Accelerated appearance of multiple B cell lymphoma types in NFS/N mice congenic for ecotropic murine leukemia viruses

Spontaneous lymphomas occur at high frequency in NFS x V+ mice, strains congenic for ecotropic murine leukemia virus (MuLV) proviral genes and expressing virus at high titer. In the present study, a total of 703 NFS x V+ lymphomas were studied by histopathology, immunophenotypic analysis, immunoglobulin heavy chain or T cell receptor beta chain rearrangements, and somatic ecotropic MuLV integrations; 90% of the lymphomas tested were of B cell lineage. Low-grade tumors included small lymphocytic, follicular, and splenic marginal zone lymphomas, while high-grade tumors comprised diffuse large-cell (centroblastic and immunoblastic types), splenic marginal zone, and lymphoblastic lymphomas. Comparison of mice of similar genetic background except for presence (NFS x V+) or absence (NFS x V-) of functional ecotropic MuLV genomes showed that NFS x V-clonal lymphomas developed at about one-half the rate of those occurring in NFS x V+ mice, and most were low-grade B cell lymphomas with extended latent periods. In NFS x V+ mice, clonal outgrowth, defined by Ig gene rearrangements, was associated with acquisition of somatic ecotropic proviral integrations, suggesting that, although generation of B cell clones can be virus independent, ecotropic virus may act to increase the rate of generation of clones and speed their evolution to lymphoma. The mechanism remains undefined, because only rare rearrangements were detected in several cellular loci previously associated with MuLV insertional mutagenesis.     

Histogenesis and clonality of pancreatic tumors induced by v-myc and v-raf oncogenes in NFS/N mice.

Newborn NFS/N mice were inoculated with pseudotypes of murine retroviruses containing murine v-raf, avian v-myc, or both v-raf and v-myc within a single construct. Foci of dysplastic acinar cells, similar to those observed in rats given chemical carcinogens, were induced in 77% of mice inoculated with the raf/myc construct with a latency as short as 15 days. However, all animals given this construct also developed fibrosarcomas, erythroblastosis, and lymphomas and died within 70 days of infection, before pancreatic acinar carcinomas developed. Dysplastic foci were also observed in mice infected with viruses containing v-raf or v-myc alone with latencies of 3-4 weeks, and carcinomas were seen after an average latency of 150 days in 31% of mice infected with either of two viruses expressing v-myc alone. Two primary carcinomas were transplanted in mice, and in vitro cell lines were developed from one of the transplants. DNA prepared from seven primary carcinomas, the two transplanted tumors, and the in vitro cell lines was hybridized with a v-myc probe. Each tumor had a unique pattern of proviral integrations that was retained, with the gain or loss of single sites, in the transplants and derivative cell lines. The clonal nature of the advanced pancreatic acinar carcinomas is discussed in relation to their histogenesis and the transforming potentials of the raf and myc oncogenes.     

High‐grade epithelial‐myoepithelial carcinoma of the parotid gland with mucous cell differentiation

Epithelial‐myoepithelial carcinoma (EMC) is a rare salivary gland tumor with a low‐grade malignancy, and EMC with high‐grade histopathological features is exceedingly rare. Furthermore, EMC with intracellular mucin is also extremely rare. We report an uncommon case of a high‐grade EMC of the parotid gland with mucous cell differentiation in a 66‐year old Japanese woman who noticed a right palpable parotid mass increasing in size within a one‐year period. The cytological specimen showed a focally biphasic structure and included isolated or discohesive piled‐up clusters with hyaline globules surrounded by neoplastic cells with nuclear atypia. The gross examination revealed a relatively well‐demarcated, multinodular gray‐whitish and solid mass. Histologically, the tumor consisted of variably sized solid nests or trabeculae with central necrosis and increased mitotic activity, and invaded into adjacent skeletal muscles. Immunohistochemically, the biphasic ductal and myoepithelial differentiation of this tumor confirmed the diagnosis of high‐grade EMC. Furthermore, numerous small nests with d‐PAS and alcian blue‐positive mucous cells predominated in about 5% of the whole tumor, and these mucous cells were encompassed by neoplastic myoepithelial cells. We should recognize this variant of EMC because we can't rule out the possibility of EMC even in the presence of mucous cells.     

Isolated Langerhans cell histiocytosis of the sublingual gland in an adult

Langerhans cell histiocytosis (LCH) is a rare disorder characterized by the proliferation of pathologic Langerhans cells. Its clinical presentation is highly variable, that range from single-system, limited disease to severe, multi-organ disease with high mortality. LCH usually affects children and young adults. The most frequent sites for LCH are the bone, skin, lung, pituitary gland, and lymph nodes. Salivary gland involvement by LCH is extremely rare, and only a few cases of LHC involving the parotid glands have been reported in the English literature. To our knowledge, the involvement of the sublingual gland as a part of single or multisystem LCH has not been previously described. Herein we reported the first case of primary LCH of the sublingual gland. A 40-year-old woman presented with a 2-month history of a painless mass on the right sublingual area. Excision of the lesion including the right sublingual gland was performed. Histopathological diagnosis of LCH was rendered. The patient remains free of symptoms 17 months after surgery.     

Multiparameter analyses of spontaneous nonthymic lymphomas occurring in NFS/N mice congenic for ecotropic murine leukemia viruses

Mouse strains congenic for ecotropic retrovirus genes have a much higher frequency of spontaneous lymphomas than the background NFS/N strain. In this study, most of these lymphomas have been identified as B-cell in origin by morphologic features, identification of immunoglobulin class, and cell-surface antigens. The classification suggested by Pattengale and Taylor proved to be applicable to the lymphomas studied. Most were of large follicular center cells and are considered typical of the type formerly designated as "reticulum cell sarcoma, type B." Many lymphomas contained a large proportion of nonneoplastic cells which partially obscured their neoplastic component. The role of ecotropic murine leukemia viruses as etiologic agents for B-cell lymphomas remains equivocal. However, because the only difference between the NFS/N and congenic mice is the expression of viruses in the latter, it appears that these viruses are somehow involved in induction of B-cell lymphomas.     

Spontaneous mutation in mice provides new insight into the genetic mechanisms that pattern the seminal vesicles and prostate gland.

The seminal vesicles and prostate gland are anatomically adjacent male sex-accessory glands. Although they arise from different embryonic precursor structures and express distinct sets of secretory proteins, these organs share common features in their developmental biology. A key shared developmental feature is the elaboration of complex secretory epithelia with tremendous surface area from simple precursor structures with juxtaposed epithelial and mesenchymal cells. In this study, new insight into the nature of the biological processes that underlie glandular morphogenesis is achieved by analyzing the phenotypes present in mice that harbor a spontaneous mutation, seminal vesicle shape (svs), previously identified for causing altered seminal vesicle morphology in adults. An examination of seminal vesicle development in svs mice provides the first evidence that the concurrent processes of epithelial branching and epithelial infolding are distinct processes under separate genetic control. It also provides the first direct evidence that the thickness and topology of the smooth muscle layer in the seminal vesicles are determined by interaction with the glandular epithelium during the branching process. In addition, the seminal vesicle phenotype in svs mice is shown to phenocopy the morphologic form present in certain other mammals such as the guinea pig, raising the possibility that the svs mutation is the sort of variant that arises during evolution. By also including an investigation of the prostate gland, this study also identifies previously unrecognized phenotypes in svs prostates, including increased gland size and dramatically reduced levels of branching morphogenesis. Finally, this study advances the goal of identifying the svs gene by mapping the svs mutation relative to known molecular markers and testing Fgfr2 as a candidate gene. The finding that the svs mutation maps to a genomic region syntenic to a region frequently deleted in human prostate tumors, together with the prostatic phenotype present in svs mice, further raises the interesting possibility that the svs mutation will identify a candidate prostate tumor suppressor gene.     

A new differentiation type of the chief cells in the cat gastric gland

We demonstrated a new differentiation type of chief cell in the cat gastric gland. 1. Numerous PAS-positive cells were distributed not only in the glandular body but also in the glandular base. 2. These cells, namely immature chief cells, contained a large number of claret-colored fine pepsinogen granules. 3. Immature chief cells did not exist in the glandular base of man and many other types of animals. 4. The PAS-positive cells in the glandular base gradually decreased in PAS-positive substance and changed into PAS-negative cells with a reticulate framework. These mature chief cells contained numerous dark blue coarse pepsinogen granules. 5. The mature chief cells reacted moderately to AB (pH 2.5), and weakly to AB (pH 0.5), while staining with PAS-AB (pH 2.5) produced a moderate to strong color reaction of AB. Such reactions were characteristic to these cells and could not be found in man or many other types of animals studied. 6. PAS-positive cells i.e. the immature chief cells, reacted strongly to AB (pH 2.5), and moderately to AB (pH 0.5), while staining with PAS-AB (pH 2.5) produced a violet color. 7. The above-mentioned reactions were the same in mucous neck cells with mean undifferentiated characteristics. Such cells do not exist in the glandular base of man and many other types of animals. 8. The glandular base is generally occupied only by mature chief cells, though a large number of undifferentiated cells or immature chief cells were distributed in the same area of the cat.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunohistology of T cell differentiation in the thymus of H-Y-specific T cell receptor alpha/beta transgenic mice

We examined the immunohistological aspects of the H-Y specific T cell receptor (TcR) alpha/beta transgene expression in the thymus of male and female transgenic (Tg) mice. Virtually all thymocytes expressed the beta transgene in both the male and female thymus. Expression of accessory molecules (co-receptors) in Tg mice deviated from control mice. In the male Tg thymus, CD8 expression was either low or absent on both cortical and medullary thymocytes. In contrast, in the thymus of female mice, CD8+ cells were found both in the cortex and in the medulla. The majority of medullary thymocytes was bright CD8+. This is in clear contrast to the CD8 distribution in control B6 mice, where only a few percent of medullary cells are CD8+. Similarly, the proportion of cells expressing CD4 antigens was reduced in the cortex and medulla of the thymus from male Tg mice, as compared to the thymus of female Tg mice and B6 control mice. Comparative analysis of the stromal cell types of the thymic microenvironments in the three groups of mice revealed that the cortical thymic microenvironment of male Tg mice differed, compared to that of female Tg mice. In particular, the deep cortex showed a closely packed meshwork of epithelial reticular cells. Moreover, H-2Db molecules (which are the restricting elements for the Tg TcR alpha/beta) were abnormally expressed in the thymic cortex of male mice. The cortical microenvironment in female mice, on the other hand, appeared normal. Together, the data indicate that TcR alpha/beta transgene expression in male mice leads to an aberrant co-receptor expression in both cortical and medullary lymphoid cells as well as an abnormal composition of the cortical microenvironment. Both phenomena may be the consequence of "negative selection" of developing H-Y-specific T cells, as it occurs only in the male Tg thymus. The absence of the H-Y antigen, but presence of the restricting element H-2Db in the thymic cortex of female mice, leads to accumulation of CD8+ in the medulla, a phenomenon interpreted as "positive selection".     

A new PAX6 mutation in familial aniridia.

Aniridia (lack of iris) is caused by loss of function mutations in one copy of the PAX6 gene. Here we present a new PAX6 splice mutation in a family with autosomal dominant aniridia. The mutation is a single nucleotide change which, although occurring within an exon, affects the splice junction consensus and results in skipping of that exon.     

Neuroendocrine differentiation in a case of acinic cell carcinoma of the parotid gland

We report a case of acinic cell carcinoma of the parotid gland with neuroendocrine differentiation. Light microscopically, the tumor appeared as clear cell-type acinic cell carcinoma. In addition, the tumor showed neurosecretory features such as Grimelius positivity and the presence of neurosecretory granules by electron microscopy. We suggest that a tumor cell arising from a stem cell can show simultaneous differentiation to both neuroendocrine and acinic cells.     

Recirculating and sessile B cell populations in normal and CBA/N mice

Chromosomally distinguishable syngeneic mice were parabiosed and the resultant chimerism was followed for 6 weeks in the lymphoid organs, by culturing their cells with polyclonal mitogens, lipopolysaccharide (LPS) for B cells and phytohemagglutinin (PHA) for T cells. As expected of a recirculating population, the T cells equilibrated completely. The B cells in lymph nodes (LN) and Peyer's patches (PP) also equilibrated completely, suggesting that they too are recirculating. B cells in the spleen and blood, however, did not equilibrate over this period. After separation of parabiosed mice, the percentage of partner cells in both the recirculating T and B lymphocyte populations declined steadily, but it continued to rise in the LPS-responsive populations in spleen and peripheral blood suggesting that they were derived from precursor populations which were themselves chimeric. Injection of lymphocytes into CBA/Ca or CBA/N mice showed that LPS-responsive populations in LN and spleen localized differently. These results have been interpreted as demonstrating two major populations of LPS-responsive B lymphocytes in the mouse, one recirculating and the other sessile. The recirculating population appears to be the only LPS-responsive population in LN and PP. In the spleen, however, the recirculating cells constitute about a quarter of the LPS-responsive cells, while the rest are sessile cells. The relationship between these two populations has yet to be clarified. CBA/N mice are deficient in both populations but the sessile one appears to be more severely depleted.     

A new coding mutation in the Tnf-alpha leader sequence in tuberculosis-sensitive I/St mice causes higher secretion levels of soluble TNF-alpha

I/St and A/Sn mice are polar extremes in terms of several parameters defining sensitivity to Mycobacterium tuberculosis. TNF-alpha, mainly produced by activated macrophages, can mediate both physiological and pathophysiological processes. Adequate TNF-alpha levels are essential for a forceful protective response to M. tuberculosis. We have functionally characterized a nonsynonymous substitution, Arg8 His, in the highly conserved cytoplasmic domain of the pro-TNF-alpha leader peptide from extremely M. tuberculosis-sensitive I/St mice. This was compared to the common pro-TNF-alpha variant found in A/Sn mice. Using cDNA constructs, both variants were constitutively expressed in HEK293A cells. A significantly higher secretion level of Arg8 His TNF-alpha was shown using flow cytometry and ELISA analysis (P=0.0063), while intracellular levels were similar for both protein variants. An even TNF-alpha distribution throughout the cells was seen using confocal microscopy. This suggests that the Arg8 His substitution affects pro-TNF-alpha processing. The I/St mouse may serve as a model to further explore the function of the well-conserved cytoplasmic region of TNF-alpha. However, other identified substitutions in the I/St promoter, introns and 3'UTR of Tnf-alpha, as well as the cellular environment in vivo may affect the balance between soluble and intracellular Arg8 His TNF-alpha before and during M. tuberculosis infection.     

A study of intermediate lobe differentiation in the human pituitary gland

The immunohistochemical demonstration of neurofilament (NF) polypeptide was used to identify nerves in a series of 17 pituitary adenomas. NF-positive fibres were present in two out of five corticotroph adenomas sited deep in the anterior lobe, in one out of five sited in the intermediate zone and in two out of seven non-corticotroph adenomas. Such nerve fibres were often seen in relation to blood vessels. The distribution of alpha-MSH immunoreactive cells was examined in 25 normal pituitaries and in 23 cases of Cushing's disease. Such cells were scattered throughout the normal gland and there was no increase in numbers in pregnancy. alpha-MSH was demonstrated in 18 corticotroph adenomas in Cushing's disease. There was no correlation with the site of the tumour or the presence of nerve fibres. alpha-MSH cells were distributed normally in the para-adenomatous gland. Crooke's hyaline change and alpha-MSH coexisted in some corticotrophs. These findings support the concept that 'intermediate lobe' function, as found in animals, has no discrete anatomical location in man.     

Immunohistochemical localization of vitamin B12 R-binder in salivary gland tumors. Implications for cell differentiation

Vitamin B12 R-binder, a specific binding protein for vitamin B12, was studied immunohistochemically in normal and 106 neoplastic salivary gland tissues with a monoclonal antibody against vitamin B12 R-binder (R-binder). In normal salivary glands, R-binder localization was restricted to the ductal systems and to mucous acinar cells; serous acinar cells, myoepithelial cells and stromal connective tissues were consistently negative. Among salivary gland tumors, R-binder was present in 87% of pleomorphic adenomas, 100% of monomorphic adenomas, and 40% of adenoid cystic carcinomas; positivity was observed only on luminal surfaces of small ductular elements, indicating that the components closely related to ductal differentiation were rather small in population. R-binder could be detected both in lacunar and non-lacunar cells within chondroid areas of pleomorphic adenomas, suggesting the possibility that chondroid regions arise from metaplastic changes in ductal epithelial cells. In mucoepidermoid tumors, mucous cells and focal squamous cells exhibited cytoplasmic staining. The staining pattern for R-binder in epithelial components of adenolymphomas showed close similarities to those found in normal large excretory ducts. Two acinic cell tumors and one case each of myoepithelioma and malignant myoepithelioma exhibited negative reactivity for R-binder, showing that these neoplasms are solely composed of tumor cells without the characteristics of ductular differentiation. The immunohistochemical examination of salivary gland tumors, employing a monoclonal anti-R-binder antibody, may have some implications for cellular heterogeneity and differentiation in various tumors.     

A new β2 microglobulin mutation found in a melanoma tumor cell line

Beta2 microglobulin mutations are an important mechanism for HLA class I total loss, (phenotype No. I) and have been described in colon carcinomas, melanomas and lymphomas. We describe a new beta2 microglobulin mutation detected in the melanoma cell line GR-34. The new mutation reported here was identified as a deletion of 4 bases (TTCT) in the highly repetitive sequence CTCTCTCTTTCT located in the leader sequence of the beta2 microglobulin gene at codon 15-16 of exon 1. The mutation produces a frameshift in the open reading frame sequence with the appearance of a stop codon at position 42. We also demonstrate that the second beta2 microglobulin gene is deleted. Comparisons with beta2 microglobulin mutations in other tumor cell lines suggest a mutation hot spot in exon 1.