Leukocyte abnormalities

The phagocytic cells of the blood constitute a crucial host defense system, whose constant role in homeostasis is dramatically demonstrated by the rapid development of overwhelming and often fatal bacterial sepsis in those conditions resulting in severe quantitative deficiencies of blood neutrophils and/or monocytes. This review does not consider disorders of bone marrow production or peripheral destruction resulting solely in insufficient numbers of circulating granulocytes or monocytes, although it should be noted that they are the most common abnormalities which affect the blood phagocyte system. Rather, this review concerns itself with qualitative abnormalities in neutrophils and blood monocytes. Certain of these qualitative abnormalities in blood phagocyte function are associated with frequent, severe, and recurrent bacterial infections leading to fatal sepsis while other qualitative defects demonstrated in vitro may have little or no clinical sequelae. These qualitative defects will be discussed in terms of specific functions which may be studied as isolated phenomena in vivo or in vitro, although individual diseases may result in a single or multiple functional defects. Generally these functions are separated into locomotion, phagocytosis, degranulation, and bacterial killing.