Question

The carrier T cell epitope on a thymus-dependent antigen ________.

1) behaves like a hapten
2) needs to be polymeric
3) need NOT to be physically connected to the B cell epitope
4) is a carbohydrate
5) stimulates help for the B cell response

Answer 1

A T cell-dependent antigen requires the help of helper T cells to stimulate a B cell response. The carrier T cell epitope on a thymus-dependent antigen needs to be physically connected to the B cell epitope and stimulates help for the B cell response.

Step-by-step explanation:

A T cell-dependent antigen is one that requires the help of helper T cells to stimulate a B cell response.

In the case of a thymus-dependent antigen, the carrier T cell epitope needs to be physically connected to the B cell epitope in order to stimulate help for the B cell response. The B cell presents the protein epitopes with MHC II to helper T cells, and the T cell binds to the B cell using its antigen receptor and activates to secrete cytokines that activate the B cell.

In contrast, a T cell-independent antigen can activate B cells without antigen processing and presentation to T cells. These antigens, such as polysaccharides and lipopolysaccharides, can activate B cells by crosslinking the surface antibodies on the B cell in the absence of T cell cytokines.