Neutrophils: activities and functions

ABSTRACT

There are three types of polymorphonuclear leucocytes the neutrophils, the basophils and the eosinophils, each serving separate functions and differentiated by the staining reactions of their prominent cytoplasmic granules. The neutrophils are the most numerous, comprising 70% of the total leucocytes in blood, and are the cells generally referred to as "polymorphs".They contain two or three types of granules, whose enzymes include peroxidase, alkaline phosphatase, acid phosphatase, ribonuclease, deoxyribonuclease, nucleotidase, glucuronidase, and lysozyme. The phagocyte is the most powerful and most important part of the defences that can operate without delay against the invading microorganism after the epithelial surface has been breached. Various substances released from bacteria attract phagocytes, but their activity is generally weak. Other bacterial substances react with complement to generate chemotactic factors such as C5a. Microorganisms can avoid the attentions of phagocytic cells by inhibiting chemotaxis, and as a result of this the host is less able to focus polymorphs and macrophages into the exact site of infection