Question

Class II MHC molecules are used to present ________ antigen to ________ cells.

	a.	intracellular; CD8
	b.	intracellular; CD4
	c.	extracellular; CD8
	d.	extracellular; CD4

Answer 1

Antigen presenting cells like macrophages engulf foreign antigen and pack them inside a vescile. These antigens are transported to endoplasmic reticulum for binding with a MHC class 2 molecules.

Once the anitgens are processed and bound to MHC class 2 molecules, the MHC class two molecules present the antigen to naive helper T cells. Helper T cells have CD 4 receptor molecules to whom the antigen are presented.

As the antigen is engulfed by the cell from outside, so such antigen is called extracellular antigen.

So, correct answer will be ( D) extracellular, CD4