The Latin loanphrase quid pro quo means a reciprocal exchange. It translates literally to something for something. There are varying recommendations for pluralizing quid pro quo, but the simplest and most likely to stick (though it doesn’t conform to Latin grammar) is quid pro quos. The phrase usually functions as a noun, but it also works adjectivally to characterize a reciprocal exchange.
Quid pro quo is established in English, so there is no need to italicize it in normal use.
His idea is to obtain a credible commitment of financial support from the Legislature as a quid pro quo for tuition increases. [Los Angeles Times]
Will Mr. Obama push back against GOP calls for radical spending cuts as a quid pro quo for raising the debt ceiling? [Globe and Mail]
The quid pro quo of privatisation was that private enterprise demonstrate fiscal responsibility. [Guardian]
The Americans have for many years of course treated an ambassadorial post as a quid pro quo for financial contributions to political campaigns … [New Zealand Herald]