ABSTRACT
Here we demonstrate that T. cruzi antigen molecule SAPA (shed acute phase antigen) with neuraminidase-trans sialidase activity triggers down-regulation of T lymphocyte proliferation by interacting with T lymphocyte muscarinic acetylcholine receptors (mAChR). SAPA attachment to mAChR from Lyt 2.2+ T cells resulted in synthesis of cyclic GMP (cGMP) and secretion of PGE2, an immunoregulator effector substance. These T suppressor cell signals were blunted by atropine and by indomethacin. Cell sorter analysis showed that the interaction of SAPA with purified T cells, affected the ratio of L3T4+/Lyt 2.2+ T cells increasing the percentage of Lyt 2.2+ T cells, effect that was inhibited by the mAChR antagonist, atropine. The interaction between SAPA and mAChR from Lyt 2.2+ T cells may result, therefore, in the down-regulation of the host immune response as consequence of T suppressor/cytotoxic cells activation and PGE2 release as they were observed. These results support the theory of an immunosuppressive state that contribute to the chronic course of Chagas'disease.
Subject(s)
Animals , Mice , Antigens, Protozoan/drug effects , Atropine/pharmacology , Cyclooxygenase Inhibitors/pharmacology , Dinoprostone/metabolism , Down-Regulation/drug effects , Indomethacin/pharmacology , Muscarinic Antagonists/pharmacology , Receptors, Muscarinic/immunology , T-Lymphocytes/drug effects , Trypanosoma cruzi/immunology , Cell Division , Chagas Disease/immunology , Chronic Disease , Concanavalin A , Cyclic GMP/immunology , Dinoprostone/immunology , Flow Cytometry , Mice, Inbred BALB C , T-Lymphocytes/cytology , T-Lymphocytes/immunologyABSTRACT
The present work was intended to evaluate the preparation of antigens, as well as the production and characterization of anti cAMP and cGMP antibodies. Such antibodies were obtained from rabbits, and we used 2'O-succinyl cyclic nucleotide derivate, conjugated with human serum albumin, as antigen. The characterization of the antibodies was monitored by their immunoreactivity with the labelled antigen [125I]-cyclic nucleotide. This assay consists in a competition between a labelled and an unlabelled antigen for a fixed number of binding sites present in the specific antibody. The antibodies were specific for the inducing antigens. Cross-reactivity tests showed low degree competition between the immunogen and other antigens. The very high affinity, high quality and specificity of the generated antibodies indicate that they may be used not only in radioimmunoassay and immunocytochemistry methodologies, but also as bioblockers of physiological pathways