RESUMO
Antititin antibody occurs in the serum of myasthenia gravis (MG) patients with thymoma (MGT), and is a diagnostic marker for the disease. The mechanism that triggers MGT development is, however, unclear. This study evaluated the role of the main immunogenic region (MIR) of titin in MGT pathogenesis. Titin MIR antiserum (antibody titre 1:16) was obtained and an in situ immunohistochemical study of thymomatous tissue samples was performed. Strong immunostaining for titin MIR was observed on epithelial cell membranes in MGT patients, and the degree of immunostaining was directly proportional to the number of epithelial cells in thymomatous tissue. Serum antititin antibody levels were closely related to titin MIR levels in thymoma cells; however, titin MIR levels did not appear to be related to MG severity. Antititin antibody may be a good surrogate marker for thymoma but is probably not involved in the pathogenesis of MGT.
Assuntos
Proteínas Musculares/imunologia , Miastenia Gravis/complicações , Miastenia Gravis/metabolismo , Proteínas Quinases/imunologia , Timoma/complicações , Timoma/metabolismo , Timo/metabolismo , Adolescente , Adulto , Idoso , Anticorpos/sangue , Criança , Pré-Escolar , Conectina , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Proteínas Musculares/química , Miastenia Gravis/sangue , Miastenia Gravis/patologia , Proteínas Quinases/química , Estrutura Terciária de Proteína , Timoma/sangue , Timoma/patologia , Timo/patologia , Adulto JovemRESUMO
Since Paracoccidioides brasiliensis and Histoplasma capsulatum are known to be present in similar environments, there have been many epidemiologic investigations regarding the prevalences of these two organisms. However, cross-reactivity can occur in paracoccidioidin and histoplasmin skin tests, and this usually results in the overestimation of the prevalence of P. brasiliensis. The prevalence of infection with P. brasiliensis was evaluated in a cross-sectional study of 298 asymptomatic school children in the Brazilian Amazon region (Mato Grosso State). In this investigation, the reactivity of children to two different P. brasiliensis antigen preparations, paracoccidioidin and a purified 43-kD glycoprotein (gp43), was compared with or without the co-administration of histoplasmin. In the group of individuals receiving paracoccidioidin who had a positive histoplasmin skin test result, the prevalence of exposure to P. brasiliensis was 44% (16 of 36). This reactivity to P. brasiliensis was significantly higher than that observed in other groups, which ranged from 4% to 6% (P < 5 x 10(-4) for each). Overall prevalence was 4.6% (95% confidence interval = 2.5-7.7%). These data suggest that gp43 provides a better estimate of exposure to P. brasiliensis when the co-administration of histoplasmin is desired.