Introductory Remarks.- Session A 1 Lymphoid Cell Differentiation and Traffic.- Introduction: On the 20th Anniversary of a Scientific Discovery.- Ontogenetic Differentiation of Epithelial and Non-Epithelial Cells in the Human Thymus.- Antigenic Changes Associated with Chicken B Lymphocyte Development.- Evidence for Surface Antigen(s) Specific for a Sub-population of Peripheral B and T Lymphocytes in the Chicken.- Separation of Germinal Centres from Chicken Spleen.- Germinal Centres and the B-Cell System: A Search for the Germinal Centre Precursor Cell in the Rat.- Migratory Patterns of the Ly Subsets of T Lymphocytes in the Mouse.- Correlation of Immunogenetic and Histological Changes in Imnunodeficient Mutant hr/hr Mice.- Morphology of the Extrafollicular Zone and Pseudo-Follicles of the Rat Lymph Node, and Their Role in Lymphocyte Traffic.- Lymphocyte-High Endothelial Venule Interactions: Examination of Species Specificity.- Basic Mechanisms of Lymphocyte Recirculation in Lewis Rats.- The Effect of Cytoskeletal Inhibitors on the Migration of Lymphocytes across Vascular Endothelium.- New Evidence on Control Mechanisms in Lymphocyte Traffic.- Separation of Earthworm Coelomocytes by Velocity Sedimentation.- Two Subpopulations of Cortisone-Resistant Lymphoid Cells in the Rabbit Thymus.- Development of an Isotope Dilution Assay to Determine the T-Cell Mass in Guinea Pigs.- Lymphocyte Production and Organ Distribution of Newly Formed Lymphocytes after Selective 3H-Deoxycytidine Labelling of Mesenteric Lymph Nodes.- Germinal Centers and the B-Cell System: B Cell Differentiation in Rabbit Appendix Germinal Centers.- The Influence of the Thymus upon the Number and Class Distribution of Immunoglobulin Containing Cells in the Bone Marrow and Other Lymphoid Organs of the Mouse.- Summing-up.- Session A 2 Immunological Function of Cell Surface Structures.- Introduction: The Immunoglobulin-like T Cell Receptor Problem.- Isolation and Partial Identification of Immunoglobulin from T Cells.- Codistribution of Antigen and Fab Determinants on Thymic Antigen-Binding Cells.- Ontogeny of Spontaneous Rosette Forming Cells in Mice.- Multiple Ig Classes on Rabbit B Lymphocytes.- C3 Receptors and Membrane Complement Components on Lymphocytes Jointly Cause Binding of EAC.- C3 and C5 Compete for the Same Binding Site on Complement Receptor Cells.- Inhibition of C3b and C3d Receptor Activity by Xenoantisera Prepared by Immunization with Cell-Bound C3 Receptor Protein.- Modulation of the Immune Response by Pretreatment of Antigen with Complement.- Characterization of an IgG-Fc Receptor Protein Isolated from Human B-Prolymphocytic and B-Chronic Lymphocytic Leukemia Cells.- Antisera Cause Alterations in Morphology and Enzyme Activity in the Plasma Membrane of Rat Thymocytes.- Modulation of Cell Membrane Antigens During Differentiation of Rat T-Lymphocytes.- Interactions Between Neuraminidase-Treated Lymphocytes and Liver Cells.- Immunological Characteristics of Neo-Antigens on the Cell Surface After Neuraminidase Treatment.- Carbohydrate Incorporation into Glycoconjugates of Mouse Thymocytes During Con A Stimulation — Involvement of Two Subpopulations.- Are Endogenous C-Type Viruses Physiologically Required for the Regulation of the Humoral Immune Response?.- Plating Inhibition Assay (PIA): A New Test for Cell Mediated Cytotoxicity.- Summing-Up: Lymphocyte Receptors.- Session A 3 Immunological Tolerance (Suppression/Deletion).- Differentiation of B Cells and the Clonal Abortion Theory.- Permanent Abolition of Reactivity to Major Histocompatibility Antigens Requires Elimination of Prethymic Precursors.- Survival and Immunological Responsiveness of Rat-Mouse Bone Marrow Chimeras.- The Control of Autoreactive Lymphocytes by a Receptor Blockade Mechanism.- Stimulation of Natural Antibodies by Self Antigens.- The Role of Antigen-Antibody Complexes in Generating Immunological Memory and Auto-Antiidiotypic Immunity.- Germinal Center Formation in BSA-Tolerant Chickens.- Studies of Allospecific Suppressor Cells in Culture.- Regulation of Delayed Type Hypersensitivity to Sheep Red Blood Cells: Demonstration of Suppressor T Cells and a Soluble Suppressor Factor.- Induction of Tolerance to DNCB-Contact Sensitivity in Guinea Pig Fetuses.- Suppressor Cells for in Vivo Cytotoxic Responses — Regulation of the in Vivo Activation of Cytotoxic T-Lymphocytes by Suppressor Cells.- Demonstration of Cell Mediated Autoimmunity and Induction of a Suppressive Control Mechanism.- Suppressor T Cells in Induction and Maintenance of Low Zone Tolerance to Bovine Serum Albumin.- Cation-Induced Immunosuppression: The Effect of Lithium on Arthus Reactivity, Delayed Hypersensitivity and Antibody Production in the Rat.- Characterization of Reactive and Suppressive Cells in the Mouse Embryonic Liver by Peanut Agglutinin (PNA).- The Effect of Adjuvant Induced Suppressor Cells on in Vitro and in Vivo Lymphocyte Responses.- Middle Ear Transplantation: A New Concept in Clinical Otology.- Summing-Up.- Session A 4 In Vivo Relevance of Non-Lymphoid Cells in the Immune Reaction.- Introduction: Heterogeneity of the Cellular Immune Response.- Mast Cells in Local Antibody Formation and Allograft Rejection.- Marginal Zone and Marginal Sinus Macrophages in the Mouse are Distinct Populations.- Cells Containing Birbeck Granules in the Lymph and the Lymph Node.- Macrophage-Lymphocyte Interaction Following Concanavalin A-Stimulation As Monitored by Chemiluminescence.- Cell Cooperations in the Mitogen-Induced Transformation of Human Blood Lymphocytes in Healthy Persons and in Hodgkin’s Disease.- The Antigen Binding Dendritic Cell of the Lymphoid Follicles: Evidence Indicating Its Role in the Maintenance and Regulation of Serum Antibody Levels.- The Concept of Drug-Carriers in the Treatment of Parasitic Diseases.- Recycling (Shuttle) of Cell Surface During Endocytosis.- The Effect of Various Prostaglandins on Plasma Membrane Receptors and Function of Mouse Macrophages.- Modulation of Phagocytosis Induced Prostaglandin Release from Macrophages.- Neoformation of Lymphatics in the Mouse Omentum.- Properties of Mononuclear Phagocytes Derived from the Small Intestinal Wall of Rats.- Graft-Versus-Host Induced Immunosuppression Associated with an Increased Thymic Mitogen Response.- Thymic Microenvironment Changes Associated with Graft-Versus-Host Immunosuppression.- Local Cellular Reactions following Intracutaneous Injections of Various Adjuvants in Rats and Guinea-Pigs.- Summing-Up.- Session A 5 Soluble Mediators of Immunity.- Studies on MIF and the Role of Macrophage Associated Esterases in the Response of the Macrophage to MIF.- Chemical Characterization of Radiolabeled Lymphocyte Activation Products of Guinea Pig Associated with Macrophage Migration Inhibitory Activity (MIF).- Murine MIF Does Not Contain Ia Determinants.- Different Cellular Site for the Production of Murine Macrophage Migration Inhibitory Factor and Immune Interferon (Type 11).- Biochemical Characterization of the Human Lymphokine Leukocyte Migration Inhibitory Factor (LIF): Role of cGMP as a Specific Inhibitor of the LIF Esterase Activity.- Some Characteristics of the Antigen — Dependent Migration Inhibition Factor.- A Mediator Acting as a Costimulator for the Development of Cytotoxic Responses in Vitro.- Colony Stimulating Activity of Human Spleen Cell Culture Supernatants.- Detection of Thymosin in Thymic Epithelial Cells by an Immunoperoxidase Method.- Characterization of Thymus Extracts Which Stimulate Incorporation of Galactose into Glycoconjugates of Rat Bone Marrow Cells.- Generation of an Eosinophilotactic Factor from Human PMNs by Various Mechanisms of Cell Activation.- The Effect of Histamine on Lymphocytes: Release of an Inhibitor of Eosinophil Chemotactic Migration.- Summing-up.- Session B 1 Functional and Morphological Aspects of Malignant Lymphomas.- Multidisciplinary Study of Non-Hodgkin Lymphomas: Electron Microscopy, Immune- and Enzyme- Histochemistry.- Correlation of Biochemical and Immunological Markers with Conventional Morphology and Clinical Features in 120 Patients with Malignant Lymphomas.- Biology of Lymphoma Transformation.- Demonstration of Intracytoplasmic Immunoglobulin, Lysozyme, and Albumin and Isoelectric Focusing Pattern of Tissue Immunoglobulin in So-Called Reticulum Cell Sarcoma (Immunoblastic or Large Cell Lymphoma).- Alkaline Phosphatase Positive Lymphomas and Lymphocytes.- Definition of Germinal Center Cell-Derived Lymphomas by Analysis of Complement Receptor Subtypes and Morphological Criteria.- Spleen Cell Populations in Hodgkin’s Disease.- Isoelectric Focusing Pattern of Acid Phosphatase in Normal Splenic Tissue, in the Lysosomal Fraction of Viable Splenic Lymphocytes and in Cases of Hairy Cell Leukemia.- A Molecular Approach Delineating Surface Markers on Human T-Lymphocytes.- Effect of Thymic Humoral Factor (THF) in Vitro on Bone Marrow and Blood Cells from B, T and Null Cell Acute Lymphatic Leukemia (ALL).- Serum and Secretory Immunoglobulin Levels in Pre-leukaemic AKR Mice and Three Other Mouse Strains.- Adult T Cell Leukemia. Histological Features of the Lymphoid Tissues.- Membrane Glycoprotein Patterns of Normal and Malignant Human Leukocytes.- In Vivo Activity of Lymphocytes Sensitized in Vitro by Antigen-Fed Macrophages: Inhibition of Lymphoma Growth.- Summing-up.- Session B 2 Immunopathology of Parasitic Diseases.- Malaria Infection in Mice. Plasmodium Berghei Infection in Mice: A Model for Immune Complex Disease and Autoimmunity.- Suppressor Cells in Trypanosoma Congolense-Infected Mice.- Immune Depression in Trypanosoma Congolense-Infected Mice.- Relevance of Polyclonal Antibody Formation to the Development of Autoimmunity: The Model of African Trypanosomiasis.- In Vivo and in Vitro Interaction of Trypanosoma Cruzi with Mouse Macrophages and Heart Muscle Cells — Film Presentation.- Comparison of the Ability of Eosinophils and Neutrophils, and of Eosinophils from Patients with S. Mansoni Infection and Normal Individuals, to Mediate in Vitro Damage to Schistosomula of S. Mansoni.- Significance of Local Formation of Immune Complexes within Granulomata in Schistosomiasis.- Thymus-Dependence and Kinetics of Intestinal Mast Cells and Globule Leucocytes.- Inhibition of Lymphocyte Proliferation During Parasitic Infection with Nippostrongylus Brasiliensis.- Immunopathology of M. Lepremurium (MLM) Infection in B6 C3HAN and (C3HxB6) F1 Mice.- Genetics and Mechanisms of Resistance or Susceptibility to Murine Listeriosis.- Genetic Control of Susceptibility to T. Congolense Infection in Inbred Strains of Mice.- Session C Immunological Reactions and Immunotherapy of Malignant Diseases.- Pregnancy-Associated Glycoprotein (?2-PAG) in the Sera of Children with Malignancies.- Circulating Human T Cell Subset with a Reversible E-Rosetting Capacity in Cancer and Normals-Hypothesis on the Regulatory Mechanism Influencing Their Role in CMI.- A Tumor T Cell Line Which Can Be Specifically Activated by Antigen.- A Model of Target Cell Recognition and Lysis by Natural Killer Cells.- The Stimulation of a T Cell Response in the Syngeneic Host by the P-815 Mastocytoma Cell and the Isolation of a Tumor-Associated Antigen Which Has Some H-2 Antigen Characteristics.- Cytotoxic T Cell Responses to a Syngeneic Tumour: Conditions for Primary Activation in Vitro and Biological Activity in Vivo.- Opposite Effects of T-Cells on Syngeneic Tumor Growth in Vivo: Tumor Inhibition by Mature Lymphocytes and Enhancement of the Same Tumors by Immature Cells.- Tumor Metastases and Cell-Mediated Immunity in a Model System in DBA/2 Mice. 2. Characteristics of a Metastasizing Variant of a Chemically Induced Lymphoma.- Characterization of Lymphocytes Invading Experimental Tumors.- Functional Activity of Human Tumor-Infiltrating Macrophages.- Approaches to Effective Tumor Immunotherapy with Cells and the Enzyme Neuraminidase.- Summing-Up.- Session D Immunoprophylaxis and Therapy of Infectious Diseases.- The Production and Role of Cytotoxic T Cells in Influenza Virus Infection in Mice: Do the Same Rules Apply in the Response to Any Foreign Antigen?.- Virus Spike Protein Complexes and Virosomes as Effective Subunit Vaccines.- Posttransfusion Hepatitis (PTH): Frequency, Serological Type and Possible Role of Pre-Existing Anti-HBs in Protection.- Immunopathological Alterations of Lymphatic Tissues in Mice Infected with Lymphocytic Choriomeningitis Virus.- Light and Electron Microscopic Characteristics of Sinus Reactions and Cellular Traffic in the Hilar Lymph Node Complex (HLNC) in Rabbits Undergoing a Pulmonary Cell-Mediated Immune Reaction.- Peripheral Blood Lymphocyte Subpopulations in Multiple Myeloma.- Closing Session Conclusions and Outlook.- General Summary.