The original post: /r/askscience by /u/CheeseCatsBirds on 2024-10-30 01:12:10.

In the process of B cell development and the two auto reactivity checkpoints, the book I’m reading (Janeway) keeps talking about being antigen dependent. What it doesn’t mention is, whether this is self antigen or foreign antigen throughout the B cell development process, especially with the auto reactivity checkpoints, how does the B cell differentiate between self antigen and foreign antigen and its development?

For example, if it sees soluble self antigen in the bone marrow or the spleen, that self antigen might be really small and so probably isn’t contributing to any sort of co stimulatory stuff, so how the heck does it know what is foreign and what is self? Or does it even differentiate at this stage between those antigens? But wouldn’t it need to in case, it’s in the bone marrow and sees an antigen which is specific to, but that’s actually a pathogen so it should keep going in the process instead of being killed because it’s thinking that it’s self antigen?

As you can see, I’m very confused, any insight would be deeply appreciated.