Interaction of Erythrocytes and Endotoxins

CONSIDERABLE diversity of opinion exists as to the sensitivity of haemagglutination tests. The discrepancy in results may to some extent be attributed to technical differences. The factors influencing the reaction, the elution of endotoxin in vitro and the uptake by erythrocytes in vivo have been examined using a dehydrated endotoxin derived from S. typhi (TO–901). This powder consisted of 68.5 per cent ash, 7.8 per cent moisture, 1.6 per cent protein, 2.2 per cent lipids and, based on L-rhamnose hydrate as standard, 2.7 per cent rhamnose. If the method of calculation described by Webster et al. 1 is adopted the polysaccharide content is 14.3 per cent and the endotoxin approximately 20 per cent. The powder was dissolved in isotonic saline, heated to 56° C. for 30 min. and stored at 4° C. for at least 24 hr. before use. The solution had a slight buffer action, pH 7.2. Erythrocytes from healthy rabbits were washed and measured with the haematocrit. A volume of 0.2 ml. packed cells was used in most experiments.