6533b824fe1ef96bd12812e7

RESEARCH PRODUCT

Interaction of Bacterial Endotoxin (LPS) with Fluid Phase and Macrophage Membrane Associated C1q, the FC-Recognizing Component of the Complement System

subject

description

The bactericidal activity of normal serum was first described by Buchner in 1889 (10). This effect is abolished when serum has been incubated for 30 min at 56°C. Gram positives are less sensitive than Gram negative bacteria to direct killing, although gram positive cocci are opsonized by the action of serum mediated by antibodies and complement (22). It was found that most of the smooth strains of gram negative bacteria are serum resistant; whereas, the corresponding rough forms are extremely serum sensitive (32, 37). Thus evidence was provided that the composition of the bacterial surface may influence the reaction of the bacteria with the lytic system. The bacteriolytic properties of serum are mediated by the so called MAC (Membrane Attack Complex). This hydrophobic complex is inserted into cell membranes as a diner and produces lysis (24). The antibody-dependent activation of the classical complement pathway as well as the activation of the alternative complement pathway by bacteria has been extensively studied. However, several bacterial strains are rapidly killed in non-immune sera. Furthermore, it was reported that Cl is absorbed to Mycoplasma pneumoniae in the absence of antibodies. The direct interaction with Cl and the activation of the classical complement cascade had even more biological consequences for these bacteria than activation of the alternative pathway (8).