Introduction to Immunology Flashcards
Fundamental importance of immunology in most __________
not just ____________ ______, _______, ________ ___________, ___________
specialties
autoimmune disease
allergy
immune deficiency
transplantation
you may have an immune repsonse to what different things?
- infection
- injury
- cellular damage/stress
what are examples of immunotherapy?
- Vaccines
- Immunomodulators
- Monoclonal antibodies
- Cellular therapy
what are the different influences on the immune system?
- Age
- Obesity
- Fitness (exercise)
- Diet
- Co-morbidities
what are the different physical and chemical barries in the body?
the immune system is comprised of a gorup of ____, ___________ and _________ that work together to protect the body
major component of the immune system is the ________ __________
cells
molecules
receptors
lyphatic system
the specalised cells of the immune system develop in the ____ ________ during ___________
all develop from a ____________ ____ cell
bone marrow
haematopoiesis
hematopoitic stem
hematopoitic stem cells divide into what two linages?
myeloid (mature in bone marrow, as do B lymphocytes)
lymphoid (t lymphocytes migrate to the thymus to complete their maturation)
what makes up the innate and adaptive immune systems?
Innate immune response is the first line of defence and is responsible for a fast but not very specific response to invaders. Present from birth but no immunological memory
Adaptive immune response is much slower. Highly specific to each different pathogen and establishes an immunological memory of the pathogen for future potential encounters
There are two types of adaptive responses, what are they?
those being the cell mediated via T lymphocyte activity
and humoral responses by B-lymphocytes and the antibodies they produce
An essential component of the immune system is the ability to distinguish between foreign threats, healthy host cells, and damaged host cells. This distinction is done through the recognition of _______
antigens
Whilst we tend to refer to the term ‘antigen’ as a marker of something ‘foreign’, in fact every one of the cells in our body expresses certain special marker molecules that advertise ‘self’
All our nucleated cells display these self-markers via a cell membrane protein called what?
the Major Histocompatibility Complex I (or MHC I)
In normal circumstances, host cells expressing MHC I display their own unique and healthy self-markers, or fingerprints, to reassure the immune system and prevent unnecessary reactions.
___ are genetically coded cell surface proteins that are vital for this presentation of both antigens and self-markers to the immune system
In humans the MHC is also referred to as what?
MHC
a human leukocyte antigen, or HLA
what are the two types of MHC?
The MHC has two types, class I and class II
what is the structure of MHC 1 molecules?
found on the cell surface of all nucleated cells in the body
They display self-markers but also present intracellular foreign antigens to the immune system
If a host cell becomes infected by an intracellular pathogen (for example, a virus), the class I MHC molecules present endogenous (or intracellular) antigens from this pathogen on its cell surface
what is the strucutre and function of MHC 2 molecules?
found only on professional antigen presenting cells and are responsible for presenting exogenous, or extracellular antigens from pathogenic invaders.
Examples of professional antigen presenting cells include: Dendritic cells, Macrophages and B lymphocytes.
These antigen presenting cells are responsible for bringing antigens to the attention of T lymphocytes via these MHC molecules.
T lymphocytes are not able to recognise and react to free-floating antigens, and therefore need them presented to them in a way they understand before they will become activated:
what ways can antigen be presented to T lymphocytes?
antigen-presentation is done by ‘professional antigen presenting cells’ and nucleated host cells as described before
Professional antigen presenting cells present extracellular antigens via MHC II molecules to CD4+ helper T lymphocytes
Any nucleated host cell can present intracellular antigens via their MHC I molecules to CD8+ cytotoxic T lymphocytes
Foreign antigen attached to APCs via MHC II is recognised by CD4+ cell, what does this cause?
causes release of CD4+ cytokines. This activates B lymphocytes to release specific antibodies against the foreign invader, improves macrophage phagocytosis and recruits primed CD8+ cells to target the foreign invader directly.
what is autoimmunity?
Unfortunately, sometimes our immune system can incorrectly identify a normal healthy host self-marker as ‘foreign’ or a threat, and cause it to initiate a immune response. This is referred to as autoimmunity
what is tolerance?
A mechanism that aims to prevent these unnecessary reactions to healthy host cells is the development of immunological tolerance
Tolerance, as it suggests, means the immune system learns to becomes “tolerant” or unresponsive to a particular antigen
This usually refers to the body tolerating its own self-antigens
Immunological tolerance can be classified into ______ and ___________ tolerance depending on where the state of tolerance is initiated
central
peripheral
Central tolerance is developed within _______ lymphoid organs, where immature immune cells are taught to be able to discriminate between host and non-host
primary
where do T and B cells develop central tolerance?
T lymphocytes develop this central tolerance within the thymus, while the B cells develop central tolerance within the bone marrow
Any cell showing inappropriate responses are either edited, transformed, or destroyed
what is peripheral tolerance and where does it happen?
Peripheral tolerance is created within secondary lymphoid organs, containing mature immune cells that have already been released into the circulation
If any of these mature cells then starts to inappropriately recognise and react to self-antigens, they are made useless, are destroyed, or are suppressed by regulatory T lymphocytes.
Immune tolerance is important as it can prevent over-reactivity of the immune system
Unfortunately, however, it can also be _______ by intracellular _________ or _______ cells in an attempt to evade the host immune responses
exploited
pathogens
malignant
Name 5 different physical or chemical barriers that help prevent the human body from pathogen invasion?
- Lysozyme (anti-bacterial enzyme) in tears, saliva and sweat
- Mucociliary escalator
- Intact skin surface with sebum to lower pH
- Intact mucosal membranes
- Acidic pH of stomach
- Rapid pH change in duodenum and alkaline pH in jejunum and ileum
- Normal flora in bowel and vagina and on skin surface
- Flushing of urinary tract
Match up the following clinical problems with the corresponding physical or chemical barrier that would normally prevent this occurring.
- Mucositis - inflammation and ulceration of mucosal membranes (e.g. after chemotherapy)
- Sjogrens syndrome (associated with loss of tear production)
- Cystic Fibrosis
- Toxic megacolon due to Clostridium difficle infection
- Burns
- intact mucosal membranes
- lysozyme in tears
- mucociliary tract
- normal gut microbiota
- skin
what are the primary and secondary lyphoid organs
Which of the following cells originates from a lymphoid progenitor cell?
Macrophage
Plasma cell
Platelet
Erythrocyte
Mast cell
plasma cell
Which of the following cell acts as a professional antigen presenting cell?
Neutrophil
Natural killer cell
Macrophage
T lymphocyte
Mast cell
macrophage
What immune cell would be responsible for recognising a virally infected host cell?
NK cell
Macrophage
CD4+ T helper lymphocyte
Mast cell
Eosinophil
NK cell
Which of the following cells is not capable of phagocytosis?
Macrophage
Basophil
Neutrophil
Eosinophil
Monocyte
eosinophil
Which 3 cell types are vital for targeting parasites or organisms too large for phagocytosis?
Mast cells
Basophils
Eosinophils
