Common sense should already suggest that trade is mutually benefical because well, I get stuff that I wanted, and you get stuff that you want. Why should trade only specifically benefit some certain classes of society?
Read the article on comparative advantage. http://en.wikipedia.org/wiki/Comparative_advantage
This is the reason why we specialize and trade, because everybody will be better off.
Research shows, as the middle class increases in wealth, then so does the whole economy and through increasing H1B's, we are eliminating the middle class american worker to jobs overseas.