Immune response Flashcards
What is the innate immune system?
Refers to non-specific defense mechanisms that activate within initial exposure to an antigen; includes germline-encoded receptors - unchangeable genome binds to particular ligands
What are the physical barriers of immunity?
Skin, mucous, epithelial cells
Which immunological factors form the humoral system?
Complement, lectins (collectins, ficolins), lectins prevent polysaccharide capsule bacteria from bindin, pentraxins, antimicrobial peptides
Which immunological cells are responsible for the adaptive immune system?
Neutrophils, macrophages, dendritic cells, and natural killer cells
What is the adaptive immune system?
Highly specialized defense mechanism against specific pathogen-variable receptors that undergo maturation (DNA recombination), memory response
Which microbial factors are used in the adaptive humoral response?
Antibodies, complement
What immunological cells form the adaptive immune system?
Cytotoxic T cells, t helper cells, t regulatory cells, b lymphocytes, and plasma cells
What are the four main pathological niches?
Extracellular
Intracellular
surface adherent
Intracellular cytosolic
What are extracellular niches?
Staphylococcus, streptococcus, candida, microbiota (worms), Pathogens secrete toxins and are suspended in tissue
What are intracellular niches?
Salmonella requires host cell organelles to translate and synthesize proteins (viruses)
What are surface adherent niches?
Enteropathogenic and enterohaemorrhagic E.coli Require close proximity to host cells. Adhesive tips enable bacteria to attach to specific host cells receptors. Cell wall adhesins are surfaced proteins in the cell wall of bacteria that bind tightly to specific receptor molecules on host cell surface membranes
What are intracellular cytosolic niches?
Phagocytosed pathogen integrates and suspends in the cytosol of cell (Listeria)
What is the circulating life span of neutrophils?
6 hours, short lived, followed by macrophages
How are Naive neutrophils activated?
Activated upon interaction with the pathogen and are attracted towards the area of infection by chemotaxis
Which class of chemotactic protein is released for neutrophil chemotaxis?
Leukotrienes
Where do neutrophils arise from?
Bone marrow through differentiation of HSCs into lymphoid precursors, neutrophils are unable to replicate.
What is the purpose of phagocytes?
Control infection (undergoing phagocytosis to hydrolyse pathogens, reducing pathogenic load), and limit/repair tissue damage
What does unregulated phagocytic activity result in ?
Granuloma (Collection of neutrophils/macrophages that exclude of an area) formation; excessive inflammation and inappropriate adaptive immunity, and tissue damage
What are interleukins?
Are communicatory glycoproteins released by leukocytes that regulate immune response-cytokines
Which receptors does IL bind onto?
IL receptors, consequently contributing to gene expression of naive cells activates macrophages
What are the three stages that occur for the sequence of molecular and cellular events in terms of activation of host immunological cells?
1) Microbial ligand detection
2) Naive host cells undergo gene-expression changes
3) Cytokine and chemokine release causes signal transduction
Where do macrophages reside?
Tissue-resident or circulatory
Which cytokines induce macrophage activation?
IL-12/18/1, TNF & IL-6
What functions are displayed by activated macrophages?
Phagocytosis and migration; cytokine/chemokine production, expression of cell surface molecules; antimicrobial activity; antigen presentation and T cell activation
What inflammatory properties are expressed by activated macrophages?
They are anti-inflammatory