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What are the three types of professional antigen presenting cells
Dendritic cells, macrophages, B cells
What kind of antigens do macrophages present
Particulate antigens, intracellular and extracellular pathogens
Once a dendritic cell or macrophage presents a specific antigen a T cell recognizes what happens to the T cell
It begins to proliferate and differentiate to effector cells
How do T cells enter lymph nodes or regular tissues
The of the same mechanism of neutrophils that is rolling tight adhesion diapedesis and tissue migration
Describe the intracellular signaling pathway that turns on inside an activated T cell
Tyrosine kinases activate Phospholipase Cg. This cleaves PIP2 to DAG and IP3. Dag and calcium activate Protein Kinase C (PKC). IP3 causes the release of calcium. The release of calcium activates the phosphatase calcineurin. PKC and calcineurin activate transcription factors NFkB and NFAT which induce the cell to divide.
What is co stimulation mediated by
CD80 and CD86 on the APC which binds to CD28 on naïve T cells to deliver the costimulation
What happes to the T cell once the response to the non self antigen is complete
The T cell upregulates expression of CTLA4
What happens to the T cell in the absence of costimulation
It becomes anergic or permanently inactive
What is the source and effects of IL4 and IL5
TH2 and humoral immune response such as IgA, IgG1, IgE antibody production and class switching
What happens to activated T cells with regards to IL2
they begin to make their own IL2 and change receptors from a low affinty dimer to a high affinty trimer
What do TH1 cells do
inflammatory and cellular immune response by making TNF and IL12 and INF gamma secretion. Host defense against intracellular microbes
What do th2 cells do
humoral antibody immune response IL4 il5 il13 secretion, host defense against helminths and allergic reactions
What happens do down or upregulate the th1 or th2 responses
th2 secretes TGF beta and IL10 which inhibit activation and growth of TH1, th1 secretes IFN gamma which inhibits proliferation of th2 cells
Why do cd8 cells not require further costimulation after being stimulates
the IL2 they produce is an autocrine growth factor
How else can apoptosis be triggered via CTl's
interaction of CTL FASL with the Fas in the target cell
how do th1 cd4 cells accomphlish this microbiocidality
the interaction between cd40 on the macrophage and cd40L on the t cell and via th1 cytokines
what happens when intracellular pathogens cannot be totally eliminated
th1 cells induce granuloma formation
where are granulomas commonly seen and why
tuberculosis, parasitic infections and granulomatous disease. The pathogens have evolved mechanisms to resists macrophage mediated killing
What happens when th2 cells talk to B cells
B cell proliferation and differention into antibody secreting plasma cells
what is the difference between protective immunity and immunological memory
protective immunity is due to recent infections that have induced antibodies, immunological memory is due to a memory response from a previous infection from a while ago
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