Phagocytosis, a crucial process in the immune system, involves the engulfment and destruction of foreign particles and cellular debris. Targets typically include bacteria, viruses, fungi, parasites, dead or dying cells, and abnormal cells like cancer cells. For example, during an infection, neutrophils and macrophages, types of white blood cells, actively engulf and neutralize invading bacteria.
This process is essential for maintaining tissue homeostasis and protecting the organism from infection and disease. Its historical significance lies in its early discovery as a fundamental mechanism of immunity by Elie Metchnikoff in the late 19th century, paving the way for understanding the cellular basis of immune responses. Dysfunction in this process can lead to increased susceptibility to infections or contribute to autoimmune disorders.