Immunology

Adaptive immunity is an important part of the immune system. It is protection from an infectious disease agent that is mediated by B- and T- lymphocytes following exposure to specific antigen, and characterized by immunological memory. Adaptive immunity can result from either previous infection with that agent or vaccination (immunity, active), or transfer of antibody or lymphocytes from an immune donor (immunization, passive).Adaptive immunity is defined by the presence of lymphocytes, either T or B cells, and includes both CD8+ cytotoxic T cells that are the effector cells that directly destroy tumor cells, CD4+ helper T cells that regulate CD8+ T-cell and B-cell function, and B cells that present antigen and produce antibodies. Vertebrates can develop a broad and almost infinite repertoire of antigen-specific receptors, which allows vertebrates to recognize almost any potential pathogen or toxin and to mount antigen-specific responses to it. Two types of adaptive immunity systems have evolved in vertebrates in order to generate immune receptor diversity. The jawed vertebrates strategy uses the V(D)JC recombination to achieve combinatorial diversity of immunoglobulin-based B cell receptors and T cell receptors. The jawless vertebrate strategy uses the somatic rearrangements of variable leucine-rich cassettes in the variable lymphocyte receptors (VLRs). The hallmarks of an adaptive immune system is the production of antigen-specific recognition receptor by somatic gene rearrangement. The long life of some antigen-primed cytotoxic lymphocytes and plasma cells provide protective memory to prevent reinvasion.

Cytokines are involved in most biological processes including embryonic development, disease pathogenesis, innate responses to infection, antigen-specific immunity, and cognitive changes. (1). One important hallmark of cytokines and growth factors is that they can play both beneficial and harmful roles, depending on context.

Inflammation is a response triggered by damage to living tissues. The inflammatory response is a defense mechanism that evolved in higher organisms to protect them from infection and injury. Its purpose is to localize and eliminate the injurious agent and to remove damaged tissue components so that the body can begin to heal. The response consists of changes in blood flow, an increase in permeability of blood vessels, and the migration of fluid, proteins, and white blood cells (leukocytes) from the circulation to the site of tissue damage. An inflammatory response that lasts only a few days is called acute inflammation, while a response of longer duration is referred to as chronic inflammation.