COMPLEMENT ACTIVATION BY Tityus serrulatus VENOM AND TsTX-I

Bertazzi, D.T., Talhaferro, V.L., Lazzarini, M., Azzolini, A.E.C.S., Assis-Pandochi, A.I., Arantes, E.C. 

Departamento de Física e Química, FCFRP, USP, Ribeirão Preto, SP, Brasil.

Aim: The effect of  Tityus serrulatus venom and a purified toxin (TsTX-I) on the lytic activity of the classic (CP) and alternative (AP) pathways was examined in order to assess the involvement of complement in the acute inflammatory reaction seen following venom injection.

Methods and results: Male Wistar rats (200 g) received 500 mL of venom (150 mg/kg, i.p.) and were sacrificed 0.5, 1, 2, 4, 24 and 48 h later. Rats treated with TsTX-1 (150 mg/kg, i.p.) were sacrificed 1 and 24 h after toxin injection. A kinetic assay was used to assess the effect of venom and toxin on complement. Serum was mixed with erythrocyte antibody (CP) or rabbit cell (AP) suspensions and the  kinetics of lysiswas monitored by the change in absorbance at 700 nm. The time required for the absorbance to decrease to half its initial value (t_1/2) was calculated from the lysis curve. Increased lytic activity associated with CP and AP occurred at all intervals. Venom produced activities that were 154-170% and 184-220% of the control values for CP and AP, respectively. TsTX-I increased the activities to 132-121% and 128-130% for CP and AP, respectively. The lytic activity of serum from rats treated with venom was abolished by zymosan, indicating that it was dependent on complement. The hematocrit was higher than in the controls from 0.5–4 h after venom administration, but recovered to normal values after 24 h.

Conclusions: The increase in the lytic activity of serum from rats treated with venom and TsTX-I may partly be the result of hemoconcentration. The elevated activity after 24 h may be a consequence of increased synthesis of complement components, as seen with other acute phase proteins in rats treated with this venom.

CORRESPONDENCE TO:

DANIELA TRINCA BERTAZZI, Avenida do Café, Bloco D, Apto 104, Ribeirão Preto, SP, CEP: 14050-230, Brasil, Email: danibert@gly.fcfrp.usp.br