In neutropenic children aged 6 months to 4 years the presence of neutrophil specific antibodies can result in increased destruction of the body’s own neutrophils. This process, termed autoimmune neutropenia, is the most common cause for neutropenia of this age group. Although these infants often have very low absolute neutrophil counts, they usually do not suffer from severe bacterial infections. Anti-neutrophil antibodies may be detectable by immunological blood tests that can be performed in specialized laboratories, but the absence of a positive test to these antibodies does not rule out the diagnosis of autoimmune neutropenia, nor does a positive test rule out congenital neutropenia. Patients should be kept under medical care, but may not necessarily require treatment with antibiotics or G-CSF. Depending on the frequency of infections and the neutrophil counts, prophylaxis with an oral antibiotic may be considered by the treating physician. For the few children who develop severe infections or have significant impairment of life style (such as frequent visits to emergency rooms), treatment with G-CSF is almost always effective. In most children the blood counts normalize by age 3-5 years.
Autoimmune neutropenia is also seen in adults, predominantly in women. The adult form of autoimmune neutropenia is less likely to resolve spontaneously and more likely to be associated with other autoimmune disorders. There is no evidence for any increased risk of MDS or leukemia in patients with autoimmune neutropenia, whether or not they receive G-CSF therapy.