Cloning and Culturing of Fetal Mouse Natural Killer Cells

The ability to study the properties and functions of individual cells is a major goal of cell biologists. Nowhere is this more true than in studies of the immune system, in which the complexity is such that results obtained at the population level often obscure critical aspects of the function and diversity of the component cells. The study of individual cells per se is still technically difficult and of necessity limited in scope, leading to the compromise in which populations of cells derived from a single parent cell (clones) are studied. Considerable valuable information can be obtained from even relatively small clones of limited life span (ref. 1 , Chapter 2 ), but the ultimate aim is to produce clonal populations of cells that show indefinite growth and retain normal physiological properties, thereby permitting large-scale and long-term studies. The discovery of methods for cloning mouse and human T cells led directly to major advances in our understanding of the recognition mechanisms and functional capabilities of “individual” T cells. More recently, the development of procedures for the cloning of human NK cells was instrumental in the discovery of killer cell immunoglobulin-like inhibitory (KIR) receptors (2 , 3 ; and Chapter 1 ).