Assessment of pyrogenic response of lipoteichoic acid by the monocyte activation test and the rabbit pyrogen test

- Pyrogenic response of LTA was evaluated in parallel with in vivo/in vitro studies.
- MAT detected LTA pyrogenic concentration (50,000 ng/mL) corresponding to 5.41 EEU/mL.
- MAT was more sensitive than RPT.
- Complementary studies should be performed involving the use of other NEP in MAT.

Lipoteichoic acid (LTA) is a non-endotoxin pyrogen of a great importance in the pathogenesis of sepsis. The Rabbit Pyrogen Test (RPT) is able to detect all types of pyrogens but involves the use of animals. The Bacterial Endotoxin Test (BET) cannot fully replace the RPT because it only detects endotoxins. The Monocyte Activation Test (MAT) is sensitive to all types of pyrogens and it is based on the same biological mechanism that is responsible for the fever reaction in humans. Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) has recommended its use for other pyrogens than endotoxin because its equivalence to RPT can be demonstrated. The aim of this study was to evaluate the pyrogenic responses of the RPT and MAT that was induced by LTA. Different LTA concentrations were assayed by the MAT in parallel to the RPT. The results showed that the MAT was more sensitive than the RPT, demonstrating that the MAT detected LTA. This result may contribute to the acceptance of this test by the Brazilian regulatory agencies as a replacement for the animals used in the RPT.