Work‐up in the case of granulocyte antibodies

Abstract

Granulocyte allo‐ and autoantibodies have been implicated in a variety of clinical conditions such as primary and secondary autoimmune neutropenia (AIN), alloimmune neutropenia (NAIN), transfusion‐related acute lung injury (TRALI) as well as febrile and severe pulmonary transfusion reactions. The classic granulocyte agglutination test (GAT) in combination with the granulocyte indirect immunofluorescence test (GIFT) can detect nearly all relevant antibodies. HNA‐1, ‐2, 4, 5 and HLA class I antibodies are clearly detectable in the GIFT while HNA‐3 antibodies strongly agglutinate neutrophils in the GAT. The glycoprotein‐specific and highly sensitive monoclonal antibody‐specific immobilization of granulocyte antigens (MAIGA) test detects all human neutrophil antigen (HNA) antibodies except for HNA‐3 but is time‐consuming and requires highly skilled personnel. For TRALI diagnostics, laboratory testing is completed by the indirect lymphocyte immunofluorescence test (LIFT), and HLA class I and II ELISAs or fluorescent bead‐based assays (Luminex). The latter also enable faster and more automated HNA antibody detection but to date not all specificities, especially HNA‐3, can be reliably detected so that still the classical tests have to complete the methodological spectrum. HNA allelotyping by PCR methods is the first choice for all HNA except for HNA‐2 because the molecular reason for the HNA‐2null phenotype is not completely understood. Establishing a PCR‐SSP reaction for the main CD177*787A>T polymorphism comprises the risk to miss other causes so that HNA‐2 is still typed serologically. Granulocyte serology even today is widely based on a variety of manual methods, requires experienced laboratory staff and profound knowledge of granulocyte immunobiology.