Leukocyte Antigen and Antibody Detection Assays: Tools for Assessing and Preventing Pulmonary Transfusion Reactions

Antibodies to neutrophil and HLA antigens can cause pulmonary transfusion reactions, and in some cases acute lung injury. When evaluating cases of pulmonary transfusion reactions, it is often necessary to test donors for neutrophil and HLA antibodies and also type the recipient for neutrophil and HLA antigens. A variety of enzyme-linked immunosorbent assay (ELISA) and flow cytometry–based solid phase assays are available to test for HLA class I and class II antibodies, but not neutrophil antibodies. Screening for neutrophil antibodies requires the preparation of panels of fresh neutrophils and testing in agglutination, immunofluorescence, or flow cytometry assays. Genotyping of HLA class I and II antigens is performed with a variety of sequence-specific primers, sequenced-specific oligonucleotide probe, and sequence-based typing assays. Neutrophil-specific antigens HNA-1a, -1b, -1c, -4a, and -5a can be genotyped, but not HNA-2a or -3a. Phenotyping of HNA-2a can be performed with CD177 monoclonal antibodies, but the gene encoding HNA-3a has not been identified, and the genomic basis for the HNA-2a–negative phenotype is not known. In conclusion, patients and donors involved with pulmonary transfusion reactions can be quickly typed for HLA antigens and tested for HLA antibodies, but testing for neutrophil antibodies and antigens requires the use of a reference laboratory.