Immunity and the GI Tract

Genesis James
Flashcards by Genesis James, updated 4 months ago
Genesis James
Created by Genesis James 4 months ago
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Medicine Flashcards on Immunity and the GI Tract, created by Genesis James on 09/25/2019.
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Microfold (M) cells function in luminal antigen sampling by transporting luminal substances across epithelium to underlying APCs - utilized by salmonella and shigella as a route of invasion through mucosal barrier Diagram Of Salmonella Infection The Three Main Routes Of Salmonella Invasion Of The (image/png)
Paneth cells - defensin production (poke holes in pathogens to lyse them
Peyer's Patches enriched in lymphoid tissue: - key sites for coordinating immune responses to pathogens - promote tolerance to harmless microbes and food - contain M cells Peyers Patch (image/jpeg)
Neutralization of microbes in the lumen is done by... ...secretory IgA and IgM in the lamina propria
Antibiotic peptides kill pathogens or reduce their entry into epithelium
intraepithelial lymphocytes (IELs) - innate lymphocytes and memory T cells - eliminate infected and damaged cells - help shape subsequent adaptive immune responses
lamina propria lymphocytes (LPLs) - memory T cells : B cells = 4:1 - NK and plasma cells - IL-22 from Th17 cells helps maintain epithelial cell barrier - plasma cells secrete IgA
intestinal dendritic cells - project dendrites between epithelial cells for antigen sampling - process and present antigens from microbes
serum IgA circulates as a monomer in the serum (very little)
secretory IgA - dimer with J chain found in fluids - secretory chain makes it more resistant to proteolytic cleavage by enzymes found in external body fluids - does not activate complement (IgG or pentameric IgM) - prevents binding of pathogens to host cells
Rotavirus symtpoms - destruction of absorptive enterocytes by inducing apoptosis - virus-induced down-regulation of expression of absorptive enzymes
rotavirus immunity IFN-g and IgA
attenuated vaccine (sabin vaccine against polio) - virulent pathogen introduced into non-virulent host - pathogen learns how to survive in a non-human host, so it loses it virulence factors in humans - when introduced into human hosts, Abs are produced against pathogen without it causing harm - only one booster needed - humoral and cell-mediated immunity - HOWEVER, pathogen can revert back to virulent form
killed vaccine (silk vaccine against polio) - virus is killed via chemicals or radiation with g-rays - multiple boosters needed due to inefficient mimicking of original virus OR different route of transmission - mainly humoral immunity - CANNOT revert back to virulent form
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