SEPTIC BURNED PATIENT - MODEL FOR STUDYING THE ROLE OF COMPLEMENT AND IMMUNOGLOBULINS IN OPSONIZATION OF OPPORTUNIST MICROORGANISMS

Abstract

The effects of septicemia on complement [C] levels and activities and opsonic function in septic and nonseptic burned patients were studied. None of the non-septic burned patients had consumption of classical pathway activity during their clinical course. Patients who did not survive septicemia had consumption of all of the classical C components (C1-C5) prior to and during their septic episodes. Patients who survived septicemia had multiple patterns of classical C pathway consumption. In these patients, classical pathway activity was restored to normal following the last positive blood culture. Alternative C pathway consumption was demonstrated in only 1 of the septic burned patients, as evidenced by decreased factor B and C3b INA levels and decreased C3 and C5 conversion in sera treated with 10 mM ethylene glycol tetraacetic acid and 10 mM MgCl2 (MgEGTA) and in untreated sera. In all of the other septic patients and in the non-septic patients, reduction in C3 and C5 conversion in MgEGTA sera and untreated sera was not associated with a decrease in factor B or C3b INA. Reduction in complement levels and activities did not reduce the ability of the patients'' sera to promote phagocytosis and intracellular killing of their infecting microorganisms by normal human peripheral polymorphonuclear leukocytes. Measurement of classical pathway activity in burned patients may be used as a diagnostic tool for predicting the severity of septic episodes and for monitoring recovery. C consumption did not reduce the opsonic capacity of the patients'' sera for their infecting microorganisms. Current concepts regarding the role of immunoglobulins and C in opsonization of opportunist micro-organisms may require reevaluation.