Lonomia obliqua: THE VENOM ACTION ON FACTOR XIIIA

BATISTA, I.F.C.(1), RIBEIRO, A.L.Q.(1), PREZOTO, B.C.(2), CHUDZINSKI-TAVASSI, A.M.(1)

(1)Laboratório de Bioquímica e Biofísica, (2)Laboratório de Farmacologia, Instituto Butantan.

Lonomia obliqua and Lonomia achelous caterpillars contain toxic substances that in contact to human skin, causes severe damage to the healthy, like urticant dermatitis, allergy of the respiratory system, severe hemorrhagic disturbances. The main problem observed in the patients who had contact to the Lonomia bristles is a severe consumptive coagulopathy, which generally leads to a hemorrhagic syndrome. Lonomia achelous venom contains a toxin that degrades FXIIIa either in vivo or in vitro.

Objective:to analyze the action of Lonomia obliqua crude extract (LOCBE) in the plasma Factor XIIIa activity.

Methods:The influence of the venom in the Factor XIIIa (FXIIIa) was analyzed in vitro by gel filtration chromatography and SDS-PAGE and in vivo, infusing LOCBE to wistar rats and following blood clot parameters, the FXIII and fibrinogen levels, before and after envenomation.

Results: According to the gel filtration and SDS-PAGE performed in the in vitro experiments, there is no degradation or complex formation when the purified FXIII is incubated with the venom. Another important finding is that the FXIIIa activity is absolutely maintained after the incubation. Concerning to the in vivo experiments, the plasma of envenomed rats have the level of FXIIIa reduced to 50% and the fibrinogen is totally consumed. However, when defibrinogenated plasma is incubated with LOCBE no consuption was observed.

Conclusion: the results suggest that the reduction of FXIIIa observed in the rats and probably in envenomed patients is caused by the consumption of fibrinogen and not by the FXIIIa inhibition or degradation as occur in L. achelous patients.

Supported by FAPESP

CORRESPONDENCE TO:

BATISTA, I.F.C., Laboratório de Bioquímica e Biofísica, Instituto Butantan, Avenida Vital Brazil, 1500, São Paulo, SP, 05503-900, Brazil, Email: bel.batista@zipmail.com.br