Neutropenia, Neutrophil Dysfunction, and Bacterial Infection in Patients with Human Immunodeficiency Virus Disease: The Role of Granulocyte Colony-Stimulating Factor

Neutropenia frequently complicates infection due to human immunodeficiency virus (HIV). The etiology of neutropenia in this setting includes bone marrow infection or infiltration, myelosuppressive therapies, the presence of antibodies to HIV, and accelerated apoptosis. Protection against microbial invaders by neutrophils is further compromised by impaired chemotaxis and phagocytosis, production of toxic oxygen species, and expression of cellular adhesion molecules. Neutropenia is a significant risk factor for bacterial infection in HIV-infected patients. Endogenous cytokines, such as granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor, regulate neutrophil count and function. Treatment with recombinant human methionyl G-CSF (filgrastim) has lessened neutropenia in patients with HIV infection. Clinical trials have shown that the incidence of bacterial infections and the number of consequent days of hospitalization for HIV-infected patients receiving filgrastim therapy are lower. Filgrastim treatment also allows administration of larger doses of myelosuppressive agents.