Exogenous Pathway of Antigen Presentation | MHC II Processing

Antigens from the extracellular space and sometimes also endogenous ones,[8] are enclosed into endocytic vesicles and presented on the cell surface by MHC-II molecules to the helper T cells expressing CD4 molecule. Only APCs do express the class II of MHC molecules on the surface in large quantity, such as dendritic cells, B cells or macrophages, so expression of MHC-II molecules is more cell-specific than MHC-I.
APCs usually internalise exogenous antigens by endocytosis, but also by pinocytosis, macroautophagy, endosomal microautophagy or chaperone-mediated autophagy. In the first case, after internalisation, the antigens are enclosed in vesicles called endosomes. There are three compartements involved in this antigen presentation pathway: early endosomes, late endosomes or endolysosomes and lysosomes, where antigens are hydrolized by lysosome-associated enzymes (acid-dependent hydrolases, glycosidases, proteases, lipases). This process is favored by gradual reduction of the pH. The main proteases in endosomes are cathepsins and the result is the degradation of the antigens into oligopeptides.
MHC-II molecules are transported from the ER to the MHC class II loading compartment together with the protein Invariant chain (Ii, CD74). A non classical MHC-II molecule (HLA-DO and HLA-DM) catalyses the exchange of part of the CD74 (CLIP peptide) with the peptide antigen.

[@darianleduc]

I keep coming back to your videos to understand the immune system. Not sure why, but I get the most understanding out of your vids. Many thanks

[@hussainbiology]

thanks Darian for appreciation.... Glad to know that it helps ✌️

[@Habira03]

Whenever my exams are near and i need to watch a video, i always watch urs, they're not long, but capture every single thing!!!! Thank you so much💛

[@hussainbiology]

thanks for appreciation... Glad u like my stuff

[@srijalshukla7814]

Your hardwork is genuinely reflected in your videos ❤️... Amazing explanation...🤩🤩...!!!

[@mudavose07]

Thank you sir what a good explanation... You have helped many souls

[@hussainbiology]

thanks for appreciation..Glad it helps ✌️

[@maham671]

Amazing vedio keep it up sir thank you so much

[@blazincate9348]

Very helpful explanation, thank you so much!

[@hussainbiology]

thanks for appreciation

[@nehemiahwilson6864]

Very nicely explained sir.

[@hussainbiology]

thanks for appreciation..Glad it helps....✌️

[@bhuvankumar1393]

Thank you so much sir... your videos are really helpful for me ❤

[@rohinick4675]

Great attempt, really useful. Make more vedios

[@hussainbiology]

thanks for appreciation

[@q-rioustv654]

Nice explanation sir..... 🙏🙏🙏🙏

[@rimjhimmathur2002]

Superb!

[@RR-zl5kg]

THIS IS AMAZING!!!!!

[@hussainbiology]

thanks for appreciation..Glad it helps....✌️

[@nil7425]

Thanks a lot sir... ❤️

[@izzahnabilah4905]

u rly are the best!!!

[@hussainbiology]

thanks for appreciation.glad u like my content

[@constancekunda6232]

Best video l swear 🙏🙏🙏🙏🙏🙏🙏🙏❤️❤️

[@hussainbiology]

thanks for appreciation

[@sharonsysy]

thank you for the video!!

[@youngcartoon7196]

Super sir

[@SowmyaSwimInScience]

nice

[@bilalahmadmalik3987]

Its called exogenous pathway because antigen does not enter the ER . IS IT SO Sir??

[@hussainbiology]

Bcx Exogenous Antigens are only presented by MHC ( the Endogenous Antigens are not able to bind MHC in this pathway bcz of Invariant Chain present on MHC )

[@ranjanachauhan92]

Properly explained

[@hussainbiology]

thanks for appreciation

[@battulanarsimlu9511]

Super

[@user-jg4ou2qo5u]

시발 존나 감사합니다 ㅠㅠ!! 우릭 교수님 ㅈㄴ 음음거려서 알아먹기 힘들어요 ㅠㅠ

[@Nikita-hs6nt]

Too good 🙃

[@hussainbiology]

thanks for appreciation

[@malandacharles1388]

Helpful.

[@ayezabhat5026]

Thanku

[@hussainbiology]

thanks for appreciation.....Glad to know that it helps

[@sonaliyadav6663]

Sir your video lecture are very helpful ,please upload some more videos on immunology ( heavy and light chain gene rearrangement of antibodies).

[@naziyasheikh5811]

Can you please share link of endogenous pathway

[@hussainbiology]

czcams.com/video/1bk0hiFaxg0/video.html

[@NidhiKumari-by8ys]

Link is not in description

[@dheerajshah8503]

Hello sir why all cells do not have mhc 2 ??

[@dipanshisharma95]

very well

[@nermeenmostafa3111]

Genius

[@hussainbiology]

thanks

[@handam3725]

Usefulness ..... but why mist of biologic video is indian ?? And thanks for exaplained 🌹🌹

[@hussainbiology]

thanks for appreciation... Glad to know that it helps.

[@handam3725]

@@hussainbiology hello ....how are you .... can l ask you Questions about some indian words ?!

[@daniyalyounas9455]

Can anyone tell me that how i get the related picture because i cant find it

[@hussainbiology]

What u need??

[@daniyalyounas9455]

@@hussainbiology thanks sir your lecture help me alot because i need a realted pic for my presentation. But now i get it....so thanks

[@daniyalyounas9455]

@Petar P. i just take screenshot of it and use it in my presentation

[@biology_mcqs3037]

👍

[@user-tr7ri9gm6p]

very good video, but you need to be slower to make your content more understandable, thank you.

[@hussainbiology]

Thanks for appreciation...Glad to know that it helps...And surely i am working on it to slow down my speed

[@user-tr7ri9gm6p]

@@hussainbiologywe will be waiting for your amazing videos, keep safe.

[@aparnaadhikari8795]

Where can we find your notes?

[@risharajkhowa5060]

😍😍😍😍

[@hussainbiology]

thanks Risha...

[@conceptum4250]

Sir ye video kse shoot krte ho

[@hussainbiology]

Camera se

[@conceptum4250]

Sir koi app hai iske liye speed adjust krne ke liye

[@hussainbiology]

@@conceptum4250 Adobe Premiere , Final Cut Pro , Davinci Resolve and many more

[@sudhapasupureedi3347]

Where is link

[@kdramaloverarmy8997]

HLA-DO role???

[@kdramaloverarmy8997]

Please explain the role of HLA - DO ??

[@minezurc783]

[E = \alpha m_Hc^2]

[@user-wu4gr2uq8n]

yor videos are too easy to understand , compare to others.

[@hussainbiology]

thanks