Lecture 20 Flashcards
What is viraemia?
Viruses in the blood
What is Bacteraemia?
Bacteria in the blood stream
What are the factors of the micro-organism which determine the immune response?
Type of micro-organisms
Dose
Virulence of the organism
route of entry
What are the host factors that help determine what immune response is used?
Integrity of non-specific defences
Competence of the specific immune system
Genetic Capacity to respond normally to a specific organism
What are the specific immune factors?
Direct neutralisation by antibodies
Opsonisation and phagocytosis
Complement-mediated efects
MHC-Restricted T cell mediated cytotoxicity
Inflammatory and immunoregulatory cytokines
Anti-viral cytokines
Why does the immune response to intracellular pathogens need to be different?
The pathogen is not as accessible as extracellular pathogens are therefore more cytotoxic T cells are required
How can the immune system respond to viruses?
If there are already specific antibodies already present during infection viruses are prevented access to target tissues
If there are no specific antibodies present, then the infection will become well established in this case the interferon system and helper t lymphocytes are used
How does the interferon system work?
An infected cell becomes alerted to the viral activity and begins production of the glycoprotiens interferons these are released from the infected cell resulting in nearby cells altering their ribosomal activity so that the viruses struggle to hijack them causing induced viral resistance
The interferon also attracts natural killer cells and promote the activity of killing virus infected cells with out use of an antigen
how does the immune system respond to bacterial infections?
Antibodies may cause inactivation, destruction or opsonisation of bacteria
The effect of antibodies can be combated by bacteria which replicate intracellularly or have outer structures that are poorly recognised by the immune system
What are the three classes of CD4 T cells?
TH1, TH2 and TReg
What is the role of TH1 Cells?
Elimination of intracellular infections via production of cytokines which upregulate Cytotoxic T Cell and Natural Killer activity
What is the role of TH2 Cells?
Defence against large extracellular pathogens which is mediated by stimulation of B cells
How do TH2 and TH1 cells interact?
When activated each cell type will promote its own activity and suppress the activity of the other T cell class
What are the features that the immune system and nervous system have in common?
Receptors and process’ of information across self/non self boundary
Respond to a diverse range of stimuli
Response is generally specific for stimulus
System adapts it resources from a range of available resources
Capacity to respond to unexpected stimuli is a fundamental property
Ability to remember specific stimuli and to modify and tailor subsequent responsiveness
Regulated by complex internal networks
How do the immune system and nervous system interact?
Hormones of the hypothalamus-pituitary-adrenal axis affect immune activity
Cytokines affect brain activity
Neuropeptides are produced by activated lymphocytes
Sympathetic and Parasympathetic innervate all lymphoid organs and modulate lymphocyte activation
What is the effect of cortisol?
Inhibition of T and B cell activity
What is the effect of IL-1?
Increases body temperature, sleep cycles
What are the different immune system control mechanisms?
Balance of innate/adaptive mechanisms
Nature of antigen, route of entry, concentration of antigen
Presence, concentration and class of specific antibodies
Current immunological state
Antigenic history of the individual
HLA and TCR genes
Status of helper T cells and cytokine network
Interactions with nervous system
What are the psychoneuroimmune connection and health?
Extensive network of interconnections between the nervous and immune systems resulting in each system affect one another causing changes in thoughts, feelings and behaviours
What are the effects of IL-1 on the brain/nervous system?
Increase in body temperature
Increased desire for sleep and changes in sleep patterns
Reduced desire for social interaction
Reduced desire for food
Changes in perception
It is believed the purpose of these effects are to reserve energy for the immune system to deal with the infection
What is the relationship between stress and immunity?
When people perceive there lives to be stressful there are reduced antibody responses to vaccine antigens
Reduced production of cytokines associated with wound healing
Increased susceptibility to upper respiratory infections
When people have rich social support these effects on immunity and health are reduced
