[The complement system--a fascinating biological cascade. 2--clinical aspects].

Knowledge about the complement system has increased considerably the recent years. Research in the field of activation and regulation of the system has contributed to a more dynamic conception of how the system functions under physiological and pathophysiological conditions. In the first paper, the author considered some important physiological mechanisms. In this paper, he discusses some clinical aspects of complement deficiencies and pathological complement activation. He briefly reviews relevant laboratory tests for clinical evaluation of complement, with particular emphasis on interpretation of the results.