IN-VITRO REDUCTION OF ENDOTOXIN CONCENTRATIONS WITH THE 5S FRAGMENT OF IMMUNOGLOBULIN-G

Endotoxin has long been implicated as an inducer for the development a nd progression of gram-negative sepsis, Accordingly, antiendotoxin the rapy has been considered one of the major targets for the treatment of sepsis, To investigate the influence of a human immunoglobulin C (IgG ) derivative, the 5S fragment of IgG (5S-IgG; Gamma-Venin, Centeon Pha rma GmbH, Frankfurt-Niederrad, Germany), on endotoxin release during b acterial proliferation and under antibiotic bactericidal action, time- kill studies were performed by using Escherichia coli ATCC 25922 start ing inocula of 10(3), 10(5), and 10(7) CFU/ml with cefotaxime (120 mu g/ml) alone and in combination with 5S-IgG (2,100 mu g/ml). Samples we re collected for bacterial colony count and endotoxin concentration de terminations; the area under the free endotoxin concentration curve (A UFEC) was calculated by using the trapezoidal rule, Colony counts show ed that cefotaxime had a rapid bactericidal effect because it achieved greater than a 4-log decrease in the numbers of E. coli CFU per milli liter over the first 2 h; the addition of 5S-IgG did not appear to alt er the kinetics of killing. Comparison of the AUFEC revealed that the addition of 5S-IgG resulted in a mean reduction of 50, 66, and 27% in the free endotoxin concentration at starting inocula of 10(3), 10(5), and 10(7) CFU/ml, respectively, Moreover, experiments were conducted w ith a starting inoculum of 10(5) CFU/ml and various amounts of 5S-IgG (2 to 20 mg/ml) to further investigate the dose-effect relation of 5S- IgG on endotoxin release, Decreased AUFECs were observed with increasi ng concentrations of 5S-IgG, suggesting the dose-dependent antiendotox in activity of 5S-IgG, Further study is required to investigate the me chanism(s) responsible for this observation, the biological significan ce of this antiendotoxin activity, and the potential utility of 5S-IgG as an adjuvant therapy in the treatment of gram-negative sepsis.