I had infectious mononucleosis when i was 12. I'm 17 now but I have a friend who!

I had infectious mononucleosis when i was 12. I'm 17 now but I have a friend who now has mono, can I catch it?

Does my body becomes immune to it after I first catch it?

You can still catch it. I got mono twice. Talk with your doctor and find out what you can do to at least protect yourself against it. But the best thing to do is stay away from your friend for a while. Also if you start to have any symptoms of mono go to the doctor immediately. When I got it the 2nd time it was completely worse than the 1st time. I actually ended up in the hospital because my immune system basically crashed. Good luck!