TABLE 1.

Causes of neutropenia in HIV infection.

Cause	Potential mechanism
HIV toxicity to HSPCs	HIV infection and replication in HSPCs Cytotoxicity of HIV proteins including gp120, Nef, Gag p24 and Tat
Impairment of hematopoietic niche	HIV infection of niche cells Local production of HIV by infected niche cells Impairment of niche cell-cell contact support to hematopoiesis Disruption of hematopoietic growth factor and cytokine environment in the niche network
Autoimmune disorders	Generation of anti-neutrophil autoantibodies
Marrow toxicity of secondary infections	Invasion of the bone marrow by pathogens responsible for secondary infections Increase in peripheral destruction of granulocytes
Hemophagocytic syndrome	Activation of histiocytes and phagocytosis of hematopoietic precursor cells
Therapeutic agents with myelotoxicity	Cytotoxicity to HSPCs
Confounding factors such as alcohol abuse	Cytotoxicity to HSPCs Disruption of hematopoietic niche environment