L2L3 Flashcards
Skin
Watertight lipid layer, beta-defensins, and cathelicidins
Gut
Low pH, antimicrobial peptides, and mucus
Lung
Mucociliary clearance, surfactant proteins, and defensins
Classical pathway
Triggered by antibodies binding to antigens
Alternative pathway
Triggered by spontaneous hydrolysis of C3
Lectin pathway
Triggered by mannose-binding lectin binding to pathogen surfaces
Properdin
Stabilizes the C3 convertase of the alternative pathway, enhancing complement activation
C3
Central to all three complement activation pathways, amplifies immune response by promoting opsonization, inflammation, and membrane attack complex formation
Opsonization
Process where pathogens are marked for phagocytosis by immune cells through antibody or complement binding
C1 inhibitor (C1-INH)
Prevents activation of the classical and lectin pathways
Factor H and I
Regulate the alternative pathway by degrading C3b
Decay-accelerating factor (DAF)
Prevents formation of C3 convertase on host cells
CD59
Inhibits the formation of the membrane attack complex (MAC)
Phagocytes
Cells that engulf and destroy pathogens, including macrophages, monocytes, and dendritic cells
Antigen-presenting cells (APCs)
Cells that process and present antigens to T cells, such as macrophages and dendritic cells
Macrophages
Tissue-resident phagocytes producing inflammatory mediators, cytokines, and reactive oxygen/nitrogen species
Monocytes
Blood-circulating precursors to macrophages that produce inflammatory mediators and cytokines
Dendritic cells
Phagocytic cells producing reactive oxygen species and presenting antigens to T cells
Neutrophils
First responders producing reactive oxygen/nitrogen species and antimicrobial peptides
Natural killer (NK) cells
Lymphoid-origin cells inducing apoptosis in virus-infected and cancer cells via perforin and granzymes
Eosinophils
Cells involved in parasitic infections and releasing histamine-like substances
Basophils
Cells involved in allergic reactions and histamine release
Mast cells
Cells releasing mediators in early immune responses, particularly in allergic reactions
Chemotaxis
Movement of phagocytes toward an inflammatory site guided by chemokine gradients
Phagocytosis
Process where phagocytes engulf pathogens, forming phagosomes, which fuse with lysosomes to kill pathogens
Pattern recognition receptors (PRRs)
Receptors that detect pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs)
Toll-like receptors (TLRs)
Membrane-bound PRRs recognizing PAMPs and initiating cytokine secretion
RIG-I-like receptors (RLRs)
Cytoplasmic PRRs detecting viral RNA and activating antiviral responses
NOD-like receptors (NLRs)
Cytosolic PRRs involved in inflammasome activation and cytokine production
Inflammasome
A protein complex converting pro-IL-1_ and pro-IL-18 into their active forms
IL-6
Cytokine inducing fever, lymphocyte activation, and antibody production
CXCL-8
Chemokine recruiting neutrophils, basophils, and T cells to infection sites
TNF
Cytokine causing vasodilation, fever, and endothelium activation
IL-12
Cytokine activating NK cells and inducing Th1 differentiation
RIG-like receptors (RLRs)
Important PRRs in antiviral responses, recognizing viral RNA
Antigen cross-presentation
Mechanism where extracellular antigens are presented on MHC class I molecules to activate cytotoxic T cells
Perforin
Protein forming pores in target cell membranes during apoptosis
Granzyme
Protease entering cells via perforin pores to induce apoptosis
Caspase-3
Executioner caspase activating apoptosis pathways in target cells
