Autoimmune neutropenia

Autoimmune neutropenia (AIN) is a rare autoimmune disorder in which the immune system mistakenly attacks neutrophils, a type of white blood cell that plays a critical role in defending the body against bacterial and fungal infections. The resulting decrease in neutrophils (neutropenia) increases the risk of infections, although the severity varies depending on the neutrophil count and the underlying cause.

Autoimmune neutropenia may occur on its own (primary autoimmune neutropenia) or develop secondary to another autoimmune disease, immune deficiency, blood disorder, infection, or, less commonly, certain medications. Primary autoimmune neutropenia occurs most often in infants and young children and usually resolves spontaneously within two to three years. Secondary autoimmune neutropenia is more common in adolescents and adults and is typically associated with an underlying autoimmune or hematologic disorder that also requires treatment.

Diagnosing autoimmune neutropenia can be challenging because no single laboratory test is definitive. Healthcare providers typically combine repeated complete blood counts (CBCs), clinical history, review of medications, testing for autoimmune diseases and infections, and, when necessary, bone marrow examination. Although tests for antineutrophil antibodies may support the diagnosis, their sensitivity and specificity are limited, so results must be interpreted alongside the overall clinical picture.

Frequent bacterial infections, recurrent ear infections, sinus infections, skin infections, mouth ulcers, gingivitis, sore throat, fever, pneumonia, delayed wound healing, and, in some people, few or no symptoms despite persistently low neutrophil counts. Severe neutropenia can increase the risk of serious or life-threatening infections.

Systemic lupus erythematosus (SLE), rheumatoid arthritis (including Felty syndrome), Sjögren disease, autoimmune lymphoproliferative syndrome (ALPS), common variable immunodeficiency (CVID), large granular lymphocytic (LGL) leukemia, autoimmune hemolytic anemia, immune thrombocytopenia (ITP), Evans syndrome, autoimmune thyroid disease, and other autoimmune cytopenias.

Autoimmune neutropenia is a rare disorder. Primary autoimmune neutropenia most commonly develops in infants and young children, usually before 3 years of age, and the majority of cases resolve spontaneously within two to three years.

Secondary autoimmune neutropenia is more common in adults and is usually associated with another autoimmune disease, immune deficiency, hematologic disorder, infection, or, less commonly, certain medications. Adult cases occur more frequently in females, reflecting the higher prevalence of autoimmune diseases among women.