Gastrointestinal diseases present a considerable problem in human medicine in terms of both morbidity and mortality. The aim of this book is to cover the different immunological disorders of the gut with special reference to immunopathological and protective mechanisms. It will be of general interest to clinicians, scientists and students concerned with the gastrointestinal tract. Topics covered include: the current status of research into toxin-secreting pathogens, Campylobacter, Giardia and HIV; the immunological features of idiopathic inflammatory gut diseases such as Crohn's disease and intractable diarrhoea; the genesis of the flat mucosa; the iatrogenic diseases of the gut such as graft-versus-host disease and small bowel allografts; the immune mechanisms and lesions in the gut of patients with parasitic nematode infections (very important in the tropics). Basic background on the immune apparatus in the intestine is also discussed, as are the effects of inflammation on intestinal permeability.