I would like to thank all my co-workers who have collaborated with me, from 1963 until now, in biological and clinical research in the field of cancer active immunotherapy, of its immuno prevention and immunorestoration. They will often be quoted in this book. I am particularly grateful to those who have helped me to write it by reviewing some chapters: D. BELPOMME, J. F. DOR~, IRENE FLORENTIN, A. GOUTNER, I. J. Hm, R. HUCHET and MARIE-CHRISTINE SIMMLER. I also thank NICOLE VRIZ, MARIE-CLAUDE SCHNEIDER, FENELLARIsELEY and M. JUVET for their willing and efficient co-operation in the preperation of the manuscript. I am finally grateful to all authors of books or articles who authorized me to reproduce their figures or tables. Paris, April 1976 G. MAT~ Contents Chapter 1. Introduction and Definitions 1 Chapter 2. Biological Basis: Tumour Associated Antigens, the Immune Machinery and Its Behaviour Concerning Cancer Cells 5 2. 1. Tumour-Associated Antigens 5 2. 2. The Immune Machinery 19 2. 2. 1. Humoral Mediated Immunity and Cell Mediated Immunity 19 2. 2. 2. T- and B-Lymphocyte and Monocyte Differen tiation 22 2. 2. 3. T-Lymphocyte Functions 25 2. 2. 4. B-Lymphocyte Functions 30 2. 2. 5. Macrophage Functions 31 2. 2. 6. K-Cell Function 32 2. 3. The Immune Machinery and Cancer Cells 33 2. 3. 1. Mechanisms Involved in Tumour Cell Rejec tion 33 2. 3. 1. 1. In vivo Evidence for Tumour Immunity 33 2. 3. 1. 2.