Introduction to Immunology Flashcards
What is the basic sequence of events that occur during a viral infection?
There is a rise in type 1 interferon and a rise in NK cells that flattens out the viral replication. The adaptive immune response then begins – there is a rise in Cytotoxic T lymphocytes and antibodies, which allows the complete removal of virus from the body.
State some differences between innate and adaptive immune responses.
The innate immune response is present from birth. It is not very specific and it is fast acting. Innate immunity relies on pre-formed and rapidly synthesised components. Adaptive immune response is the opposite.
State the two types of triggers of the innate immune response and give an example of each.
DAMP – high extracellular ATP
PAMP – bacterial cell wall components
What does the acute phase response respond to?
It is an inflammatory response to tissue damage.
What is a main clinical feature of the acute phase response and what causes it?
Fever – caused by Interleukin-1
What are the acute phase proteins and what do they do?
C-reactive protein – this and serum amyloid protein bind to bacterial cell wall components
Serum amyloid protein
Mannan-binding lectin – binds to mannose, which isn’t commonly found in mammalian cells
These are soluble PRRs which, once bound, helps activate the complement system
What are the five classes of immunoglobulin and what are their distinct features?
G – monomer - 75% of serum Ig. It passes from mother to foetus. Involved in the secondary immune response.
A – dimer – found on mucosal surfaces – has a secretory component to resist degradation by proteases found in the mucosa
M – pentamer – has 10 binding sites so is good at agglutinating pathogens. Involved in the primary immune response.
E – monomer – binds to basophils and mast cells and aids degranulation – involved in immune responses
D – monomer – very low serum concentration – involved in B lymphocyte signalling
How do antibodies kill viruses?
Opsonisation – make them more easily phagocytosed
Binding and preventing entry
Activating complement
Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) – coating in antibody means that infected cells are more easily killed by NK cells
What is the difference between B cell receptors and T cell receptors?
B cell receptors are membrane-anchored forms of the antibody that the B cell will secrete if activated. It can bind to intact antigens.
T cell receptors can only bind to processed antigens, which are presented on MHC molecules.
Describe the process of clonal selection.
Lymphocytes circulate through the lymph until they meet its complementary antigen. When the lymphocyte meets its antigen it will bind and become activated and begin to replicate itself. This is called clonal expansion.
What are the three main types of antigen presenting cell and what do they do?
Macrophages, Dendritic Cells, B cells – they pick up antigens and move to the lymph nodes where circulating lymph nodes can find the antigens.
What are the primary lymphoid organs?
Bone marrow and thymus
What are the secondary lymphoid organs?
Lymph nodes, Spleen, Mucosa-Associated Lymphoid Tissue (MALT)
