Schwann Cells As Antigenpresenting Cells

The task of displaying the antigens of cell-associated microbes for recognition by T lymphocytes is performed by specific molecules that are encoded by genes comprising the major histocompatibility complex (MHC). The physiologic function of MHC molecules is the presentation of peptides to T cells. Two types of MHC gene products can be distinguished, MHC class I molecules and MHC class II molecules, which differ functionally. Each MHC molecule consists of an extracellular peptide-binding cleft,...

Reciprocal Relationships Form Myelinated Axons

Myelinating Schwann cells differentiate from immature Schwann cells in response to axonal signals, of which neuregulin-1 may be key (see Chapter 2 by Mirsky and Jessen). These axonal signals cause Schwann cells to express the transcription factors Egr2 Krox-20, Brn-5 and Oct6, thereby altering the expression of numerous genes, including the components of the myelin lamellae. The maintenance of the mye-linating phenotype, moreover, appears to depend on a continuous relationship with an axon, as...

Extracellular Matrix In Endoneurium

Every nerve is characterised by the epineurium, surrounding the whole nerve the perineurium, surrounding fascicles of nerve fibres and the endoeurium, defined as the area contained within the perineurium, and in which the single fibres are contained. The adult endoneurium contains abundant amounts of extracellular matrix, which can be present in extracellular spaces among nerve fibres, associated with fibroblasts and organised in basal laminae around Schwann cells or endothelia or anchored or...

Specialisations At Nodes Of Ranvier

Nodes of Ranvier are the sites of action potential propagation, and share many characteristics with axon initial segments, the site of action potential initiation. By restricting currents to nodes, myelin lamellae facilitate saltatory conduction. The idea that myelin contains functional gap junctions is inconsistent with the notion that myelin 'insulates' axons. Rather, myelin lamellae facilitate saltatory conduction by reducing the capacitance of the internode, and by organising axonal ion...

Mdc1a

Brett et al 1998 Di Muzio et al. 2003 Shorer et al. 1995) Brett et al 1998 Di Muzio et al. 2003 Shorer et al. 1995) n.d. not determined n.s. not shown are synthesised by both myelin-forming and non-myelin-forming Schwann cells (Feltri et al. 1994 Niessen et al. 1994 Masaki et al. 2000 Previtali et al. 2003a, 2003b), except for a1 1 integrin, whose expression is restricted to mature non-myelin-forming Schwann cells (Stewart et al. 1997). Schwann cells that are destined to form myelin start to...

Pathology Of

Acute inflammatory demyelinating polyradiculoneuropathy In the common AIDP form of GBS post-mortem studies identified multi-focal endoneurial lymphocytic infiltration as the earliest pathological event (Asbury et al. 1969). This was associated with macrophage invasion and segmental demyelination, which resembled that reported in experimental autoimmune neuritis (EAN) (Waksman and Adams 1956). At the electron microscope level, this macrophage invasion involved the penetration of the Schwann cell...

Antigen Recognition By Schwann Cells

Two types of responses to invading organisms can take place in the human immune system an acute response launched within hours, and a delayed response occurring within days. The immediately responding system is called innate immune system, and it evolves stereotypically and at the same magnitude regardless of how often the infectious agent is encountered. The strategy of the innate immune response may not be to recognise every possible antigen, but rather to focus on a few highly conserved...

Schwann cells as immunomodulatory cells

KIESEIER, WEI HU AND HANS-FETER HARTUNG INTRODUCTION The nervous system has long been considered an immunologically privileged site. This concept was based on the premises that (1) there is a more or less strict anatomic separation between the systemic immune compartment (blood) and the neural tissue (2) molecules required for antigen presentation are absent under normal circumstances (3) there is no lymphatic drainage and (4) immune surveillance by T cells is lacking. It is now...

Introduction to the Schwann cell

The Schwann cell is named in honour of the German physiologist Theodor Schwann (1810 1882, Figure 1.1) who is now acknowledged as the founder of modern histology. In addition to describing the Schwann cell, he made numerous contributions to the fields ofbiology, physiology and histology not least as one of the instigators and main advocates of cell theory. The cell theory defined the cell as the base unit of all living organisms, and had great influence on the study of both plants and animals....

Plp1

During development, Schwann cell precursors from the neural crest migrate out and contact the developing peripheral axons (Harrison 1924 Le Douarin and Dupin 1993). These 'immature' Schwann cells then ensheath bundles of developing axons, a process called 'radial sorting', and further differentiate into myelinating or non-myelinating Schwann cells (Webster 1993). Schwann cells that establish a one-to-one association with an axon, called the 'promyelinating stage' of Schwann cell development,...

Are Perisynaptic Cells At The Nmj Of Schwann

Although it has been widely accepted that the motor nerve terminal is capped with non-neuronal cells, whether these synapse-associated cells indeed originate from Schwann cells was questioned in the late 1960s. Based on electron microscope observations, Shanthaveerappa and Bourne (1967) used the term 'PSC' as an abbreviation for 'perisyn-aptic cells', which they believed were perineural epithelial cells, rather than Schwann cells (Shanthaveerappa and Bourne 1966 Shanthaveerappa and Bourne...

Outline Of The Schwann Cell Lineage

As stated earlier, Schwann cells in spinal nerves arise from the neural crest. In mature nerves two morphological variants of Schwann cells, both associated closely with axons, exist throughout peripheral nerves (Figure 2.1). These are myelinating and non-myelinating Schwann cells, which surround large- and small-diameter axons, respectively (Bunge 1993b Garbay et al. 2000 Jessen and Mirsky 1999 Jessen and Mirsky 2002 Lobsiger et al. 2002 Corfas et al. 2004 Jessen and Mirsky 2004 Sherman and...

Y90c

D6Y, H10P, S15F, S22F, D32G, D46V, H52Y, I69T, T95M G134R R198S K207del EC extracellular TM transmembrane IC intracellular PKC protein kinase C. although axonal loss of large diameter nerve fibres was also severe (no fibres > 7 mm). Macrophages were found in areas of segmental demye-lination but only in a few nerve fibres (< 2 ). Teased fibre immunohis-tochemistry shows voltage-gated sodium channel subtype 1.8 (Nav1.8) expressed at the nodes of Ranvier around the areas of segmental...

The Tripartite Organisation Of

The NMJ is arguably the best-studied synapse due to its large size, relatively simple organisation and easy accessibility for in vivo observations and experimental manipulations (Katz 1966 Salpeter 1987 Sanes and Lichtman 1999 Ko and Thompson 2003). The NMJ is a tripartite synapse composed of the motor nerve terminal, the postsynaptic specialisations with acetylcholine receptors (AChRs), and PSCs. The frog, Rana pipiens (Figure 5.1a d) and mouse, Mus musculus (Figure 5.1e h) are the best...

Brief History Of Ferisynaftic Schwann Cells

While Theodor Schwann was credited for observing rows of his namesake cells along peripheral nerve fibres, the first hint of the existence of PSCs can be attributed to Louis-Antoine Ranvier (1878), Figure 5.2 Selective ablation of frog PSCs in vivo. (a) Fluorescent image of frog NMJs (labeled with PNA, green) treated with mAb 2A12 and complement. The complement-mediated lysis of PSCs is confirmed with positive staining of ethidium homodimer-1 (red), which labels nucleic acids in the cell bodies...

Schwann Cells As Immunocompetent Cells

In summary, our current knowledge of the potential immunocompe-tence of Schwann cells suggests that Schwann cells can induce an immune response within the peripheral nerve via pattern-recognition receptors, but also trigger a T cell response via the presentation of Figure 7.1 Immunocompetence of Schwann cells. (a) Antigen presentation Schwann cells are able to process and present endogenous antigens to immune cells. Schwann cells are able to express the major histocompatibility (MHC) class I...

Molecules That Control Gliogenesis From The Neural Crest

Whether glial differentiation from the neural crest represents the default mode of differentiation, as has been suggested for CNS gliogen-esis (Doetsch 2003 Gotz 2003), remains to be determined. The in vitro data on the action of NRG1, BMP2 4 and Notch activation, three major signals implicated in this process, are however consistent with this idea. NRG1 suppresses neuronal development, an action also shared by Notch activation, whereas BMP2 4 activates neuronal development and overrides the...

Sox2

Figure 2.3 Some of the factors that have been implicated in the control of early Schwann cell development and myelination. Evidence for molecules shown in bold is based on in vivo observations of mutant animals. The other molecules have been implicated in vitro. In some cases the in vitro evidence is substantially more complete than in others. Sox-10 is required for the generation of all peripheral glia from the neural crest Britsch et al. 2001 , while BMPs inhibit glial differentiation Shah et...