Abstract
The experiments were performed in order to define whether the heated-cells of Bacillus thuringiensis subsp. thuringiensis would activate the alternative pathway of complement system in human serum. The heated-cells of Bacillus thuringiensis subsp. thuringiensis were added to human serum, and the mixtures were incubated at 37°C for 30min. The hemolytic activities (CH50) of complement in this serum were titrated using sheep red blood cells. Then, the activities (SFU) of both C3 and C4 complement components in this serum were also titrated using intermediate cells. These cells were found to decrease in >86.4% of the titers of CH50 of complement in human serum. They also consumed 86.3% of the titers of SFU of C3 complement component in human serum. However, the consumption of C4 complement component was found to be only 22.8%. On the immunoelectrophoresis, conversion of C3 complement component from β1C to β1A region was observed in the serum treated with the heated-cells of Bacillus thuringiensis subsp. thuringiensis. Factor B component, which activates C3 complement component in this serum, was also converted from B to Ba and Bb. The results of these experiments strongly show that the heated-cells of Bacillus thuringiensis subsp. thuringiensis are able to activate complement system in human serum, mainly via the alternative pathway.
