Immunity Flashcards
The discrimination between ‘self’ and ‘nonself’ and the subsequent destruction and removal of foreign material is accomplished by?
Innate immune system
Adaptive immune system
What are some components involved in innate immunity?
- Macrophages
- Granulocytes
- Natural Killer Cells
- Complement
- Other chemicals e.g HCl and Lysozyme
What are the two types of adapted immunity?
Cell mediated
Humoral
What components are involved in cell mediates adaptive immunity?
Antigen presenting cells
T-cells
What components are involved in the humoral adaptive immunity?
T cells
B cells
Antibodies
Complement
Outline the characteristics of innate and adaptive immunity
Innate: - immediate action - non-specific response - response not enhanced on repeated exposure to pathogen Adaptive: - delayed action - specific response - response enhanced by repeated exposure to pathogen
What are the first line defence for innate immunity?
1) Mechanical Barrier
2) Chemical and biochemical inhibitors
3) Normal flora
What are the second line defence for innate immunity?
- Cells: Natural killer cells, Phagocytes
- Soluble factors
- Inflammatory barriers
Some mechanical barriers for first line innate immunity include:
- Intact skin
- Mucous coat
- Mucous secretion
- Blinking reflex and tears
- The hair at the nares
- Coughing and sneezing reflex
Some chemical and biochemical inhibitors for first line innate immunity include:
- sweat and sebaceous secretions
- hydrolytic enzymes in saliva
- HCl of stomach
- Proteolytic enzyme in small intestine
- lysozyme in teas
- acidic pH in the adult vagina
Examples of how normal flora help with first line innate immunity
- provide competition for essential nutrients
- production of inhibitory substances
The immune system is…
the body’s defence mechanism. It comprises of an interacting set of specialised cells AND proteins designed to identify and destroy foreign invaders
The immune system must be able to differentiate between material that is:
- a normal component of the body (self) and material that is not native to the body (non-self)
Cells involved in specific immune mechanisms are:
i)
ii)
i) heamatopoietic leucocytes
ii) non-hematopoietic cells
Heamatopoietic cells include:
- lymphoid cells such as
- monocytic myeloid cells such as
- T-lymphocytes, B-lymphocytes, NK cells
- macrophages, neutrophils, eosinophils, basophils + mast cells
What are the characteristics of the lymphoid heamatopoietic cells?
a) T-lymphocytes:
- antigen specific cells carrying CD3 complex; CD4, CD8.
- dominant lymphocyte (70%)
- cytokine production
- activates other cells (T-help CD4)
- suppressors other cells (T-supp CD8)
b) B-lymphocytes:
- antigen specific cells
- antibody production
- less common lymphocyte (20%)
c) NK cells
- not antigen specific
- carries Fc receptors
What are the characteristics of monocytic myeloid haemotopoietic cells?
a) macrophages
- non specific
- APC (+ antigen processing cells)
- carry Fc receptors
- phagocytic
- produce cytokines
b) neutrophils
- non specific
- carry Fc receptors
c) Eosinophils
- non specific
- carry Fc receptor
- produce allergic mediators
d) Basophils and mast cells
- non specific
- carry Fc receptor
- produce allergic mediators
What are the non-haemotopoietic cells and what is their function?
- Dendritic cells
- Astrocytes
- Endothelial cells
INVOLVED IN ANTIGEN PRESENTATION
What are all the antigen presenting cells. State if they’re heamotopoietic or non-haemotopoietic.
a) macrophages: haemotopoietic
b) dendritic cells: non-haemotopoietic
c) astrocytes: non-haemotopoietic
d) endothelial cells: non-haemotopoietic
State the source for:
- NK cells
- phagocytes (macrophages, neutrophils, eosinophils etc)
- bone marrow precursors
- stem cells
NK cells are responsible for? (ADCC)
Antibody dependent cell-mediated cytotoxicity
NK cells are cytotoxic for:
- tumour cells
- viral infected cells
- bacterial, fungal and parasitic infected cells
Name some soluble factors and their function or where they are found.
- complement (proteins in serum, body fluids)
- interferons (protects against viral infections)
- lysozyme (hydrolyses cell wall)
- lactoperoxidase (saliva + milk)
- lactoferrin, transferrin (iron binding protein)
What are the different types of interferon?
- alpha
- beta
- gamma
What cell is alpha interferon secreted by?
alpha
What cell is beta interferon secreted by?
fibroblasts
What cell is gamma interferon secreted by?
t-lymphocytes
What cell is alpha interferon induced by?
viruses
What cell is beta interferon induced by?
viruses
What cell is gamma interferon induced by?
specific antigens
What are the actions of interferons?
- activate T cells
- activate macrophages
- activate NK cells
Define phagocytosis
The engulfment, digestion and subsequent processing of microorganisms by macrophages and neutrophils
What are the three steps to phagocytosis?
1 - Chemotaxis and attachment
2- Ingestion
3 - Killing (2 routes; O2 dep, O2 indep)
Chemotaxis and attachment stage of phagocytosis involves:
Attraction by chemotactic substances (microbes, damaged tissues)
Attachment by phagocyte surface receptor
Ingestion stage of phagocytosis involves:
Phagocyte pseudopodia surround organism forming phagosome.
Attachment enzymes and co-factors enhance phagocytosis.
Fusion with phagocyte granules, and release of digestive toxic contents.
What are the inflammatory barriers?
Inflammatory response
a) release of chemical mediators e.g histamine, fibrin, kinin, cytokine
b) vasodilation of capillaries
Vasodilation of capillaries causes:
- redness of tissue
- increase tissue temperature
- increase capillary permeability
- influx of fluids
- influx of phagocytes into tissues
Process by with acquired immune response is initiated:
- recognition of antigen by specific lymphocytes
- activation of these specific lymphocytes
- proliferation and differentiation in effector (B) cells
- Effector (B) cells eliminate antigen
- Return of homeostasis and memory cell development
- Memory cells produce a more rapid and long response on re-exposure to same antigen
Explain how vaccinations can be
a) prophylactic
b) therapeutic
a) to prevent the effects of a future infection by any natural or ‘wild’ pathogen
b) vaccines against certain cancers
Vaccinations work by:
producing immunity against pathogens, by introducing live or killed antigens that stimulate the body to produce antibodies against more dangerous forms
Tolerance is a specific…
immunologic unresponsiveness
Unresponsiveness to ___- ______ is known as ___-______ and is the normal homeostatic state
self-antigens
auto-tolerance
What are the two mechanisms by which B cells become tolerant to self cells?
1 - clonal deletion (central; when B-cell precursors are in bone marrow)
2 - clonal anergy i.e. lack of reaction (peripheral)
What occurs in T-cell clonal deletion (central tolerance)
T-cells acquire ability to distinguish self from non self in fetal thymus. This involves killing T-cells that react AGAINST the antigens that are present in the foetus at that time
What occurs in T-cell clonal anergy (peripheral tolerance)
Some self-reactive cells are not killed in thymus. Functional inactivation of surviving self-reactive T cells takes place.
