what is the immune system?
Body’s defence system of cells and proteins that are able to identify invading organisms and then inactivate and eliminate them.
when is an innate immune response initiated?
initiated immediately on infection
what is a innate immune response?
non-specific defence against a wide range of pathogens
what is a Adaptive immune response ?
a response to a specific antigen and generates immunological memory
what does Adaptive immune response allow ?
Allows for a rapid response if the same infection hits with the same pathogen
Name five types of pathogens?
Bacteria Viruses Fungi Protozoa Helminth parasites
How are cells of the immune system being generated?
through hematopoiesis
where does hematopoiesis take place?
bone marrow
what does a Hematopoietic stem cell give rise too?
two progenitor cells
what 2 progenitor cells do Hematopoietic stem cell give rise to?
A. Common myeloid progenitor
B. Common lymphoid progenitor
Common myeloid progenitor, allows us to produce what?
- Megakaryocyte / erythrocyte progenitor
- Granulocyte and macrophage progenitor
Megakaryocytes produce?
platelets
erythrocyte progenitor produces?
erythrocytes
macrophage progenitor produce?
a dendritic cell
Granulocyte produce ?
a mast cell
Common lymphoid progenitor, leads to the production of what?
B cells and T cell pre cursor
Common lymphoid progenitor, produce B cells which produce?
plasma cells
Common lymphoid progenitor, produce T cell pre cursors, which produce?
Thymocytes (T-cell progenitor), which produces effector T cells
what T cells are produced by the effector T cells?
- cytotoxic T cells
- T helper cells
- Regulatory T-cells
what white blood cells are involved in the innate immune system?
neutrophil, eosinophil, basophil, NK cells
what’s involved in the adaptive immune system ?
B cell, plasma cell, cytotoxic T cell, regulatory T cell, T helper cell.
what protein are involved int he immune system?
Major Histocompatibility Complex , Cytokines, Chemokines, Complement, Cell surface receptors, cytotoxins.
what things are involved in both type of immune responses?
macrophage, mast cell and dendritic cell
name 3 Granulocytes
(Polymorphonuclear leukocytes) ?
neutrophil, eosinophil, basophil
where are macrophages located?
in tissues
what are macrophages?
large phagocytes
How do macrophages respond to pathogens?
respond to pathogens by using different receptor
example: Toll-like receptors
what happens to macrophages when infection is detected?
they are activated and secrete cytokines to recruit other cells
what’s another word for white blood cell?
leukocytes
what percent of our white blood cells is neutrophils?
60–80%
what sends neutrophils to the site of infection?
Recruited by cytokines
How do neutrophils pass the wall of vessels?
a process called diapedesis
what do neutrophils do to bacteria?
engulf and phagocytose bacteria, Enzymes then kill the phagocytosed bacteria and digest them
what percent of leukocytes
is eosinophils?
1.5%
How do eosinophils get to the site of infection?
Attracted to site of infection by chemokines
what do eosinophils defend us from?
parasitic invaders (worms)
what do eosinophils do to the parasites?
granules contain toxic molecules that attack parasites
what percent of leukocytes
is Basophils?
less than 1%
are pastils non-phagocytic?
yes
what do basophils defend us against and how?
May defend against large parasites by releasing toxic substances
what do basophils secrete?
Histamine and Leukotriene C4 which attract neutrophils and eosinophils
what do basophils contribute to?
allergic reactions
where aremast cells located?
in tissues
where are Natural killer cells found?
Circulate in the blood but are also present in tissues
(Natural killer cells)
cytotoxic lymphocytes contain what?
Perforins
Granzymes
Natural killer cells can do what ?
recognise and kill virus-infected cells and cancer cells
and stimulate macrophages
what is the innate immune response?
- injured tissue cells release histamine, causes capillaries to dilate.
- macrophages and dendritic cells, phagatosize pathogens and release cytokines, causing inflammatory response
- macrophages squeeze through capillary and the phagaocytize pathogens.
- Blood clotting walls off capillary, preventing blood loss.
what are symptoms of inflammatory?
redness, heat, swelling and pain
what do virus infected cells secrete?
interferons
in what manners to interferons act?
paracrine and autocrine manner
what do interferons do?
- Induce resistance of neighbouring cells to the virus
what do interferon sod linked to NK?
- Increase expression of activating ligands for NK cells on the surface of infected cells
- Activate NK cells to kill virus-infected cells
the complement system, involves plasma proteins that do what?
Plasma proteins that mark pathogens for destruction
what protein tags a pathogen for destruction?
Protein C3b
what are the three pathways in the complement system?
Alternative pathway
Lectin pathway
Classical Pathway
what are some characteristics of the adaptive immune system ?
Specificity
Diversity
Immunological memory
Life-long immunity
what are some specific defences of the active immune system?
Humoral Immunity
Cell mediated immunity
where are B and T cells found?
lymphoid tissues
what are the primary lymphoid tissues?
bone marrow and thymus
what are the secondary lymphoid tissues ?
stimulation of lymphocytes
GALT
MALT
what is lymphocyte recirculation?
lymphocytes move continuously from the blood to secondary lymphoid tissues to lymph and back to blood.
where do B-cells mature?
Bone Marrow
B cells have what on their surface?
specific antigen receptors on their surface
what happens when B cells are activated?
it will differentiate to a plasma cell and start secreting immunoglobulins (antibodies)
what are plasma cells known as?
effector cells
whats the life span fo plasma cells?
4-7 days
what can plasma cells do?
Produce antibodies – can mark antigens for destruction
whats the life span of memory B cells?
long
memory B cells have a ?
Rapid activation in a second encounter with the same antigen
How do antibodies differ form each other?
Size Charge Amino acid sequence Carbohydrate content Effect
what are the 5 classes of antibodies?
IgG1, IgG2, IgG3, IgG4 IgA1 and IgA2 IgM IgD IgE
what function are all classes of antibodies capable of ?
Neutralisaton, agglutination and enchanting NK cell activity
which antibodies are involved in Opsonisation ?
IgG and IGM
what is Opsonisation ?
attaching antigens to phagocytes
which antibody is involved in the Sensitisation of mast cells ?
IgE
which antibodies are involved in the Sensitisation of basophils ?
IgD, IgE
what’s the structure of IgM like?
5 Y shaped antibodies in a pentagon structure
whats the most common class of antibody produced in a primary response ?
IgM
what roles in antigen disposal does Igm have?
neutralises antigen
agglutinates antigen
activates complement
what shape are IgD, IgE and IgG?
just a Y shape
why is IgD important?
its an antigen receptor on B cells
whats the most common type of antibody in the blood?
IgG
what the most major class of antibody produced in seconds responses?
IgG
why Is IgG important?
crosses placenta, important in fatal and newborn immunity.
which antigen is linked to allergies?
IgE
what rolein antigen disposal does IgE play?
neutralises antigen
agglutinates antigen
binds to basophils an dames cells to make histamine
whats the structure of IgA
two Y’s joined at the tail horizontally
IgA is present in ?
breast milk so is important in immunity of new borns
what roles in antigen disposal does IgA play?
neutralises antigen
agglutinates antigen
when are T-cells activated?
upon contact with an antigen
what are the 3 regions of a T cell receptor?
- variable region
- constant regions
- transmembrane region
what happens during T-cell mediated immune respnse?
- Antigen presenting cells will ‘carry’ the antigen into the lymph nodes
- T-cells that have the matching T-receptor will start proliferating and differentiate into effector cells.
T-cell -mediated immune response.
after T cells are activated what do they do?
After their activation T-cells travel to infected tissues
In T-cell -mediated immune response
Cytotoxic T-cells will secrete ________ (perforin, granzymes) and induce ______ in target cells
- cytotoxins
2. apoptosis
what do T-helper cells do?
secrete cytokines
In T-cell -mediated immune response
Regulatory T cells will ______ the activities of the other _____ T-cells
- suppress
2. effector
which immune response is specific?
Adaptive immune response
which immune response as greater diversity?
Adaptive immune response
which immune response has memory?
Adaptive immune response
which immune response malfunctions often?
Adaptive immune response
