The adaptive immune system refers to a specific type of immunity which is found only in vertebrates. Adaptive immunity is defined by the presence of specialized immune cells (i.e., lymphocytes such as T and B cells). The B cells produce molecules known as antibodies which destroy specific pathogenic microorganisms (e.g., bacteria, viruses) and thus prevent diseases in the future. On the other hand, the innate immune system is the first (and evolutionary more ancient) defense line against pathogenic infections or tissue injury. Innate immunity includes, among others, physical barriers, anatomical barriers, phagocytic enzymes (i.e., lysozymes), phagocytic cells (i.e., macrophages), inflammation, etc. Inflammation is defined as an innate immune response composed of complex biological processes that protect the body by eliminating harmful microorganisms and intracellular danger signals, thereby regulating signaling pathways of many diseases.
