Autoimmune Neutropenia Updates: Etiology, Pathology, and Treatment

Autoimmune neutropenia (AIN) is defined as a neutrophil count <1.5 x 10(9)/L caused by increased peripheral destruction of neutrophils from an underlying autoimmune mechanism in which autoantibodies are directed against a patient's own neutrophils. AIN has a multifactorial etiology ranging from an idiopathic primary phenomenon to secondary disorders associated with established autoimmune diseases. Primary AIN is more prevalent in children, generally self-limited, and typically manifests as a sole hematologic abnormality. Secondary AIN is more common in adults and often occurs in the setting of concurrent autoimmune diseases, infections, malignancies, or medications. It may be seen posttransplantation or occasionally with neurological diseases. Various laboratory modalities are used to detect anti-neutrophil antibodies. Although biologic agents such as rituximab and alemtuzumab (Campath-1H) have been used in the management of AIN, granulocyte colony-stimulating factor remains the first-line therapy. In this article we provide a review of the pathogenesis of AIN, its clinical presentation, and the current treatment options.