Final answer:
Leukocytosis means increased white blood cells in the blood, often involving nonfunctional cells, which increases disease risk. It contrasts with leukopenia, which indicates too few leukocytes to fight off infections effectively.
Step-by-step explanation:
The term leukocytosis refers to the condition of having an excessive proliferation of leukocytes (white blood cells), resulting in a higher than normal count in the bloodstream. While leukocyte counts are increased in leukocytosis, the cells may not always be functional, which can leave an individual at increased risk for disease. This is contrary to leukopenia, where there is a below-normal production of leukocytes, leading to a decreased ability to ward off infections. In general, white blood cells play a vital role in the immune system, working to identify and neutralize pathogens such as bacteria, viruses, and other foreign organisms.