Cometary Organic Macromolecules in Interplanetary Dust Particles?

in Lunar and Planetary Institute Science Conference Abstracts 34 (2003, March 01)

Based on the determination of N concentrations in D-rich molecules in IDPs and new 14N/15N ratios in comets, it is proposed here that organic chemistry of IDPs may provide a direct link with comets.

Cytokine Production by Human Thymic Epithelial Cells: Control by the Immune Recognition of the Neurohypophysial Self-Antigen

in Regulatory Peptides (1996), 67(1), 39-45

Oxytocin (OT) has been shown to be the dominant peptide of the neurohypophysial family expressed by thymic epithelial and nurse cells (TEC/TNC) in various species. Thymic OT is not secreted but, after ... [more ▼]

Oxytocin (OT) has been shown to be the dominant peptide of the neurohypophysial family expressed by thymic epithelial and nurse cells (TEC/TNC) in various species. Thymic OT is not secreted but, after translocation of a hybrid neurophysin/MHC class I protein, is integrated within the plasma membrane of TEC, thus allowing its presentation to pre-T cells. In order to further demonstrate that thymic OT behaves like a membrane antigen, we assessed the effect of mAbs to OT on cytokine productions by cultures enriched in human TEC. 75-85% pure TEC cultures were prepared from human thymic fragments. Using immunofluorescence and confocal microscopy, ir-OT, ir-interleukin-1 beta (IL-1 beta), ir-interleukin-6 (IL-6) and ir-leukemia inhibitory factor (LIF) could be detected in these TEC cultures. ir-OT was restricted to TEC, while some ir-IL-6 and ir-LIF were also seen in occasional fibroblasts. In basal conditions, ir-IL-6 and ir-LIF (but not ir-OT and ir-IL-1 beta) were detected in the supernatants of human TEC cultures. MAbs to OT induced a marked increase of ir-IL-6 and ir-LIF secretion in TEC cultures. No significant effect was observed using mAbs against vasopressin, mouse immunoglobulins, or control ascitic fluid controls. These data show that OT is fully processed and recognized by specific mAbs at the outer surface of TEC plasma membrane. They further support that thymic OT behaves as the self-antigen of the neurohypophysial family. [less ▲]

Evidence That Insulin-Like Growth Factor 2 (Igf2) Is the Dominant Thymic Peptide of the Insulin Superfamily

in Thymus (1993), 21(2), 115-27

The central T-cell tolerance of neuroendocrine functions has been proposed to be primarily induced by the thymic repertoire of neuroendocrine self antigens. The present study aimed at characterizing the ... [more ▼]

The central T-cell tolerance of neuroendocrine functions has been proposed to be primarily induced by the thymic repertoire of neuroendocrine self antigens. The present study aimed at characterizing the human thymic insulin-related autoantigen able to represent the pancreatic B-cell function in face of the developing T-cells. Immunofluorescence studies were performed on human and rat thymic sections, as well as on the rat IT-45R1 thymic epithelial cell line using several antibodies to epitopes of the insulin peptide superfamily. These studies identify beyond any doubt that insulin-like growth factor 2 (IGF2) is the dominant thymic peptide of the insulin family. The sequence of an insulin-derived autoantigen is proposed. This autoantigen is a nonamer and has a hydrophobic residue leucine (L) at position 9. In the human species, this autoantigen would primarily be tolerogenic for the pancreatic B-cell endocrine function during fetal development. [less ▲]

Le langage universel de la communication cellulaire et sa pathologie. Les chemins communs du langage intercellulaire

in Revue Médicale de Liège (1992), 47(3), 109-15

At the Cutting Edge. Biosynthesis and Paracrine/Cryptocrine Actions of 'Self' Neurohypophysial-Related Peptides in the Thymus

in Molecular & Cellular Endocrinology (1991), 76(1-3), 27-31

Neuroendocrinology of the Thymus

in Hormone Research (1989), 31(1-2), 81-4

The neuropeptides oxytocin (OT) and vasopressin (VP) are synthesized in the human thymus in a similar way as in the hypothalamo-neurophypophyseal system. Immunocytochemistry with polyclonal and monoclonal ... [more ▼]

The neuropeptides oxytocin (OT) and vasopressin (VP) are synthesized in the human thymus in a similar way as in the hypothalamo-neurophypophyseal system. Immunocytochemistry with polyclonal and monoclonal antibodies revealed that immunoreactive OT- and VP-producing cells are localized in the subcapsular cortex and medulla of human and murine thymuses. The epithelial nature of the neuroendocrine thymic cells is demonstrated by their immunostaining with a monoclonal antibody against cytokeratin. An original example of a neuroendocrine-immune microenvironment is given by the thymic nurse cells which are composed of a large neuroendocrine epithelial cell enclosing numerous mitotic immature thymocytes. These observations and the previously reported mitogenic and immunomodulatory properties of VP and OT upon mature T cells and thymocytes strongly support the existence of a neuroendocrine thymo-lymphoid axis and an active role of thymic VP and OT in T cell differentiation and activation. [less ▲]