Report on the Fourth International Granulocyte Immunology Workshop: progress toward quality assessment

A formal quality assurance (QA) scheme has been established to facilitate proficiency testing for granulocyte antibodies and antigens.

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.

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.

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.