Answer:
Monocytes. They have a longer lifespan than many white blood cells and help to break down bacteria.
Lymphocytes. They create antibodies to fight against bacteria, viruses, and other potentially harmful invaders.
Neutrophils. They kill and digest bacteria and fungi. They are the most numerous type of white blood cell and your first line of defense when infection strikes.
Basophils. These small cells seem to sound an alarm when infectious agents invade your blood. They secrete chemicals such as histamine, a marker of allergic disease, that help control the body's immune response.
Eosinophils. They attack and kill parasites and cancer cells, and help with allergic responses.