quick teach back for my own benefit: some antigens can induce a type IV hypersensitivity when it is cell mediated. Other hypersensitivites are much quicker because they are antibody mediated, but here, it takes time for the new antigen to cause the reaction. First the antigen arrives, dendritic cells phagocytose it and present it on an MHC II and present it to CD4 cells. Once the TCR binds the MHC II, the CD4 cell has to differentiate and because the dendritic cell released IL-12, its like, I think I'll become a TH1 cell. So TH1 cells release IFN-g to bring more macrophages to the site so that they can respond to the antigen. This causes a localized immune response that can be damaging to host tissue, causing the type IV hypersensitivity that we experience as patients.
Well it's 2 months later and I forgot this topic. So I've returned to finish the job. You're often trying to determine whether it's a type 1 hypersensitivity or a type 2. And it seems that the biggest distinguishing factor is which type of t helper cell is induced. In type 1, TH2s predominate and in type 2, TH1s predominate.
Please make more videos. I love the way you teach. Of all the videos I watch, yours is the most excellent of all. I learned a lot and finally understand the concept. I love the exam at the end of the video. Thank you. Keep it up. You have the talent. You are awesome.
That's now a relief ..I understood all four hypersensitivity reactions because of our wonderfully summarized content.... Thanks for it... Thank you very much..😊
It would be good to mention metals under the Type IV sensitivity. Up to 20% of the population has a Type IV nickel sensitivity. People can also be sensitive to cobalt, gold, and even titanium. I suspect a Type IV sensitivity may be involved with Hashimoto's. I only ever lost thyroid function while taking iodine.
Perfect video! Thank you so much! I have some questions. So does this mean that in the tuberculosis mycobacteria infection, we have T cells that activate at the lung level after 48 hours at the most? And then we have the manifestation of the disease? Moreover, in these hypersensitivity reactions there is always a need for a first sensitization? Is contact hypersensitivity also delayed?
Great video! I have some questions tho: 1. Why are B cells excluded from this type of response? I mean, is there like a genetic predisposition for certain reaction to only happen in t or b cells when it comes to hypersensitivity... I ask that because I am confused since a protein could also (at least I think so, correct me if I'm wrong), activate B cell response if found in circulation? Like superantigene for example? 2. Also, just non related to this topic basic immunology question: I was tought that CD4+ cells when are presented with peptide carried by APC(in T cell dependent B cell response) differentiate into CD4+ T helper cells that later on help B cells proliferate more strongly. My confusion is, what signals them to differentiate into those T helper cells, how do they "know" that B cells are over there, crying out loud, begging for decent proliferation? :)
The type of reaction an antigen will stimulate solely depends on the antigen itself.... There are different kinds of phagocytic receptors on APC .. depending on which receptor is activated and internalised during phagocytosis by APC , there will be production of different cytokines from the APC..depending upon cytokines.. there will be recruitement of neutrophils(as seen in extracellular bacteria infections) or lymphocytes( seen in chronic inflammation , helminth infection) .. plus the cytokines released by APC also help in maturation of cd4 t helper cells into different subtypes.. these subtypes are specific in there function..For eg, one subtype will mediate activation of cd8 t cells(therefore used in cytotoxic cell mediated immunity)and another subtype of cd4 activated t cell will stimulate B cell to undergo class switching( to release IgE ab as against helminth infection
Firstly,I thank you for your great effort 💟 Your Qs are very smart 💪❤ So,I'd like to guide me to a link containing large numbers of Qs like yours, plZz ✨❤ As I have an exam on coming tuesday😥 & our Dr likes such these Qs 😰 So could you help me PLZz?! 🙈 following you from EGYPT❤
quick teach back for my own benefit: some antigens can induce a type IV hypersensitivity when it is cell mediated. Other hypersensitivites are much quicker because they are antibody mediated, but here, it takes time for the new antigen to cause the reaction. First the antigen arrives, dendritic cells phagocytose it and present it on an MHC II and present it to CD4 cells. Once the TCR binds the MHC II, the CD4 cell has to differentiate and because the dendritic cell released IL-12, its like, I think I'll become a TH1 cell. So TH1 cells release IFN-g to bring more macrophages to the site so that they can respond to the antigen. This causes a localized immune response that can be damaging to host tissue, causing the type IV hypersensitivity that we experience as patients.
Well it's 2 months later and I forgot this topic. So I've returned to finish the job. You're often trying to determine whether it's a type 1 hypersensitivity or a type 2. And it seems that the biggest distinguishing factor is which type of t helper cell is induced. In type 1, TH2s predominate and in type 2, TH1s predominate.
@@devinyoung5735 incorrect, type 2 hyper sensitivity doesn’t have a predominant th cell.
I've looked at so many videos regarding this topic and yours is by far the absolute best god bless you where've you been all this time my guy
Thank you for the kind comments
Bravo 👏👏 very unique quality of knowledge you present ! I salute you very much 👏👏👏
Please make more videos. I love the way you teach. Of all the videos I watch, yours is the most excellent of all. I learned a lot and finally understand the concept. I love the exam at the end of the video. Thank you. Keep it up. You have the talent. You are awesome.
Thanks for the generous comment- all the best to you
so simple so beautifull .. a big thank youu
Greatly explained ....very simple and conceptual .....Plz have more videos on autoimmune disorders
That's now a relief ..I understood all four hypersensitivity reactions because of our wonderfully summarized content.... Thanks for it...
Thank you very much..😊
You’re welcome I’m glad it was helpful
It would be good to mention metals under the Type IV sensitivity. Up to 20% of the population has a Type IV nickel sensitivity. People can also be sensitive to cobalt, gold, and even titanium. I suspect a Type IV sensitivity may be involved with Hashimoto's. I only ever lost thyroid function while taking iodine.
What amazing explanation ❤️
That was short and so helpful
The analogy made me smile, esp the “you are brave” part. I wont have gotten a rash for sure😂 good job presenting the info.
Thank you very much. Glad you liked that joke attempt
Thank you so much for the wonderful explanation 😊👏
how amazing this video
perfect 🤩🤩
u r just amazing
Great video!!!!
Thank you love your way
so helpful , thank u
WONDERFULLY EXPLAINED ❤🎉
Glad it was helpful!
very simplified
Ohhh i wish i could give u more likes , i was going insane watching different videos on hypersensitivity u explained very well tysmmmm❤
Wow, thank you!
Amazing
thank you ,it is absolutely useful❤
Glad it was helpful, thanks 😊
Perfect video! Thank you so much! I have some questions. So does this mean that in the tuberculosis mycobacteria infection, we have T cells that activate at the lung level after 48 hours at the most? And then we have the manifestation of the disease?
Moreover, in these hypersensitivity reactions there is always a need for a first sensitization?
Is contact hypersensitivity also delayed?
I loved it😄😍
Thanks
Helpful
Thank youuu
can i know the book you used as a reference? your vid is absolutely amazing i'm lovin it
i know my comment is not relevant to this video but please make one for systematic lupus erythematous pathogenesis
best explanation ;)
Thanks 🙏
wonderful presentation, but in the discussion the fas ligan was attached to the target cell , the fas receptor on the cd8 is this the case, thanks
Very informative video
So nice of you
Wow thank you so much 🙏
Kamsamnida
@@physiopathopharmaco4190 😁🙏💓
hi. your videos are very educative. thank you. please share your references.
Great video! I have some questions tho:
1. Why are B cells excluded from this type of response? I mean, is there like a genetic predisposition for certain reaction to only happen in t or b cells when it comes to hypersensitivity... I ask that because I am confused since a protein could also (at least I think so, correct me if I'm wrong), activate B cell response if found in circulation? Like superantigene for example?
2. Also, just non related to this topic basic immunology question: I was tought that CD4+ cells when are presented with peptide carried by APC(in T cell dependent B cell response) differentiate into CD4+ T helper cells that later on help B cells proliferate more strongly. My confusion is, what signals them to differentiate into those T helper cells, how do they "know" that B cells are over there, crying out loud, begging for decent proliferation? :)
The type of reaction an antigen will stimulate solely depends on the antigen itself.... There are different kinds of phagocytic receptors on APC .. depending on which receptor is activated and internalised during phagocytosis by APC , there will be production of different cytokines from the APC..depending upon cytokines.. there will be recruitement of neutrophils(as seen in extracellular bacteria infections) or lymphocytes( seen in chronic inflammation , helminth infection) .. plus the cytokines released by APC also help in maturation of cd4 t helper cells into different subtypes.. these subtypes are specific in there function..For eg, one subtype will mediate activation of cd8 t cells(therefore used in cytotoxic cell mediated immunity)and another subtype of cd4 activated t cell will stimulate B cell to undergo class switching( to release IgE ab as against helminth infection
nice
1)- a-c 2)- a-d 3)- c 4)- b
why?
best video everrrr♥️♥️♥️♥️
Awesome 👏 Thanks Crystal!!!
Thanks for your efforts; keep going 🔥🔥
I LOVE U
👍🏼👍🏼
Does this type of reaction affects kidney function ?
This is great
But i thought B cells sometimes can also be APCs
They can, but Type IV doesn't involve antibodies
Firstly,I thank you for your great effort 💟
Your Qs are very smart 💪❤
So,I'd like to guide me to a link containing large numbers of Qs like yours, plZz ✨❤
As I have an exam on coming tuesday😥
& our Dr likes such these Qs 😰
So could you help me PLZz?! 🙈
following you from EGYPT❤
www.amboss.com/us
1 a and c
2 a and d
3 c
4 false
C
A and d
C
B