J. J. van den Oord

Expression of MHC products by normal and abnormal bile duct epithelium

Using antibodies directed to beta 2-microglobulin (b2-m) and HLADR antigens, the expression of MHC products by normal and abnormal bile ducts in 90 paraffin-embedded biopsies showing various liver diseases, was studied. Normal and abnormal bile ducts constantly expressed b2-m. Increased b2-m expression was found in 17/19 PBC, and 4/7 chronic aggressive hepatitis or cirrhosis of viral etiology with hepatitic bile duct lesions. Normal bile ducts failed to express HLADR antigens. Aberrant HLADR display was found in 24/26 PBC and 10/16 chronic aggressive hepatitis or cirrhosis of viral etiology with hepatitic bile duct lesions. It is concluded that the pattern of the major histocompatibility complex (MHC) display does not discriminate between PBC and hepatitic bile duct lesions. Enhanced expression of class I MHC products at the surface of medium-sized bile ducts in PBC may render these structures more susceptible to lysis by cytotoxic T-cells, whereas its significance in chronic aggressive hepatitis or cirrhosis remains unknown. Aberrant expression of HLADR antigens by abnormal bile ducts in PBC and chronic aggressive hepatitis or cirrhosis of viral etiology is probably induced by gamma-interferon, liberated by intra-epithelial lymphocytes, and may serve to enhance the immune response, either by attracting HLADR-restricted cytotoxic T-cells or by the presentation of non-self antigens at the surface of bile duct epithelium.

Leukemia-associated lymph node infiltrates of plasmacytoid monocytes (so-called plasmacytoid T-cells): evidence for two distinct histological and immunophenotypical patterns

The medium-sized mononuclear cell with plasmacytoid features, formerly known as “T-associated plasma cell” or “plasmacytoid T cell,” has recently been shown to express several myelomonocyte and monocyte-macrophage associated antigens, suggesting a monocytic origin, and it has been renamed “plasmacytoid monocyte.” The present study describes the clinical and pathological features of two patients with generalized lymphadenopathy and leukemia (chronic myelomonocytic leukemia in Case 1, and acute non-B, non-T lymphoblastic leukemia in Case 2), and whose lymph node biopsies showed large numbers of plasmacytoid monocytes associated with the leukemic infiltrates. Case 1 was strikingly similar to three previously reported cases of so-called “plasmacytoid T cell” lymphoma, all associated with a myeloproliferative disorder. In our case, the destructive growth pattern of the plasmacytoid monocytes and the de novo expression of CD5 on these cells favored their neoplastic nature; the sharing of some markers of plasmacytoid monocytes with the myelomonocytic infiltrate suggested they were part of the tumoral proliferation. In Case 2, plasmacytoid monocytes displayed an immunophenotype guide similar to that reported in reactive conditions and were antigenically unrelated to the leukemic cells; plasmacytoid monocyte clusters occurred also in the lymphoid parenchyma spared by the leukemic infiltrate. These findings led us to interpret the large numbers of plasmacytoid monocytes in this second case as a tumor-associated host reaction.

Differential expression of the calcium-binding proteins MRP8 and MRP14 in granulomatous conditions: an immunohistochemical study

MRP14 and MRP8 are well‐characterized calcium‐binding proteins present in myeloid cells and mononuclear phagocytes. These antigens can easily be visualized in paraffin‐embedded tissue, making use of monospecific polyclonal antibodies. This study evaluates MRP14 and MRP8 expression in mononuclear phagocytes in various granulomatous conditions. MRP14 is strongly expressed in all granulomatous conditions. MRP8 is variably expressed. Mononuclear phagocytes in granulomas of foreign body type, cat‐scratch discase and erythema nodosum strongly express MRP8. In contrast, MRP8 expression is weak or absent in mononuclear phagocytes of sarcoidosis and tuberculosis. These results show differences in immunophenotype between non‐phagocytic mononuclear phagocytes in delayed hypersensitivity type granulomas and phagocytic mononuclear phagocytes in non‐hypersensitivity and non‐immunological granulomas.

POU5F1, encoding a key regulator of stem cell pluripotency, is fused to EWSR1 in hidradenoma of the skin and mucoepidermoid carcinoma of the salivary glands.

The EWSR1 gene is known to play a crucial role in the development of a number of different bone and soft tissue tumours, notably Ewings sarcoma. POU5F1 is expressed during early development to maintain the totipotent status of embryonic stem and germ cells. In the present study, we report the fusion of EWSR1 and POU5F1 in two types of epithelial tumours: hidradenoma of the skin and mucoepidermoid carcinoma of the salivary glands. This finding not only broadens considerably the spectrum of neoplasms associated with EWSR1 fusion genes but also strengthens the evidence for shared pathogenetic mechanisms in the development of adnexal and salivary gland tumours. Reminiscent of the previously reported fusion genes involving EWSR1, the identified transcript is predicted to encode a chimeric protein consisting of the EWSR1 amino‐terminal domain and the POU5F1 carboxy‐terminal domain. We assessed the transcriptional activation potential of the chimera compared to the wild‐type proteins, as well as activation of transcription through the oct/sox composite element known to bind POU5F1. Among other POU5F1 target genes, this element is present in the promoter of NANOG and in the distal enhancer of POU5F1 itself. Our results show that although the chimera is capable of significant transcriptional activation, it may in fact convey a negative regulatory effect on target genes. Copyright

The value of ileoscopy with biopsy in the diagnosis of intestinal Crohn’s disease

Studies to determine the diagnostic value of ileoscopy and biopsy are not available. In an attempt to clarify the role of this technique in the diagnosis of intestinal Crohns disease, 110 patients with a radiological diagnosis of inflammatory disease of the terminal ileum were examined in a prospective study. Suspicion of Crohns disease was rejected in 28 patients. In 18 patients the terminal ileum was normal, while 10 patients had lymphoid nodular hyperplasia. Endoscopic lesions with a predictive value of 0.96 were found in 25 of 48 patients with the final diagnosis of Crohns disease. Diagnostic granulomas were only found in 4 patients, but lesions consistent with Crohns disease were present in the pathology sections of 17 patients. It was concluded that ileoscopy with biopsy is a valuable tool in the diagnosis of inflammatory ileal disease and can provide useful information about the nature and extent of the inflammation.

Identification of a ZEB2-MITF-ZEB1 transcriptional network that controls melanogenesis and melanoma progression

Deregulation of signaling pathways that control differentiation, expansion and migration of neural crest-derived melanoblasts during normal development contributes also to melanoma progression and metastasis. Although several epithelial-to-mesenchymal (EMT) transcription factors, such as zinc finger E-box binding protein 1 (ZEB1) and ZEB2, have been implicated in neural crest cell biology, little is known about their role in melanocyte homeostasis and melanoma. Here we show that mice lacking Zeb2 in the melanocyte lineage exhibit a melanoblast migration defect and, unexpectedly, a severe melanocyte differentiation defect. Loss of Zeb2 in the melanocyte lineage results in a downregulation of the Microphthalmia-associated transcription factor (Mitf) and melanocyte differentiation markers concomitant with an upregulation of Zeb1. We identify a transcriptional signaling network in which the EMT transcription factor ZEB2 regulates MITF levels to control melanocyte differentiation. Moreover, our data are also relevant for human melanomagenesis as loss of ZEB2 expression is associated with reduced patient survival.

The MYB-NFIB gene fusion-a novel genetic link between adenoid cystic carcinoma and dermal cylindroma.

We have recently shown that the recurrent t(6;9)(q22 ∼ 23;p23 ∼ 24) translocation in adenoid cystic carcinoma (ACC) of the breast and head and neck results in a fusion of the two transcription factor genes MYB and NFIB. Here we demonstrate, for the first time, that benign sporadic, dermal cylindromas also express the MYB–NFIB gene fusion. RT–PCR and immunohistochemical analyses revealed that eight of 12 analysed tumours (67%) expressed MYB–NFIB fusion transcripts and/or stained positive for MYB protein. Nucleotide sequence analyses confirmed that the composition of the chimeric transcript variants identified was identical to that in ACC, suggesting a similar molecular mechanism of activation of MYB in cylindroma as in ACC. In contrast, no evidence for the presence of the MYB–NFIB fusion was found in other types of basaloid skin and salivary gland tumours, indicating that the fusion indeed has a restricted expression pattern. Our findings broaden the spectrum of neoplasms associated with MYB oncogene activation and reveal a novel genetic link between ACC and dermal cylindroma. These results, together with our previous observations, further strengthen the evidence for common molecular pathways of importance for the development of both benign and malignant breast, salivary and adnexal tumours. Copyright

A recommended procedure for ultrastructural immunohistochemistry on small human tissue samples.

Various fixation and staining procedures for the demonstration of surface and cytoplasmic antigens have been described. An immunostaining procedure was sought that would allow the demonstration of these antigens, especially in small human tissue samples at the ultrastructural level. A modification and adaptation of the technique of Eldred, Zucker, Karten, and Yazula (J Histochem Cytochem 31:285, 1983) was applied on several varieties of human tissue, including liver, skin, and lymphoid tissue, using monoclonal and polyclonal antibodies in an indirect peroxidase procedure. In this way a reliable and generally applicable procedure was developed that satisfied the following demands: Use of a universal fixative that allows preservation of the antigenicity of various antigens; Adequate penetration of the tissue by the immunological reagents; Optimal preservation of subcellular structures; and Possibility to store the tissue samples for considerable periods of time.

Immunopathology of trachomatous conjunctivitis.

Upper palpebral conjunctival biopsy specimens obtained from eight patients with active trachoma were examined by routine histological and immunohistochemical methods. The epithelium expressed class I major histocompatibility complex (MHC) products throughout and class II MHC products in the superficial layers. The epithelial inflammatory infiltrate consisted of polymorphonuclear leucocytes, macrophages, T lymphocytes, and dendritic cells. In the underlying stroma the inflammatory infiltrate was organised as B lymphoid follicles, and there was also a diffuse infiltrate consisting of plasma cells and scattered B lymphoid cells, dendritic cells, T cells, macrophages, and polymorphonuclear leucocytes. Each type of cell has its special location in the tissue. Plasma cells were located on a subepithelial band and as a dense infiltrate round the acini of accessory lacrimal glands. IgA+ plasma cells outnumbered IgG+ cells, whereas IgM+ and IgE+ cells were few. Our data provide good evidence for the presence of both humoral and cell mediated immune responses and a possible role for autoimmune mechanisms in the conjunctival tissues of trachoma patients.

Neuronophagia in the motor cortex in amyotrophic lateral sclerosis.

This study was designed to identify which phagocytic cells in the cerebral cortex of amyotrophic lateral sclerosis (ALS) patients are involved in the process of neurono‐phagia. For this purpose a number of single and double immunocytochemical stains were carried out on five ALS cases which were selected on the basis of the presence of degenerative and phagocytic phenomena in the cerebral cortex. The cortical degenerative process is mainly present in the third and fifth layers and is not restricted to the fifth layer which contains the cell bodies of the Betz cells. The present study indicates that a number of cells are involved in the process of phagocytosis in ALS. Resident macro‐phages (from microglial or perivascular origin) and astrocytes seem to play an immunologically‐mediated role in the disappearance of neurons. Some of the cells involved in the degenerative process, i.e. rounded macrophages and microglia, expressed major histocompatibility class II antigen. The phagocytic cells in neuronophagia were phenotypically identical to perivascular macrophages and not to microglia. Therefore, the process of phagocytosis of neurons appears to be primarily the task of the perivascularly located macrophage.