White blood cells, specifically leukocytes, constantly patrol the bloodstream to identify and eliminate harmful pathogens, such as bacteria, viruses, and fungi. This process, known as immune surveillance, helps the body defend against infections and maintain overall health. When a white blood cell encounters a foreign invader, it can engulf and destroy it or produce antibodies to mark it for destruction by other immune cells. This continuous monitoring helps prevent infections and maintain homeo

How your immune system works