Well, I guess it really depends on how sick you are. I've been getting over a cold for a few weeks now, but I've been training anyway. Actually, I got antsy on my grave shift last night, and ran in -20 degrees. I'm not feeling any worse than I did before, so I say go for it. Just don't get other people sick, like if you're rolling with people, wash your hands/face beforehand and make sure you aren't coughing or sneezing on them. Two guys in my class are fighting next month, and if I were them I'd be pissed if someone got me sick before my fight. Pump the vitamin c, take Emergen-C and Airborne to knock that shit out quick.
You're starting Cell-Mass? Are you bodybuilding or something? If so, lifting isn't going to hurt when you're sick.