Exam 3: Dr. Pinchuk Mucosal Immunity Flashcards
What are unique features of mucosal immunity?
Combined area of the mucosal surface is much greater than that of the skin
Three quarters of the body’s lymphocytes are in secondary lymphoid tissues serving mucosal surfaces, and similar proportion of all antibodies made by the body is secreted dimeric IgA
GI tract has contiuous contacts with large populations of commensal microorganisms and substantial quantities of proteins derived from the animals and plants
What is the major challenge for mucosal immunity?
To make immune responses to eliminate pathogens, limit the growth and location of commensal microorganisms, and do not attack the food
What can be found in GALT?
Lamina propria Mesenteric lymph nodes Palatine tonsils Adenoids Lingual tonsils Peyer's patches M cells Isolated lymphoid follicles Intestinal epithelium
What is the germinal center full of?
B cells
What are M cells specialized to do?
Transport microorganisms to GALT
Are M cells antigen presenting cells?
No, but they are closely associated with DCs
How does antigen uptake and transport by M cells occur?
M cells are interspersed between enterocytes and in close contact with DCs
M cells take up antigen from the gut lumen by endocytosis
Antigens are released beneath M cells and taken up by DCs
DC dendrites also span the gut wall and engulf antigens
What can DCs do with their processes?
Extend them across the epithelial layer to capture antigen from the lumen of the gut
What are most immune system cells in the mucosal tissues?
Activated effector cells
What happens to naive lymphocytes that are activated in mucosal tissues?
The return to the tissues as effector cells
How can secretory IgA bind pathogens?
IgA can export toxins and pathogens from the lamina propria while being secreted
IgA is able to bind and neutralize antigens internalized in endosomes
Secreted IgA on the gut surface can bind and neutralize pathogens and toxins
Secreted IgA binds pathogen on M cell surface and takes it to lymphoid tissue
Secreted IgA picks up antigen in the endosomes of the M cell and takes it to lymphoid tissue
What are cytoplasmic NOD-like receptors?
Signaling PRRs
What kind of immune response to enterocytes have?
Innate
What does the binding of microbial PAMPs to their signaling PRRs promote?
The synthesis and secretion of intracellular regulatory moecules such as cytokines, chemokines, defensins that are crucial to initiating immunity and adaptive immunity
What are Th2 cells responsive to?
The host rather than helminths