Immune system detecting non-self??

[Wabba Fig!]

Hi!
So my class has started learning about the immune system with macrophages, phagocytes, self and non-self and all that.
I came upon this question and was confused! Please help me out!

Immune system cells can detect non-self cells by the presence of..

This is not a multiple choice question by the way.
I think the answer is MHC markers but I am not so sure. Any guesses?

Thank you!

[alondouek]

I would say 'antibodies', but it's been a while since I did immunology so I'm not 100% sure

[Russ]

if you say "non self molecules" then you can't be wrong, but your teacher might not accept it. Antigens is not strictly correct but is close enough to also be acceptable. The basic principle of detecting non self is that the immune system starts off being able to respond to/destroy both self and non self, but the cells that respond to self molecules are gotten rid of. So the defining factor in what allows us to detect non self is the presence of foreign, antigenic material.

[Wabba Fig!]

I would say 'antibodies', but it's been a while since I did immunology so I'm not 100% sure

if you say "non self molecules" then you can't be wrong, but your teacher might not accept it. Antigens is not strictly correct but is close enough to also be acceptable. The basic principle of detecting non self is that the immune system starts off being able to respond to/destroy both self and non self, but the cells that respond to self molecules are gotten rid of. So the defining factor in what allows us to detect non self is the presence of foreign, antigenic material.

Ohhh, thanks a lot! 

[Scooby]

Yeah, the answer they're looking for is antigens