1. Neutrophil antigens include P, I, and HLA class I antigens but not ABO antigens. Important human neutrophil antigens (HNA) systems include HNA-1 to HNA-5 which are defined by alleles of genes encoding neutrophil surface glycoproteins. 2. HNA typing is performed using PCR or sequencing based techniques while HNA antibody detection uses assays like GIFT-FC, GCLT, and MAIGA. 3. HNA incompatibility can cause conditions like neonatal alloimmune neutropenia and transfusion related acute lung injury. HNA typing and antibody screening are important for investigating and managing these conditions.