6 Antigen Presenting Cells Flashcards
* Describe and sequence the trafficking of T cells, and the role of adhesion molecules in this process * Describe and distinguish the three types of antigen presenting cells * Describe and sequence the process of T cell activation and the development of the different types of armed effector T cells
What are the three types of Antigen Presenting Cells?
Dendritic Cells
Macrophages
B Cells
Where does activation of naive T cells exclusively occur?
Secondary Lymph
What two signals are required for T cell activation?
MHC:peptide
B7 binding to CD28 (costimulation)
What class of immune cell only expresses B7 signal?
APCs
What are lectins that bind to carbohydrates?
Selectins
What are mucin like vascular addressins?
Adhesion molecules that target carbohydrates
What is an example of an integrin?
LFA- (lymphocyte function adhesion molecule 1)
What are targets for integrin binding?
Immunoglobulin superfamily receptors
ICAMs, CD2, LFA3
What do naive T cells depend on to bind to endothelial walls?
CD34 on endothelium to bind to
What binds to CD34 on high endothelial walls?
L-selectin
What is the first adhesive molecule pairing to occur in Naive T cell diapedesis?
GlyCAM1 and CD34
What is the second, tightening, adhesive molecule paring to occur in Naive T cell diapedesis?
LFA1 binding to ICAM1 on endothelium (cytokine activated)
What is diapedesis?
Lymphocyte movement from blood into lymph
Where do activated T cells go?
Inflammatory sites
Why do we not want activated T cells in secondary lymph?
They will destroy good tissue
What prevents CD8 cells from re-entering secondary lymph?
They do not express L selectin
What do activated CD8 cells express to bind them to activated endothelium?
LFA1
VLA4
to bind to endothelial VCAM1
Where are dendritic cells located in the lymph node?
T cell areas
Where are B cells located in the lymph node?
Follicles
How do dendritic cells take up antigen?
Macropinocytosis
Phagocytosis
Viral Infection
How do macrophages take up antigen?
Phagocytosis
How do B cells take up antigen?
Ig-Receptor Antigen specific binding
What does MHC expression look like in Dendritic Cells?
Low on tissue DCs
High on lymph DCs
Viral An presented
What does MHC expression look like in Macrophages?
Bacterial and Cytokine presentation
What does MHC expression look like in B cells?
Increase with activation???
What An do DCs present?
Viral
Allergens
(peptides)
What an to macrophages present?
Bacteria
virus and particulate second
What An to B cells present?
Toxins
virus and soluble antigens
What cell is only mainly found in the Lymph?
B call
What cell goes back to the bone marrow following activation?
Plasma B Cell
What cell type makes the most B7 of APCs?
Dendritic Cells
What cell type is mainly for intracellular infections?
Dendritic Cells
What are DCs in dermis of skin?
Langerhan cells
What is typical of mature Dedritic cells?
B7 production
High MHC I and II levels
Chemotractant to promote sampling
What is typical of immature Dendritic cells?
NO b7 Expressed Epithelium PAMPs Some MHC Complement receptors LFA adhesion molecules still expressed
