Biomedical subjects
TL Whiteside
Publications and source records attributed to TL Whiteside.
Measurements of Natural Killer (NK) Activity and NK-Cell Quantification
Natural killer (NK) cells are a subset of lymphocytes with a distinct morphology and the ability to kill certain target cells via one or more cytolytic mechanisms. Measurements of in vitro NK activity from heparinized whole blood, or lymphocytes isolated from human peripheral blood or tissue, may be performed by a variety of techniques. Procedures using standard 51Cr-release assays as well as nonradioactive labeling materials are described in detail in this article, and advantages and disadvantages of these methods are discussed. Quantification of assay results, as percentage of specific lysis, lytic units, and cytolytic units, is explained with attention given to the limitations of each of these calculations. Quality control (QC) procedures that are needed to assure reproducible, reliable NK-cell assays for serial monitoring are described, and suggestions are provided for developing a QC program for these assays. Since NK cells can perform multiple functions, and the mechanism of NK-cell-mediated cytotoxicity is complex, the rationale for selecting a particular assay to measure NK activity is discussed.
Antitumor Functions of Natural Killer Cells and Control of Metastases
Natural killer (NK) cells have been recognized as effector cells responsible for the elimination of blood-borne metastases. Newer evidence suggests that NK cells play an important role in the control of solid tissue metastases. NK cells have the ability to kill a broad variety of fresh or cultured "NK-resistant" tumor cell targets by mechanisms that are not dependent on perforin or granzyme secretion. Also, a subset of interleukin 2 (IL-2)-activated NK cells, which are called A-NK cells, is capable of extravasation, movement in solid tissues, localization to the sites of metastases, and killing tumor cells in situ. Studies in experimental animals and in cancer patients indicate that systemic adoptive immunotherapy with A-NK cells and IL-2 is a tolerable and promising treatment for advanced solid tissue as well as hematologic neoplasms. In this article, antitumor functions of A-NK cells in vitro and in vivo are reviewed, and the mechanisms responsible for their antitumor effects are considered.