When a person has a good white blood cell count, it means his body produces between 4,500 and 10,000 white blood cells per microliter, according to WebMD. White blood cells are used to protect the body against harmful organisms.
In normal circumstances, white blood cells are much fewer than red blood cells. However, when a person has an infection or disease, his body produces more white blood cells to deal with the condition, according to WebMD. Doctors normally check the number of cells in a person to determine if the individual has been attacked by a virus or bacteria, states MedlinePlus.