Hollow-fiber dialyzers and their pyrogenicity testing by Limulus amebocyte lysate

Aqueous extracts of cellulose hollow fibers (CHF) exhibit positive reactions in some Limulus amebocyte lysate (LAL) tests. However, in spite of LAL activity, the extracts produce no fever reaction in rabbits. A comparison of lysates from different suppliers shows pronounced activity differences when extracts of cuprammonium-derived CHF are tested. One of the lysates, which is fully reactive against standard endotoxin, shows no reaction with such extracts, nor do CHF extracts diminish its sensitivity to standard endotoxin. Investigations of the cuprammonium process have shown that endotoxins introduced by the linters are degraded and washed out. Other endotoxin introduction, particularly by the process water, has been excluded. Oxidative or acidic degradation of cellulose does not result in the formation of LAL-reactive material (LAL-RM). On the other hand, sterile cotton wool shows LAL reactivity, and cellulose acetate regains LAL reactivity when it is saponified. Thus, it appears likely that the LAL-RM found in CHF is of purely cellulosic origin and crossreacts with a number of commercially available lysates.