Upon investigating the underlying molecular mechanism, they observed that mTORC1
hyperactivation enhances the level of the stress hormone FGF21 by depletion of the amino acid glutamine.
By binding not only CD28 but also its coligand B7 - 2 directly, superantigens potently
enhance the B7 - 2 / CD28 interaction, inducing thereby T - cell
hyperactivation.