Decreased Heat-Labile Opsonic Activity and Complement Levels Associated with Evidence of C3 Breakdown Products in Infected Pleural Effusions

Abstract

A B S T R A C T Heat-labile opsonic activity was measured simultaneously in serum and pleural fluid of patients with transudates, infectious exudates (with positive or negative bacterial culture) and neoplastic exudates, using two different complement-dependent phagocytic tests: the killing of Staphylococcus aureus Wood 46 variant strain (K50 opsonic titers) and the assessment of ingestion rate of endotoxin-coated paraffin particles (Oil Red 0 uptake test). K50 opsonic titers were lower in culture-positive pleural effusions as compared to culture-negative (P < 0.002) or neoplastic effusions (P < 0.002). These results were corroborated by the Oil Red 0 uptake test. The data obtained with the two assays showed a significant correlation (P < 0.001).The hemolytic activity ofcomplement (CH50) as well as the levels ofC3 breakdown product, C3d, were measured in the same sera and pleural fluid samples and in an additional group ofpatients with pleural effusions of the same etiology. Effusions with positive cultures showed lower CH50 values (P < 0.01) and higher C3d values (P < 0.05) when compared to culture-negative pleural fluids. Finally, evidence for immune complexes in pleural effusions and sera was looked for by determination of Clq binding activity. Levels were higher in culture-positive effusions when compared to culturenegative fluids (P = 0.005).K50 opsonic titers showed a positive correlation with CH50 values (P < 0.001) for all fluids tested. Similarly Clq binding activity correlated with C3d levels in ef-A preliminary report of this work was presented at

Pathogenesis of Foreign Body Infection: Description and Characteristics of an Animal Model

“…None of these controls exhibited any bactericidal activity against the test strain. The lack of bacterial killing with heatinactivated serum as the opsonic source confirmed the previously defined opsonic requirements of S. aureus strain Wood 46 [13,24,26].…”

“…The same phagocytic bactericidal assay previously described by our laboratory [13,24], was used throughout the present study to measure opsonic activities of tissue cage fluid and serum, the opsonic coating of S. aureus in the animal model, and the overall killing by as well as the ingestion rate of PMNLs.…”

“…The incubation and plating conditions have been described [13, 24,25]. The reciprocal value of the dilution of serum or tissue cage fluid that gave 50070 killing of S. aureus was defined as the opsonic titer [13,24]. Controls included (1) heat-inactivated (at 56 C for 30 min) pooled serum or tissue cage fluid with PMNLs; (2) PMNLs without serum or tissue cage fluid; and (3) 10070 pooled serum without PMNLs.…”

“…Figure 3 shows complement-mediated opsonic activity and total hemolytic complement levels in sterile tissue cage fluids, expressed as 50% killing and CHso units, measured at various intervals after surgery. Both values in tissue cage fluid decreased progressively with time, the opsonic activity being 14.4% and the complement level being 14 In view of these low levels of 500/0 killing, CHso, and C3 in tissue cage fluid, we considered the possibility that this fluid might be unable to promote adequate opsonization, as has been described for empyema [13]. To test this hypothesis, S. aureus strain Wood 46 was preopsonized in vitro with pooled guinea pig serum before inoculation into tissue cages.…”

“…Although polymorphonuclear leukocytes (PMNLs) accumulating around a foreign body appear microscopically normal, their functional status as well as the opsonizing capacity of the surrounding fluid have never been explored because of the lack of an appropriate animal model. In the present communication we describe the development of an animal model that reproduces the clinical characteristics of a foreign body infection and thus allows the in vitro evaluation of the various phagocytic steps in its neighborhood [13][14][15][16].…”