Failure of antisera to J5 and R595 rough mutants to reduce endotoxemic lethality

Rabbit antisera to J5 (Rc) Escherichia coli and R595 (Re) Salmonella minnesota rough mutants were selected for the highest content of hemagglutinating antibodies to their respective core glycolipids. Despite titers of 1:2560 vs. J5 and 1:640 vs. R595 core glycolipids, the antisera failed to passively protect ICR or CF-1 mice against lethality induced by endotoxins from a variety of wild-type, smooth enterobacteria: E. coli O111:B4, E. coli O127:B8, Salmonella typhimurium, S. minnesota, and Citrobacter freundii. J5 antisera, however, reduced lethality from J5 core glycolipid. In contrast, O-specific rabbit antisera were consistently protective against the lethal activity of wild-type, smooth enterobacterial endotoxins, but such protection was limited to the homologous endotoxin. These findings are consistent with in vitro demonstrations of a highly restricted ability of antibodies to J5 and R595 core glycolipids to bind to endotoxins from wild-type, smooth enterobacteria.