Immunopharmacology is defined as that part of pharmacology that deals with drugs acting on the immune system and, in addition, with the pharmacological actions of substances derived from the immune system. In order to lend sharper definition to the term immunopharmacology the subject matter has been divided according to clinical and pragmatic criteria. The division into immunosubstituion, immunosuppression, antiallergic substances and immunostimulation gives the heterogeneous material a tighter structure than would any classification according to origin, chemical structure or mechanism of action.Immunopharmacology is defined as that part of pharmacology that deals with drugs acting on the immune system and, in addition, with the pharmacological actions of substances derived from the immune system. In order to lend sharper definition to the term immunopharmacology the subject matter has been divided according to clinical and pragmatic criteria. The division into immunosubstituion, immunosuppression, antiallergic substances and immunostimulation gives the heterogeneous material a tighter structure than would any classification according to origin, chemical structure or mechanism of action.1 Definition and History.- 2 The Immune System A Short Introduction to its Structure and Function.- 2.1 The cells of the immune system.- 2.1.1 T- and B-lymphocytes.- 2.1.1.1 Lymphocyte receptors.- 2.1.1.2 Immunological memory.- 2.1.1.3 Generation of receptor diversity in lymphocytes.- 2.1.1.4 Effector functions of T-cells.- 2.1.1.5 Transplantation reactions and MHC antigens.- 2.1.2 Macrophages.- 2.1.3 Neutrophils.- 2.1.4 Eosinophilic granulocytes.- 2.1.5 Mast cells and basophils.- 2.1.6 NK- and K-cells.- 2.2 Humoral components of the immune system.- 2.2.1 The structure and function of antibodies.- 2.2.1.1 Antibody diversity.- 2.2.1.2 Physico-chemical aspects of antibody binding.- 2.2.2 Lymphokines and cytokines.- 2.2.2.1 Interferons (see also Chapter 6).- 2.2.2.2 The interleukin fal#˜