Macrophages and neutrophils are professional "phagocyte" or eating cell (phago = "eating", cyte = "cell"). Circulating neutrophils are rapidly recruited to sites of infection where they bind and ingest microorganisms (e.g. bacteria and fungi) by a process known as phagocytosis. This process typically triggers production of active oxygen metabolites and the fusion of cytoplasmic toxic granules with pathogen-containing vacuoles resulting in pathogen destruction (1).

Phagocytes defects can result from a low number or impaired function of phagocytic cells. Quantitative defects include severe congenital neutropenia. Neutropenia is defined as a decrease in the absolute numbers of neutrophils in the blood (2). These patients usually present with oral ulcer, otitis, pneumonia, diarrhea, skin abscess, and oral fungal infection (candidiasis)(3). Granulocyte colony stimulating factor (G-CSF), a growth factor for neutrophils, is an effective treatment for several of these conditions(4).

Functional defects include granule abnormalities, leukocyte adhesion deficiencies ( Type I and II resulting in impaired leukocyte migration) and inability of phagocytic cells to create the active oxygen metabolites that characterizes chronic granulomatous disease (CGD). CGD patients usually present with recurrent lymphadenitis (inflammation of a lymph nodes marked by swollen painful lymph nodes). Additional findings may include bacterial liver abscesses, infection at multiple bone sites or in the small bones of the hands or feet, or a family history of recurrent infections of unusual pathogens. The most common offending organism is S aureus. Patients who have CGD also have an increased susceptibility to developing a variety of inflammatory or rheumatic diseases such as inflammatory bowel disease and lupus-like syndrome(5). CGD patients are treated with long-term antibiotic prophylaxis, long-term gamma-interferon (a protein that activates phagocytes), aggressive treatment of acute infections with antibiotics in adequate doses, and surgery, if indicated. Bone marrow transplantation may be considered for patients who have recurrent serious infections despite antibiotic and interferon-gamma prophylaxis or those who have HLA-matched normal siblings(5).

1. Kobayashi SD, Voyich JM, Burlak C, DeLeo FR. Neutrophils in the innate immune response. Arch Immunol Ther Exp (Warsz ) 2005;53:505-517.

2. Schaffer AA, Klein C. Genetic heterogeneity in severe congenital neutropenia: how many aberrant pathways can kill a neutrophil? Curr Opin Allergy Clin Immunol 2007;7:481-494.

3. Rezaei N, Farhoudi A, Ramyar A, Pourpak Z, Aghamohammadi A, Mohammadpour B et al. Congenital neutropenia and primary immunodeficiency disorders: a survey of 26 Iranian patients. J Pediatr Hematol Oncol 2005;27:351-356.

4. Stein SM, Dale DC. Molecular basis and therapy of disorders associated with chronic neutropenia. Curr Allergy Asthma Rep 2003;3:385-388.

5. Boxer LA. Neutrophil abnormalities. Pediatr Rev 2003;24:52-62.