Adaptive Immunity

Adaptive (acquired) immunity

consists of lymphocytes and serum proteins called antibodies is activated once inflammation activates it, slowly augments the initial defenses and promotes processes against reinfection

T lymphocytes

stem cells that go into the thymus and differentiate

B lymphocytes

stem cells that go to specific regions of the bone marrow and differentiate

Antigens

generally small molecules (usually within proteins, carbohydrates, or lipids) found on the surface of microbes, infected cells, or abnormal tissues, molecular targets of antibodies and lymphocytes

Clonal diversity

before birth each individual has produced a population of lymphocytes capable of recognizing many antigens, refers to the process by which the extensive diversity of antigen receptors on B and T cells is established

Clonal deletion

self-reactive lymphocytes also are created but are then removed from the body

Immunocompetent

able to respond to antigens, B and T lymphocytes leaving the primary lymphoid organs

Secondary lymphoid organs

where B and T lymphocytes migrate to through the blood and lymphatic vessels

Clonal selection

differentiation of immunocompetent B and T cells into highly specialized effector cells and differentiation of T and B cells into very long-lived memory cells after being exposed to an antigen

Humoral immunity

antibodies circulate in the blood and defend against extracellular antigens, such as microbes and microbial toxins

Cellular immunity

Tc cells defend against intracellular pathogens (e.g., viruses) and abnormal cells, such as cancer cells

Exogenous antigens

extracellular non-self antigens that enter the body and circulate in blood and lymph, include infectious agents, allergens, and chemical agents

Endogenous antigens

intracellular non-self antigens that have been generated when the cell has become abnormal because of injury, infection (e.g., viruses), or mutation of its DNA, as occurs in cancer

Hapten

molecules too small to induce an immune response by themselves but become immunogenic after combining with larger molecules that function as carriers

Superantigens (SAGs)

can activate a large population of immune cells, resulting in overproduction of immune cytokines, result can be serious disease and even shock and death

B-cell receptor (BCR)

complex of cell surface–bound antibody and other molecules involved in intracellular signaling, recognize a specific antigen and communicate this information to the cell’s nucleus

Inducible

characteristic of the adaptive immune system, once an antigen is encountered by a particular lymphocyte (clonal selection), many copies of the same lymphocyte are generated to adequately respond to that antigen (clonal expansion)

Tolerance

the ability of the adaptive immune system to remove or suppress adaptive immune responses to self-antigens or to innocuous non-self antigens

Autoimmune

lack of tolerance to self-antigens, immune system attacks the host

Central tolerance

achieved within the bone marrow for B lymphocytes and within the thymus for T lymphocytes, developing lymphocytes that bind with high affinity to self-antigens within these organs are either killed (clonal deletion) or altered

Macrophages

phagocytes that are derived from circulating monocytes and reside in tissues, especially near epithelial surfaces, detect both PAMPs and DAMPs

Conventional dendritic cells

especially important to the adaptive immune responses because once they have recognized and phagocytosed antigens, capable of migrating to secondary lymph tissues, present these antigens to areas of highly concentrated lymphocytes

Plasmacytoid dendritic cells

secrete type I interferons that are important to antiviral immunity and are involved in stimulation of other immune cells

Monocyte-derived dendritic cells

begin as circulating immune cells and, like conventional dendritic cells, can carry antigens into lymphoid tissue, more susceptible to chemicals produced by infectious organisms and tumors and are less effective

B lymphocytes

not phagocytes but can detect antigen with their surface receptors (BCRs) and endocytose BCR/antigen complexes

Treg cells

secrete cytokines that suppress the immune system and promote tolerance, regulatory and makes sure healthy tissue isn’t attacked

Plasma cells

activated B cells that produce antibodies that are capable of detecting the identical antigen as was bound by the BCR

Transitional B cells

immature B cells

Memory B cells

non antibody producing, remember specific antigens so an immune response can be mounted quicker with subsequent infections

IgG

most abundant class of antibody, in the blood and accounting for most of the protective activity against infections (crosses placenta)

IgM

first produced in response to infection, largest antibody, activates other immune cells

IgA

found in blood and in bodily secretions, saliva and breast milk, protects mucus membranes

IgE

normally at low concentrations, specialized functions as a mediator of many common allergic responses, defense against parasitic infections

IgD

functions as a part of the BCR antigen receptor on the surface of early B cells

Neutralization

antibodies can affect infectious agents or their toxic products, inactivating or blocking the binding of antigens to receptors

Agglutination

antibody protect against infection by clumping insoluble particles that are in suspension

Precipitation

antibody protect against infection by making a soluble antigen into an insoluble precipitate

T helper cells

CD4 + cells, release cytokines and chemokines

T-cytotoxic (Tc) cells

CD8+ T cells, directly kills infected and abnormal cells

Memory T cells

remember specific antigens so the immune response is quicker with subsequent infections

Natural killer (NK) cells

lymphoid cells, target virus infected cells and cancer cells without prior exposure

Secretory (mucosal) immune system

partially independent immune system that protects the external surfaces of the body through lacrimal and salivary glands and a network of lymphoid tissue, IgA

Systemic immune system

operates through entire body, primarily bloodstream and internal organs (IgG, IgM, IgE). inflammatory response to pathogens

Primary response

first exposure, IgM first antibody produced- then IgG, memory cells generated

Secondary response

re-exposure, large quantities of IgG and some IgM quick activation of B cells

Naturally acquired immunity

active- antigen is introduced by pathogen which induces antibody production and memory

passive- antibodies transferred from mother to child

Artificially acquired immunity

active- antigen produced via vaccine

passive- introduced through medical interventions

Epitope

part of an antigen that binds with an antibody