are these antigens? (immune system)

Tricky question. Every tissue type has its own special markers. In fact, numerous cell surface markers are now identified (over 220!) I can't quite remember from years ago, but I recall that every person has a unique marker expressed on every cell of their body. When immune system cells are created, they go through this process that desensitizes them from attacking cells that possess this marker. In HIV, for example, the virus camouflages itself in normal cells so that the immune system doesn't illicit a response. If cells lack this marker, for whatever reason, the immune system will illicit a response. Therefore, the immune system is constantly checking and circulating.