Bergsteinsdottir, Kristin; (1992) Studies of calcium channels in cultured neuroblastoma and muscle cells using monoclonal antibodies. Doctoral thesis (Ph.D.), University College London.

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Abstract

This thesis deals with: (A) The regulation of the major histocompatibility complex class II molecules on Schwann cells in vivo and in vitro, (B) the induction of the major histocompatibility complex class II molecules on oligodendrocytes and (C) the effect of collagen type I, which is a major component of the extracellular matrix, on the function of enteric glial cells. The expression of class II molecules on Schwann cells in vivo and in vitro was investigated, in particular the question of whether Schwann cells are able to present mycobacterial antigen to sensitized lymphocytes. When Schwann cells were cocultured together with antigen and T cells they could support the lymphoproliferative responses of mycobacteria-reactive T lymphocytes without pretreatment with interferon-γ. After the incubation period essentially all of the Schwann cells expressed class II antigen. T cell derived interferon-γ and tumor necrosis factor appeared to mediate the T cell induced class II expression on the Schwann cells. It was also found that the injection of cytokines or mycobacterial antigens into the living sciatic nerve, and crushing the nerve induced class II expression on some Schwann cells. Another molecule which is important in the T cell mediated immune response is interleukin-1. It was found that Schwann cells produce interleukin-1 when they are incubated with mycobacterial antigens or cytokines, and the interleukin-1 activity was seen both in the Schwann cell supernatant and in the cell lysate. These results further support the view that Schwann cells can function as antigen presenting cells and may participate in neuroimmunological responses within peripheral nerves. When rat oligodendrocytes derived from the optic nerve were incubated with interferon-γ in the presence of dexamethasone they expressed the major histocompatibility complex class II molecules. Collagen is a major component of the extracellular matrix and there is now evidence from several studies, particularly on epithelial cells but also on muscle cells, that collagen type I can influence cell proliferation, differentiation, migration and specific gene expression. A possible role for type I collagen in the induction of differentiation of neural cells was investigated, using the enteric nervous system of the gut. When the myenteric plexus of a newborn guinea pig is taken into culture and grown on a 2-dimensional substrate, the glia start to divide and migrate away from the neurons, and the network-like arrangement of the plexus breaks down. To test whether collagen type I could prevent these changes, the myenteric plexus freshly dissected from the gut was embedded in a 3-dimensional collagen gel and grown in a defined medium containing 0.5% FCS. In this case the glial cells did not migrate away from the neurons and the plexus stayed as a network. When a disaggregated culture of the myenteric plexus was embedded in a 3-dimensional collagen gel the cultures rearranged into a network of small ganglia and interconnecting strands, very similar to the myenteric plexus in situ. Electron microscopy showed that the ultrastructure of a reformed plexus was very similar to that seen in situ. These results show that type I collagen prevents the breakdown of the myenteric plexus and also induces network formation in a disaggregated culture.

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