My question relates to the role of the B cell in role in being an APC.
I understand that dendritic cells are normally the main type of APC, and that the B7 protein has to be present on the APC in order to activate the T cell to become a helper T cell.
However when this activated t cell activates the B cell in order for the b cell to differentiate, it must bind to the B cells’ MHC class II and antigen combination on the b cell to ensure it is stimulating the right b cell.
But what I am confused about is, during this process of the b cell internalising antigen and presenting to the activated t cell, dose the B cell produce the B7 proteins as well?
Because surely if it did, the dentdritic cell would not be needed in the frist place to activate the t cell and only the b cell would have been needed, as the 2 signals needed by the T cell (antigen on MHCII and B7) would have been given by the B cell.
Therefore wouldn’t there be no use for the other apcs in this type of immune reponse, because the b cell can always provide both signals to activate the t cell?
When are B7 proteins expressed on APCs?
Can you also tell me whether I have got this concept right about whether B cells must internalise atigen via their BCR and express it via their MHCII in order for the T cells to respond to them?
Thankyou very much, I am so confused!!
