Final answer:
The percentage of neutrophils in healthy adults typically ranges from 50 to 70 per cent of the total white blood cell count. Neutrophils are larger than red blood cells and play a crucial role in the body's defence against infections by engulfing and destroying pathogens.
Step-by-step explanation:
In healthy adults, the percentage of neutrophils should normally comprise 50-70 per cent of the total leukocyte (white blood cell) count. Neutrophils act as the first responders to the site of infection, launching a rapid and nonspecific defence against pathogens primarily through phagocytosis, a process where they engulf and destroy bacteria and other foreign substances.
These cells are identified by their granules, which are most visible using chemically neutral stains, and their size, which is about 10-12 µm in diameter, making them larger than erythrocytes (red blood cells). The characteristic appearance of a neutrophil includes a nucleus with lobes that can range from two to five, with the number increasing as the cell ages. An increase in the number of lobes is typically associated with older neutrophils, also known as 'polys' or polymorphonuclear cells.
Abnormally high counts of neutrophils may indicate an infection, inflammation, or stress response, such as from a burn injury. Conversely, low counts can be a sign of drug toxicity or other disorders, potentially increasing susceptibility to infections.