Clinical symptoms and neutropenia: the balance of neutrophil development, functional activity, and cell death

Neutrophilic granulocytes form the major type of leukocytes with counts ranging from about 1500-5000 cells/ micro l of blood under normal conditions. Neutrophils protect our body against bacterial and fungal infections. For this purpose, these cells are equipped with a machinery to sense the site of an infection and, upon local extravasation, rapidly move towards the site with invading micro-organisms, to ingest and kill them. As will be described, for proper functioning of this line of defence, a number of prerequisites have to be fulfilled. The quantitative defects are diagnosed more often and easier than the mere qualitative phagocytic defects. Nonetheless, functional defects may accompany neutropenia. These functional defects are seen in severe congenital neutropenia of which the gene defect has recently been elucidated, as well as in the more complex and syndromal forms of neutropenia such as Shwachman syndrome or the metabolic disease glycogen storage disease type 1b (non-a). The background of functional neutrophil defects is briefly reviewed.