Cancer Immune Therapy Edited by G. Stuhler and P. Walden ...

Fig. 5.5 Different immune effector mechanisms.
(A) MHC class I molecules are crucial
structures for antigen presentation to T lymphocytes
and the physiological ligands for NK receptors.
Two distinct signals are required for the initiation
and maintenance of an effective immune
response. The first is provided by the interaction
of MHC class I/peptide complex with the TCR,
the second is mediated by a number of co-stimulatory
molecules, e.g. B7/CD28. MHC class I
Color Plates
molecules often disappear from the tumor cell
surface to escape T cell recognition. Therefore
patients must be monitored for the expression
of these molecules prior to T cell-based immunotherapy.
(B) Tumor cells lacking MHC class I
molecules could be efficiently recognized by NK
cells. (C) HLA-G expression of tumor cells can
inhibit NK cell-mediated lysis suggesting that
HLA-G expression is a novel immune escape
mechanism.
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