MAST CELLS ARE NOT ACTIVATED BY Tityus serrulatus VENOM (TSV).

KWASNIEWSKI F. H.(1), CONCEIÇÃO I. M.(2), FREITAS T. A.(2), ZULIANI J.(2)

(1)Integrated Nucleus of Biotechnology, UMC; (2)Laboratory of Pharmacology, Butantan Institute, São Paulo, Brazil.

In Brazil T. serrulatus are responsible by the fatal accidents and it was experimentally suggested that mast cells (MC) have a role in the lung edema, an important feature observed in severe cases of envenomation. Our goal was to study the role of MC in airways edema and haemorrhage induced by Tsv, and also to investigate if MC are activated by Tsv. Male Wistar rats (160-200g) were used in this study. The increase in vascular permeability and haemorrhage in the airways were evaluated by extravasation of Evans blue dye and cianometahaemoglobin methods respectively, 0.5 and 1h after iv injection of Tsv (200µg/kg, diluted in NaCl 0,9%). Control groups received NaCl 0,9%. The role of MC was evaluated pre-treating (30 min) the animals iv with pirilamine (6 mg/kg) or ketotifen (5 mg/kg). The effect of Tsv on MC was studied by histology of mesenteric MC, and by the release of 5-hydroxytryptamine (5-ht, measured by HPLC) by mesenteric and peritoneal MC in vitro, and in vivo in broncho-alveolar lavage after poisoning. In airways Tsv induced an increase of dye extravasation (trachea 80%, upper bronchi 100%, inner bronchi 325%, lungs 528%) and haemoglobin concentration (trachea 138%, upper bronchi 85%, inner bronchi 186%, lungs 250%), both not modulated by pirilamine or ketotifen. 5-ht was not found in in vitro challenged MC or in broncho-alveolar lavage. Our data shown that MC do not have a role in the increased vascular permeability and haemorrhage in the airways after Tsv injection. The lack of a role for MC in this model of scorpionism is probably due to an incapacity of Tsv to induce MC degranulation.

KEY WORDS: scorpion venom, mast cell, vascular permeability, haemorrhage

FINANCIAL SUPPORT: CNPq; FAEP (Fundação de Amparo ao Ensino e Pesquisa)/UMC.

CORRESPONDENCE TO:

Fábio Henrique Kwasniewski, Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes, Av. Dr. Cândido Xavier de Almeida Souza 200, Centro Cívico, CEP 08780-911 - Mogi das Cruzes, SP. Email: fhkwas@umc.br