Immunity to Infection: Sequence and Timing Flashcards
What are the steps go the immune response to infection?
Microbial detection
innate immune response
Adaptive immune response
Memory response
What are the main features of the innate immune system?
Physical barriers
Humoral: Complement, Lectins, Pentraxins, Antimicrobial peptides
Cellular: Neutrophils, Macrophages, Dendritic cells and NK cells
What are lectins?
Proteins that bind sugars
What does humoral mean?
Plasma components
What are the main features of the adaptive immune system?
Humoral: Antibodies
Cellular: Cytotoxic T-cells, T-helper cells, T-reg cells, B-lymphocytes and plasma cells
What are the main differences between innate and adaptive?
Timing Cell types Receptors and ligands Cytokines and chemokines Molecular effector machineries
How does an immune response to infection start?
Tissue damage
Detection of pathogens
Who are the first responders?
Neutrophils and macrophages
What initially happens?
Neutrophils response first (short-lived 6hrs)
Macrophages follow
Naive cells become activates upon interaction with microbes
Phagocytes control infection and limit/repair tissue damage
Why would uncontrolled activity be bad?
Granulomas
Excessive inflammation and inappropriate adaptive immunity
Tissue damage
What are lnterleukins?
Small molecules used from communication between leukocytes
What is the general sequence of molecular and cellular events?
Microbial ligands
Naive host cells
Cytokines and chemokines
Activated host cells
What is macrophage activation?
Expression of many new genes
induced by microbes and cytokines
What is enhanced in activated macrophages?
Phagocytosis and migration Cytokine/Chemokine production Expression of cell surface molecules Anti-microbial activity Antigen presentation and T-cell activation
Are phagocyte responses pathogen specific?
Yes
What are interferons?
Special cytokines
Direct antiviral responses
How do dendritic cells and macrophages activate T-cells?
Present antigens in combination with MHC-I or MHC-II
Cytokines produced, produce suitable milieu for T-cell activation
T-cells then provide cytokines that activate phagocytes
How do T-cells help B-cells produce antibodies?
T cell activation by MHC and foreign peptide recognition
B cell activation for antibody production against antigen
What does phagocyte activation allow for?
Enhanced killing of pathogens
Inflammation
What does direct killing of infected cells do?
Removes replicative niches
What does B cell activation do?
Antibody production and affinity maturation
What does the innate lymphoid cells do?
Early responders
MHC independent reaction
Where are memory cell stored?
Mainly in the spleen
Summarise the sequence of the immune response
Sequential change from naive to activated
Driven by gene expression change driven by cytokines
Differentiation of precursor cells into specific lineages of cells
