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Lipopolysaccharide (LPS) from Lrptospira interrogans serovar copenhageni was prepared from the aqueous phase of a phenol/water extract. Electron microscopic examination of negatively stained LPS showed a mixture of ribbon-like, round and ring structures. Carbohydrate analysis of the preparations revealed pentoses, hexoses, heptoses, hexosamines, and a 2-keto-3-deoxyonic acid which was chromatographically different from authentic 2-keto-3-deoxyoctonic acid (KDO). The major fatty acids of the LPS were hydroxylauric, palmitic and oleic acids. Although the leptospiral LPS preparations did not contain KDO or hydroxymyristic acid, they were otherwise morphologically and chemically similar to the LPS of other Gram-negative bacteria.

Lipopolysaccharide (EPS), glycolipoprotein (GLP) and lipid extract were prepared from Leptospira interrogans serovar copenhageni. GLP, lipid extract or purified fatty acids from lipid extract produced cytotoxic effects seen as cell enzyme leakage followed by cytotoxic death when tested in mouse fibroblast L929 cells in tissue culture. A11 extracts also agglutinated mouse erythrocytes but purified LPS was not cytotoxic. Neither GLP nor LPS were pyrogenic but both gelled Lzmulus amoebocyte lysatc. Specific anti-GLP IgG neutralized the cytotoxic and haemagglutinating effect of GLP ; however, at higher concentrations it enhanced the cytotoxicity of GLP and mediated iysis of the erythrocytes. A high dose of leptospires (ix. organisms) killed weanling mice causing pathological changes similar to those seen in acute Ieptospirosis. Similar results were obtained with live, dead, pathogenic and saprophytic leptospires. The results suggest that toxicity is involved in leptospiral infection and that lipid components either of whole leptospires or of a leptospiral GLP may contribute to the pathogenesis of acute leptospirosis.