The magnitude and rapidity of the changes in the concentrations of APPs, together with their short half-life, suggest an important role for these proteins in the establishment of host defense. APPs are regarded as having general functions in trapping of micro-organisms and their products, in activating complement, in binding cellular remnants like nuclear fractions, in neutralizing enzymes, scavenging free radicals, and in modulating the hosts immune response. Despite vast pro- and anti-inflammatory properties ascribed to individual APPs, their function during health and disease remains incompletely defined.