L12- Adaptive Immune Response Part 2 Flashcards
T cells mature in the thymus whereas B cells are mature in tissues following contact with antigens, name two key lymphoid tissues where lymphocytes accumulate
Lymph nodes
Spleen
MALT
The T cell receptor is the part of the lymphocyte which is recognising the presenter antigen and MHC molecule, what other complex is necessary for activation of the T cells?
CD3 complex
Which T cells recognise peptides presented by MHC class 1 molecules?
Cytotoxic T cells (CD8+)
Which T cells respond to
a) extracellular microbes
b) intracellular microbes
a) cd4+ T cells
b) cd4+ and cd8+ T cells
4 signals produced by the interaction of an APC and a T cell are necessary for fulll activation of the T cel the first is between the TCR and the peptide and MHC molecule, the second is the presence of the CD3 complex, what are the last two?
Activation of CD28 on T cells by B7 and release of cytokines
Naive CD4+ cells can become one of four fates, what are they?
Th1 - activation of CD8 cells, recruitments of macrophages and B cell activation
Th2 = B cell activation, eosinophil activation, mast cell activation
Th17 - nuetrophil recruitment and activation
Treg - tolerance
Dependent on the cytokines released from T cells
Cell mediated immunity is defence against IC and EC pathogens (bacteria, viruses and fungi). Upon this kind of infection cytokines cause naive CD4+ cells to differentiate into TH1 cells. What does this cause?
Activation of CD8+ cells
Recruitment of macrophages and activation
B cells are stimulated to produce igG or IgA
Upon a parasitic infection, naive CD4+ cells differentiate into Th2 and Th17 cells what are the actions of these?
Th2 activates B cells to produce IgE
Activates eosinophils and mast cells
Th17 - recruits and activates neutrophils
What kind of cell do some naive Cd4+ cells always differentiate into upon infection?
Treg cells to suppress the immune response
What two molecules are released by cytotoxic T cells to kill infected MHC class 1 APC’s?
Perforin and granzyme
Antibodies are made up of a light chain and a heavy chain, the area in which peptides bind to them is the B cell receptor specifically the CDR which is highly variable, B cells can recognise microbes in their native state, I.e. they don’t require APC’s. They can be activated by microbes directly or by T helper cells.
The three signals that are require for efficient B cell activation are
1) activation by peptide binding B cell
2) T helper cells presenting peptide to MHC class molecules on B cell
And….
3) CD40L on Th cell binding CD40 on B cell this causes a heavy chain switch so that the B cell starts producing the correct immunoglobulin to the pathogen (IgM production is T helpher cell independent)
Which immunoglobulin (antibody) is produced independent of T helper cells?
IgM when B cells differentiate to plasma cells
Which immunoglobulins can be made as a result of T helper cells by B cells
IgG, IGA, igE
The ratio of IgG to IgM will tell us whether the infection has occurred before and what stage it is in. What can we tell from a High IgM:IgG ratio?
That the patient hasn’t had the infection before and it is in the early acute phase
Explanation - hasn’t had it before because otherwise IgG would quickly rise due to presence of B memory cells
What action do the following immunoglobulins have a) IgA B) IgM C) IgG D) IgE
a) mucosal immunity (e.g. in breast milk)
b) complement activation
c) neonatal immunity/ toxin neutralisation
d) parasitic immunity
