In recent years there have been many technical developments in immunology that have potential or actual applications in many other branches of the life sciences. These developments include a number of ultrasensitive systems for the detection and assay of a wide range of biological materials, including micro-organisms and their products, as well as techniques for isolating and purifying micro-organisms and other antigenic materials. Two developments in particular have greatly extended the scope and applicability of immunological methods. These are the production of monoclonal antibodies and the introduction of enzyme linked immunoassay as a simple, safe and economical alternative to radioimmunoassay. This book is based on information gathered at the Society for Applied Bacteriology Autumn Demonstration Meeting held at the South Bank Polytechnic, London on October 15th, 1986.