Abstract |
The aim of this project was to answer to the question if it is possible to create an in vitro culture system of human B lymphocytes that will be able to react with "self antigens" producing IgG antibodies with high specificity and affinity for the antigen. We are trying to mimic, with the best way, the array of events witch occurs inside the Germinal Centers during a natural humoral response. These events concern mainly the direct contact and interaction between the specific B and T cells witch signal the isotype switch and the induction of somatic mutations to Ig genes inducing their affinity maturation. The selected B cell antigen epitopes come, within synthetic procedures, from the well characterized VNTR regions of human mucins. These molecules show high levels οf glycosylation and they are normally expressed in the mucus epithelium of many tissues such as the intestine. Sometimes, many types of cancer cells from adeno-carcinomas are characterized by an increased number of these mucins with different or absent glycosylation. Thus, the exposure of their protein skeleton in the surface of cancer cells, due to defective glycosylation, make these regions good targets for immuno-therapy. This approach, with the in vitro immunization system, showed production of a specific antibody against the Muc3 peptide with low density. This IgG antibody, was tested by ELISA assay and FACs analysis and showed a great specific inhibition with the soluble Muc3 peptide, and a specific intracellular binding on intestinal cancer cell lines, respectively. It was also tested on formalin-fixed tissue sections from adeno-carcinomas samples, by immunoperoxidase staining, where was found specific dim binding reaction only on malignant intestinal sections.
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