Of the many special roles played by proteolytic enzymes in immune reac tions, this book addresses different aspects of membrane peptidases, s ignal transduction via ligation of membrane peptidases (especially of dipeptidyl peptidase IV/CD26 and aminopeptidase N/CD13), and regulatio n of membrane peptidases in vivo and in vitro. A number of newly disco vered peptidases (including cathepsin F, W and X, carboxypeptidase X, attractin) are described, with special emphasis given to the role of p eptidases in immune and defense reactions and in the pathogenesis of i nflammatory and other diseases, including rheumatoid arthritis, pancre atitis, multiple sclerosis, Alzheimer's disease and tumours of various origins. The focus on the involvement of a selection of proteolytic e nzymes in immune reactions and diseases is a unique feature of this mu ltifaceted work , which combines biochemical, immunological and clinic al research reports with literary reviews of the field.