V(D)J recombination

So these three genes are called the variable gene, diversity gene, and joining gene.

which together are called the VDJ genes.

And this recombination is pretty interesting.

Essentially, you're taking little bits of each of these genes and making this variable region gene.

Therefore, they only bind to a very specific pathogen.

an easier way to think about this is imagine taking a deck of cards and taking just three of the suits let's say hearts diamonds and clubs and now these are going to be the three different vdj genes and so what you do is you take these three suits and obviously there's a bunch of cars in each suit and you shuffle them you shuffle up all these cards and now you lay them down Well, each time you shuffle them and lay them down, you're going to get a completely different sequence of cards as you lay them down each time you shuffle them.

So in the same way, these B cells, as they develop, create these very unique and random variable region genes through this process of VDJ recombination.

And based on some data that I was looking at, this paper claims that because of this recombination process, our B cells are able to produce at least 1 trillion different antibodies based on this random recombination process.

And then to just double check and confirm that these changes were unique, were intrinsic to the T cells and not coming from maybe the interaction with other cells within the immunological system, the They used a model of mice that was deficient for LAG.

So that too is, I think, like an enzyme that allows T cells to, that allows immune cells generally to go undergo VDJ, a combination where their receptors can be, you know, changed and amended so that they can recognize a wide range of perfidines.

So these LAG2 deficient mice could only recognize, only had like one kind of receptor for T cells, I think.

So they used them and then they noticed that, and these cells, these the mice also only had CD8 cells.