Reinhard Pabst

Apoptotic, but not necrotic, tumor cell vaccines induce a potent immune response in vivo

Prophylactic tumor vaccination against subsequent tumor challenge depends on effective cross‐priming in vivo. Professional APCs process tumor antigens from whole tumor cells and present them to CD4+ and CD8+ T cells. Data suggest that dendritic cells process antigens more efficiently from necrotic cells than from apoptotic cells in vitro. We compared the effect of apoptosis vs. necrosis in vivo using different tumor models (CT26, RENCA, B16 and CT26‐HA). Apoptosis was induced by γ‐irradiation prior to injection and verified in vivo. Apoptotic CT26‐HA, CT26‐wt or RENCA prevented tumor outgrowth in 100%, 75% and 100%, respectively, of mice for more than 30 days after challenge. In contrast, injection of necrotic tumor cells led to protection of no more than 0–30%. Prolonged tumor‐free survival was also observed in mice after vaccination with irradiated B16 cells. In vivo protection experiments correlated very well with in vitro cytotoxicity assays. Immunohistochemical analysis of the vaccine site showed a strong CD4+ and CD8+ T‐cell response after injection of apoptotic cells, which was accompanied by the presence of dendritic cells. In contrast, necrotic cell vaccines attracted a strong local macrophage response. Our data clearly demonstrate that only apoptotic tumor cell vaccines induce a potent antitumor immune response.

Cytokeratin 18 is an M-cell marker in porcine Peyer's patches.

The intermediate filaments of the dome epithelium of porcine Peyers patches were studied by immunohistochemistry. The labelling patterns of monospecific antibodies directed against cytokeratins 8, 18 and 19 differed considerably. About 40% of the dome epithelial cells were intensely labelled by three different anti-cytokeratin 18 antibodies, indicating that large amounts of cytokeratin 18 are present in these cells. In order to verify that these cytokeratin-18-immunoreactive cells were M-cells, uptake studies using fluorescein-labelled yeast particles were performed. Numerous yeast particles were found exclusively in dome epithelial cells that were highly positive for cytokeratin 18, thus representing M-cells. In contrast, the content of cytokeratin 19 in M-cells was lower than that in neighbouring enterocytes. The labelling intensity of cytokeratin 8 did not differ between M-cells and enterocytes. In addition, the absence of vimentin and desmin from the dome epithelium of porcine Peyers patches was demonstrated. The results show (1) that porcine M-cells differ from enterocytes in the composition of their cytoskeleton, (2) that cytokeratin 18 is a useful marker for detecting porcine M-cells and (3) that this marker directly correlas with M-cell function.

Lymphocyte traffic through lymph nodes and Peyer's patches of the rat: B- and T-cell-specific migration patterns within the tissue, and their dependence on splenic tissue

The migration routes of lymphocyte subsets through organ compartments are of importance when trying to understand the local events taking place during immune responses. We have therefore studied the traffic of B, T, CD4+, and CD8+ lymphocytes through lymph nodes and Peyers patches. At various time points after injection into the rat, labeled lymphocytes were localized, and their phenotype characterized in cryostat sections using immunohistochemistry. Morphometry was also performed, and the recovery of 51Cr-labeled lymphocytes in these organs was determined. B and T lymphocytes entered the lymph nodes via the high endothelial venules in similar numbers. Most B lymphocytes migrated via the paracortex (T cell area) into the cortex (B cell area), and then back in substantial numbers into the paracortex. In contrast, T lymphocytes predominantly migrated into the paracortex and were rarely seen in the cortex. No obvious differences were seen between various lymph nodes and Peyers patches and the routes of CD4+ and CD8+ lymphocytes. After injection of lymphocytes into animals with autotransplanted splenic tissue, the number of B lymphocytes that had migrated into the B cell area of lymph nodes and of Peyers patches was significantly decreased, whereas CD4+ lymphocytes migrated in larger numbers into the T cell area of both organs.

Distribution of immunocompetent cells in various areas in the normal laryngeal mucosa of the rat.

The larynx can be divided into a supraglottic, a glottic and a subglottic area, each serving different functions. In many cases of laryngitis the site of infection is located in one area, leaving other areas unaffected. It seems reasonable to speculate that the underlying cause of the heterogeneous infection pattern in the larynx is the different processing of infectious agents. Therefore, the number and distribution of granulocytes, macrophages, dendritic cells, natural killer cells and T and B lymphocytes in the normal laryngeal mucosa of young rats were studied. The results show that, with the exception of granulocytes, all subpopulations were present in different numbers. Many macrophages and dendritic cells but only a few natural killer cells and T and B lymphocytes were located in the mucosa. Dendritic cells, natural killer cells and T and B lymphocytes were rarely present in the vocal fold area, whereas in the subglottic area they were present in high numbers. Thus, differences in the composition of immunocompetent cell populations between laryngeal areas were detectable.

Selective alterations in mast cell subsets and eosinophil infiltration in two complementary types of intestinal inflammation: ascariasis and Crohn's disease.

Objective: Numbers of mast cells (MCs) of different subpopulations and the extent of eosinophil infiltration were compared in Crohn’s disease and ascariasis. These two types of intestinal inflammation are complementary with regard to T cell response (TH1 versus TH2), prevalence and environmental factors. Methods: Histochemical, immunohistochemical and ultrastructural tools were applied to biopsies of morphologically uninvolved colon, ileum and duodenum from Crohn’s and ascariasis patients, as well as resection margins and tissues from an experimental porcine ascariasis model. MC subsets were defined by their dye-binding properties, and their chymase content was analysed using biochemical tools. Results: The TH2 (IgE-mediated) response in ascariasis was characterised by a dramatic increase in mucosal- type MCs (MMCs) and eosinophils in both the mucosa and the deeper layers of the intestinal wall and a simultaneous decrease of connective tissue-type MCs (CTMCs). Uninvolved intestine of Crohn’s patients showed moderate proliferation of CTMCs in the deeper layers of the intestinal wall, but a significant decrease of the MMCs, associated with moderate eosinophilia in all layers of the gut. Similar changes were present in the uninvolved duodenum of Crohn’s patients. Comparable amounts of chymase could be extracted from mucosal and submucosal duodenum, with similar proportions of its two principal isoforms in each. Conclusions: Our results indicate that T cell responses (TH1 or TH2) are associated with different MC subsets in intestinal inflammation. Changes remote from the focus of inflammation point to the systemic nature of the different MC responses.

The emigration of lymphocytes from palatine tonsils after local labelling

SummaryLymphocytes in the palatine tonsils of normal young pigs were selectively labelled by minute multiple injections of fluorescein isothiocyanate into the tonsils. One day later the numbers of tonsil-derived lymphocytes were determined in cervical, bronchial and mesenteric lymph nodes, spleen, Peyers patches, thymus, bone marrow and blood. Although not all tonsillar lymphocytes could be labelled by this technique, a total of ∼0.6×109 lymphocytes emigrated from the tonsils. Relatively more lymphocytes were found in lymph nodes than in the spleen and very few in the thymus, Peyers patches and bone marrow. This organ distribution was different from the results from selectively labelling lymphocytes in lymph nodes, spleen and bone marrow.

Die medizinische Dissertation Eine Bestandsaufnahme aus der Sicht erfolgreicher und gescheiterter Promovenden

ZusammenfassungHintergrund: Die Zahl der Medizinstudenten, die ihr Studium mit einer Dissertation abschließen, hat sich in den letzten Jahren kontinuierlich verringert. Um die Ursachen der “Promotionsmüdigkeit” deutscher Medizinstudenten zu analysieren, befragten wir sowohl erfolgreiche als auch gescheiterte Promovenden nach ihrer Einschätzung zum Stellenwert medizinischer Dissertationen und nach den individuellen Gründen, die zum Abbruch der Promotionsarbeit führten. Befragte Personen und Methoden: Wir befragten in zwei repräsentativen Erhebungen erfolgreiche und gescheiterte Promovenden nach ihrer Einschätzung über Sinn und Unsinn einer Dissertation. Insgesamt konnten wir die Meinung von 321 Ärztinnen und Ärzten auswerten, von denen 181 promoviert und 140 ohne Titel waren. Ergebnisse: Bei 96% aller Befragten bestand eine initiale Promotionsabsicht. 67% der nicht promovierten Befragten hielten eine Dissertation heute für nicht mehr zeitgemäß und entbehrlich. Die erfolgreichen Promovenden realisierten ihre Dissertation in 80% mit dem ersten Thema, sie bewerteten die Betreuung durch ihre “Doktorväter” als sehr gut bis gut. Die nicht promovierten Befragten berichteten über bis zu vier frustrane Promotionsversuche. In den meisten Fällen führten nicht private Gründe, sondern eine unzureichende Betreuung zum Abbruch der Promotion. Über 90% der erfolgreichen Promovenden bewerteten die Dissertation auch persönlich als sinnvoll; sie würden nachrückenden Kolleginnen und Kollegen ebenfalls zu einer Dissertation raten. Bei etwa einem Drittel der nicht promovierten Kolleginnen und Kollegen besteht auch heute noch Dissertationswunsch. Schlußfolgerung: Unsere Untersuchungen zeigen, dass der Stellenwert medizinischer Dissertationen hoch einzuschätzen ist. Daher sollten sie fester Bestandteil medizinischer Ausbildung und universitärer Forschung bleiben.AbstractBackground: The actual value of medical dissertations is under current discussion. Studies concerning medical dissertation focused on successful candidates only. Therefore, data about physicians without “MD” are still lacking. Persons and Methods: We therefore performed a representative study of both, physicians with and without the “Dr. med.” degree. Using an anonymous questionnaire we asked for reasons to perform a doctoral thesis. Results: A total of 321 questionnaires could be evaluated (successful candidates n = 181; unsuccessful candidates n = 140). Nearly 96% have attempted to perform a medical dissertation at the beginning of their studies. Only 4% never had this intention. However, 67% answered that writing a medical dissertation has no relevance in clinical practice. For 80% of the successful physicians, it was the first attempted dissertation, they judged the supervision as very good or good. Physicians who did not write a medical dissertation stated that deficits in planning and supervising were the main reason for prematurely breaking off. 90% of the successful dissertationists thought that it had been personally meaningful and recommended the procedure to younger physicians. However, two-third of the practicing physicians without “MD” still intend to write a thesis. Conclusion: We conclude that the medical dissertation is highly rated in terms of personal and scientific value and should therefore remain a part of medical studies and science.

Wissenschaftler in deutschen anatomischen Instituten: Longitudinale Studie hinsichtlich der Anzahl, des Geschlechts, der Dienststellung und der akademischen Ausbildung

Zusammenfassung In der folgenden Arbeit ist die Entwicklung des Geschlechterverhaltnisses, der Dienststellungen und der Art der akademischen Ausbildung von Wissenschaftlern in den deutschen anatomischen Instituten in einem Zeitraum von 6 Jahren (1993–1999) aufgefuhrt. Aus dem Jahre 1999 sind sowohl die anatomischen Institute der alten als auch der neuen Bundeslander berucksichtigt worden. Aus der Erhebung des Jahres 1993 wurden, wegen der damals noch nicht vollstandig geklarten Einordnung in Stellenarten in den neuen Bundeslandern, in erster Linie die Institute der alten Bundeslander berucksichtigt. Bezuglich der Geschlechterverteilung gab es uber die Zeit keine Veranderungen. Insbesondere auf den Professorenstellen (C4, C3 und C2) sind weiterhin nur sehr wenige Frauen zu finden. In der Gruppe der wissenschaftlichen Mitarbeiter ist der prozentuale Anteil der Frauen etwas hoher. In beiden Erhebungen ist die uberwiegende Anzahl der Wissenschaftler/innen Mediziner/in. Das Verhaltnis zwischen nicht-habilitierten und habilitierten Wissenschaftlern hat sich in den letzten 6 Jahren zugunsten der Habilitierten verandert (1,5 im Jahre 1993 versus 1,2 im Jahre 1999). Zusammenfassend lasst sich sagen, dass Untersuchungen dieser Art eine notwendige Grundlage fur die Diskussionen uber die Zukunft und die Mitarbeiterentwicklung der anatomischen Institute einerseits und die Gleichstellung von Mannern und Frauen andererseits bilden.

Wissenschaftler in deutschen Anatomischen Instituten — Anzahl, Dienststellung, Qualifikationen und Geschlecht —

Zusammenfassung Die Wissenschaftler in den deutschen anatomischen Instituten werden nach ihrem Ausbildungsstudiengang und Geschlecht sowie der Eingruppierung in Stellen fur Professoren und wissenschaftliche Mitarbeiter aufgefuhrt. Es handelt sich um Angaben aus allen deutschen Instituten fur Anatomie, die im Marz 1993 erhoben wurden. Auf hoher dotierten Professorenstellen, die in der Regel mit Leitungsfunktionen verbunden sind (C4- und C3-Professoren) sind nur wenige Frauen zu finden und die weit uberwiegende Anzahl der Stelleninhaber sind Mediziner. Bei Privatdozenten und auserplanmasigen Professoren sowie wissenschaftlichen Mitarbeitern ergibt sich ein ganz anderes Bild. Wegen der noch nicht abgeschlossenen Eingruppierungen an den Instituten der neuen Bundeslander sind fur diese Institute nur eingeschrankte Aussagen moglich.

Age-Dependence of Lymphocyte Production in Peyer’s Patch Follicles in Contrast to the Other Peyer’s Patch Compartments and the Thymus

The gut-associated lymphoid tissue consists of intraepithelial and lamina propria lymphocytes and organized lymphoid tissue, the Peyer’s patches (PP). In pigs there are two types of PP, discrete ones in the jejunum (jejPP) and a continuous PP in the ileum (ilPP). Their role in the pig’s lymphoid system is not known: probably antigen from the gut lumen crossing the epithelium of the PP stimulates their lymphocytopoiesis.