T- and B-cell activation

Question 1

Naive T-cell activation

Answer 1

Dendritic cell presents antigen to T-cell

*Signal 1
Antigen is presented on MHC II from APC to TCR on Th cell

or

Antigen is presented on MHC I from APC to TCR on Tc cell

*Signal 2 (costimulatory signal)
B7 (APC) - CD28 (T cell)

*Activated!
Th cell produces cytokines
Tc cell is able to recognize and kill virusinfected
cell

Question 2

B-cell activation and
class switching

Answer 2

*Signal 1
B cell presents antigen on MHC II to TCR on Th cell

*Signal 2
CD40 receptor (B cel)l binds CD40 ligand (CD40L) (Th cell)

*Activated!
Th cell secretes cytokines that determine Ig class switching of B cell