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Altered MHC class I antigens in tumors
I Algarra1, A Collado, F Garrido
1Departamento de Análisis Clínicos, Hospital Universitario Virgen de las Nieves, Granada, Spain.
International Journal of Clinical & Laboratory Research
|January 1, 1997
Summary
Malignant tumors often lose or reduce MHC class I antigens, unlike normal tissues. This immune evasion strategy, seen in experimental and human cancers, impacts immunotherapy effectiveness.
Area of Science:
- Immunology
- Oncology
- Cancer Research
Background:
- Malignant tumors frequently exhibit reduced or absent Major Histocompatibility Complex (MHC) class I antigens compared to autologous normal tissues.
- This downregulation is a common phenomenon observed in both experimental tumor models and a significant percentage (40%-90%) of human cancers.
- Tumor populations are often heterogeneous in their expression of MHC class I, comprising clones with varying antigen levels.
Purpose of the Study:
- To review MHC alterations in experimental and human tumors.
- To demonstrate the relevance of altered MHC phenotypes for immunotherapy.
Main Methods:
- Analysis of MHC class I antigen expression in cloned experimental tumors before in vivo passaging.
- Evaluation of MHC class I expression in human tumors using anti-HLA class I monoclonal antibodies.
- Review of existing literature on MHC changes in various tumor types.
Main Results:
- MHC class I loss or downregulation is prevalent in invasive tumors.
- Tumor heterogeneity for MHC class I expression is a common feature.
- Altered MHC phenotypes may represent tumor escape mechanisms from immune surveillance by T cells and natural killer (NK) cells.
Conclusions:
- Altered MHC class I expression in tumors significantly influences tumor behavior and immune interactions.
- Understanding these MHC changes is crucial for developing effective immunotherapeutic strategies targeting T cell and NK cell-mediated responses.