Phagocytosis

Phagocytosis is a process in which phagocytes, a type of white blood cell, engulf and hydrolyse pathogens. It is a non-specific part of the immune response; any microorganism with foreign antigens can be killed in the process of phagocytosis.

Process of phagocytosis

 * Chemoattractants released by a pathogen attract a phagocyte to the pathogen, down a concentration gradient.
 * Receptors on the phagocyte's cell surface membrane bind to the pathogen's surface.
 * The phagocyte changes shape to engulf the pathogen via endocytosis in a vesicle called a phagosome.
 * Lysosomes within the phagocyte fuse with the phagosome and release enzymes known as lysozymes, which hydrolyse the pathogen, killing it as a result.
 * The pathogen's antigens are presented on the phagocyte's cell surface membrane. Other products made by hydrolysing the pathogen are either absorbed into the phagocyte's cytoplasm, or expelled from the phagocyte via exocytosis.