PATH20001 Topic 2 - Immunity and Immune-mediated Diseases

AIRE (Autoimmune regulator)

A gene that plays a crucial role in establishing central tolerance by promoting the expression of tissue-specific antigens in the thymus.

Anaphylactic shock

A severe, life-threatening allergic reaction characterized by widespread vasodilation, increased vascular permeability, and potential shock

Antibody-dependent cell cytotoxicity (ADCC)

A mechanism by which antibodies bind to target cells and recruit immune cells (e.g., natural killer cells) to destroy the target cells.

Autoimmune disease

A condition in which the body's immune system mistakenly attacks and destroys healthy body tissues.

Autoimmunity

The state or process of an immune response against one's own body tissues.

B-cell receptor (BCR)

A membrane-bound receptor on B-cells that binds to specific antigens, initiating an immune response.

B-cell

A type of lymphocyte that produces antibodies and plays a crucial role in humoral immunity.

Bone marrow

The soft, spongy tissue found within the cavities of bones, responsible for the production of blood cells.

Central Tolerance

The process by which self-reactive lymphocytes are eliminated or inactivated in the central lymphoid organs (thymus and bone marrow) during their development.

Complement

A complex system of proteins that work together to enhance the ability of antibodies and phagocytic cells to clear pathogens and damaged cells from the body

Cytokine

A broad category of small proteins secreted by various cells, particularly those involved in the immune system, that act as signaling molecules to regulate immune responses and other biological processes.

Cytotoxic T-cell

A type of T-cell that can directly kill infected or cancerous cells by releasing cytotoxic molecules.

DAMP (Danger-associated molecular pattern)

Molecules released by damaged or stressed cells that can activate the innate immune system and promote inflammation.

Defensins

A family of antimicrobial peptides produced by various cells, including neutrophils and epithelial cells, that play a role in innate immunity by disrupting the membranes of microorganisms.

Delayed-type hypersensitivity (DTH)

A type of cell-mediated immune response that occurs several days after exposure to an antigen, characterized by the recruitment and activation of T-cells and macrophages at the site of antigen exposure.

Eicosanoid

A group of signaling molecules derived from arachidonic acid, including prostaglandins, leukotrienes, and lipoxins, which play roles in inflammation, immunity, and various physiological processes.

Endogenous

Originating from within an organism or system.

Exogenous

Originating from outside an organism or system.

Histamine

A set of HLA (Human Leukocyte Antigen) alleles inherited together from a single parent.

HLA haplotype

A gene complex encoding major histocompatibility complex (MHC) proteins, which are crucial for immune recognition and transplant rejection.

Human Leukocyte antigen (HLA)

A gene complex encoding major histocompatibility complex (MHC) proteins, which are crucial for immune recognition and transplant rejection.

Immunodeficiency

A state in which the immune system is impaired or compromised, leading to an increased susceptibility to infections and other diseases.

Immunoglobulin

Immunoglobulins (Ig) or antibodies are glycoproteins produced by plasma cells.

Intravasation

The process by which cells or substances enter a blood or lymphatic vessel from the surrounding tissue

Leukotriene

A type of eicosanoid derived from arachidonic acid, produced by leukocytes and involved in inflammatory and allergic responses.

Lipoteichoic acid

A component of the cell wall of Gram-positive bacteria that can stimulate the immune system and contribute to inflammation.

LPS (lipopolysaccharide)

A major component of the outer membrane of Gram-negative bacteria, which can trigger a strong immune response and inflammation.

MHC I (Major Histocompatibility Complex Class I)

A set of genes that encode proteins involved in presenting peptide antigens to cytotoxic T-cells, playing a crucial role in immune recognition and transplant rejection.

MHC II

A set of genes that encode proteins involved in presenting peptide antigens to helper T-cells, playing a crucial role in immune recognition and transplant rejection.

Molecular mimicry

A phenomenon in which molecules or structures from pathogens or self-antigens resemble each other, leading to an immune response against self-tissues.

Myeloperoxidase

An enzyme found in neutrophils and monocytes, which generates reactive oxygen species and contributes to the killing of microorganisms during the respiratory burst.

Natural Killer cell (NK cells)

A type of lymphocyte that can recognize and kill virus infected or cancerous cells without prior sensitization, playing a crucial role in innate immunity.

Natural Killer T-cell (NKT cell)

A specialized subset of T-cells that share characteristics of both T-cells and natural killer cells, playing a role in immune regulation and tumor surveillance.

Neoantigen

A new antigen that is not normally present in the body, often arising from mutations or alterations in cellular proteins, which can trigger an immune response

Opsonin

A molecule (e.g., antibody, complement protein) that enhances the recognition and phagocytosis of pathogens or foreign particles by immune cells.

Opsonization

The process by which opsonins (e.g., antibodies, complement proteins) bind to pathogens or foreign particles, marking them for recognition and phagocytosis by immune cells.

PAMP (Pathogen-associated molecular Pattern)

Conserved molecular structures found in various pathogens, which are recognized by pattern recognition receptors (PRRs) of the innate immune system, triggering an immune response.

Peripheral tolerance – anergy

A state of functional inactivation or unresponsiveness of self-reactive lymphocytes, preventing them from mounting an immune response against self-antigens.

Peripheral Tolerance - Deletion

The process by which self-reactive lymphocytes are eliminated or induced to undergo apoptosis in peripheral tissues, preventing autoimmunity.

Peripheral Tolerance – Ignorance

A mechanism of peripheral tolerance in which self reactive lymphocytes fail to encounter their specific self-antigens and remain inactive or "ignorant" of these antigens.

Peripheral Tolerance - suppression

A mechanism of peripheral tolerance in which regulatory cells (e.g., regulatory T-cells) actively suppress or inhibit the activation and function of self-reactive lymphocytes.

Peripheral Tolerance

The mechanisms by which self-reactive lymphocytes that have escaped central tolerance are controlled or eliminated in peripheral tissues, preventing autoimmunity.

Plasma cell

A terminally differentiated B-cell that produces and secretes large quantities of antibodies

Polymorphism

The occurrence of two or more distinct forms or variants of a gene or trait within a population.

Primary Immunodeficiency

A genetic or congenital disorder that impairs the normal development or function of the immune system, increasing susceptibility to infections and other immune-related diseases.

PRR (Pattern recognition receptor)

A receptor found on cells of the innate immune system (e.g., macrophages, dendritic cells) that can recognize and bind to conserved molecular patterns (PAMPs) found in pathogens, initiating an immune response.

Secondary immunodeficiency

An acquired or induced impairment of the immune system often caused by factors such as infections, medications, or underlying medical conditions, leading to an increased susceptibility to infections and other immune-related diseases

Self-tolerance

The ability of the immune system to recognize and tolerate self-antigens, preventing autoimmune reactions against the body's own tissues.

T-cell receptor

A receptor found on the surface of T-cells that recognizes and binds to specific antigen peptides presented by major histocompatibility complex (MHC) molecules, initiating an immune response.

T-helper cell

A type of T-cell that plays a crucial role in coordinating and regulating the immune response by producing cytokines and interacting with other immune cells, such as B-cells and macrophages.

Thymus

A specialized organ of the lymphatic system, located in the upper chest, where T-cells mature and undergo selection processes to establish self-tolerance.

Tolerance

The ability of the immune system to recognize and accept self-antigens or foreign antigens without mounting an immune response, preventing autoimmunity or excessive inflammation.

Type I hypersensitivity

Also known as immediate or anaphylactic hypersensitivity, it is an allergic reaction mediated by IgE antibodies and mast cells/basophils. It occurs rapidly (within minutes) after exposure to an allergen and can cause symptoms like hives, asthma, and anaphylaxis.

Type II hypersensitivity

Also called cytotoxic hypersensitivity, it involves IgG or IgM antibodies binding to antigens on the surface of cells, leading to cell destruction by complement activation or antibody-dependent cell-mediated cytotoxicity (ADCC). Examples include hemolytic anemia and some types of thrombocytopenia.

Typer III hypersensitivity

Also known as immune complex-mediated hypersensitivity, it occurs when antigen-antibody complexes deposit in tissues and activate complement, leading to inflammation and tissue damage. Examples include serum sickness and some forms of glomerulonephritis.

Typer IV Hypersensitivity

Also called delayed-type hypersensitivity (DTH), it is a cell mediated immune response mediated by T-cells rather than antibodies. It typically develops over 24-72 hours after exposure to an antigen and can cause inflammation, tissue damage, and granuloma formation. Examples include contact dermatitis and the tuberculin skin test.