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Non clinical assessment of immunotoxicity of human cellular products in vivo is limited by the lack of availability of pharm-tox models enabling a full range of human innate and adaptive responses. We previously demonstrated improved development of human adaptive T and B cell responses in mice receiving human hematopoietic stem cell transplantation (HSCT) in combination with prime/boost immunization with induced dendritic cells (iDCs), i.e. monocytes derived the stem cell donor reprogramed with a lentiviral vector for co-expression of GM-CSF, IFN-alpha and the CMV antigen pp65 that self differentiate into DCs in vivo (Salguero et al, 2014 J. Immunology; Daenthanasanmak et al, 2015 Mol. Ther. Meth.). For these previous studies, mice were kept for 6-10 weeks after iDC administration, and we did not observe signs of tumorigenicity or graft-versus-host disease (GVHD). After consultation with the German regulatory authorities, we were requested to perform pharm-tox analyses 26 weeks after iDC immunization. We report here a pilot-feasibility study with humanized mice showing long-term (more than 33-36 weeks after HSCT) robust immune reconstitution with human T cells (control mice, n=2 Vs. iDC-immunized mice, n=6). Longitudinal analyses of human immune reconstitution in blood samples confirmed accelerated development of CD4+ effector memory T cells 5-10 weeks after iDC immunization. No weight loss, GVHD or malignancies were observed after iDC immunization. 3/6 immunized mice developed skin erythema and inflammation around 23 weeks after iDC immunization and were sacrificed earlier for analyses. Analyses of all mice were performed at autopsy by macroscopic observations, H&E histopathology, immunohistochemistry and flow cytometry of target organs. Positivity for anti-human nuclei antibody, anti-human HLA-DR and anti-human CD3 leucocytes were detected in several tissues (spleen, bone marrow, brain, lungs, skin, eyelids, liver, and kidneys), confirming the long-term persistency of human T cells in the humanized mice. In inflamed skin, abundant human CD4+ T cells were localized in the basal layers of the epidermis and hair follicles in the dermis. Human macrophages (CD68+) could be detected in several tissues, but were rare in inflamed skin. However, in the inflamed dermis areas of ulceration, mouse macrophages (F4/80+) were observed frequently with strongly positive cytoplasm. Mice with ulcerations had significantly higher levels of several human inflammatory cytokines in plasma (IFN-gamma, IL-6, GM-CSF and IL-8) than immunized mice with no skin inflammation or control mice. In summary, a long-term pilot study exploring a hybrid human-mouse model system was feasible and iDCs accelerated mature human T cell reconstitution with no signs of tumorigenicity or GVHD. However, accumulation of human CD4+ memory T cells and activated mouse macrophages in inflamed skin was associated with elevated levels of human inflammatory cytokines resembling a ""cytokine storm"".

Histopathological examination of the nasal passages requires a standardized approach for recording lesion distribution patterns. Nasal diagrams provide guidance to map the lesions. Information on lesions exists for rodents, dogs, and monkeys, which all have been used in inhalation studies. Recently, minipigs have garnered interest as an inhalation model because minipigs resemble humans in many features of anatomy, physiology, and biochemistry and may be a good alternative to monkeys and dogs. The present work explored the microanatomy and histology of the nasal passages of Göttingen minipigs from postnatal day 1 until 6 months of age. Six nasal levels were selected, which allow examination of the squamous, transitional (nonciliated) and ciliated respiratory, and olfactory epithelia; the nasopharynx; and relevant structures such as the vomeronasal organ, olfactory bulb, and nasal/nasopharynx-associated lymphoid tissue. © 2012 by The Author(s).

A multicentric basal cell carcinoma was diagnosed in a male multimammate mouse (Mastomys spp.) with widespread cutaneous alterations. Macroscopically, the skin was thickened and extremely wrinkled. Histopathological examination showed multicentric expanding cell-rich tumors composed of basaloid cells interpreted as basal cell carcinoma. Immunohistochemistry detected strong cytokeratin 14 positivity in the epidermal basal layer and in loosely arranged areas of these tumors but only a minimal positive reaction in densely packed areas of tumor cells. Furthermore, samples from the abdomen showed 3 nodular proliferations diagnosed as keratoacanthomas.

The International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice is a global project that is publishing criteria for both proliferative and nonproliferative changes in laboratory animals. This paper presents a set of general suggestions for terminology across systems. These suggestions include the use of diagnostic versus descriptive terms, modifiers, combination terms, and grading systems; and the use of thresholds, synonyms, and terminology for some processes that are common to several organ systems. The purpose of this paper is to help the reader understand some of the basic principles underlying the International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice process.

Historical data for Leydig cell tumors from untreated or vehicle treated rats from carcinogenicity studies collected in the RITA database are presented. Examples are given for analyses of these data for dependency on variables considered to be of possible influence on the spontaneous incidence of Leydig cell tumors. In the 7453 male rats available for analysis, only one case of a Leydig cell carcinoma was identified. The incidence of Leydig cell adenomas differed markedly between strains. High incidences of close to 100% have been found in F344 rats, while the mean incidence was 4.2% in Sprague-Dawley rats and 13.7% in Wistar rats. Incidences in Wistar rats were highly variable, primarily caused by different sources of animals. Mean incidences per breeder varied from 2.8 to 39.9%. Analyses for the dependency on further parameters have been performed in Wistar rats. In breeders G and I, the Leydig cell tumor incidence decreased over the observation period and with increasing mean terminal body weight. The incidence of Leydig cell tumors increased with mean age at necropsy and was higher in studies with dietary admixture compared to gavage studies. These parameters had no effect on Leydig cell tumor incidence in breeders A and B. Animals from almost all breeders had a considerably higher mean age at necropsy when bearing a Leydig cell adenoma than animals without a Leydig cell adenoma. Studies with longitudinal trimming of the testes had a higher incidence than studies with transverse trimming. The observed dependencies and breeder differences are discussed and explanations are given. Consequences for the use of historical control data are outlined. With the retrospective analyses presented here we were able to confirm the published features of Leydig cell adenomas and carcinomas. This indicates that the RITA database is a valuable tool for analyses of tumors for their biological features. Furthermore, it demonstrates that the RITA database is highly beneficial for the definition of reliable historical control data for carcinogenicity studies on a scientifically solid basis.

We hypothesized that formation of pulmonary emphysema could be diminished after previous activation of stem cells. Animals received either a daily dose of the hematopoietic growth factors (GF; recombinant rat stem cell factor plus recombinant granulocyte colony stimulating factor; n= 6, Elastase/ GF group) or vehicle ( n= 9, Elastase/ Sham group) starting 3 days before intratracheal instillation of elastase or vehicle and continued for another 25 days. Control animals were treated with NaCl ( n= 9, Sham/ Sham group). On day 25, in all animals, a 2-mL pump was implanted subcutaneously that delivered 200 mu g/ h 5-bromo2- desoxyuridine ( BrdU) until study termination. Compared to controls, the Elastase/ Sham group exhibited elevated total lung capacity (TLC) and functional residual capacity (FRC), significantly increased mean free alveolar pathway, alveolar volume, and decreased septal density. The Elastase/ GF group showed ( 1) a significant increase of TLC and FRC, ( 2) a significant increase in alveolar size and volume, ( 3) a significant reduction of septal density, volume, and thickness. Proliferation in lung parenchyma and in terminal bronchioles remained significantly decreased in the Elastase/ Sham group and the Elastase/ GF group. Blood cell number has significantly increased in the Elastase/ GF group. The application of GF-enhanced pulmonary emphysema, presumable because of increased inflammatory activity, was a result of a preventive treatment.

Historical control tumor data are useful in the interpretation of long-term rodent carcinogenicity bioassays, especially to assess the occurrence of rare tumors and marginally increased tumor incidences. The major prerequisites to compare historical control data with studies under evaluation are the validity and consistency of the respective databases. The RITA (Registry of Industrial Toxicology Animal-data) database for historical data of tumors and pre-neoplastic lesions collects data according to highly standardized procedures including tissue sampling and trimming, histopathology according to internationally harmonized nomenclature and diagnostic criteria, and peer review. All lesions that are entered are unanimously diagnosed according to IARC (Intermational Agency for Research on Cancer)/WHO criteria. The validity of data is additionally confirmed by a complete peer review performed by a database pathologist. Equivocal diagnoses and selected cases are additionally submitted to a panel of RITA pathologists. In the RITA database, there are currently 10,896 rats from 106 studies with more than 17,604 primary tumors and 16,551 pre-neoplastic lesions. The RITA database for historical control data for Wistar and Sprague Dawley rats as well as for different mouse strains is briefly described. Based upon RITA background data, the survival rate of Wistar rats has been consistent over a period of 10 years. The occurrence of tumor-bearing animals also shows a stable percentage over a decade. Additionally, examples of how historical control data may support carcinogenic risk assessment in cases of rare tumors or marginally increased incidences of tumors and pre-neoplastic lesions are given.

A Panel of medical and veterinary pathologists reviewed published and unpublished reports dealing with studies of various white mineral oils and waxes in F344 and Sprague-Dawley rats. They also had available and studied histologic slides from both subchronic and chronic studies of certain mineral hydrocarbons 90-day oral study of low melting point wax (LMPW) in female Fischer 344 and Sprague-Dawley rats; 90-day studies of P15H* and P70H white oil and high melting point wax (HMPW) in male and female F344 rats and 24 month study of P70H white oil in male and female F344 rats. The Panel also reviewed mineral oil-induced alterations in tissues of human patients (liver, hepatic lymph node and spleen). The Panel agreed that certain of the mineral hydrocarbons produced lesions in the mesenteric lymph nodes and liver of the F344 rat and these lesions were best described as microgranulomas/granulomas. The lesions were fundamentally similar in both organs, although varying in severity with dose and type of mineral hydrocarbons. The Panel agreed that hepatic lesions with inflammatory cell infiltration, necrosis, and fibrosis were produced only by feeding of LMPW and the lesions were confined to F344 rats and not found in Sprague-Dawley rats. The most severe granulomatous lesions in the mesenteric lymph nodes were found in high dose LMPWfed F344 rats. The microgranulomas were similar in subchronic and chronic studies. Also, little difference existed between controls and treated F344 rats in the incidence and severity of the lesions after 2 years of feeding P70H white oil. The Panel agreed that some slight reversibility existed for these lesions, but also agreed that complete resolution was unlikely as regression of the lesions in the rat would likely be slow. The Panel agreed that a minimal severity infiltrate of mononuclear inflammatory cells occurred in the base of the mitral valve in a slightly increased incidence in F344 rats fed LMPW. The Panel concluded that these mitral valve alterations had little if any toxicologic significance as the focal infiltrate was minimal in severity, occurred in controls, occurred in association with murine cardiomyopathy, and were unlike the responses in the liver and mesenteric lymph nodes. The Panel agreed that the lesions observed in the liver and mesenteric lymph nodes of F344 rats exposed to MHCs, especially the LMPW, were different morphologically from changes observed in lymph node, liver, and spleen of humans that were mineral oil-users, These changes in humans are usually found incidentally in tissues taken at biopsy or autopsy. The MHC-induced lesions can be considered incidental and inconsequential in humans. Granulomatous lesions are produced in rats by MHC-feeding, especially in livers of the F344 rat with certain of the MHCs, but are not found in human tissues. This suggests a heightened and perhaps different type of toxic response in the rat compared to humans. The MHC-associated alterations in humans are ubiquitous, present after a certain age in most, if not all, humans, and consist of intra-and extra-cellular oil droplets with a minimal macrophage (including giant cells) response.

Two independent bioassays are available which have examined the potential carcinogenicity of monomeric and polymeric methylene diphenyl diisocyanate (MDI) following long-term inhalation exposure in rats. These studies are not directly comparable, however, due to differences in design and conduct of the in-life phase, and differences in nomenclature used for some of the histopathological findings. This paper presents a definitive overview ofthe pulmonary toxicity of MDI developed following a thorough review of both investigations. As part of this process, the test materials and the designs of the studies were compared, and an in-depth review of lung lesions was conducted by an independent reviewing pathologist. This included the re-examination of the original lung slides, supported by an analysis of the exposure regimens, the results of which were used to develop an accurate profile of the doses received by the animals in the two studies. Histopathological findings were then combined with this information to give an overall dose-response curve for both studies as a whole. The range of total inhalation exposures to MDI was calculated as 559, 1972, 2881, 6001, 17,575 and 17,728 mgh/m3. Major pulmonary effects included increased lung weights together with bronchiolo-alveolar adenomas and hyperplasia, and interstitial fibrosis which occurred consistently in both studies, indicating a very similar qualitative response of the lungs to polymeric and monomeric MDI. The quantitative response of the lung was clearly dose-related in each study, and when the studies were considered as a whole a reasonable overall dose-response relationship was apparent for major lung lesions. Lung tumours (in low incidences) only occurred at the highest dose level in both studies (17,575 and 17,728 mgh/m3). For inflammatory and other non-neoplastic pulmonary changes, the lowest dose examined (559 mgh/m3) was regarded as a no-observed-adverse-effect-level for both polymeric and monomeric MDI. It was concluded that the results of the two studies could be combined to serve as a basis for human risk assessment of MDI.

RITA (Registry of Industrial Toxicology Animal-data) is a pathology data base for the collection of validated histopathological data on tumours and potentially pre-neoplastic lesions observed in laboratory rodents. To enable a better comparison of information, standardized techniques for the preparation of histological slides have been established for all organs. The current paper describes the guidelines for organ sampling and trimming procedures applied in the RITA project, i.e. the number of sections to be taken, the direction in which an organ should be cut, the localization (anatomical site) from which a sample should be taken, and the size of an organ (or part of an organ) to be placed in cassettes for processing. Schematical illustrations and additional explanations are provided to support the proposed standardized procedures in histology laboratories.

Benign keratinizing cystic squamous cell tumours were induced in rat lungs by intratracheal instillation of 15 mg carbon black particles. In this species keratinizing cystic squamous cell tumours are frequently observed after inhalation of intratracheal instillation of particles. Microscopically, the tumours are formed by a sharply demarcated, mostly keratinized squamous epithelium. In the center of the mass there are usually large amounts of keratin and necrotic tumour tissue. Epithelium may be flattened to a thin layer of squamous cells, especially adjacent to pleura or interstitium surrounding major airways and vessels. Growth occurs mainly by peripheral extension into the alveolar spaces. Mitoses are rare. These benign tumours may progress to squamous cell carcinomas, which show destruction of the basement membrane, cellular atypia, disorientation of cells and frequent mitoses.

Approximately 700 cases of keratinizing cystic squamous lung lesions in rats were investigated by light microscopy in order to clarify the nomenclature and classification of these lesions. The structure of benign keratinizing cystic squamous cell tumours of the lung was compared to that of cystic squamous lesions in the skin of rats, with consideration of data from the literature.

A data base for the collection of histopathological diagnoses of neoplastic and pre-neoplastic lesions and related data from control animals involved in long-term carcinogenicity or toxicity studies has been operated since 1988. Factors which may have an influence on the spontaneous tumor rate are integrated in the data base. Systematized nomenclature and standardized diagnostic criteria have been established as well as the applied data acquisition and data validation procedure.

Mesodermale Mischtumore des Uterus (MMT's) sind selten bei Mensch und Tier. Entsprechend einer organtypischen und atypischen Differenzierung der mesenchymalen Tumorkomponente werden homologe (z.B. Karzinosarkom) und heterologe Formen (z.B. Karzinomensenchymom) unterschieden. Bei 3 Wistar Ratten wurden 1 benigner und 2 maligne MMT's diagnostiziert. Der benigne MMT bestand aus adenomatösen endometrialen Epithel in Kombination mit gut differenzierten Knorpel-, Knochen-, Fett- und Bindegewebsanteilen und wurde als "Adenomesenchymom" typisiert. Die malignen MMT's waren v.a. aus adenokarzinomatösen, osteochondrosarkomatösen und anaplastischen Anteilen zusammengesetzt. Der gutartige MMT-Subtyp "Adenomesenchymom" wurde bisher weder beim Menschen noch beim Tier beschrieben.

A rate of up to 43 per cent of malignant peripheral nerve sheath tumors (PNST) was induced in Europaen hamsters (EH) after weekly s.c. administration of 1,1-Dimethylhydrazine (UDMH). The overall neoplastic response in the treated EH was also elevated as compared to the untreated controls. Histologically, the malignant PNST were neurofibrosarcomas and melanotic as well as unpigmented schwannomas. The occurence of melanotic schwannomas is briefly discussed with regard to the histogenesis of this rare tumor type.

A recently selected strain of rats (MWF) demonstrates a greatly increased number of subcapsular glomeruli in direct contact to the renal capsule). Mature, male MWF rats are characterized by a reduced number of nephrons and an increased blood pressure. The albumin (ALB) excretion is high (