Question

Why are oncofetal proteins good targets for immune surveillance against tumors?

	A.	NK cells recognize these antigens.
	B.	Negative selection in the thymus has not taken place for these antigens.
	C.	Positive selection has eliminated T cells that recognize these antigens.
	D.	Because these antigens are ubiquitously expressed at all stages of an organism’s life.

Any help would be wonderful, thank you.

Answer 1

Oncofetal proteins are the ones that are expressed during fetal development and are also found in the blood of cancer patients. These proteins have a developmental role but are no longer expressed after this stage.

However, the cancer cells can again start the expression of these antigens to promote neoplasia.

Since these antigens are not always present, they are not used during the maturation of T cells in the Thymus. As a result, the T cells are not negatively selected for binding to these antigens.

Thus, they become good targets for the immunosurveillance of tumors, whereby once the tumor starts producing these antigens, the T cells can kick in as some of them can recognize these oncofetal antigens as foreign. Thereby leading to the elimination of these proteins and the underlying tumor mass.