All but one* of the following articles represent comprehensive reports on a workshop held between 7 and 9 May 1981 at the Institute of Virology and Immunobiology, University of Wfuzburg, Federal Republic of Germany. The title of the workshop was "The Involvement of Endogenous Retroviruses inN ormalFunction and Pathological Growth of Lymphocytes." Rather than collecting and printing manuscripts of the individual communications, the organizers asked selected parti cipants to write, after the workshop, concise articles each compris ing several contributions and discussions on major topics. In so doing, we hope to present to a larger audience a synopsis of the various information and views exchanged at the meeting. Such a procedure seemed the more appropriate as the workshop was intended to bring together specialists from two rather diverse fields: RNA-tumor virology and immunobiology. While this created some initial problems of terminology, it was quite effective in making representatives of one field more aware of the significance and the contributions ofthe other. It also great ly contributed to realization of the complexity of the problems involved in virus-induced leukemogenesis.

Inhalt
Endogenous Retroviruses of Mice and Chickens.- The Genetic Basis of Retroviral-Induced Transformation.- Expression of Xenotropic Murine Leukemia Viruses.- Expression of Endogenous Viral Genes in Mouse Lymphocytes.- Oncoviral Proteins as Cellular Antigens.- Regulation of Lymphocyte Proliferation and Differentiation by Lymphokines.- Possible Immunological Mechanisms in C-Type Viral Leukemogenesis in Mice.- Retrovirus Lymphoma-genesis: Relationship of Normal Immune Receptors to Malignant Cell Proliferation.- From the Point of View of an Immuno-logist: Enemies from Within or Friends from Long Ago?.- Perspectives on Endogenous Retroviruses in Normal and Pathological Growth.