B and T cells

[purpleannie]

Will a specific antigen initiate the response of a B and T cell so there are receptors for the same antigen in both the humoral and cell-mediated response?

[Charlatan]

Will a specific antigen initiate the response of a B and T cell so there are receptors for the same antigen in both the humoral and cell-mediated response?

 

Cancer cells hey? Ok, if you were to have a number, and add something to it, it could still be square rooted back to itself. If you were to take fixed values, like multiples of two, for instance, it would 'back track'.

 

But, this is biology, and it could send a signal and then get 'noise' [engineering... dear!] and then go back to te 'source' affecting it. Will it? Depends how much noise there is in the 'system', if not too much, yes. This is hard to define, as it is theory, but, I would say yes to all cases as there cannot be tht much noise and stil have functions. Erm...

[Greippi]

There are two types of T cell - T helper cells and cytotoxic T cells.

 

B cells recognise free native antigen, stuff that's wandering around e.g. in the blood. The B cells then differentiate in to plasma cells to produce loads of soluble antibody to "get" the antigen.

However, B cells often need T cell help to differentiate. In this case, The B cell presents the antigen to the T helper cell - so in this case the T helper cell recognises the same antigen as the B cell, with the condition that the antigen is presented by the B cell. The T helper cell then activates other immune cells to do their job in getting rid of the infection.

There are circumstances where B cells can differentiate on their own, for example when they encounter really common stuff - like the repeating carbohydrate units on a bacterial cell.

 

Cytotoxic T cells recognise and kill infected host cells. When a cell of the body gets infected by something like a virus, often the molecules on the cell surface change to indicate to the T cells that there's an infection. So, you see here there's a major difference in the types of antigen that are recognised by the different cell types.

 

And THAT is how it works in a nutshell. Hope that helped.

[CharonY]

Actually there are a couple more subtypes of t-cell types. I assume that the T-helper cell dependent activation of B-Cell is meant here, though. Regarding the receptor: they are different proteins (i.e. encoded by different genes) but can bind the same antigen. In addition, the B cell and T cell receptors usually bind to different epitopes (due to the mechanism of presentation) of the same antigen.

[Greippi]

Yes, I was speaking about T-helper cell dependent, although I did mention the independent activation as well.

 

Yes, there are quite a few more subtypes (at present I know of of 4 others, but I wouldn't be surprised if more will be discovered) of T cell (and indeed, B cell). They bind different sorts of antigen presented in different ways. For example, natural killer T-cells are a bridge between the innate and the adaptive immune responses. T memory cells persist after infection as part of the memory component of the immune system.

[dttom]

There usually are coordinated response from B- and T- populations, for the sake of maximum efficiency evolved. In a rough sense, yes the receptors bind to the same anitgen, but as CharonY has pointed out usually they target for different epitopes. But actually B-cells use mAb to bind antigen while TCR usually recognise antigen presented in peptide-MHC complex, so whether TCR binds antigen depends on your understanding of 'antigen' (whether a digest be still called antigen).

[CharonY]

Well it still is an antigen for all intents and purposes. It is just not necessarily in the original form as detected by the B cells (though sometimes it is).