I mean yes it's early in the sereis, but when they shpowed Itachi, his eyes were the regular sharingans, however the mangekyou wasnt even known when they fought.

So i have no clue if he used it or not, Itachi wasnt even trying to fight so that brings me to the conclusion it was the regular full force of the 3 spec sharingan.

Im guessing if he used mangekyou sharingan it would have probly killed Kakashi.

But then again, how many people actually know that Itachi has the mangekyou? I dont think many do.