A human or animal must defend itself against multitude of different pathogens including viruses, bacteria, fungi, and protozoan and metazoan parasites as well as tumors and a number of various harmful agents which I are capable to derange its homeostasis. For this, a plenty of effectors mechanisms capable of defending the body against such antigens and I agents have developed and these can be mediated by soluble molecules or by cells. If infections occur as a consequence of the tissue damage, the I innate and, later, the adaptive immune systems are triggered to destroy the infectious agent.