for elucidating mixtures of granulocyte- and lymphocyte-reactive antibodies (e.g., MoAb immobilization assay) and the use of methods for detecting both cytotoxic and noncytotoxic HLA class I antibodies were also associated with a higher than average performance.