Please help: Canada landing with the status of F1 and 485 pendin

I just received the letter from Canada requiring our passports for immigration visa. Since my status in the US is F1 student and 485 pending, I am wondering if there are any problems when I re-entry into USA from Canada after landing? Will USCIS think I give up the US immigration application automatically?

Could ImmCanada and other experienced friends give any suggestions? Thanks in advance!