Congenital autoimmune neutropenia in two premature neonates

Autoimmune neutropenia (AIN) has been reported in infants and children, but not in neonates. AIN is caused by antibodies produced by the patient again st their own neutrophils; therefore, it differs from the more common alloim mune neonatal neutropenia and the neonatal neutropenia because of a materna l autoimmune disease in which antineutrophil antibodies of maternal origin cross the placenta. We observed 2 cases of congenital AIN in premature neon ates. These are the youngest reported cases, and indicate that AIN can have a prenatal onset. Examination of the bone marrow biopsies revealed an incr ease in B lymphocytes and myeloperoxidase-positive cells with a maturation arrest at the myelocyte stage. Recombinant human granulocyte colony-stimula ting factor effectively treated the neutropenia, as it does in infantile AI N. Ten months after the diagnosis, 1 of the patients still requires recombi nant human granulocyte colony-stimulating administration.