Class II MHC Proteins are Present in the Plasma Membrane

Question

Class II MHC proteins are present in the plasma membrane only when
A) a helper T cell has engulfed an antigen.
B) an antigen-presenting cell has engulfed and is processing an antigen.
C) a virus-infected cell secretes interferons.
D) a cancerous cell gets attacked by NK cells.
E) the body cells are healthy.

Accepted Answer

Class II MHC proteins are primarily expressed by antigen-presenting cells and are responsible for presenting antigens on the cell surface, which can then be recognized by helper T cells in order to activate an immune response. Therefore, Class II MHC proteins are only present in the plasma membrane when an antigen-presenting cell has engulfed and is processing an antigen.