Immunity 1 and 2 Flashcards
What are the functions of the immune system?
- Protect from pathogens & foreign molecules
- Parasites
- Bacteria
- Viruses
- Fungi
- All animals exhibit some general ability to recognize
self and to repel foreign substances - Scavenge dead, dying or abnormal (cancerous) cells
Innate VS Adaptive
innate= fast acting, adapts a response as soon as it comes into contact with foreign organism, more localised, less specific as it can act on multiple different types of pathogens
adaptive= Could take days to weeks, one cell can only respond to one type of organism containing one type of antigenic material. Most times further away from region of infection
*complement proteins work on both types of responses and highly conserved amongst different taxa.
*cytokines are type of proteins or peptides that are secreted often by innate or adaptive immune cells when an infection has occurred and they regulate the immune response. Some are proinflammatory and some are anti-inflammatory.
List some external defenses
(INNATE IMMUNITY)
skin
mucous membranes
secretions
List some internal defenses
(INNATE IMMUNITY)
phagocyte cells
antimicrobial proteins
inflammatory response
natural killer cells
Describe ACQUIRED IMMUNITY
Slower responses to specific microbes
Humoral response (antibodies)
Cell-mediated response, (cytotoxic lymphocytes)
Explain a mucous layer
mucins cells produced that make the mucous more viscous. Quite dynamic and lots of antibodies being added into mucous and binding.
Hematopoietic stem cells
Where are they found?
What can they differentiate into?
What cells does the innate response have and what do they do?
What is the innate response involved in stimulating?
Hematopoietic stem cells found in the bone marrow become either myeloid progenitor cell (innate) or lymphoid progenitor cell (adaptive)
There are leukocytes which means just white blood cells and this covers both innate and adaptive.
innate response causes inflammation its is the regulation of the immune response
granulocytes e.g neutrophil, eosinophil and basophil they have granules in their cytoplasm that contain things that are excreted when they come into contact with foreign cells (they degranulate) and this elicits an inflammatory response, they excrete signalling molecules such as cytokines. They also excrete histamines and other things that have antimicrobial properties
lymphocytes are a subclass containing all lymphocytes and natural killer cells
Most of the innate response is involved in stimulating the adaptive immune response especially macrophages (antigen-presenting cells) stimulating B-cells and T-cells.
Recognizing friend from foe/danger?
innate cells looking for this
* Pathogen associated molecular patterns (PAMPs). (Ligands)
* a diverse set of microbial molecules
* Damage associated molecular patterns (DAMPs) produced by self cells e.g heat shock protein 70. This means that even thought we do have these proteins normally they shouldn’t be found outside of cells.
* misplaced self-molecules released from damaged or stressed cells
* Pattern recognition receptors (PRRs)
* TLRs, NLRs, CLRs etc
TLR’s most important to know = Toll like receptors
Acute Innate Response
Pathogen inside
degranulation
DAMPS would be detected from damaged tissue or PAMPS would be detected by a TLR4
recognition of pathogens–> mass cells degranulate and release cytokines, histamines etc. and initiation of inflammatory response and neutrophils can secrete NETS to pin down bacteria and keep it localized. Phagocytosis
We also get vasodilation as part of the inflammatory response,
fluid flows into the tissue so cells coming from central reserves can come close to capillary bed and this allows antimicrobial peptides like lysozymes to be transported more easily onto infected tissues.
neutrophils would be first then monocytes (which will differentiate into phagocytic cells) and continue to secrete cytokines or present antigenic material and go elsewhere to activate B-cells.
complement proteins -These help by binding to receptors or ligands of the microbe opsonization (this makes the things easier to phagocytose). Some also increase inflammatory responses.
Complement-mediates cytolysis= bunch of proteins that work as a cascade and punch a hole in the cell wall of the bacteria.
What cells are important in the early stages in the acute phases of the inflammatory?
what cells present antigens?
What do natural killer cells do?
*macrophages and neutrophils because they perform phagocytosis.
*dendrocytes and macrophages present antigenic material to T-cell and they both do phagocytosis
*They are part of the innate system and they kill host infected cells, they will also kill tumour cells
How can we get to pathogens that have managed to enter the bloodstream efficiently?
The body has evolved to create some kind of block for the pathogen which is our spleen, that filters any non self items out of the blood. There is also a gap between vessels after the spleen, it contains lots of phagocytic cells.
The capillary beds don’t bring all the fluid back to the vessels and some gets taken into the lymphatic system which is actually a good when it comes to fighting pathogens as this takes them to lymph nodes and here they have multiple afferent vessels going in nodes and only one efferent leaving, so pathogens have to go past loads of lymphatic cells waiting and this can elicit the immune response too.
B and T lymphocytes adaptive immune response
*requires activation by specific antigen (not general)
-involves MHC (major histocompatibility complex -consists of a genetic loci encoding many of the proteins involved in antigen presentation to T cell)
*Divided into humoral immunity (extracellular pathogens) and cellular immunity (intracellular pathogens)
T cells –>migrate to thymus, TCR, cellular
B cells–> bone marrow, BCR, humoral
first response to a particular antigen (primary response) slow
It is the basis of immune memory and immunisation (secondary response- faster)
T lymphocytes
clonal expansion and differentiation
helper T cell (CD4+)
-activated by APC via MHCII
-secrete cytokines that regulate immune response
-activate B cells
Cytotoxic T cells (CD8+) only activation if complementary receptor
-activated by APC via MHCI
-destroy (primarily) virally infected cells
-destroy tumour cells
memory cells (basis of immunisation)
B lymphocytes
how can B-cells be activated?
What do activated B-cells do?
clonal expansion and differentiation
-plasma cells (produce antibodies)
-memory cells (basis of immunisation)
antibody-antigen binding causes
need to come in contact with pathogen, internalise it and take a piece of it and present in histocompatibility complex, then go around and find a helper T cell that has already been stimulated by an APC which contains the antigen too.
*neutralisation (prevents virus/toxin interacting with cells
*preventing adherence (virus/bacteria binding to cell receptors.
*Agglutination
*opsonization (increases susceptibility to phagocytosis
*complement activation.
lymphocytes and adaptive immunity
We have high levels of B-cells and T-cells concentrated at the spleen and lymph node
spleen= In the PALS (periarterial lymphatic sheath) we have loads of T-cells, in the follicles we have lots of B-cells and lots of macrophages in white pulp
lymph nodes= all the leucocytes are diffused around inside
