Where do T cells and B cells originate and mature?
Both are produced in the bone marrow - B cells also mature in the bone marrow but T cells migrate to the thymus and mature there. Maturation involves proliferation and differentiation into CD4 or CD8 cells
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What happens to naive CD8 T-cells?
Dendritic cells present a foreign antigen to CD8 T-cells via a MHC I receptor to the CD8 co-receptor. This activates the CD8 T-cell to a CD8 cytotoxic cell which go on to destroy infected cells
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What happens to naive CD4 T-cells?
Dendritic cells present a foreign antigen to CD4 T-cells via a MHC II receptor to the CD4 co-receptor. This will become activated to a T helper cell (Th1, Th2 or Th17). These can hyperactivate B cells and also activate macrophages and NK cells
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What does Th1 do?
Releases a cytokine called IFN-gamma to recruit macrophages which generally defend against intracellular bacteria
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What does Th2 do?
Releases the cytokines IL-4 and IL-5 which recruits eosinophils which defend against worms and parasites
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What does Th17 do?
Releases the cytokine IL-17 neutrophils against extracellular bacteria
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What happens to B cells?
B cells can bind to the epitope structure of the antigen via cell-surface antibodies and release IgM or presents it on its MHC II receptor to T helper cells. This hyperactivates the B cell to proliferate and differentiate into memory or plasma cells
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What do plasma cells do?
Secrete antibodies towards that antigen which can cause neutralisation, opsonisation or complement activation via classical pathway
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What do memory B cells do?
Form a memory of this specific antigen so the next infection by the same antigen can be resolved quickly
Heterodimeric with an alpha and beta chain. There is a constant region and a variable region where the antigen binds. A disulfide bridge links the chains. These receptors can only bind to linear epitopes (in the presence of MHC receptors)
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What structures do B cell receptors have?
B cell receptors are membrane bound antibodies. They have two heavy and two light chains which are the constant and variable regions. Constant region determines antibody class and variable region binds to conformational epitopes of antigens
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What do the specific immunoglobulins do?
IgM is the first Ig made in an immune response as it is non-specific and pentameric. IgD is rare. IgA found on mucous membranes. IgE is allergy antibody. IgG is found in serum and makes up most of the immunoglobulins
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What does rituximab do?
It is a monoclonal antibody drug which targets B cells by binding to a protein called CD20 found on the cell surface. This triggers B cell death
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What is IVIG?
Therapeutic immunoglobulin, derived from blood donors. It is a limited resource so it is expensive and there is a demand management programme. It is for prophylaxis of disease, in antibody-deficient individuals or as a immunomodulatory product
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What is primary antibody deficiency?
Rare and genetic condition where there is no B cells, a failure of T cell help and/or a failure of class-switching
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What is secondary antibody deficiency?
This common and has various causes - renal or GI loss of IgG, immunosuppression, B cell depletion. It can affect any age
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Other cards in this set
Card 2
Front
What happens to naive CD8 T-cells?
Back
Dendritic cells present a foreign antigen to CD8 T-cells via a MHC I receptor to the CD8 co-receptor. This activates the CD8 T-cell to a CD8 cytotoxic cell which go on to destroy infected cells
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