Which statement is true about HLA expression?

Which statement is true about HLA expression?

• A. Found on all nucleated cells
• B. Found on red blood cells only
• C. Found on platelets only
• D. Found on extracellular matrix only

Answer: (A)

HLA molecules are major components of the MHC system that appear on the surface of cells to present peptide antigens to T cells. The most widely expressed form, MHC class I, is found on essentially all nucleated cells, which is why HLA expression is described as being present on all nucleated cells. Red blood cells lack a nucleus, so they do not display HLA in the same way, and the extracellular matrix is not a cell and does not express HLA. This pattern explains why the statement about HLA being on all nucleated cells is true.

HLA molecules are major components of the MHC system that appear on the surface of cells to present peptide antigens to T cells. The most widely expressed form, MHC class I, is found on essentially all nucleated cells, which is why HLA expression is described as being present on all nucleated cells. Red blood cells lack a nucleus, so they do not display HLA in the same way, and the extracellular matrix is not a cell and does not express HLA. This pattern explains why the statement about HLA being on all nucleated cells is true.