how immune system can recognise tumor cells?

Question

anonymous · Answer

the immune system is supposed to recognize tumor cells because they are foreign to the body's function.  the immune system has antigenic defenses.  ie, if they don't have the right "nuts and bolts", then it's considered foreign and the body will react.

with that said, cancer cells have ways of evading antigen recognition and evading the immune response as well.  hence, cancer can grow undetected for a long while.

anonymous · Answer

To elaborate, your immune system actually takes care of more than 99% of cancer cells before they become a problem.  Cancer becomes dangerous when it accumulates mutation that allow it to evade the immune system, such as mutation in the MHC.  Basically cancerous cells have to get the lucky combination of mutations or they will be destroyed by the immune system.

Also, to some extent the immune system can recognize an invasive cell by the intermediate filaments.  This is how doctors are able to identify what type of cancer a patient originally had is by the intermediate filaments.  They are slightly different depending on the cell.