[RPG] Can wizard’s staff of defense class feature stack with Wizard Utility 2 Shield on the same triggering effect

Staff of Defense class feature:

…once per encounter as an immediate
interrupt, you gain a bonus to defense
against one attack equal to your
Constitution modifier. You can
declare the bonus after the Dungeon
Master has already told you the
damage.

Shield Wizard Utility 2:

Immediate Interrupt Personal

Tigger: You are hit by an attack

Effect: You gain a +4 power bonues to AC and
Reflex defense until the end of your
next turn.

Could you activate these powers against the same triggering attack and thus stack them against the same attack?