Natural killer cells. In vitro and in vivo

Area of Science:

• Immunology
• Cell Biology
• Cancer Research

Background:

• Identification of a novel nonadherent, nonphagocytic mouse cell within lymphoid organs.
• This cell lacks mature lymphocyte surface markers but exhibits potent cytotoxic activity.
• The cell is termed a natural killer (NK) cell due to its tumor-lysing capabilities.

Purpose of the Study:

• To characterize the cytotoxic activity and properties of the newly identified NK cell.
• To investigate the target cell specificities and potential role of NK cells in anti-tumor immunity.

Main Methods:

• Assessing the cytotoxic activity of NK cells against a wide spectrum of tumor cells (syngeneic, allogeneic, xenogeneic) and normal cells.
• Evaluating the effect of pharmacologic agents (cytochalasin, cAMP-active drugs, colchicine) on NK cell activity.
• Examining evidence for clonal distribution of NK cell specificities and the involvement of a single NK cell population in lysing diverse tumor targets.

Main Results:

• NK cells effectively lyse various tumor cells, including lymphomas, with minimal activity against normal cells.
• NK cell-mediated cytotoxicity is inhibited by pharmacologic agents at similar concentrations as other cytotoxic cells.
• Evidence suggests a single NK cell population targets multiple tumor types, and their levels correlate with resistance to tumor challenge in vivo.

Conclusions:

• NK cells represent a distinct cytotoxic lymphocyte population with significant anti-tumor activity.
• NK cells demonstrate broad reactivity against tumors, independent of specific surface markers or clonal distribution.
• NK cells may play a crucial role in the host's natural defense mechanisms against neoplastic growth.