RESUMEN
Fcgamma receptor (FcgammaR)-mediated destruction of immunoglobulin-coated red blood cells (RBCs) is the underlying mechanism of haemolytic disease of the newborn. Human leucocyte antigen (HLA) antibodies in vitro are able to block monocyte FcgammaRs and prevent phagocytosis. The intention was to demonstrate this effect in vivo upon a volunteer. Plasma containing a non-cytotoxic HLA-DR alloantibody was infused into the subject. The FcgammaR blockade was achieved and persisted for about 2.5 d, but, unexpectedly, a mild transfusion-related acute lung injury (TRALI) was also caused. Monocytes disappeared completely from the peripheral blood within the first hour after infusion and a mild pulmonary oedema was observed within 3-4 h. The subject recovered within 2 d.