Immuno Histology Research Articles

Evaluation and Validation of Commercially Available Dopamine Transporter Antibodies

With a wide variety of dopamine transporter (DAT) antibodies available commercially, it is important to validate which antibodies provide sufficient immunodetection for reproducibility purpose and for accurate analysis of DAT levels and/or location. Commercially available DAT antibodies that are commonly used were tested in western blotting (WB) on wild-type (WT) and DAT-knock-out (DAT-KO) brain tissue and with immunohistology (IH) techniques against coronal slices of unilaterally lesioned 6-OHDA rats, in addition to wild-type and DAT-knock-out mice. DAT-KO mice and unilateral 6-OHDA lesions in rats were used as a negative control for DAT antibody specificity. Antibodies were tested at various concentrations and rated based on signal detection varying from no signal to optimal signal detection. Commonly used antibodies, including AB2231 and PT-22 524-1-AP, did not provide specific DAT signals in WB and IH. Although certain antibodies provided a good DAT signal, such as SC-32258, D6944, and MA5-24796, they also presented nonspecific bands in WB. Many DAT antibodies did not detect the DAT as advertised, and this characterization of DAT antibodies may provide a guide for immunodetection of DAT for molecular studies.

O-191 Assessing the use of tumour-specific DARPin-toxin fusion proteins for ex vivo purging of cancer metastases from human ovarian cortex tissue fragments before autotransplantation

Abstract Study question Is it possible to eradicate cancer cells from ovarian cortex by using tumour-specific designed ankyrin repeat protein (DARPin)-toxin fusion proteins, without compromising the ovarian tissue? Summary answer Purging ovarian cortex ex vivo from experimentally induced breast cancer tumour foci is possible by tumour-targeted DARPin-toxin fusion proteins trough inhibition of protein synthesis. What is known already Ovarian tissue cryopreservation and autotransplantation is a successful technique for fertility restoration in cancer patients. The procedure is not without risk since malignant cells may still be present in the graft. Procedures to detect cancer cells render the tissue fragment useless for autotransplantation. Strategies to circumvent this problem such as in vitro maturation of follicles or the construction of artificial ovaries are pursued but are still experimental. Alternatively, we have shown ex vivo purging of ovarian cortex is possible by elimination of rhabdomyosarcoma after treatment with verteporfin. This allows treatment of cortex fragments before autotransplantation without compromising ovarian tissue integrity. Study design, size, duration Human ovarian cortex fragments harbouring breast cancer tumour foci were exposed for 24 h to DARPins fused to the translocation and catalytic domain of Pseudomonas aeruginosa exotoxin A (DARPin-toxin fusion proteins) targeting EpCAM or HER2. After treatment with the DARPin-toxin fusion proteins the tissue was cultured for an additional 6 days to allow any remaining tumour cells to form foci. In addition, the functional integrity of the ovarian tissue was analysed after purging. Participants/materials, setting, methods Breast cancer cell lines expressing different levels of EpCAM and HER2 were introduced in human ovarian tissue to form tumour foci. After purging with DARPin-toxin fusion proteins, the presence of any remaining cancer cells in the tissue was analysed with (immuno)histochemistry and RT-qPCR. Possible detrimental effects on the viability of ovarian cortex and follicles were determined by (immuno)histology, a follicular viability assay and an assay to determine the in vitro growth capacity of small follicles. Main results and the role of chance Ovarian cortex harbouring EpCAM-positive breast cancer cells showed a significant decrease in the number of tumour foci after treatment with the EpCAM-targeted DARPin-toxin fusion proteins. Although exposure to the EpCAM-specific DARPin had no effect on morphology or viability of follicles, a decrease in oocyte viability after in vitro growth experiments was observed, presumably due to low level expression of EpCAM on oocytes. In contrast to the EpCAM-specific DARPin-toxin fusion protein, the DARPin-toxin fusion protein targeting HER2 had no detrimental effects on morphology, viability or in vitro growth of follicles while foci of HER2-positive breast cancer cells were severely affected as indicated by the presence of apoptotic bodies, tumour cell remnants and the absence of viable tumour cells. The histological results after purging with the HER2-specific DARPin-toxin fusions proteins were confirmed by RT-qPCR, showing a decrease to basal levels of HER2 mRNA in the ovarian cortex tissue. Limitations, reasons for caution The effect of DARPin-toxin fusion proteins depends heavily on the expression of their target on the cancer cell. The target protein should not be expressed by ovarian cortex as this may lead to tissue damage. The functional integrity of ovarian cortex after the treatment requires further investigation in vivo. Wider implications of the findings Purging metastases from ovarian cortex without harming ovarian tissue is possible by targeting tumour specific surface expressed antigens with DARPin-toxin fusion proteins. Purging ovarian cortex tissue with DARPin-toxin fusion proteins provides a feasible therapeutic strategy to prevent reintroduction of cancer by autotransplantation in case of malignancies expressing tumour-specific surface markers. Trial registration number not applicable

HDL-mediated atheroprotection in a high cholesterol diet swine model by quantitative (immuno)histology coronary profiling

HDL-mediated atheroprotection in a high cholesterol diet swine model by quantitative (immuno)histology coronary profiling

Application of a new immunohistology scoring system (IH score): Analysis of TNF-α in synovium related to disease activity score in infliximab-treated patients with rheumatoid arthritis

Objectives. This study aimed to analyze the relationship between the expression of tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6) in synovium and the disease activity score (DAS) 28 (C-reactive protein, CRP) in treatment of infliximab for rheumatoid arthritis (RA).Methods. Synovial tissues were obtained from 16 infliximab-treated patients and assessed for TNF-α and IL-6 with a new immunohistology (IH) scoring system. The validation of IH score was performed and applied for the analysis of correlation between synovial TNF-α or IL-6 and DAS28 (CRP) in addition to Rooney score.Results. The IH score had high internal validity; the IH score of TNF-α strongly correlated with serum CRP and matrix metalloprotease-3 (MMP-3), as well as DAS28 (CRP) and the Rooney score. IL-6 did not correlate with DAS28 (CRP).Conclusions. This study indicates that the IH score is useful as a new procedure to assess the cytokine expression easily and TNF-α in synovium correlates with disease activity in patients with RA treated with infliximab.

Correlations between ERG, OCT, and Anatomical Findings in therd10Mouse

Background. To evaluate the correlation between ERG, OCT, and microscopic findings in the rd10 mouse. Methods. C57BL/6J wild type mice and rd10 mice were compared at the age of 2, 3, 5, 7, 9, 12, 24, and 48 weeks (each age group n = 3) using full-field electroretinography (ERG), spectral domain Optical Coherence Tomography (sd-OCT), fluorescein angiography (FA), Hematoxylin & Eosin histology (HE), and immunohistology (IH). Results. While in wild type mice, the amplitude of a- and b-wave increased with light intensity and with the age of the animals, the rd10 mice showed extinction of the ERG beginning with the age of 5 weeks. In OCT recordings, the thickness of the retina decreased up to 9 weeks of age, mainly based on the degradation of the outer nuclear layer (ONL). Afterwards, the ONL was no longer visible in the OCT. HE staining and immunohistological findings confirmed the in vivo data. Conclusion. ERG and OCT are useful methods to evaluate the retinal function and structure in vivo. The retinal changes seen in the OCT closely match those observed in histological staining.

Abstract 357: Cardiac Fibroblasts as a Support Cell for Endothelial Cell Sprout Formation in Engineered Cardiac Tissue

Cardiac tissue engineering offers a promising approach to regenerating post-MI myocardial tissue; however, a primary impediment lies in the inability to adequately vascularize a tissue scaffold. Endothelial cells (ECs) require a support cell to form mature patent lumens and it has been demonstrated that pericytes, vascular smooth muscle cells and mesenchymal stem cells (MSCs) are able to support the formation of mature tubules/vessels. Cardiac fibroblasts (CFs) provide important electrical and mechanical components to the myocardium and are present in the native cardiac cell population, but to date have not been sufficiently studied for their role in angiogenesis in the heart. As a model of myocardial tissue, we co-cultured different concentrations of various cell types in fibrin hemispheres in appropriate combinations of their specific media, to determine the optimal sprout formation through DNA analysis, flow cytometry and immunohistology (IH). For flow cytometry, endothelial cells and mesenchymal stem cells were marked with CD31 and CD90, respectively. The highest total cell count was found in the fetal CF co-cultured populations (Fig 1A p<0.05), but ECs proliferated best with the adult and neonatal CFs (Fig 1B p<0.001). Analysis of IH images (Fig 1C, D) demonstrated that ECs formed the longest (Fig 1E p<0.05) and most numerous sprouts (p<0.002) with CFs as compared to MSCs. However, ECs were able to produce more multicellular sprouts when in culture with the MSCs (Fig 1F p<0.001). In summary, CFs provide a better support system for EC proliferation and sprout formation than MSCs, while MSCs allow for more multicellular sprouts, which is more indicative of the in vivo process.

Serum IgE Autoantibodies Target Keratinocytes in Patients with Atopic Dermatitis

Previous studies have shown that sera of patients with severe atopic dermatitis (AD) contain IgE specific for self-proteins, supporting the hypothesis of autoreactivity as a pathogenic factor in AD. In this study, we screened a large panel of AD patients (n=192) by western blotting (WB) for IgE reactivity not only against the human epithelial cell line A431 but also against primary keratinocytes (KCs). To investigate autoantigenic cell structures in detail, normal human skin and primary KCs were incubated with sera from both WB-reactive patients and, for control purposes, healthy individuals, and analyzed by immunohistology, confocal laser microscopy, and flow cytometry. Our analysis revealed that 28% of AD patients, but not healthy individuals, display serum IgE autoreactivity by WB analysis. The individual IgE reaction patterns of the sera pointed to the existence of unique as well as common specificities against epidermal or A431-derived proteins. Immunostainings identified cytoplasmic and, occasionally, also cell membrane-associated moieties as targets for autoreactive IgE antibodies. Interestingly, in certain autoreactive patients, the surface-staining pattern was accentuated at cellular contact sites. We conclude that IgE autoreactivity is common, particularly among severe AD patients, and that non-transformed primary cells are needed for characterization of the entire spectrum of IgE-defined autoantigens.

Allergiediagnostik bei Metallimplantatunverträglichkeit

To clarify a suspected implant allergy, a patch test with implant metals and bone cement components can be used. The (immuno)histology of periimplant tissue may also indicate T-lymphocyte-dominant inflammation. Identification of histological allergy characteristics and evaluation of the lymphocyte transformation test beyond indications of sensitization will be possible only when larger studies are available.

Injectable Liver: A Novel Approach Using Fibrin Gel as a Matrix for Culture and Intrahepatic Transplantation of Hepatocytes

Cell transplantation and tissue engineering with liver cells are currently under investigation as experimental therapies for certain liver diseases. In this study we evaluated a fibrin-based gel matrix as carrier for hepatocytes in culture. Furthermore, a novel technique for direct intrahepatic injection of fibrin gel-immobilized hepatocytes was developed and evaluated in a rat model. Hepatocytes were harvested from rats. Fibrin matrix was generated with modified fibrin sealant. Cells, in medium containing epidermal growth factor and insulin, were seeded in a drop of fibrin matrix onto plastic culture dishes. Cell numbers were assessed by DNA content. Hepatocyte differentiation was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistology (IH) for cytokeratin (CK)-18 and albumin. PKH26-labeled fibrin gel-immobilized hepatocytes were transplanted into liver by direct injection underneath the capsule. Fluorescence microscopy of explanted liver was performed to identify PKH26+ donor cells. Neotissue was characterized by IH for the markers CK-18, ED1, and desmin. Culture in a fibrin matrix allowed stable cell numbers and three-dimensional neotissue formation. RT-PCR and IH showed preservation of liver-specific markers CK-18 and albumin in vitro. Transplanted cells were identified by fluorescence microscopy after 2 and 7 days. CK-18 and desmin staining showed integration of hepatocytes and hepatic stellate cells into the host liver. Fibrin matrix is an appropriate environment for hepatocytes in culture. Direct intrahepatic injection of fibrin gel-immobilized hepatocytes is technically feasible. We conclude that fibrin gel immobilization is an attractive tool for the development of tissue engineering-based liver support systems.

Hemophagocytic syndrome in five patients with epstein-barr virus negative B-cell lymphoma

The recent recognition of the association of Epstein-Barr virus (EBV) with T-cell/natural killer cell (T/NK-cell) lymphoma has documented that particular types of EBV-containing T/NK-cell lymphoma are frequently complicated by hemophagocytic syndrome (HPS). This observation suggests that both EBV and proliferating T/NK-lymphoma cells play significant roles in the development of HPS. Cytokines released from neoplastic T cells are presumed to account for the activation of macrophages, which is followed by a complex cascade of cytokine production, resulting in full-blown HPS. Five patients with B-cell lymphoma complicated by HPS were studied for elevated serum cytokines, the association of EBV, and CD25 expression of lymphoma cells; the aim of this study was to verify whether the mechanisms of HPS development hypothesized for T/NK-cell lymphoma also operate in B-cell lymphoma. Sera were analyzed for the presence of inflammatory and immunoregulatory cytokines. Flow cytometry, immunohistology (IH), in situ hybridization (ISH), polymerase chain reaction (PCR), and Southern blot analysis were performed using bone marrow aspirates, biopsy specimens, and autopsy specimens. Immunophenotypic and Southern blot studies verified that the lymphoma cells of all five patients were of B-cell lineage. Bone marrow aspirates demonstrated histiocytosis with extensive hemophagocytic activity. Marked elevation of serum cytokines and expression of CD25 were observed in all five patients. However, the results of PCR, ISH using EBER1 probe, and IH for latent membrane protein indicated that these lymphoma cells were free of EBV infection. In patients with B-cell lymphoma, EBV infection is not necessarily required for the initiation of HPS. In this article, the pathogenesis of HPS assumed to be operative in B-cell lymphoma is discussed with reference to T/NK-cell lymphoma complicated by HPS.

Preeclamptic nephropathy – an endothelial lesion: A morphological study with a review of the literature

Objective: We investigated wether an endothelial lesion, postulated in pathogenesis of preeclampsia (PE) in general, is also pathogenetically relevant in the characteristic renal lesions of PE, presenting as special glomerular alterations, designated as “preeclamptic nephropathy”. Study Design: Renal biopsies of 90 women with PE were analyzed by light microscopy (LM), immunohistology (IH) and electron microscopy (EM). Corresponding with clinical data clinicomorphological correlations were performed. Results: In IH and EM the altered glomeruli demonstrate an endothelial lesion. Consecutive morphological reactions could be revealed by EM, allowing a subdivision in different stages of disease. The late stage indicates the reversibility of these renal lesions. Close correlations were found between clinical and morphological data. Focal glomerulosclerosis presents a hyperperfusion lesion, developing only facultatively in PE as a result of hyperfiltration. Conclusion: In preeclamptic nephropathy the first morphological substrate of renal changes with the key to pathogenesis presents itself as an endothelial lesion. This results in a disturbance of glomerular basement membrane permeability and in an imbalance of different mediator systems, with dominance of vasoconstrictive reactions but also coagulative-, reparation-, and proliferation-processes, leading to the characteristic glomerular alterations of preeclamptic nephropathy.

Uniform expression of cytotoxic molecules in anaplastic large cell lymphoma of null/T cell phenotype and in cell lines derived from anaplastic large cell lymphoma.

We recently provided ample evidence that anaplastic large cell lymphomas of T/null phenotype (T-/null-ALCL) genotypically represent peripheral T cell lymphomas which in up to 90% have a phenotype of cytotoxic cells with expression of granzyme B protein and perforin transcripts. However, the issue of granzyme B expression in T-/null-ALCL is still controversial due to differing results from another laboratory. To verify our earlier immunohistochemical stainings for granzyme B, we looked for granzyme B transcripts by in situ hybridization (ISH). In addition, we investigated our previously analyzed cases by immunohistology (IH) with another antibody (2G9), which reacts with two molecules known to be expressed in cytotoxic cells: T-cell-restricted intracellular antigen (TIA)-1 and granule membrane protein-17 (GMP-17). We also extended our studies to homogenous tumor cell populations provided by ALCL-derived cell lines. As evidenced by ISH, transcripts for perforin, TIA-1 and granzyme B were found in all ALCL-derived cell lines. Similarly, proteins of TIA-1/GMP-17, granzyme B and perforin were expressed in all of these lines as shown by IH. In biopsy specimens, TIA-1/GMP-17 were detected by IH in 14/16 cases of T-/null-ALCL, and granzyme B transcripts were found in 13/13 T-/null-ALCL cases, but not in 6 B-ALCL cases. The detection of granzyme B transcripts yielded results largely identical to those of IH for granzyme B protein, thus confirming our earlier data and suggesting that the regulation of the expression of this molecule largely occurs at the transcriptional level. Our data further confirm the almost uniform expression of cytotoxic molecules in both primary ALCL cases and ALCL-derived cell lines and therefore suggest that the derivation from cytotoxic T cells may be the unifying characteristic for T-/null-ALCL.

Low incidence of Epstein-Barr virus presence in primary cutaneous T-cell lymphoproliferations

Multiple biopsies taken from 76 European human immunodeficiency virus (HIV)-negative patients with primary cutaneous T-cell lymphoproliferations, including mycosis fungoides (MF), pleomorphic T-cell lymphoma (PMTCL), anaplastic large cell lymphoma (ALCL) and lymphomatoid papulosis (LyP) were investigated for the presence of Epstein-Barr virus (EBV) through a combined approach. Polymerase chain reaction (PCR) was employed for EBV-DNA detection, in situ hybridization (ISH) for cellular localization of EBV-encoded nuclear RNAs (EBER1 and EBER2) and immediate early Bam H-fragment; lower frame (BHLF) RNA, and immunohistology (IH) for the identification of EBV-encoded latent membrane protein 1 (LMP1) and of nuclear antigen (EBNA) 2 expression. EBV-DNA was detectable by PCR in 15 of 76 cases (19.7%). EBER-ISH combined with IH identified a variable, usually very low, number of infected neoplastic cells in only seven of the 15 EBV-DNA-harbouring cases. This discrepancy between the results obtained with PCR and ISH is apparently caused by the low number of the infected cells per tissue section. The PMTCL entity produced the greatest number of positive cases, whilst ALCL and LyP cases were almost constantly devoid of the virus. BHLF transcripts were not detectable in any case, nor did any of the EBER-positive cells show an LMP1 or EBNA2 expression. These data show that primary cutaneous T-cell lymphoproliferations display an infrequent association with a latent EBV infection and that the pathogenic role of the virus in the positive cases remains obscure as the virus frequently infects only a minority of the atypical cells.

Prognostic significance of p53 expression, chromosome 17 copy number, and DNA ploidy in non-metastasized colorectal carcinomas (stages IB and II).

Paraffin-embedded tumor tissue from 101 non-metastasized colorectal adenocarcinomas (tumor stages IB and II--that is, pT2 and 3, pN0, M0) was investigated for p53 expression by immunohistology (IH) (moab DO1), chromosome 17 (#17) copy number by interphase cytogenetics using non-radioactive in situ hybridization (NISH) with a centromer-specific DNA probe (D17Z1), and DNA ploidy by flow cytometry (FCM). The aims of the study were 1) to test whether numerical #17 aberrations are involved in functional TP53 loss in locally confined colorectal carcinomas; 2) to search for correlations between aberrant p53 expression and #17 aberrations with DNA ploidy and histopathology; and 3) to test the prognostic significance of these factors. Sixty cases (59.4%) showed nuclear p53 expression IH (low-grade p53 accumulation (< 50%), n = 16 (15.8%); high-grade (> or = 50%), n = 44 (43.6%)). Nish showed #17 aneusomy in 46% of the carcinomas (34% deletions, 12% gains). In FCM analysis, 43% of the carcinomas were DNA non-diploid. p53 overexpression correlated statistically significantly with FCM non-diploidy (p = 0.013). Furthermore, #17 aneusomy also correlated with FCM non-diploidy (p = 0.001). However, there was no association between #17 status and p53 expression (IH). Our data suggest a role for the TP53 gene in the aneuploidization process. Numerical deletions of #17, however, were not associated with p53 immunoreactivity in the analyzed tumors. With regard to prognosis, the most important independent variable in stage IB/II colorectal carcinomas was tumor stage, followed by high-grade p53 expression of tumor cells; #17 aneusomy was an independent risk factor for tumor relapse/progression but not for survival. As alterations of the investigated variables were not found in all carcinomas under study, different pathogenetic pathways seem to exist in colorectal carcinogenesis.

Ehrlichiosis mimicking thrombotic thrombocytopenic purpura. Case report and pathological correlation

Human ehrlichiosis is a tick-borne zoonosis caused by the newly described human hematotropic rickettsiae, Ehrlichia chaffeensis. The pathology and pathogenesis of human ehrlichiosis have not been adequately studied. Even with immunoperoxidase, the only previously known method to detect these organisms in tissue, ehrlichae are difficult or impossible to identify. This led many investigators to speculate that the pathogenesis of ehrlichiosis was not caused directly by the organism but could be caused by host-mediated injury. In this case study, a patient presented with rapidly progressive central nervous system symptoms and severe thrombocytopenia, prompting a presumptive diagnosis of thrombotic thrombocytopenic purpura (TTP). Despite corticosteroids, and later, antibiotics, the patient rapidly deteriorated and died. Postmortem examination showed hemorrhages in multiple organs and mononuclear inclusions of infection with a monocytic ehrlichia. Other findings included widespread lymphohistiocytic perivascular infiltrates, focal hepatic necroses, interstitial pneumonitis, interstitial nephritis, mononuclear phagocyte invasion and proliferation in splenic, liver, and bone marrow, and hemophagocytosis. The diagnosis was proven by serology, immuno histology with both polyclonal and monoclonal anti E chaffeensis, and polymerase chain reaction on paraffin-embedded tissues using E chaffeensis-specific oligonucleotide primers. The presence of numerous ehrlichia with notable tissue and cellular injury but without a marked host response indicate that unlike other cases of documented human ehrlichiosis, this patient died after significant direct ehrlichia-mediated injury, and that immune mechanisms initiated after ehrlichiosis played little if any role in the pathogenesis.

Epstein‐Barr virus in B‐cell non‐Hodgkin's lymphomas: Unexpected infection patterns and different infection incidence in low‐ and high‐grade types

Two hundred and eight cases of B-cell non-Hodgkin's lymphoma (B-NHL) occurring in Europeans without any signs of HIV infection were investigated for their association with an Epstein-Barr virus (EBV) infection. The polymerase chain reaction (PCR) was applied for EBV-DNA detection, in situ hybridization (ISH) for the cellular localization of EBV-encoded small nuclear RNAs (EBER) and immediate-early RNAs (BHLF), and immunohistology (IH) for the detection of EBV-encoded latent membrane protein (LMP) and EBV nuclear antigen 2 (EBNA2) expression. PCR and EBER-ISH produced congruent results in those cases with amplifiable DNA. EBV was present overall in 26 per cent (54/208) of the B-NHL cases. Through EBER-ISH, the virus could be localized merely in rare non-neoplastic bystander lymphocytes in 27 and additionally in tumour cells of 27 cases. Unexpectedly, the proportion of EBV-infected tumour cells present in the different cases varied between 1 and 100 per cent. All but three of the cases with infected tumour cells were of high-grade malignancy. Correlation with the morphological and immunological tumour phenotype revealed that all cases with more than 80 per cent EBER-positive tumour cells were either B-anaplastic large cell lymphomas (B-ALCL), sporadic Burkitt's lymphomas, or B-NHLs with partial or full plasmacellular differentiation. LMP was consistently absent from Burkitt's lymphomas and constantly expressed in B-ALCLs with EBER-positive tumour cells, while in all other instances it varied greatly and was rarer than EBER expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Frequent presence of latent Epstein-Barr virus infection in peripheral T cell lymphomas. A review.

Two-hundred and four cases of peripheral T cell lymphoma (PTCL) occurring in Europeans without any sign of HIV-infection were investigated for their association with an Epstein-Barr virus (EBV) infection. Polymerase chain reaction (PCR) was applied for EBV-DNA detection, in situ hybridisation (ISH) for the cellular localization of EBV-encoded small nuclear RNA (EBER) and immediate early gene expression (BHLF) and immunohistology (IH) for the detection of EBV-encoded latent membrane protein 1 (LMP1) and EBV nuclear antigen 2 (EBNA2) expression. PCR and EBER-ISH produced congruent results in almost all cases with amplifiable DNA, leading to the finding of an overall frequency of EBV presence in 87/204 (42.6%) of the PTCL cases. Through EBER-ISH, the virus was identified to be exclusively present in small and blastic bystander lymphocytes in 29 cases, whilst an additional infection of neoplastic T cells was observed in the remaining 58 EBV-positive cases. The entity presenting with the most frequent EBV infection of tumour cells was that of angioimmunoblastic type PTCL, whilst the primary cutaneous PTCLs only seldom harbored the virus. Forty-eight of the EBV-positive TCLs showed an infection of a small proportion (1-20%) of the tumour cell population, whilst another ten cases, belonging to the pleomorphic TCL (PMTCL) group, displayed an infection of several to almost all neoplastic T cells (20-100%). Additional lytic EBV-infected cells could be detected in four cases by BHLF-ISH. LMP1 expression was present in a small proportion of the neoplastic T cells in 24 of the 58 cases with tumour cell infection, whilst an EBNA2 expression was detectable only in one case. Some non-malignant EBV-infected B-immunoblasts and Hodgkin/Reed Sternberg-like cells also expressed LMP1 in several cases. Our data imply a role of EBV in the pathogenesis of only a few PMTCL cases with predominant tumour cell infection, whilst the pathogenic significance of an EBV infection in the other PTCLs remains unclear due to the usually partial infection of the neoplastic cell component.

Light chain deposition disease of the kidney. Morphological aspects in 24 patients.

Renal biopsies and autopsy specimens of 23 patients with light chain deposition disease (LCDD) and one with only heavy chain deposits, were studied by light (LM) and electron microscopy (EM) as well as immunohistology (IH). Thirteen patients had multiple myeloma; 1 had lymphoma, and 1 chronic myeloid leukaemia with polycythaemia vera. In nine patients, no lymphoproliferative disease was identified. The LM lesions most suggestive of LCDD, nodular glomerulosclerosis (NS) and thickening and wrinkling of the tubular basement membranes (TBM), were present in only ten and 13 patients, respectively. In five of seven specimens without NS or TBM thickening by LM, EM was negative, indicating a limited value of EM in confirming the diagnosis. Renal amyloidosis was not identified, but in one patient amyloid in the heart and tongue was seen at autopsy. One patient had both granular and extensive glomerular non-amyloid fibrillary deposits. In two patients myeloma casts were identified. Twenty-one patients showed renal LC immune reactivity, 1 had both alpha heavy and lambda LC, 1 had only detectable gamma heavy chain. One biopsy was negative by IH, but had characteristic electron dense deposits. In six patients with immune reactivity to LC, no electron dense deposits could be identified by EM. This study emphasizes the spectrum of renal changes by LM and EM in LCDD, the frequent lack of consistency between deposits detected by IH and EM and the difficulty in coming to a definite diagnosis without LM, EM and IH. The results of this study and examination of the literature indicates that extensive morphological changes are more often present in kappa than in lambda LCDD.

Frequent Latent Epstein-Barr Virus Infection of Neoplastic T Cells and Bystander B Cells in Human Immunodeficiency Virus-Negative European Peripheral Pleomorphic T-Cell Lymphomas

We investigated 81 cases of peripheral pleomorphic T-cell lymphoma (PMTCL) occurring in human immunodeficiency virus-negative Europeans for the presence of Epstein-Barr virus (EBV)-DNA through polymerase chain reaction (PCR) for the presence of EBV-encoded small nuclear RNAs (EBER) and immediate early mRNAs (Bam H-fragment, lower strand frame [BHLF]) by in situ hybridization (ISH) and for EBV-encoded latent membrane protein (LMP) and nuclear antigen 2 (EBNA2) by immunohistology (IH). EBER-ISH, which could be applied on all cases, showed an overall incidence of EBV-infected cells in 38 of 81 cases (47%) of PMTCL. These data could be confirmed by PCR, which produced congruent results in the cases with amplifiable DNA. By EBER-ISH, the virus was located in the tumor cells in 30 of the 38 EBV-positive cases, with the proportion of the infected cells ranging from 1% to 100%. In 18 of these cases and in the 8 cases without EBV-infected tumor cells, the virus was, respectively, either additionally or exclusively detectable in occasional nonmalignant lymphoid bystander cells. An LMP expression was observed in several of the EBER-expressing tumor cells in 18 cases, whereas EBNA2 was detectable only in one case, which also displayed signs of viral replication. Some nonmalignant EBV-infected B immunoblasts also expressed LMP in several cases. Primary cutaneous and enteropathy-associated PMTCL displayed less frequent EBV infection when compared with other extranodal or nodal manifestations.

The cortical epithelium of the rat thymus after in vivo exposure to bis(tri-n-butyltin)oxide (TBTO). An (immuno)histological and ultrastructural study.

Bis(tri-n-butyltin)oxide (TBTO) induces cortical atrophy in the rat thymus. We studied the potential involvement of the cortical epithelium in TBTO-induced thymotoxicity by (immuno) histology and electron microscopy. Juvenile male Wistar rats were orally intubated once with either 30 or 90 mg/kg TBTO and sacrificed 4 or 10 days later. A dose-dependent thymic atrophy occurred. Anti-keratin labelling showed epithelial cell aggregation in some animals at 10 days after exposure to 90 mg/kg TBTO, when recovery of the thymus was apparent. At the ultrastructural level, a relative shift was observed from "pale" to darker epithelial cell subtypes at the 30 mg/kg dose level, both at day 4 and day 10 after intubation. This phenomenon was not observed after exposure to 90 mg/kg TBTO. Both the altered keratin distribution and the increased electron density of the epithelium probably represent non-specific phenomena. The present morphological observations support the concept that TBTO affects the thymus via its action on lymphoid cells rather than on the epithelial compartment.