innate immunity Flashcards
what is innate immunity in terms of your line of defence in your immune system?
what is it followed by?
- The innate immune system is your first line of defence against this challenge. It is not specific, has no memory
- Followed by adaptive immunity, which is specific and can involve memory (memory responses)
what three routes of entry are there through mucosal surfaces?
what are the modes of transmission?
what are the pathogens and associated diseases?
what three routes of entry are there through external epithelia?
what are the modes of transmission?
what are the pathogens and associated diseases?
what are the 3 phases of response to an infection?
how long do each take to be initiated?
what do each involve?
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innate immunity (0-4 hours)
- Recognition by preformed, nonspecific effectors
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early induced response (4-96 hours)
- Recruitment of effector cells
- recognition and activation of effector cells
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adaptive immune response (>96 hours)
- transport of antigen to lymphoid organs
- recognition by naive B and T cells
- clonal expansion of effector cells
what are examples of mechanical barriers to infection?
what are examples of chemical barriers to infection?
what are examples of microbiological barriers to infection?
in innate immunity, what occurs after microorganisms cross an epithelial barrier?
what are examples of receptors on macrophages?
- Once across an epithelial barrier, in most cases microorganisms are recognised and ingested by mononuclear phagocytes, or macrophages.
- Receptors include (receptors which allow macrophages to take up bacteria) : Mannose receptor, glucan receptor, scavenger receptor, CD14 (LPS), CD11b/CD18 (CR3)
list some bactericidal effects and agents produced by phagocytes?
- Acidification: pH 3-4, bactericidal
- Toxic oxygen derived products: superoxide, hydrogen peroxide, hydroxyl radical
- Toxic nitrogen oxides: Nitric Oxide
- Peptides: defensins and other cationic proteins
- Enzymes: Lysosyme, acid hydrolases
- Competitors: Lactoferrin, vitamin B12 binding protein.
describe monocytes briefly
- one of the three types of phagocytic cell of the immune system.
- Circulate in bloodstream, differentiate into macrophages in tissue.
granulocytes/polymorphonuclear leucocytes:
what is the most common PMN?
why do they have short life spans and only phagocytose once?
what does neutropenia cause?
neutrophils are the most common and represent 70% of all circulating white blood cells
this may be a possible adaptation to prevent growth of parasites that can live in phagocytic cells. Alternatively since antimicrobial products damage host tissues, short lifespan may limit host damage
Neutropenia, low numbers, may be genetic or the result of medication including chemotherapy which leads to overwhelming bacterial infections
granulocytes/polymorphonuclear leucocytes:
what do granules within eosinophils contain?
when is eosinophilia seen?
when is eosinopenia seen?
Granules contain histamine, peroxidase, RNase, DNases, lipase, plasminogen, Major Basic Protein
- Eosinophilia (increase, more than 500 per microlitre blood) seen in parasitic infections of gut, some vascular diseases, Hodgkin’s Disease, Addison’s Disease
- Eosinopenia often seen when glutocorticoids used.
granulocytes/polymorphonuclear leucocytes:
what do basophils and mast cells do? (function)
what do basophils secrete?
what are mast cells mediated by?
- when activated release a number of substances that effect vascular systems
- Upon activation secrete histamine, proteoglycans, leucotrienes, some cytokines including IL-4 (potentially important for IgE and allergy)
- Most well known due to IgE mediated triggering in allergies
lymphoids: important in the adaptive response
what do B cells produce?
what do T cells do?
B cells producing antibody
T cells becoming cytotoxic T cells (CD8) or helper T cells (CD4)
what are natural killer cells?
what does IFN-alpha and IFN-beta do induce?
what is the difference between NK and CD8-T cells?
- large granular lymphocytes that can recognise virally infected cells nonspecifically by releasing IFN-alpha, IFN-beta
- induce resistance to viral replication in all cells
- increase MHC class 1 expression and antigen presentation
- activate NK cell to kill virus-infected cells
The key difference between NK and CD8 T cells is that NK cells are not antigen specific. Also they do not require to undergo the lengthy clonal expansion of T cells in lymph nodes when virus is detected
what are dendritic cells?
what are they specialised in?
- potentially the most important immune cell, bridges the innate and adaptive immune responses
- Specialised in antigen uptake and antigen presentation
what are complements?
what are they key for?
what are the three activation pathways which trigger the complement cascade?
what three things do they cause?
- they are heat labile component of plasma that act in concert with antibodies to kill some bacteria which are composed of large numbers of distinct plasma proteins
- they are key for innate response as it is always within the bloodstream which can be triggered straight away
classical pathway, lectin pathway and alternative pathway
causes:
1. recruitment of inflammatory cells
2. opsonisation of pathogens
3. lysis and death of pathogens
