In vitro hemolytic activity of Lonomia obliqua caterpillar bristle extract on human and Wistar rat erythrocytes Carla Simone Seibert a , Elvira Maria Guerra Shinohara b , Ida Sigueko Sano-Martins a, * a Laborato ´rio de Fisiopatologia, Instituto Butantan, Avenida Vital Brazil, 1500, CEP 05503-900, Sa ˜o Paulo SP, Brazil b Departmento de Ana ´lises Clı ´nicas e Toxicolo ´gicas, Faculdade de Cie ˆncias Farmace ˆuticas, Universidade de Sa ˜o Paulo, Av. Lineu Prestes, 580. CEP 05508-900, Sa ˜o Paulo SP, Brazil Received 9 September 2002; accepted 19 February 2003 Abstract Human accidental envenomation caused by skin contact with the bristles of Lonomia obliqua caterpillar causes coagulation and fibrinolysis disorders. Alterations of hematologic parameters are observed only in severe cases of envenomation, but with no clinical evidence of intravascular hemolysis. However, since we have observed intravascular hemolysis in preliminary studies using Wistar rats as an experimental model for investigating L. obliqua envenomation, the objective of the present study was to investigate the in vitro hemolytic activity of the bristle extract of L. obliqua caterpillars on human and rat erythrocytes. Our results showed that the bristle extract has indirect and direct hemolytic activity on human and rat erythrocytes, although direct hemolytic activity was only observed at higher bristle extract concentrations. We also observed that the bristle extract has a proteolytic activity on band 3 of human and rat erythrocyte membranes. Thus, crude L. obliqua bristle extract was found to contain at least two components with hemolytic activity on erythrocytes, a phospholipase enzyme and another protein with a direct activity on the erythrocyte membrane. q 2003 Elsevier Science Ltd. All rights reserved. Keywords: Hemolysis; Proteolysis; Lonomia obliqua; Erythrocyte membrane proteins 1. Introduction There are more than 165,000 species classified in Lepidoptera order whose larval stages are phytophagous, causing agricultural problems. The majority of lepidopter- ans are not of medical importance, but some genera such as Megalopyge (Mcgovern et al., 1961; McMillan and Purcell, 1964), Thaumetopoea (Katzenellenbogen, 1955), Euproctis (Higuchi and Urabe, 1959; Blair, 1979) and Latoia (Kawamoto, 1978) cause dermatitis after skin contact with caterpillar bristles. The moths of Lonomia obliqua (Satur- niidae, Hemileucinae) have a larval (caterpillar) stage, which are characterized by six instars. They are considered polyphagous and have been frequently found in the neighborhood of farm houses, especially in the fruit trees. In this stage, L. obliqua has gregarious habits forming caterpillar colonies. Envenomation occurs involving one or more specimens usually in instars 4–6 of the larva. These caterpillar toxins enter the human skin through the urticating spines of the larvae (Veiga et al., 2001), causing coagulation and fibrinolysis disturbances in human beings, and also in animal models, such as rats and rabbits (Kelen et al., 1995; Reis et al., 2001a,b; Marval et al., 1999; Prezoto et al., 2002). Human accidents, showing severe hemorrhagic mani- festations caused by the skin contact with caterpillar bristles of the Lonomia achelous (Lemaire, 1974, 1988), were firstly reported in the tropical forests of Venezuela, (Arocha-Pi- n ˜ango, 1967) and in north of Brazil (Fraiha et al., 1986). This envenomation had been considered rare until 1989, 0041-0101/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0041-0101(03)00040-0 Toxicon 41 (2003) 831–839 www.elsevier.com/locate/toxicon * Corresponding author. Tel.: þ 55-11-37267222; fax: þ 55-11- 37261505. E-mail address: lusiada@uol.com.br (I.S. Sano-Martins).