Poster 43 - Effect of fraction IX-4 from Tityus serrulatus scorpion venom on the human C3 activation

Poster 43. Congresso da Sociedade Brasileira de Toxinologia, 8., Symposium of the Pan American Section of the International Society on Toxinology, 8., 2004, Angra dos Reis, Brasil. Abstracts... J. Venom. Anim. Toxins incl.Trop. Dis., 2004, 10, 3, p.402.

Effect of Fraction IX-4 from Tityus serrulatus Scorpion Venom on the Human C3Activation and LyticActivity of the Complement System.

Depto. de Física e Química - Faculdade de Ciências Farmacêuticas de Ribeirão Preto – USP, Brasil.

Due to its diverse biological activities, the complement system (CS) provides key mediators of inflammation as natural response of the host tissue to any injury. The CS activation by animal venoms has been described and resulted in important discoveries. The aim of the present study was to investigate the action of fraction IX-4 from of Tityusserrulatus venom on the CS, using in vitro assays.

Methods: Tityusserrulatus venom was extracted and chromatographed as previously described (Toxicon 27, 907-916). Fraction IX was rechromatographed on a column of CM-Cellulose –52 which was equilibrated and initially eluted with 0.02 mol/L, pH 4.7 ammonium acetate buffer. Subfractions were then eluted in a stepwise system using 0.02, 0.5, 1.0 and 2.0 mol/L buffer. Complement consumption by fraction IX or subfractions was evaluated using in vitro haemolytic assays and two-dimension immunoelectrophoresis of C3, a complement component.

Results: Four subfractions were obtained from the rechromatography of fraction IX. Pre-incubation of fraction IX or subfraction IX-4 with normal human serum (NHS) induce a concentration reduction in hemolytic activity of the complement alternative pathway, with IC50 (sample concentration inhibiting 50% of the lytic activity) of 1.71 mg/mL and 1.43 mg/mL, respectively. Change in electrophoretic mobility of C3, after incubation of NHS (50mL) with fraction IX or subfraction IX-4 (2mg/mL), were identical to those obtained after incubation with zymosan (positive control), indicating CS activation.

Conclusion: Pre-incubation of NHS with fraction IX or subfraction IX-4 reduced the haemolytic activity of the serum and cleaved C3, indicating that both are able to activate the CS. CS activation probable plays an important role in the inflammatore response observed in scorpion envenomation, justifying the research of scorpion components responsible for its activation.