Maja Marković, 2nd year, 2013/2014 Mentor: A. Žmegač Horvat

Antigen word origin: antibody generator / anti(body)-gen = any substance foreign to the body that evokes an immune response parts of bacteria, viruses, parasites, foods, venoms, blood components, and cells and tissues of various species, including other humans

epitope - a molecular region on the surface of an antigen capable of eliciting an immune response and combining with a specific antibody

antigen ≠ immunogen hapten - a small molecule that can elicit an immune response only when attached to a large carrier such as a protein urushiol → quinone (reacts with skin proteins) hydralazine (blood pressure-lowering drug) → drug-induced lupus erythematosus halothane (anesthetic gas) → hepatitis penicillin-class drugs → autoimmune hemolytic anemia

allergens = antigens which produce an abnormally vigorous immune response to a perceived threat that would otherwise be harmless to the body

superantigens (SAg) produced by pathogenic microbes as a defense mechanism against the immune system cause non-specific activation of T-cells → polyclonal T cell activation and massive cytokine release (interferon gamma → macrophages → proinflammarory cytokines IL-1, IL-6, TNF-alpha) antigen-induced T-cell response: % → 25 % shock and multiple organ failure

tumor antigens presented by MHC I or MHC II molecules on the surface of tumor cells tumor-specific antigens (TSAs) - presented only by tumor cells tumor-associated antigens (TAAs) - presented by tumor cells and normal cells cytotoxic T lymphocytes may be able to destroy tumor cells before they proliferate, B-cells recognize mutated cell receptors used as tumor markers (alphafetoprotein, carcinoembryonic antigen CA-125, MUC-1, epithelial tumor antigen ) and vaccines

Antibodies large glycoproteins, part of the immunoglobulin superfamily produced by plasma cells soluble or membrane-bound basic structure: "Y"-shaped molecule two identical heavy chains (α, ε, γ, δ, and μ, define the class) two identical light chains (λ and κ) connected by disulfide bonds constant and variable regions

Fab region - antigen-binding paratope - at the amino terminal end of the antibody, variable domains from the heavy and light chains F V region, variable loops of β-strands, three each on V L and V H Fc region - ensures that each antibody generates an appropriate immune response for a given antigen (recognition of opsonized particles, lysis of cells, and degranulation of mast cells, basophils and eosinophils)

more than 350 types of molecules markers on the cell surface critical in antigen recognition (CD4, CD8) cell surface receptors for growth factors (CD135)

MHC molecules = major histocompatibility complex (human leukocyte antigen, HLA) a set of cel-surface molecules encoded by a large gene family in all vertebrates MHC-I: all nucleated cells; cytotoxic T lymphocyte MHC-II: dendritic cells, mononuclear phagocytes, B lymphocytes, some endothelial cells, epithelium of thymus; helper T lymphocytes

MHC determines compatibility of donors for organ transplant and one's susceptibility to an autoimmune disease via crossreacting immunization

Sources Taradi, Milan: Imunologija, 7. dopunjeno izdanje,