Autoimmune neutropenia (AIN), also know as autoimmune leukopenia or autoimmune granulocytopenia, is a blood disorder in which a person's antibodies attack and destroy his or her own neutrophils, resulting in a decreased number of these cells. Neutrophils are a type of white blood cell, or leukocyte, that helps the body fight off infection. Neutropenia is the general term for a decreased neutrophil count, regardless of the cause of this state. Patients with a low number of neutrophils are more prone to infection and can become very ill. The treatment needs of people with neutropenia vary depending on the severity of the neutropenia.
Reaching a diagnosis of autoimmune neutropenia requires a full blood count, and may also require a bone marrow test. To give a diagnosis of neutropenia in general, a sample of blood is taken and the white blood cells in the sample are counted. Then, the percentage of neutrophils in the white blood cells is determined by a procedure called a white blood cell differential analysis. This results in a number called the absolute neutrophil count (ANC), which needs to be under 1500 neutrophils per microliter of blood for a diagnosis of neutropenia.
Once neutropenia has been established, the cause of it still needs to be determined. Making a diagnosis of autoimmune neutropenia can be difficult because the antibodies which are attacking the neutrophils may not be easy to find. A bone marrow test may be conducted to eliminate the possibility of other types of neutropenia in which not enough neutrophils are created in the marrow. In autoimmune neutropenia, a sufficient number of neutrophils are created, but these cells are prematurely killed by the neutrophil-specific antibodies.
Autoimmune neutropenia can be mild, moderate, or severe. Some people with autoimmune neutropenia, especially very young children, will have a spontaneous remission of the condition after a couple of years and may never need any treatment. This spontaneous remission is less likely in older children and adults, who will likely have the condition for their whole lives, though it's possible that it will never cause any significant problems.
People with autoimmune neutropenia are more susceptible to infection because the body cannot fight off invading cells as effectively. Many patients will only experience a slightly increased susceptibility, and these patients will only need antibiotics and similar treatments when an infection is present. Other patients may suffer from severe infections or chronic infections, in which case treatment with white blood cell growth factors may be needed to get the patient's white blood cell count up to a stable level. Making lifestyle modifications to reduce the risk of infection is important for people with all types of neutropenia, such as being extra careful with hygiene, avoiding ill people, and maintaining good health through diet and exercise.