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MHC restricted and non-restricted killer lymphocytes.
1Department of Experimental and Clinical Microbiology, University of Sheffield Medical School, UK.
Blood Reviews
|September 1, 1990
Summary
Cytotoxic lymphocytes, including T-cells and natural killer (NK) cells, defend against infections and cancer. Impaired cytotoxicity can lead to disease proliferation.
Area of Science:
- Immunology
- Cellular Biology
Background:
- Cytotoxic lymphocytes are key immune cells, comprising MHC-restricted cytotoxic T-cells and non-restricted natural killer (NK) cells.
- Monocyte/macrophage lineages and Fc-receptor expressing cells also exhibit cytotoxicity via antibody-dependent cellular cytotoxicity (ADCC).
- T-lymphocytes recognize antigens in the context of MHC class I, while NK cells (large granular lymphocytes, LGL) kill non-specifically without prior sensitization.
Purpose of the Study:
- To elucidate the mechanisms and regulation of cytotoxic lymphocyte activity.
- To differentiate between T-cell and NK-cell mediated cytotoxicity.
- To understand the role of cytotoxic cells in defense against pathogens and cancer.
Main Methods:
- Phenotypic marker analysis (CD16+, CD56+, CD3-) to distinguish LGL from T-lymphocytes.
- Assessment of cytotoxic molecule release at the target-effector cell interface.
- Investigation of regulatory factors like IL-2, IFN, prostaglandins, and TGF-beta on cytotoxic activity.
Main Results:
- Both T-cells and LGL utilize cytotoxic molecules for target cell lysis.
- LGL possess regulatory functions via cytokine release and distinct surface markers (CD16+, CD56+) lacking CD3.
- Cytotoxicity is enhanced by IL-2 and IFN, and suppressed by prostaglandins and TGF-beta.
Conclusions:
- Cytotoxic lymphocytes are crucial for combating microbial infections and neoplasia.
- Dysregulation of cytotoxicity, through suppressor factors or reduced cytokine production, can promote disease progression.