Fibrinogen enhances complement-mediated augmentation of retention of polymorphonuclear leukocytes by nylon columns

Retention of polymorphonuclear leukocytes (PMN) by nylon columns is significantly increased when PMN are suspended in zymosan-activated plasma. In zymosan-activated plasma, 25.8 +/- 4.9% of PMN were retrained as compared with 11.1 +/- 2.7% suspended in zymosan-activated serum (ZAS) (P = 0.001) and 7.9 +/- 3.2% in fresh serum (P = 0.0005). Addition of heated plasma (56 degrees C for 30 min) to ZAS restored optimal retention. These results suggested a role for a heat-stable factor(s) in plasma, which augmented complement-mediated enhancement of PMN adhesiveness. This study was designed to determine whether fibrinogen enhanced retention by nylon columns of PMN in the presence of activated complement. Addition of defibrinated plasma to ZAS failed to enhance adhesiveness to nylon. The retention of PMN suspended in ZAS was 11.1 +/- 2.7%, as compared with 10.5 +/- 3.7% in ZAS plus defibrinated plasma. Retention of PMN suspended in ZAS plus fibrinogen was 27.92 +/- 13.2% as opposed to 16.35 +/- 7.5% (P = 0.045) in ZAs. In contrast, retention of cells in serum was 12.96 +/- 7.5%. These results suggest that the process which enhances PMN adhesiveness involves the interaction of cells, activated complement, and fibrinogen.