Neonatal alloimmune neutropenia is due to maternal production of antibodies directed against neutrophil specific antigens (NA1, NA2, NB1, NC1) reacting with fetal-neonatal and paternal neutrophils. The incidence is about 0.5-2 per 1000 live births. The affected infants may develop skin or severe, rarely fatal, systemic infections. Treatment with steroids, exchange transfusion, leukocyte transfusion, intravenous immunoglobulin have given inconsistent results.

We recently observed a term infant with severe neutropenia, absolute neutrophil count 0.17Ă—109/L at birth, sepsis by Staphylococcus aureus and severe perianal skin infection resistant to antibiotic therapy. Search for anti-neutrophil antibodies by GIFT (granulocyte indirect fluorescence test) was positive both in mother and infant. On the ninth day of life we started treatment with 10 μg/kg/day of G-CSF. Serum concentration of G-CSF rose from a pretreatment value of 449 pg/ml to >25000 pg/ml after G-CSF. The infant presented a significant rise of neutrophil counts (from 0.45Ă—109/L to 1.25Ă—109/L) after three days of treatment. After ten days G-CSF was suspended due to the high neutrophil count(20Ă—109/L). Neutrophil chemotaxis, phagocytosis and expression of CD11a-CD11b was normal after G-CSF. The clinical condition improved dramatically in correspondence with the neutrophil rise, with resolution of sepsis and complete healing of skin lesions. No adverse events were observed after G-CSF treatment.

Upon a literature search we found six more cases of alloimmune neutropenia treated with G-CSF; of these, five infants had a favorable response, which seems a much higher response rate as compared to previous treatments. In conclusion, although further studies on larger population of infants are necessary to confirm the efficacy and to rule out the possibility of significant side effects, we feel that G-CSF treatment should be given high priority in infants with alloimmune neutropenia.