The limulus amebocyte lysate test micromethod and application in the control of sera and vaccines

To estimate the amount of endotoxin in sera and vaccines relatively high quantities of limulus lysate are necessary. Because this makes the control rather expensive, a micromethod was developed in which the amount of limulus lysate was reduced fivefold. This method was used to estimate endotoxin in typhoid vaccines. The relation between the reactions in man and the amount of endotoxin in the vaccines was examined. In these experiments it appeared that the limulus amebocyte lysate (LAL) test demonstrates predominantly the endotoxin in solution. The test was also used as a control test for calf sera. The culture quality of these calf sera as estimated by the lymphocyte stimulation test appeared to be influenced by previous bacterial contamination as could be demonstrated with the LAL test.