Peyer’s Patches: The Immune Sensors of the Intestine
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kiny
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I posted it because of the inflammation they saw in that German study of lymphoid follicles, they have seen it a few times before but I wasn't aware of those studies. I read about the lymphoid drainage issues but I didn't know they could pinpoint this as the very first clinical events they can see during colonoscopy.
Peyer's patches are like mini lymph nodes in a way, they don't need lymph nodes to start off an adaptive immune response, they are samplers of pathogenic antigen from the lumen. There's space for T cells and B cells to be active around the follicle.
The M cell is like a cap around the lymphoid follicle, it samples pathogenic bacteria from the lumen that are going to break through the primary epithelial defense, it's a mini-lymph node that activates the adaptive immune system. Lymph flows from it to the bigger lymph nodes and it drains the peyer's patch. Well it's supposed to, but in crohn's disease there's issues with that I believe.
A peyer's patch look a lot like a lymph node, it's a small container where B and T cell are ready to fire off an adaptive immune response, but it doesn't need lymph and a dendritic cell carrying an antigen all the way up to the lymph node, it has it's own little tools and lymphocytes.
They're called "Peyer" because the person who discovered them was called Johann Peyer.
Peyer's patches are like mini lymph nodes in a way, they don't need lymph nodes to start off an adaptive immune response, they are samplers of pathogenic antigen from the lumen. There's space for T cells and B cells to be active around the follicle.
The M cell is like a cap around the lymphoid follicle, it samples pathogenic bacteria from the lumen that are going to break through the primary epithelial defense, it's a mini-lymph node that activates the adaptive immune system. Lymph flows from it to the bigger lymph nodes and it drains the peyer's patch. Well it's supposed to, but in crohn's disease there's issues with that I believe.
A peyer's patch look a lot like a lymph node, it's a small container where B and T cell are ready to fire off an adaptive immune response, but it doesn't need lymph and a dendritic cell carrying an antigen all the way up to the lymph node, it has it's own little tools and lymphocytes.
They're called "Peyer" because the person who discovered them was called Johann Peyer.
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kiny
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peyer's patches
You can see they have no Villi on them, or mucus for that matter. They are completely exposed and are there to sample antigen content that is going to break through and bind to epithelial cells, it discriminates what it samples, it doesn't care about lumen content like harmless commensals moving about, it specifically wants bacteria of invasive nature.
kiny
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Some more ranting. Virgin T cell travel around a bit usually, they don't stay in one spot, they kind of travel through lymphatics through nodes and sit there a bit checking out if what dendritic cells have to tell them, they dock with them and check antigen MHC II from dendritic APC and then they become activated, CD4+ and CD8+ cell each do their thing. But experienced T cell don't travel around like virgin T cell anymore, they go to specific places where they were active before, if they were active in for example a peyer's patch, they will sort of travel there and stay there, they are now experienced T Cell.
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