NK Cells and Other Natural Effector Cells reviews the state of knowledge on NK cells and other natural effector mechanisms. The coverage of immune effector systems ranges from basic studies on their nature, regulation, and mechanisms of action to important practical issues such as their role in host resistance, their modulation by therapeutic intervention, and alterations of their activity in disease. The book is organized into 12 parts. Parts I and II examine the characteristics of NK cells and other natural effector cells, respectively. Part III focuses on the cell lineage of NK and related effector cells, providing evidence for or against T cell lineage, for or against macrophage lineage, and for or against other or separate lineage. Part IV deals with the genetics of natural resistance in the mouse and rat. Part V presents studies on the regulation of cytotoxic activity. Part VI examines the specificity of natural effector cells, covering the nature of target cell structures and the nature of recognition receptors in effector cells. Part VII discusses the cytotoxicity by cultured lymphoid cells while Part VIII turns to the mechanisms of cytotoxicity. Part IX deals with natural cell-mediated reactivity against primary tumor cells and against non-tumor targets. Part X examines NK cell tumors or the presence of NK cells at the site of tumor growth. Part XI presents clinical studies with natural effector cells. Part XII provides evidence for in vivo reactivity of natural effector cells.