DEMONSTRATION OF A LOCAL EXHAUSTION OF COMPLEMENT COMPONENTS AND OF AN ENZYMATIC DEGRADATION OF IMMUNOGLOBULINS IN PLEURAL EMPYEMA - A POSSIBLE FACTOR FAVORING THE PERSISTENCE OF LOCAL BACTERIAL-INFECTIONS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 42  (3) , 506-514
Abstract
Local bacterial infections such as abscesses or purulent exudates most often contain numerous, easily culturable bacteria despite an intense inflammatory reaction characterized by polymorphonuclear leukocyte ingress. To understand the mechanisms leading to such a persistent infection, pleural empyema was used as a model and measured the levels and catabolism of complement [c] as well as of Ig in 28 infectious pleural effusions associated with either a positive or with a negative bacterial culture [in humans]. Classic and alternative pathway hemolytic activities, factor B and C4 [complement component 4] hemolytic activities as well as native C3 were markedly decreased or undetectable in most culture-positive effusions when compared to culture-negative effusions (P < 0.005); breakdown products of factor B and C3 were markedly increased in culture-positive fluids. Out of 14 culture-positive fluids 11 exhibited IgG breakdown as opposed to none of the culture-negative fluids. In 7 out of 14 culture-positive fluids, incubation with 125I-IgG led to their in vitro breakdown. This proteolytic activity could be abolished by culture-positive fluid preincubation with normal sera. Increased C catabolism and Ig breakdown, both leading to local consumption of immune reactants, could be one of the causes for bacterial persistence in pleural empyema.