The direct bactericidal activity of IgG antibodies isolated from serum of patients with suppurative inflammatory processes caused by Staphylococcus aureus

Okulich V.K., Senkovich S.A., Lepteeva T.N., Shilin V.E., Denisenko A.G.

Vitebsk State Medical University, Belarus

The bactericidal activity of polyclonal IgG against St. aureus was established.
Objectives. To evaluate the activity of polyclonal IgG isolated from patients with purulent-inflammatory diseases and donors against St. aureus in plankton form, as well as the ability of immunoglobulins to destroy the exopolymeric matrix of staphylococcal biofilm.
Material and methods. Using the developed method the ability of polyclonal IgG isolated from 45 patients with purulentinflammatory diseases and 16 donors was determined to have a bactericidal effect on the plankton form of St. aureus without the participation of complement and immune cells. An estimation of the ratio of viable and dead bacteria was made by laser scanning confocal microscopy using propidium iodide as a marker of dead bacteria. The ability of IgG to destroy the exopolymeric matrix of St. aureus biofilm was assessed. The relation of immunoglobulin activity to St. aureus cells and
biofilm matrix with clinical and laboratory manifestations of purulent-inflammatory diseases was analyzed.
Results. It was shown that IgG isolated from patients with purulent-inflammatory diseases and donors may have their own bactericidal activity against St. aureus without
participation of the complement system and immune cells, while in patients with purulent-inflammatory diseases this activity is significantly higher than in persons without purulent-inflammatory processes. The ability of IgG isolated from patients with purulent-inflammatory diseases to cleave the exopolymeric matrix of S. aureus biofilm was significantly higher than in persons without purulent-inflammatory
diseases.
Conclusion. The findings suggest the presence of mechanisms of antibacterial activity of IgG against St. aureus, which is not associated with participation of the complement system and immune cells.