Innate Immune System Flashcards

Flashcards covering key vocabulary from the Innate Immune System lecture.

Primary Protective Barriers

Anatomical, chemical, and biological barriers that prevent pathogen access to the host.

Cytokines and Chemokines

Chemical mediators produced by the innate immune system to recruit immune cells to the site of infection.

Antigen-Presenting Cells (APCs)

Cells that activate the adaptive immune system by presenting antigens.

Anatomical Barriers

Physical barriers like skin and mucosal epithelium that prevent pathogen entry.

Chemical Defenses

Chemical substances like low pH, antimicrobial peptides, and enzymes that kill or inhibit pathogens.

Commensal Microflora

Microorganisms that compete with pathogens for nutrients and attachment sites, supporting the host's immune system.

Epidermis

The thin outer layer of skin, composed of densely packed, mostly dead cells filled with waterproof keratin.

Dermis

The connective tissue layer of the skin containing blood vessels, hair follicles, and glands.

Psoriasin

An antimicrobial peptide secreted by the skin to defend against E. coli.

Mucosal Epithelium

The outer layer of epithelial cells lining the gastrointestinal, respiratory, and urogenital tracts.

Lysozyme

An antibacterial enzyme found in saliva, tears, and mucus that attacks the cell wall of Gram-positive bacteria.

Defensins, Cathelicidins, Histatins

Antimicrobial peptides secreted by phagocytes.

IgA

An antibody that opsonizes bacteria and viruses in mucosal secretions.

Opsonisation

A process where opsonins make a microorganism more susceptible to phagocytosis.

Opsonins

Freely circulating molecules (e.g., antibodies and complement fragments) that attach to the surface of microbes, making them more susceptible to ingestion by phagocytes.

Pulmonary Surfactant

A substance comprised of lipids and proteins that prevent alveoli from collapsing during exhalation and opsonize pathogens.

Collectins

Components in pulmonary surfactant that opsonize pathogens and facilitate phagocytosis.

Antimicrobial Peptides

Positively charged peptides and proteins that disrupt microbial membranes and inhibit synthesis of DNA, RNA, or proteins.

Pathogen-Associated Molecular Patterns (PAMPs)

Particular molecular patterns displayed by microorganisms that are not present in/on the host cells.

Pattern Recognition Receptors (PRR)

Receptors that detect PAMPs and initiate an immune response.

Mannose-binding lectin (MBL)

A soluble PR molecule that recognises mannose, fucose and N- acetylglucosamine residues which are common in bacteria but not in human.

Phagocytic Receptors

Receptors on phagocytes that stimulate phagocytosis by direct recognition of PAMPs or by binding to opsonins.

C-type lectin receptors

Bind to carbohydrate residues on pathogens and stimulate phagocytosis.

Scavenger receptors

Bind to anionic polymers and lipoproteins and stimulate phagocytosis.

Complement receptors (CRs)

Bind to complement fragments and stimulate phagocytosis.

Fc receptors

Bind to opsonising antibodies and stimulate phagocytosis.

Oxidative Attack

A mechanism of phagocytosis that employs reactive oxygen and nitrogen species (ROS and RNS) to kill pathogens.

Non-Oxidative Attack

A mechanism of phagocytosis where lysosomes merge with phagosomes to form phagolysosomes, destroying the pathogen with proteolytic enzymes and antimicrobial peptides.

Reactive Oxygen Species (ROS)

Molecules such as superoxide and hydrogen peroxide produced during the respiratory burst to kill phagocytosed pathogens.

Reactive Nitrogen Species (RNS)

Molecules such as nitric oxide, produced during the respiratory burst.

Respiratory Burst

Transient increase of O2 consumption upon the binding of PRR to target PAMPs

Toll-like receptors (TLR)

Proteins on plasma membrane and intracellular vesicles upon activation induce changes in the expression of various genes.