Characterization of CD177-reactive iso- and auto-antibodies.

BACKGROUND: CD177 is a surface protein on neutrophils and a main mediator for the surface expression of proteinase 3 (PR3). Its functions are largely unknown. At least three types of antibodies have been described to target CD177: isoantibodies, which are formed in CD177-null individuals as a result of an immune reaction following transfusion or pregnancy; autoantibodies present in sera from patients with autoimmune neutropenia; and antineutrophil cytoplasmic antibodies in sera from patients with glomerulonephritis with polyangiitis. In this study, we aimed to compare the binding characteristics of auto- and iso-antibodies to optimize their detectability in the neutrophil serology laboratory. STUDY DESIGN AND METHODS: The reactivity of iso- and auto-antibodies against CD177 was studied using granulocytes, "native" CD177/PR3 complex, and recombinant CD177 or PR3. RESULTS: All iso- and auto-antibodies were reactive with CD177/PR3 when immobilized with monoclonal antibody (moab) 7D8. Seventy-five percent of autoantibodies, but none of the isoantibodies, did not react with CD177/PR3 immobilized with moab MEM166. The majority of autoantibodies did not react with recombinant CD177, whereas most isoantibodies tested positive. DISCUSSION: Our results suggest that iso- and auto-antibodies against CD177 target different epitopes. Isoantibodies mainly target CD177 alone, while the majority of autoantibodies target a native epitope present on the neutrophil surface, but absent from recombinant CD177 which lacks PR3. Moab MEM166 binds to the native epitope and hinders the binding of CD177 autoantibodies. The results may help to design diagnostic strategies, especially for the identification of autoantibodies.

Neonatal Immune Incompatibilities between Newborn and Mother.

Background: Incompatibilities between the mother and unborn baby can cause complications that must be identified early to initiate the appropriate treatment. For example, neonatal alloimmune thrombocytopenia (NAIT), neonatal alloimmune neutropenia (NAIN), and morbus hemolyticus neonatorum affect children worldwide. Aim: This literature review aims to depict the similarities and differences between these three disorders from a clinical and mechanistic point of view. Material and Methods: The current literature review entailed conducting a systematic search to locate articles on the three conditions. Different electronic databases, including PsycINFO, PubMed, Web of Science, and CINAHL, were searched using the search terms "neonatal alloimmune thrombocytopenia", "neonatal alloimmune neutropenia", "morbus hemolyticus neonatorum", "NAIT", "FNAIT", "fetal", "NAIN", and "hemolytic disease of the newborn". Results: This review shows that these three diseases are caused by incompatibilities between the maternal and fetal immune systems. Furthermore, these conditions can lead to severe complications that hinder fetal development and cause death if not well managed. Discussion: The current literature review shows that NAIT, NAIN, and morbus hemolyticus neonatorum are rare conditions that occur when the mother produces antibodies against the fetal immune system. Thus, there is a need for the early detection of these conditions to initiate appropriate treatment before the child experiences adverse effects. Conclusion: The development of NAIT, NAIN, and morbus hemolyticus neonatorum is linked to the production of antibodies against the fetal immune system and fetal antigens. Further studies are required to determine potential interventions to reduce the risk of developing these three conditions.