"Che" It is a word used as a vocative, to catch attention of the speaker, but only used with friends or family, is very informal.
The Italian language hasn´t got big influence in the Spanish of Argentina today. In the past, due to immigration, people mingled a few words or mixed Italian and Spanish (a phenomenon called "cocoliche"). Italian and Spanish languages are very similar because of their Latin origin. Of course, people with Italian grandparents still have a few words or phrases in their vocabulary.