Lectinas da subtribo Diocleinae como ferramentas histoquímicas. Avaliação em tecidos normais e transformados do sistema nervoso, colo uterino e mama

Abstract

The seed leetins from members of the sub-tribe Diocleinae, show a quaternary structure dependent on the pH, leading to an equilibrium among the monomeric, dimeric and tetrameric forms, and the establisment of the predominant form is essential for the best understanding of their activies. The different biological properties of the lectins are due to their ability to interct with carbohydrate and, thus, with the cell surface sugar residues. Such attachment may induce a variety of changes in cell, which are an expression of biological activities of lectins. Studies of these activities, and the search for others, stíll unknow, are of interest for several reasons: they are useful for detection and assay of lectins; they serve as a basis for the manifold applications of lectins and for development of new ones and they provide us with a means to investigate different cellular and subcellular processes, especially those initiated at the cell surface Numerous studies have been carried out comparing the extent and pattern of lectin binding to normal and malignant cells. Thus, the possibility of using lectins from Canavalia, Cratylia e Dioclea species as histochemieal molecular marker in mammary, brain and cervix uterine normal and transformed tissues were analysed. The binding pattern, was compared to those obtained from the Canavalia ensiformis lectin, Concanavalina A. The purified and peroxidase conjugated lectins were used in direct and indirect metods, with tissues previously treated with 0.1% trypsin solution and 0.3% methanol H202.Solution. The binding was revealed with diaminobenzidine-H2O2, and haematoxylin was used to counterstaining and optic microscopy was used to evaluate the intensity of binding. The binding inhibition were investigated with D- manose, 0- glicose and methyl-a-D-mannoside sugares, at concentrations from 20 to 30 mM. Distinct binding patterns of the lectins studied were observed associated to different tissues pathologies of mammary, brain or cevix uterine. In addition, the best inhibition results to normal as well as transformed tissues with benign and malignant neoplasics were obtained with methyl-a-Dmannoside, reforcing so, that the Diocleinae lectins, bound to glucose and/or mannose containing residues in the membrane surface glycoconjugates, and can be used as molecular marker for these transformed tissues.