Immunity Flashcards
What is the innate immune system?
The first line of defence in the body
What cell types make up the adaptive immune response
B cells (plasma and memory cells)T cells (Th and Tc cells)NK cells (Natural Killer)
Where are immune cells found in the body
Lymph nodes/lymphatic vesselsThymusSpleenBone marrow
What are the two parts of the adaptive immune system
Humoral immunity Cell-mediated immunity
What are the key features of humoral immunity
Acts against antigens; antibody mediatedUtilises B lymphocytesActs by circulating antibodies in serum; defends against extracellular pathogens/bacteria/virus
What are the key features of cell-mediated immunity
Acts against viruses/bacteria/fungi/parasites/cancer/transplants etc. Utilises T lymphocytesActs by direct cell contact or secreted soluble products; defends against intracellular bacteria
What physiological VASCULAR changes occur during the innate inflammatory response
Dilation of small arterioles (increasing blood flow)Increased vascular permeability (plasma leaks into inflamed area)Mediators (PGs, histamine, PAF, bradykinin, NO) cause vasodilation and permeability.
What physiological CELLULAR changes occur during the innate inflammatory response
Chemical mediators producedWhite blood cells move into inflamed tissues to help destroy microorganisms
What physiological changes occur during the INDUCTION phase of the adaptive inflammatory response
Lymphocytes primed, ready to recognise specific antigenic moleculesT helper cell regulate development of response (T1 - cell-mediated; T2 - antibody-mediated)
What physiological changes occur during the EFFECTOR phase of the adaptive inflammatory response
Antigen-bearing cells destroyed through action of secreted antibodies.
What physiological changes occur during the EFFECTOR phase of the adaptive HUMORAL response
Lymphocytes converted to Th2 cells.Th2 cells stimulate B lymphocytes to convert to plasma cells.Plasma cells enter blood, and secrets antibodies for antigen recognition/degradation.
What physiological changes occur during the EFFECTOR phase of the adaptive CELL-MEDIATED response
Lymphocytes converted to Th1 cells, which are converted to cytotoxic (Tc) cells. Tc cells activate other immune molecules and kills antigen presenting cells.
Give some examples of factors that can induce the inflammatory response
Microorganisms (bacteria/viruses)Radiation (heat, UV, radioactivity)Biochemical damage (metabolic poisons, anoxia)Mechanical trauma (scratch, cut)Non-harmful factors (grass, pollen etc)
Give some examples of innate immunity
Cough reflexEnzymes in tears/skin oilMucusSkinStomach acid
What are the two components of the innate inflammatory response
Vascular eventsCellular events
Give examples of unwanted inflammatory/immune responses
Schistosomiasis. most tissue damage/symptoms are due to immune responseAnthracosis (black lung disease). Caused by immune response to coalSevere acute respiratory syndrome (SARS). Deaths are due to excessive immune response.
How do phospholipase A2 (PLA2) mediators work
Enzyme found in most cell types. Stimulation of cells by inflammatory mediators/cell damage activates PLA2.PLA2 metabolises phospholipids in the cell membrane as first step in forming:Prostagladins, leukotrienes, platelet activating factor.
Describe the cascades activated by plasma factor 12.
PF12 found in blood plasma. When it leaks into tissues, comes into contact with extracellular proteins (e.g. collagen). This convers PF12 to Factor 12a. Factor 12a activates protease enzymes in signalling pathways. This generates:Bradykinin; ‘complement’ factors (can activate mast cells, or attach to microorganisms to degrade or facilitate degradation)
How do ‘reactive’ oxygen molecules act as a chemical mediator in the inflammatory response
Macrophages have enzymes that can synthesis: Superoxide anion (O2-), hydrogen peroxide (H2O2), Nitric oxide (NO) etc.Kills microorganisms by reactions that cause damage to lipid/protein structure. Can damage own cells.
Give some examples of pro-inflammatory cytokines
Interleukin 1-alpha and 1-betaTumour necrosis factor-alphaInterferons (esp interferon-gamma)
What role do cytokines play in the inflammatory response
Cytokines are peptides synthesised/released by immune cells.Can be pro- or anti- inflammatoryCytokines bind to receptors on target cells, activated intracellular signalling pathways (promoting/inhibiting gene transcription in targen nucleus)
What chemical mediators are derived from mast-cells
Various receptors on mast-cell membranes can bind to:IgE antibodies and some complement factorsWhen they bind to the receptor the mast cell releases:Histamine, leukotrienes, PGD2, platelet activating factor (PAF)
