This volume of Current Topics in Microbiology and Immunology is concerned with a class of molecules that are the most potent polyclonal stimulators of T lymphocytes of several species. These molecules have been named "superantigens" because they use a mechanism of T cell stimulation closely mimicking MHC-restricted recognition of specific antigen: they act on variable parts of T cell antigen receptors and are presented by MHC class II molecules. Prototypes of these molecules are the pyrogenic exotoxins produced by S. aureus and S. pyogenes, of which the staphylococcal enterotoxins and the toxic shock syndrome toxin are the best known. Superantigens also occur endogen ously in mice, most notably the enigmatic Mis determinants, that have withstood characterization for nearly 20 years. Only very recently was it found that Mis is probably encoded by endogenous retroviruses. The list of candidates that are implicated as being superantigens is growing. In many cases, however, the proof that a given molecule indeed falls into this category is still missing.

Dieses bereits in 5. Auflage erfolgreiche Kurzlehrbuch der Immunologie erläutert die Vielfalt molekularer und zellbiologischer Mechanismen von Immunreaktionen bei Mensch und Tier. Es wird erklärt, was das Immunsystem bei der Infekt- und Tumorabwehr oder bei einer Schwangerschaft leistet und wie Allergien und Autoimmunkrankheiten entstehen können. Immunologische Therapiestrategien bei Tumoren, Allergien und Autoimmunkrankheiten sowie die Wirkungsweise von Impfungen werden erörtert. Kurze Beschreibungen von wichtigen Arbeitsmethoden dienen als Blick in die Praxis. Fragen führen durch das Buch, und MEMO-Boxen fassen wichtige Punkte zusammen. Schließlich finden Leserinnen und Leser im Anhang interessante "Fakten und Zahlen". Studierende und Berufstätige aller biologischen, biochemischen, medizinischen, pharmazeutischen und veterinärmedizinischen Fachrichtungen sind besonders angesprochen. Das Buch soll ihr Interesse für die Immunologie wecken und das Verstehen erleichtern.

The international workshop on "Specificity and Function of Clonally Developing T Cells" was held at SchloG Rei- sensburg (near UIm, West Germany) on March 17-20, 1985. The meeting brought together immunologists study- ing clonal T-cell development in man and mouse in various in vitro systems at the cellular as well as molecular level. It was an attempt to provide an overview of the current research interests of groups working on (a) the developmen- tal potential of in vitro expanding primary T-cell clones (investigated using limiting dilution analysis) and cloned T -cell lines established in long-term culture; (b) the signals required for the expression of particular patterns of (func- tional and antigen receptor) phenotypes by T cells which are either freshly explanted in vitro, or maintained in vitro as cloned long-term lines; and (c) the generation of an MHC-restricted T-cell repertoire. In the study of thymocytes emphasis has shifted towards the presumably immature adult/embryonic subset(s) which is (are) devoid of subset-specific differentiation markers (L3T4, Lyt-2). Neither the signal requirement(s) for clonal expansion in vitro of these cells, nor their precursor role for any functional T -cell lineage are as yet unambiguously established. The multiple modes of human T-cell activation (e.g., via Tp44, T11, T3/Ti molecular complexes) were em- phasized by a number of presentations and raised the ques- tion of whether these different modes of activation induce different functional activities in individual T-cell clones.