Immune Mechanisms Flashcards

A set of vocabulary flashcards covering the fundamental concepts of immunology, including innate and acquired immunity, the structure and function of antibodies, the complement system, and immune system disorders.

Gut associated lymphoid tissue (GALT)

A specific group of mucosa associated lymphoid tissues situated in the small intestine, including Peyer's patches, tonsils, and adenoids.

Peyer's patches

Organized lymphoid tissue patches found along the intestine that contain B lymphocytes in germinal centers and T lymphocytes to defend against gastrointestinal pathogens.

Innate immunity

The inborn, natural resistance of the body to pathogens and toxins, determined by an individual's genetic and constitutional makeup.

Lysozyme

A hydrolytic enzyme found in high concentrations in most tissue fluids, except cerebrospinal fluid, sweat, and urine, that kills bacteria by splitting the structural mucopeptides of their cell walls.

NK (natural killer) cells

A subpopulation of lymphocytes that provide non-specific cellular defense against viruses, tumor cells, and other infected cells.

Acquired immunity

Resistance that an individual develops during their lifetime which is antigen-specific and can be either antibody-mediated or cell-mediated.

Active acquired immunity

Resistance obtained when the body's own immune system synthesizes antibodies and produces immunocompetent cells in response to antigenic stimulation.

Passive acquired immunity

Immunity transferred to a recipient in a ready-made form, such as maternal antibodies passing to a fetus via the placenta or to a newborn through breast milk.

Epitopes

Specific determinant sites on an antigen molecule that are responsible for the antigen's specificity.

Major histocompatibility complex (MHC)

A complex of genes located on the short arm of chromosome $6$ that encode antigens present on the plasma membranes of an individual's cells.

MHC class I molecules

Surface proteins found on virtually all body cells except red blood cells, encoded by a subclass of MHC genes.

MHC class II antigens

Proteins found specifically on immunologically reactive cells such as B lymphocytes, macrophages, monocytes, and activated T lymphocytes.

Immunoglobulins (Igs)

$\gamma$ globulins produced in response to antigenic stimulation that react specifically with the antigens that triggered their production.

$$\text{IgG}$$

The most extensively studied immunoglobulin class that protects body fluids and is the only class capable of placental transfer.

$$\text{IgA}$$

A class of antibodies that protects body surfaces and is found in high concentrations in human colostrum.

$$\text{IgM}$$

The antibody class that protects the blood stream and is typically the first to be produced during a primary antibody response.

Clonal selection theory

A theory put forward by Burne in $1957$ stating that antigens select and stimulate specific clones of genetically identical B cells.

Agglutination

An immune reaction where antibodies cause particles like bacteria or red cells to clump together, increasing their susceptibility to phagocytosis.

Complement system

A system of $11$ enzymatic proteins ($\text{C1}$ through $\text{C9}$, $\text{B}$, and $\text{D}$) present in blood and tissue fluids that aid in opsonization, lysis, and chemotaxis.

Cytokines

Small protein molecules, such as interleukins and interferons, that act like hormones to regulate the immune response.

Immune tolerance

A state of unresponsiveness to a specific antigen, which can be natural (to self-antigens) or acquired.

Autoimmunity

An immune response directed against the body's own cells or tissues, potentially caused by forbidden clones or the exposure of hidden antigens.

Allograft (homograft)

The transplantation of tissue from one person to another person within the same species.

Type I hypersensitivity

An immediate, allergic reaction mediated by $\text{IgE}$ antibodies, histamine, and serotonin, often associated with asthma or anaphylaxis.

AIDS (acquired immune deficiency syndrome)

A life-threatening condition caused by infection with the human immunodeficiency virus ($\text{HIV}$), characterized by a reduction in the number of T cells.