Immunology Flashcards
What are mucosal tissues important for and where are they located?
- important for gas exchange, food absorption, sensory activities and reproduction
- found in the respiratory tract, GI tract and urogenital tract
- contain lots of lymphocytes (T and B cells)
What do mesenteric lymph nodes do and where are they located?
- within gut next to SI
- have arteries, veins and lymph vessels coming in and out
- adaptive immune response
- have follicles that contain naive B cells
What are the two formations of lymphoid cells in mucosal lining?
- scattered in the lining of the villi
- organised lymphoid tissues eg Peyer’s patches which is where immune system is induced
- both connected to mesenteric lymph nodes
What is the structure of the Peyer’s patches?
- covered in M cells with membrane ruffles
- initiate immune response
What do M cells do?
- M cells take up antigens and transport them and bind them using vesicles using dendritic cells which activate T cells
What are the two compartments of the mucosal immune system?
- epithelium (integrins and DC cell) and the lamina propria (macrophage, mast cell, dendritic cell, IgA, plasma cell, CD4 T cell)
- lamina propria contains activated immune cells to help prevent infection
Where do T cells move to before and after activation?
- T cells enter Peyer’s patches
- encounter antigen so become activated by dendritic cells with antigen
- T cells express homing receptors
- activated T cells activate B cells (IgM but also IgA with activation) and drain via mesenteric lymph nodes to thoracic duct and return to gut lamina propria via bloodstream
- homing receptors direct them here
What do the activated B cells do?
- B cells activated by T helper cells
- B cells express IgA antibodies
- Th2 cells activate IgA plasma cells
- MadCam is on the lamina propria and binds to homing receptors on the T cells
- so cells can move across tissue
Where are CD8 and CD4 cells located?
CD8 are in the epithelia (killer cells)
CD4 are in the lamina propria (helper cells)
Where are the dendritic cells?
in the epithelia and can obtain antigen and are activated to present it on an MHC class 2 are also in the lamina propria
When are homing receptors expressed?
following lymphocytes activation by dendritic cells
What do IgA antibodies do?
- bind to pathogens to neutralise them
- can bind to antigen in lamina propria and take it to lumen to be taken away
- can take antigen out of infected cell
What are the most common primary immunodeficiency diseases?
Selective IgA deficiency Common Variable Immune Deficiency X-Linked Agammaglobulinemia Chronic Granulomatous Disease Severe Combined Immunodeficiency Disease- defect in T and B cell immunity, viruses are common
What is allergy driven by?
- type 1 hypersensitivity
- IgE from plasma cells binding to Fc receptor on mast cells
- mast cells then secrete signals to B cells to make IgE
How is allergy diagnosed?
skin prick test
challenge test
