Video Transcript
Fill in the blank. Cells that display foreign antigens
on their cell surface are called blank cells. (A) antigen-altering, (B)
antigen-adapting, (C) antigen-presenting, or (D) antigen-digesting.
Cells that display antigens on
their cell surface do this with the help of proteins called major histocompatibility
complexes, or MHCs for short. Every cell of the human body with a
nucleus possesses MHC proteins on its cell surface membrane. When a pathogen invades the body,
it is engulfed by specialized white blood cells called phagocytes in a process known
as phagocytosis. This involves taking the pathogen
inside the phagocyte before digesting it with enzymes. Some phagocytes are known as
antigen-presenting cells.
Following phagocytosis,
antigen-presenting cells are able to process the fragments of the digested pathogen,
which are called antigens, and assemble an MHC molecule around them. This is now known as an MHC-antigen
complex. Once the MHC-antigen complex has
been assembled, it is transported from the inside of the cell to the cell surface
membrane. Here, the antigen can be presented
to other cells of the immune system, which will become activated and ultimately
clear the pathogen from the body.
We have therefore determined that
the correct answer is (C). Cells that display foreign antigens
on their cell surface are called antigen-presenting cells.
