Comparison of HA-1A and E5 monoclonal antibodies to endotoxin in rats with endotoxaemia.

OBJECTIVE: To investigate the ability of two anti-endotoxin IgM antibodies (10 mg/kg) to prevent the hyperdynamic response induced by infusion of Escherichia coli rough mutant endotoxin core types R1 and R2 in rats. DESIGN: Randomised blind laboratory study. SETTING: University department of surgery. MATERIAL: 8 groups of 5 male Sprague-Dawley rats and 10 control animals. MAIN OUTCOME MEASURE: Percentage change in cardiac output during the period of observation. RESULTS: E5 provided significant protection against R1 (p = 0.04) but not against R2. HA-1A gave significant protection against R2 (p < 0.04) but not against R1. In clinical isolates of E. coli the R1 type predominates (about 70%). CONCLUSION: These results may reflect true differences in specificity between the antibodies, but there remains the possibility that these are non-specific effects. Further controls with irrelevant murine and humanized IgM monoclonal antibodies are in progress.