Biological behavior of Leishmania (L.) amazonensis isolated from a human diffuse cutaneous leishmaniasis in inbred strains of mice S.M.N. Cupolilo1,2, C.S.F. Souza1, A.L. Abreu-Silva1,3, K.S. Calabrese1 and S.C. Gonçalves da Costa1 1Laboratório de Imunomodulação, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Manguinhos, Rio de Janeiro, RJ, Brasil, 2Departamento de Patologia, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, Brasil and 3Departamento de Patologia, Universidade Estadual do Maranhão, Maranhão, Brasil Offprint requests to: Sylvio Celso Gonçalves da Costa, Laboratório de Imunomodulação, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil, 4365 - Pavilhão Carlos Chagas - 3º andar - Manguinhos - Rio de Janeiro - Brasil - CEP: 21045-900. Fax: 55 21 2560-6572. e-mail: sycosta@ioc.fiocruz.br   Summary. After a subcutaneous injection of 100000 purified amastigotes of an isolate from a diffuse case of cutaneous leishmaniasis caused by the MHOM/BR/76/Ma-5 strain of Leishmania amazonensis, three inbred mouse strains developed a progressive nodular lesion, which evolved to an ulcerated lesion. Based on these data, mice of BALB/c, C57BL/6 or C57BL/10 could be classified as susceptible. The majority of mice developed metastases in the footpads, ear, tail, nose and oral mucosa. Amputation of the members related to the primary lesion was frequent. Experiments using the limiting dilution analysis showed that there was no correlation between lesion and parasite load. It has been demonstrated that these mouse strains could be considered excellent models for mucocutaneous leishmaniasis when infected with L. amazonensis. Metastatic lesions caused destruction of the nasal region with many parasitized macrophages under the epithelial surface of the nasal mucosa. Bone destruction occurred with an extensive inflammatory reaction presenting macrophages heavily parasitized by amastigotes. The parasites also spread to the periodontal ligament and other structures of the oral cavity, which could induce a severe inflammatory process. This study indicates that both nasal and oral lesions in mice infected by L. amazonensis were characterized by an inflammatory reaction with the presence of a high parasite load within macrophages. Histol. Histopathol. 18, 1059-1065 (2003) Key words: Inbred mice, Leishmania amazonensis, Oral and nasal mucosa, Pathology, TNFa DOI: 10.14670/HH-18.1059