A partial glossary of scientific terms

Elicitation: The excessive, abnormal secondary response to a sensitizing agent that results in inflammator tissue damage. Also called "effector stage." See hyper sensitivity and type I-IV hypersensitiviti

ELISA: Enzyme-linked immunosorbent assay. Binder-ligand assay in which the antibody or antigen used is linked to an enzyme. The presence of binder-ligand pairs can be determined by adding chromogenic (color-producing) substrate whose enzymatic conversion causes a detectable cole change.

Embryonic antigens: A protein or carbohydrate antigen normally expressed solely in the embryo. Inappropriate expression in a tumor cell can make it a tumor-associated antigen.

embryonic stem (ES) cells: Early embryonic cells with the potential to give rise to any cell type.

emerging infectious disease: A disease with the potential to have great impact on the global population because it is causec by a newly developed pathogen or one that is changing in character.

encapsulated bacteria: Bacteria with a polysaccharide coating (capsule) that inhibits phagocytosis.

encapsulation: A mechanism mediated by PRRs in higher invertebrates by which pathogens too large to be phagocytosed are surrounded by many phagocytic cells, sealing them off from the hemolymph Encapsulated pathogens are then killed by phagocyte ROI and lysosomal enzymes. Enhanced 1 molecules produced by granular cells.

endorine: A molecule that acts in an endocrine fashion affects cells systemically or over substantial distance

endocytic pathway: Intracellular system of membrane-bound vesicles, including endosomes and endolysosomes, th contain hydrolytic enzymes and other molecules and substances necessary for the digestion of internalized materials. Responsible for exogenous antigen processing and presentation.

endogenous antigen: An antigen that originates within a cell in the host, as in a protein synthesized in a cell infectec by a virus or intracellular bacterium.

endogenous antigen processing and presentation: A mechanism by which endogenous antigens in the cytosol are degraded into peptides via proteasomes and complexed to MHC class I in the rER. The peptide-MHC class I complex is then displayed on the cell surface. This pathway operates in almost all nucleated cell types. Als known as the "cytosolic antigen processing pathway."

endotoxic shock: A sometimes fatal collapse of circulatory and metabolic systems induced by overwhelming amounts of cytokines (particularly IL-1 and TNF) released into the circulation by macrophage: in response to infection with gram-negative bacteria or their components (especially LPS). Alsc known as "septic shock."

endotoxins: Toxins released from the cell walls of damaged gram-negative bacteria. Endotoxins induce the production of cytokines that cause fever, increase capillary permeability, and may lead to endotoxic shock. The lipid A portion of lipopolysaccharide (LPS) is the most significant endotoxin.

enhanceosome: A multi-protein transactivator complex that binds to an active promoter to initiate or support gene transcription. See SXY-CIITA regulatory system.

enhancer: Short region of DNA containing a collection of DNA-binding motifs. Nuclear transcription factors that bind to an enhancer may influence the transcription of a target gene on the same chromosome positively or negatively. Enhancers can be positioned external to or within a gene and may be active only within certain cell types or at certain times.

enterocytes: Gut epithelial cells that actively absorb nutrients. Express Toll-like receptors and produce cytokines that support HEL activation.

envelope (in HIV): Phospholipid bilayer surrounding a viral core. In the case of HIV, the envelope contains spikes made up of the HIV proteins gp41 and gp!20.

enzyme replacement therapy: Treatment in which a genetically deficient individual, such as a PI patient, is injected with a stabilized form of a missing enzyme whose activity in the blood is sufficient to mitigate disease.

eosinophils: Connective tissue granulocytes with bilobed nuclei and granules that stain reddish with acidic dyes. The granules contain highly basic proteins and enzymes effective in the killing of larger parasites. Eosinophils also play a role in allergy.

epidermis: Top layers of skin that contain mainly keratinocytes plus elements of SALT, but no blood vessels