the mhc class 1 molecule is recognized by cytotoxic t cells cell type.
the mhc class 1 molecule is recognized by which cell type?
cytotoxic t cells
non-professional antigen presenting cells include all nucleated cell types in the body. they use an mhc class i molecule coupled to beta-2 microglobulin to display endogenous peptides on the cell membrane. these peptides originate within the cell itself, in contrast to the exogenous antigen displayed by professional apcs using mhc class ii molecules. cytotoxic t cells are able to interact with endogenous antigen presented using an mhc class i molecule. non-professional apcs do not typically express mhc class ii molecules. however, it has been observed that antigen presentation to cd4+ cells via mhc class ii is not restricted to the classically professional apcs. other leukocytes, including granulocytes such as mast cells and neutrophils, can be induced to do so, as can endothelial and epithelial cells under certain circumstances. even so, there is little evidence that these atypical apcs are able to activate naive cd4+ t cells.
antigen-presenting cell
the down regulation of the invariant chain (ii) becomes important when considering the two pathways by which antigens are presented by cells. most recognized tumor antigens are endogenously produced, altered gene products of mutated cells. these antigens, however, are normally only presented by mhc class i molecules, to cd8 t cells, and not expressed on the cell surface bound to mhc class ii molecules, which is required for presentation to cd4 t cells. research has shown that the two pathways by which antigens are presented cross over in the endoplasmic reticulum of the cell, in which mhc class i, mhc class ii and endogenously synthesized antigenic proteins are all present. these antigen proteins are prevented from binding to mhc class ii molecules by a protein known as the invariant chain or ii, which, in a normal cell, remains bound to the mhc class ii molecule until leaving the er. down regulation of this ii, using antisense technology, has yielded promising results in allowing mhc class i tumor antigens to be expressed on mhc class ii molecules at the cell surface (qui, 1999).
cd4+ t cells and antitumor immunity