Neutrophil pseudoplatelets: their discrimination by myeloperoxidase demonstration.

Neutrophils, especially in acute infection or the myeloid leukemias, may shed platelet-sized particles that can readily be distinguished from true platelets because they contain neutrophil myeloperoxidase. This enzyme, unlike platelet peroxidase, is not inhibited by glutaraldehyde. The myeloperoxidase and acid hydrolase levels and continuous plasma membranes of these cell-like particles suggest that they are functional cellular entities. They further differ from platelets in that they contain nuclear remnants, occur in bacteria-laden pus and inflammatory exudates, are ingested by macrophages, and do not adhere to each other or aggregate. They could be involved in the immune response to pathogens or contribute to trauma and healing by facilitating deployment of neutrophil acid hydrolase, neutral protease, and myeloperoxidase.