You may have an infection or inflammation if your white blood cell count is greater than normal. It might also signify an immune system issue or a bone marrow illness. A high white blood cell count might also be caused by a drug response. The more common types of high white blood cells include neutrophils and eosinophils. The white blood cell count measures the number of different types of white blood cells in a specific volume of blood. White blood cells are essential for protecting us from infection. They help fight off bacteria, viruses, and some other organisms that can cause disease. There are two main types of white blood cells: granulocytes and lymphocytes. Granulocytes are responsible for fighting off infections and diseases. They include neutrophils and basophils. Neutrophils are the most common type of granulocyte and they account for about 75 percent of all granulocytes. Eosinophils are another type of granulocyte and they are involved in attacking parasites and other organisms that enter our bodies through our skin or via our digestive systems. Basophils act as an emergency defense mechanism against insect bites and stings. They produce chemicals that cause swelling and irritation at the site of the attack to prevent further invasion by insects. Lymphocytes are responsible for clearing out pathogens that escape detection by other immune system cells.