T-cell-mediated autoimmunity: novel techniques to characterize autoreactive T-cell receptors

Histological samples of autopsy or biopsy tissue provide the best available evidence that autoreactive T cells are involved in the immunopathogenesis of many autoimmune diseases. However, morphology alone does not provide information on the antigen-specific T-cell receptor (TCR) of these cells, let alone on their antigen specificity. In this review article we discuss a number of emerging possibilities for identifying TCR sequences directly from biopsy tissue. We also review the methods for expressing presumably autoreactive TCR molecules and speculate on how the expressed TCR might be used to identify target antigens. Such information should eventually provide new insights into disease pathogenesis which lead to better therapies.     

Serum-induced chronic pancreatitis

Summary Clinical research into patients with idiopathic chronic pancreatitis points to a possible immunopathogenetic process in a number of cases.In order to examine the behaviour between the exocrine pancreas under the influence of anti-rat-pancreas immune serum produced in rabbits, a 1.00 ml immune serum is administered once a week over a maximum 26 week period into Wistar-rats by intraperitoneal injection. By electrone-microscopy a much reduced production of enzymes apparently takes place, though to differing extent. There is also destruction of the basal membrane of acinocytes; the production of interstitial oedema, the new formation of collagen fibres and the proliferation of connective tissue cells. Under a conventional light microscope the first changes become noticeable after 8-12 weeks of study. These take the form of localised cell decay, deterioration and lysis of acinocytes; and an increasing non-specific inflammation. There is also the new formation of connective tissue. After 20–26 weeks the exocrine pancreas is characterised by reduction of parenchyma, acino-ductal metaplasia, chronic inflammatory infiltrates of differing density, fibrous and irregular calibres of the smaller and larger ducts.The findings are almost identical to the structural changes of chronic idiopathic pancreatitis in human beings. The results support the view of an immuno-pathologic aetiology for human chronic idiopathic pancreatitis.Supported by Deutsche Forschungsgemeinschaft     

The Resistance of Certain Tissues to Invasion: Penetrability of Explanted Tissues by Vascularized Mesenchyme

If puppy tissues are explanted onto the chick chorioallantoic membrane, those tissues which normally have a blood supply are rapidly invaded by vascularized mesenchyme of host origin. Hyaline cartilage, a tissue virtually devoid of blood vessels, is impenetrable by proliferating mesenchyme of the host, while calcified cartilage, which normally is vascularized, is penetrable. The stroma of the cornea, another normally avascular tissue, is readily penetrable, but Descemet's membrane forms a barrier to invasion by host tissues. The experimental system used permits the design of experiments in which the study of factors responsible for the resistance of tissues such as cartilage to invasion can be undertaken.     

Pattern and persistence of the epitope-specific IgM response against human cytomegalovirus in renal transplant patients.

The humoral immune response against human cytomegalovirus (HCMV) was evaluated in immunocompromised patients by Western blotting (WB) based on recombinant viral envelope (gB and gH) and tegument (pp150 and pp65) proteins. Three groups of patients were investigated: (a) 74 renal transplant recipients; (b) 24 hemodialysis patients, both groups without clinical evidence of viral infections; and (c) 19 renal transplant patients with manifest HCMV infections. The results obtained suggest that (i) the WB is considerably more sensitive, recognizing the HCMV-specific IgM response rather than the enzyme-linked immunosorbent assays. An IgM response was detected in one-third of all clinically asymptomatic renal patients. (ii) The virus-specific IgM response is primarily directed against the pp150 epitope. (iii) In patients with clinically manifest HCMV disease, additional IgM reactivities are most frequently directed against the glycoprotein B epitope. (iv) The severity of HCMV infections correlates with the extent of the IgM antibody response, i.e. with the number of specific epitopes involved. (v) After transplantation, IgM reactivity and its epitope-specific pattern persist for years.     

Prevalence of human T-Cell lymphotropie virus infections in Germany

The extent of human T-cell lymphotropic retorvirus HTLV-I and HTLV-II infections in the general population in central Europe has not been investigated fully. Two hundred forty-eight thousand blood donors from southern Germany were examined serologically for antibodies to the human lymphotropic retroviruses HTLV-I and HTLV-II: 0.021% were confirmed postive and 0.056% were “indeterminate”. A limited number of seropositives and “indeterminate” samples were analyzed by polymerase chain reaction (PCR): the seropositives were confirmed as positive and 43% of the “indeterminate” samples were PCR-positive. The range of 0.021% HTLV-positives in 248,000 donors, i.e. about two in 10,000 individuals, mirrors closely the published data for the United States. © 1994 Wiley-Liss, Inc.     

Central nervous system involvement in arthrogryposis multiplex congenita: Overview of causes,diagnosis, and care

Arthrogryposis or AMC, arthrogryposis multiplex congenita, is defined as multiple congenital joint contractures in more than two joints and in different body areas. The common cause of all AMC is lack of movement in utero, which in turn can have different causes, one of which is CNS involvement. Intellectual disability/CNS involvement is found in approximately 25% of all AMC. AMC with CNS involvement includes a large number of genetic syndromes. So far, more than 400 genes have been identified as linked to AMC, with and without CNS involvement. A number of neonatally lethal syndromes and syndromes resulting in severe disability due to CNS malfunction belong to this group of syndromes. There are several X‐linked disorders with AMC, which are primarily related to intellectual disability. A number of neuromuscular disorders may include AMC and CNS/brain involvement. Careful clinical evaluation by a geneticist and a pediatrician/pediatric neurologist is the first step in making a specific diagnosis. Further investigations may include MRI of the brain and spinal cord, electroencephalogram, blood chemistry for muscle enzymes, other organ investigations (ophtalmology, cardiology, gastrointestinal, and genitourinary systems). Nerve conduction studies, electromyogram, and muscle pathology may be of help when there is associated peripheral nervous system involvement. But most importantly, genetic investigations with targeted or rather whole exome or genome sequencing should be performed. A correct diagnosis is important in planning adequate treatment, in genetic counselling and also for future understanding of pathogenic mechanisms and possible new treatments. A multidiciplinary team is needed both in investigation and treatment.     

The osmotic behaviour of toad skin epithelium (Bufo viridis)

The effect of saline adaptation on the intracellular Na, K, Cl, P concentrations and dry weight content of the toad skin epithelium (Bufo viridis) was studied using the technique of electron microprobe analysis. The measurements were performed on isolated abdominal skins either directly after dissection or after additional incubation in Ussing-type chambers.Adaptations of the toads to increasing NaCl concentrations for 7 days resulted in increased blood plasma osmolarity and a parallel increase in the cellular electrolyte, P and dry weight concentrations of the epithelium, the K increase representing the most significant fraction of the intracellular osmolarity increase. No evidence was obtained to show that the nucleus and cytoplasm reacted differently from each other and all living epithelial cell types basically showed the same response.Incubation of the isolated skins under control conditions showed a drastic inhibition of the transepithelial Na transport after adaptation to high salinities. In spite of the large variations in the transport rate almost identical intracellular electrolyte concentrations were observed. In tap water adapted toads the average cellular concentrations were 8.8 mmole/kg wet weight for Na, 109.6 for K, 41.5 for Cl, and 135.3 for P, respectively. Incubation of the skin with Ringer's solution of different osmolarities demonstrated that the epithelial cells are in osmotic equilibrium with the inner bathing solution. The results are consistent with the view that the osmotic adaptation is mainly accomplished by the movement of water.This work was supported by grants from the Deutsche Forschungsgemeinschaft and the Stiftung Volkswagenwerk     

Elektronenmikroskopische Untersuchungen am embryonalen Mycetom der Kleinzikade Euscelis plebejus Fall. (Homoptera,Cicadina)

Zusammenfassung Die a-Symbionten von Euscelis plebejus treten während der Embryonalentwicklung ihres Wirts in zwei morphologischen Typen auf, die als Infektionsstadium und als vegetative Form beschrieben werden. Die Infektionsstadien teilen sich durch septenartiges Einwachsen der Symbiontenmembranen. Infektionsstadien von Zikadensymbionten waren bisher nur während der Ovarialinfektion aus den Mycetomen weiblicher Imagines bekannt. Die a-Infektionsformen sind gekennzeichnet durch ihr elektronendichtes Cytoplasma, eine ungleichmäßige Verteilung der Ribosomen mit einer ribosomenfreien Randzone und durch Membrankörper. Das Cytoplasma der vegetativen Symbionten erscheint elektronendurch lässiger. Die Ribosomen liegen homogen in der Cytoplasmagrundsubstanz verteilt.Die a-Symbionten liegen vom Zeitpunkt der Eiablage bis zum Eindringen in die a₁-Mycetocyten als Infektionsstadien vor. Nach der Aufnahme in die a₁-Mycetocyten nehmen sie das Aussehen vegetativer Formen an. Im transitorischen Mycetom erscheinen erneut Infektionsstadien während der Übersiedelung in die zweikernigen a₂-Mycetocyten.Jeder Symbiont wird von zwei eigenen Membranen umgeben. Beim Eindringen von Ooplasma in den Symbiontenball wird jeder Symbiont von einer Wirtsmembran umhüllt, die er bis zur Infektion der Wirtszelle behält. In den Mycetocyten umgibt eine offensichtlich vom Wirtscytoplasma erneut gebildete Hüllmembran die vegetativen Symbionten. In den vegetativen a-Symbionten tritt häufig ein mikrofibrillärer kristallartiger Einschlußkörper auf. — Kernäquivalentstrukturen waren in keinem Symbiontenstadium cytologisch mit Sicherheit nachzuweisen.

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Electron microscopic studies on the embryonic mycetome of the leafhopper Euscelis plebejus fall. (Homoptera, cicadina)

Summary During the embryonic development of their host the a-symbiotes of the leafhopper Euscelis plebejus appear in two different morphological types: infective form and vegetative form. The infective forms are able to multiply by ingrowth of their membranes. Until now infective forms of leafhopper symbiotes were only known from the ovarial infection by adult female mycetomes. The infective form of the a-symbiote is characterized by its electron dense cytoplasm, an asymmetric distribution of the ribosomes, a ribosome-free border, and by membraneous bodies. The cytoplasm of the vegetative form is less electron dense and the ribosomes are scattered throughout the cytoplasm.From the time of oviposition until they enter the a₁-mycetocytes, the a-symbiotes are found as the infective form. After entering the a₁-mycetocytes they take on the appearance of the vegetative form. In the transitory mycetome the infective forms appear again during the transition into the binucleate a₂-mycetocytes.Each symbiote is surrounded by two unit membranes of its own. As the ooplasm penetrates the symbiote mass, each symbiote is also surrounded by a host membrane, which remains until the infection of the host cells. In the mycetocytes the vegetative symbiotes have a new membrane around them, which is obviously developed from the cytoplasm of the host cell. In the vegetative a-symbiotes there is frequently a paracrystalline inclusion. — It was impossible to demonstrate nucleoid structure with certainty in any symbiote form.

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Abkürzungen a a-Symbionten - a_i a-Infektionsstadien - a_v vegetative a-Symbionten - a-Mc a-Mycetocyt - a-Z a-Zelle - eK elektronendichter Körper - ER endoplasmat. Retikulum - M₁ innere Symbiontenmembran - M₂ äußere Symbiontenmembran - M₃ Hüllmembran - Mf Mikrofibrillen - Mi Mitochondrien - Mk Membrankörper - Mt Mikrotubuli - Nu Zellkern - Py Kernpyknosen - Ri Ribosomen - Sb Symbiontenball - Sm Symbiontenmembranen - t t-Symbionten - t_v vegetative t-Symbionten - t-Mc t-Mycetocyt - t-Z t-Zelle - Zm Zellmembran Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.Herrn Prof. Dr. K. Sander danke ich für stete Förderung meiner Arbeit und Frau A. Kaufmann für die Einführung in die elektronenmikroskopische Technik.     

Differentiation markers of Sertoli cells and germ cells in fetal and early postnatal human testis

The definition of the temporal sequence of appearance of fetal markers during prenatal and early postnatal development in Sertoli and germ cells may be important for understanding the mechanisms underlying their reexpression in disorders of the adult testis. For this reason, we studied the expression of Sertoli and germ cell markers in 25 human testes spanning a period from 8 gestational weeks to 4 years. Well-characterized antibodies were employed to anti-Müllerian hormone (AMH), cytokeratin 18 (CK18), vimentin (VIM), M2A-antigen (M2A), germ cell alkaline phosphatase (GCAP), and somatic angiotensin-converting enzyme (sACE) on formalin-fixed and microwave-pretreated paraffin sections. In Sertoli cells, AMH and VIM were consistently present. While VIM and CK18 were coexpressed in embryonic testes, CK18 was progressively downregulated and completely absent from the 20th gestational week. M2A was absent or moderately expressed in fetal Sertoli cells but increased during further development. In germ cells, M2A was consistently found in primordial germ cells (PGCs) as well as in M- and T₁-prespermatogonia. In contrast, sACE and GCAP were absent from PGCs but were a distinct feature of late M- and early T₁-prespermatogonia and appeared predominantly between the 18th and the 22nd gestational weeks. Both T₂-prespermatogonia and postnatal prespermatogonia were devoid of any marker. While CK18 represents a differentiation marker for fetal Sertoli cells, M2A, GCAP, and sACE can be used as differentiation markers for the discrimination of different germ cell types during human prespermatogenesis. Because various immunophenotypes reflect distinct differentiation stages, this knowledge may be important for understanding adult testicular pathology.