The Histological Composition of Capsular Contracture Focussed on the Inner Layer of the Capsule: An Intra-Donor Baker-I Versus Baker-IV Comparison.

BACKGROUND: Capsular contracture remains one of the major complications after breast implantation surgery. The extent of capsular contraction is scored using the Baker scale. The aim of this study was to compare intra-individual Baker-I with Baker-IV capsules, and in particular the prevalence and histological properties of the inner capsule layer. METHODS: Twenty capsules from ten patients were included after bilateral explantation surgery due to unilateral capsular contracture (Baker-IV) after cosmetic augmentation with textured implants. All capsules underwent (immune-)histochemical analysis: haematoxylin-eosin (morphology), CD68 (macrophages), cytokeratin (epithelial cells) and vimentin (fibroblasts), and were visually scored for cell density and the presence of an inner layer and measured for thickness. RESULTS: Baker-IV (n = 10) capsules were significantly thicker compared to Baker-I (n = 10) capsules (P = 0.004). An inner layer was present in 8 Baker-I capsules. All Baker-I capsules were vimentin and CD68-positive and cytokeratin-negative. Positive vimentin was seen throughout the inner layer, and CD-68 staining was observed adjacent to the intermediate capsule layer. In contrast, only 2 Baker-IV capsules had an inner layer, of which only 1 showed the same profile as Baker-I capsules (P = 0.016). No cytokeratin positivity was seen in any capsule. In Baker-IV capsules, outer layers showed more positivity for both vimentin and CD68. CONCLUSION: The inner layer is morphologically consistent with synovial metaplasia and is more prevalent in healthy, uncontracted Baker-I capsules. This inverse relation between the presence of the inner layer and higher Baker classification or pathological contracture could indicate a protective role of the inner layer against capsular contracture formation. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Increased epidermal thickness and abnormal epidermal differentiation in keloid scars.

BACKGROUND: The pathogenesis underlying keloid formation is still poorly understood. Research has focused mostly on dermal abnormalities, while the epidermis has not yet been studied. OBJECTIVES: To identify differences within the epidermis of mature keloid scars compared with normal skin and mature normotrophic and hypertrophic scars. METHODS: Rete ridge formation and epidermal thickness were evaluated in tissue sections. Epidermal proliferation was assessed using immunohistochemistry (Ki67, keratins 6, 16 and 17) and with an in vitro proliferation assay. Epidermal differentiation was evaluated using immunohistochemistry (keratin 10, involucrin, loricrin, filaggrin, SPRR2, SKALP), reverse-transcriptase polymerase chain reaction (involucrin) and transmission electron microscopy (stratum corneum). RESULTS: All scars showed flattening of the epidermis. A trend of increasing epidermal thickness correlating to increasing scar abnormality was observed when comparing normal skin, normotrophic scars, hypertrophic scars and keloids. No difference in epidermal proliferation was observed. Only the early differentiation marker involucrin showed abnormal expression in scars. Involucrin was restricted to the granular layer in healthy skin, but showed panepidermal expression in keloids. Normotrophic scars expressed involucrin in the granular and upper spinous layers, while hypertrophic scars resembled normotrophic scars or keloids. Abnormal differentiation was associated with ultrastructural disorganization of the stratum corneum in keloids compared with normal skin. CONCLUSIONS: Keloids showed increased epidermal thickness compared with normal skin and normotrophic and hypertrophic scars. This was not due to hyperproliferation, but possibly caused by abnormal early terminal differentiation, which affects stratum corneum formation. Our findings indicate that the epidermis is associated with keloid pathogenesis and identify involucrin as a potential diagnostic marker for abnormal scarring.

Overexpression of P70 S6 kinase protein is associated with increased risk of locoregional recurrence in node-negative premenopausal early breast cancer patients.

The RPS6KB1 gene is amplified and overexpressed in approximately 10% of breast carcinomas and has been found associated with poor prognosis. We studied the prognostic significance of P70 S6 kinase protein (PS6K) overexpression in a series of 452 node-negative premenopausal early-stage breast cancer patients (median follow-up: 10.8 years). Immunohistochemistry was used to assess PS6K expression in the primary tumour, which had previously been analysed for a panel of established prognostic factors in breast cancer. In a univariate analysis, PS6K overexpression was associated with worse distant disease-free survival as well as impaired locoregional control (HR 1.80, P 0.025 and HR 2.50, P 0.006, respectively). In a multivariate analysis including other prognostic factors, PS6K overexpression remained an independent predictor for poor locoregional control (RR 2.67, P 0.003). To our knowledge, P70 S6 kinase protein is the first oncogenic marker that has prognostic impact on locoregional control and therefore may have clinical implications in determining the local treatment strategy in early-stage breast cancer patients.

Nuclear beta-catenin is a molecular feature of type I endometrial carcinoma.

Two types of endometrial carcinoma can be distinguished: type I tumours, which are oestrogen-related and are typically low-grade endometrioid carcinomas; and type II tumours, which are unrelated to oestrogen stimulation and are often non-endometrioid carcinomas. The molecular abnormalities involved in carcinogenesis appear to be different for these tumour types. The aim of this study was to test the hypothesis that an abnormality in the Wnt/beta-catenin signalling pathway is a molecular feature of type I endometrial carcinoma. This study investigated nuclear beta-catenin by immunohistochemistry in 233 endometrial carcinomas and analysed its correlation with several immunohistochemical, histological, and clinical parameters, such as proliferation rate (Ki-67), expression of oestrogen and progesterone receptors, and survival. Nuclear beta-catenin expression was observed in 39 cases (16%). All tumours expressing nuclear beta-catenin were endometrioid adenocarcinomas, were significantly better differentiated, and were more often hormone receptor-positive than tumours without nuclear beta-catenin. No correlation with proliferation rate was found. It was found that several features of type I endometrial carcinoma occur significantly more often in tumours expressing nuclear beta-catenin, suggesting that an abnormality in the Wnt/beta-catenin signalling pathway, resulting in nuclear beta-catenin immunopositivity, is a molecular feature of a subset of type I endometrial carcinomas.

Chondrosarcoma is not characterized by detectable telomerase activity.

Reactivation of telomerase, an enzyme which elongates human telomeres, is associated with cell immortilization. In approximately 90% of malignant tumours telomerase activity can be demonstrated, whereas in benign tumours it is mostly absent. Chondrosarcomas are relatively rare malignant cartilaginous neoplasms. A small number of chondrosarcomas located centrally in bone arise secondarily to an enchondroma, while the majority of chondrosarcomas developing from the surface arise within the cartilage cap of an osteochondroma. The histological distinction between a benign lesion and low-grade chondrosarcoma is generally considered difficult. To investigate whether the progression towards chondrosarcoma is characterized by reactivation of telomerase activity, this study determined telomerase activity in ten enchondromas, five osteochondromas, and 37 chondrosarcomas using the TRAP assay. In all tumour samples except one, telomerase activity was absent. By adding tumour lysates to the positive control, an increasing inhibition of telomerase activity was found with an increasing chondroid matrix, suggesting that it may contain inhibitory factors. Inhibition due to endogenous RNAse or Taq-polymerase inhibitors was excluded. The lack of detectable telomerase activity in the high-grade component of a dedifferentiated chondrosarcoma without matrix favours the possibility that telomerase is truly absent. Either its true absence or inhibitory effects disabling telomerase detection exclude the telomerase TRAP assay as a diagnostic tool in the differential diagnosis of benign and low-grade malignant cartilaginous tumours.

Assessment of problems in diagnostic and research immunohistochemistry associated with epitope instability in stored paraffin sections.

Loss of antigenicity or epitope instability, especially after tissue sections have been prepared, may affect immunohistochemical staining results. To obtain insight into the magnitude of this problem, we conducted a systematic investigation. A total of 20 monoclonal and 12 polyclonal antibodies were used for immunohistochemistry using formalin-fixed, paraffin-embedded sections that were stored for periods ranging from 15 to 360 days at temperatures of 4 degrees C, 21 degrees C, and 37 degrees C. After 1 year of storage. immunohistochemical results appeared to be impaired with four antibodies at 4 degrees C, 11 antibodies at 21 degrees, and 16 antibodies at 37 degrees C. It was found that staining results using polyclonal antisera are affected to the same extent by this phenomenon compared to antibodies of monoclonal origin. No indication was found that antigen retrieval could restore the effect of epitope instability. An additional experiment, in which the influence of section adhesives on epitope instability was investigated, revealed that none of the applied adhesives hampers immunohistochemical reactivity for a storage time of up to 6 months.

A possible role of CD46 for the protection in vivo of human renal tumor cells from complement-mediated damage.

It is still unclear which membrane-bound regulatory proteins (mCRP) are important in vivo to protect tumor cells from complement-mediated damage. To address this question, the expression levels of CD46, CD55, and CD59 were measured semi-quantitatively in situ on renal cell carcinomas and compared with the expression level and cellular distribution of these mCRP in proximal tubuli within each patient (n = 31). It was also determined whether the expression of mCRP on tumor cells is associated with deposition of C3d and C5b-9. CD46 expression was decreased on tumor cells; in contrast, CD55 was expressed on tumor cells (12 out of 31 samples), while it was not detected on proximal tubular epithelial cells (PTEC). Also, expression of CD59 on tumor cells was increased as compared with its expression on PTEC. Furthermore, the localization on the cell surface of mCRP as observed on PTEC was altered on tumor cells. Because expression of mCRP may limit a complement-mediated anti-tumor response, we determined whether complement deposition was associated with the expression level of CD46, CD55, and CD59. The presence of C3d on tumor cells was associated with a low expression level of CD46 (p < 0.02). The expression level of CD46 was also associated with a low tumor stage (p < 0.04). The results suggest that in vivo CD46 plays a role in the protection of human renal tumor cells from complement-mediated injury.

Up-regulation of PTHrP and Bcl-2 expression characterizes the progression of osteochondroma towards peripheral chondrosarcoma and is a late event in central chondrosarcoma.

Chondrosarcomas are malignant cartilage-forming tumors arising centrally in bone (central chondrosarcoma) or within the cartilaginous cap of osteochondroma (peripheral chondrosarcoma). For hereditary multiple osteochondromas, two responsible genes, EXT1 and EXT2, have been cloned. Their recently elucidated role in heparan sulfate biosynthesis and Hedgehog diffusion leads to the hypothesis that EXT inactivation affects fibroblast growth factor (FGF) and Indian Hedgehog (IHh)/parathyroid hormone-related peptide (PTHrP) signaling, two important pathways in chondrocyte proliferation and differentiation. The expression of PTHrP, PTHrP-receptor, Bcl-2, FGF2, FGFR1, FGFR3, and p21 is investigated by immunohistochemistry in osteochondromas (n = 24) and peripheral (n = 29) and central (n = 20) chondrosarcomas. IHh/PTHrP and FGF signaling molecules are mostly absent in osteochondromas. Although no somatic EXT mutations were found in sporadic osteochondromas, the putative EXT downstream targets are affected similarly in sporadic and hereditary tumors. In chondrosarcomas, re-expression of FGF2, FGFR1, PTHrP, Bcl-2, and p21 is found. Expression levels increase with increasing histological grade. Up-regulation of PTHrP and Bcl-2 characterizes malignant transformation of osteochondroma because PTHrP and Bcl-2 expression is significantly higher in borderline and grade I peripheral chondrosarcomas compared with osteochondromas. In contrast, up-regulation of PTHrP and Bcl-2 seems to be a late event in central cartilaginous tumorigenesis because expression is mainly restricted to high-grade central tumors.

Loss of heterozygosity and DNA ploidy point to a diverging genetic mechanism in the origin of peripheral and central chondrosarcoma.

Chondrosarcomas are malignant cartilaginous tumors arising centrally in bone (central chondrosarcoma), or secondarily within the cartilaginous cap of a hereditary or sporadic exostosis (peripheral chondrosarcoma). Loss of heterozygosity (LOH) was studied by microsatellite analysis at the loci harboring the EXT genes (implicated in hereditary multiple exostoses), the EXT-like genes, and at 9p21, 13q14, 17p13, and chromosome 10. Nineteen of 20 peripheral chondrosarcomas showed LOH at all loci tested, while only 3 of 12 central chondrosarcomas exhibited LOH, restricted to 9p21, 10, 13q14, and 17p13. LOH at 9p21 did not appear to involve the CDKN2A gene, as assessed by SSCP analysis. DNA flow cytometry demonstrated a wide variation in the ploidy status in peripheral chondrosarcomas (DNA indexes, 0.56-2.01), whereas central chondrosarcomas were predominantly peridiploid. Near-haploidy found in peripheral chondrosarcomas could explain part of the high LOH percentages. Ki-67 immunohistochemistry suggested a higher proliferation rate in peripheral chondrosarcomas. Our results indicate that peripheral chondrosarcomas, arising secondarily to an exostosis, may obtain genetic alterations during malignant transformation, with subsequent genetic instability as demonstrated by a high percentage of LOH and a wide variation in ploidy status. In contrast, peridiploidy and a low percentage of LOH in central tumors suggest that a different oncogenic molecular mechanism may be operative.

Oncogene alterations in carcinomas of the uterine cervix: overexpression of the epidermal growth factor receptor is associated with poor prognosis.

The involvement of human papillomavirus (HPV) in the development of carcinomas of the uterine cervix has been firmly established. However, other genetic alterations also play an important role in the pathogenesis of cervical cancer. Therefore, we have investigated the role of several (onco)genes in cervical carcinoma. In tumors from 136 patients with stage I and II cancer of the uterine cervix, the expression of epidermal growth factor receptor (EGFR), c-erbB-2/neu, p53, and murine double minute 2 (MDM-2) was studied using immunohistochemistry. In 32 cases, amplification of EGFR, c-erbB-2/neu, MDM-2, and c-myc was studied by Southern blot hybridization. The expression levels of these proteins were correlated with HPV positivity, International Federation of Gynecologists and Obstetricians stage, lymph node metastases, tumor diameter, vessel invasion, and disease-free and overall survival. Moderate/strong expression of EGFR was observed in 54% of tumors. c-erbB-2/neu was focally positive in 12 cases. p53 showed moderate/strong expression in 32% of the tumors. Thirteen % of tumors showed a moderate/strong expression of MDM-2, and this expression was correlated to p53 expression (P<0.001). Only moderate/strong expression of EGFR was associated with reduced disease-free (P = 0.002) and overall survival (P = 0.003). In multivariate analysis, the association of EGFR overexpression with poor prognosis was independent from lymph node status. Gene amplification was found for EGFR (four cases), c-erbB-2/ neu (two cases), and c-myc (six cases). In two tumors, rearrangement of c-myc was found, probably due to the integration of HPV. In conclusion, overexpression of the EGFR is an independent predictor for prognosis in earlier stages (stage I and II) of cervical cancer. p53 and MDM-2 expression are correlated to each other and may play a role in the interaction with HPV. The importance of c-erbB-2/neu and c-myc amplification is relatively small in stage I and II cervical cancer.

Immunohistochemical detection of p53 and Bcl-2 in colorectal carcinoma: no evidence for prognostic significance.

To evaluate the prognostic significance of immunohistochemically detected p53 and Bcl-2 proteins in colorectal cancer, tissue sections from 238 paraffin-embedded colorectal carcinomas were immunostained for p53 (MAb DO-7 and CM-1 antiserum) and Bcl-2 (MAb Bcl-2:124). Staining patterns were assessed semiquantitatively and correlated with each other and with sex, age, tumour site, Dukes' classification, tumour differentiation, mucinous characteristics, lymphocyte and eosinophilic granulocyte infiltration, and patient survival. In our series, 35% of carcinomas showed no nuclear staining and 34% (DO-7) to 40% (CM-1) showed staining in over 30% of tumour cell nuclei. A majority of carcinomas that had been immunostained with CM-1 showed cytoplasmic staining, but this was not observed with DO-7. With respect to Bcl-2, 51% of tumours were completely negative, 32% displayed weak and 15% moderate staining; only 3% showed strong positive staining. No evidence was found for reciprocity between Bcl-2 expression and nuclear p53 accumulation. From 13 cases containing tumour-associated adenoma, four were Bcl-2 negative in premalignant and malignant cells, in another four cases these cells showed similar staining intensities and in the remaining cases only the malignant colorectal cells were Bcl-2 negative. Therefore, our data indicate that Bcl-2 is dispensable in the progression towards carcinoma. Except for an association between nuclear p53 accumulation and mucinous tumours (P = 0.01), no significant correlation was found between the clinicopathological parameters mentioned above and immunostaining pattern of (nuclear or cytoplasmic) p53 or Bcl-2.

Expression of growth factors and their receptors in adamantinoma of long bones and the implication for its histogenesis.

Adamantinoma of long bones is a rare bone tumour with (immuno-) histological features of epithelial cells, surrounded by various amounts of osteofibrous tissue. Recent studies have indicated that cells with an epithelial phenotype are most probably the malignant element. There is still debate as to whether the fibrous part should be designed as a benign neoplastic element of a biphasic tumour or as a reactive non-neoplastic tissue next to an epithelioid bone tumour. The expression of fibroblast growth factor type 2 (FGF-2), epidermal growth factor (EGF), and their respective receptors FGFR-1 and EGFR, as well as the proliferation marker Ki-67, was studied in both constituents of adamantinoma in serial sections of 25 cases by immunohistochemistry. Expression of FGF-2 and its receptor was present in both constituents of adamantinoma, but predominated in the epithelial component. Expression of EGF and its receptor was restricted to the epithelial component of adamantinoma. Comparing osteofibrous dysplasia (OFD)-like adamantinoma with classic epithelial cell-rich adamantinoma, the expression of FGF-2, EGF, and EGFR was more intense and in a higher percentage of cells in classic adamantinoma. Proliferative activity was found nearly exclusively in the epithelial component. These data further substantiate the hypothesis that epithelial cells constitute the proliferating tumour cell population responsible for the malignant behaviour of adamantinoma. The data indicate that during progression, the epithelial cells acquire expression of FGF-2, EGF, and EGFR, accompanied by a higher proliferative activity. Within the epithelial cell population, there exists an autocrine pathway of growth stimulation. Furthermore, these data point to an interaction between the epithelial and fibrous components, in which the epithelial cells additionally stimulate fibrous cell growth via a paracrine pathway involving FGF-2.

Distribution of extracellular matrix components in adamantinoma of long bones suggests fibrous-to-epithelial transformation.

Adamantinoma of long bones is a rare skeletal tumor of unknown origin with epithelial and fibrous elements. The ill-defined distinction between the two components in some cases earlier led to the assumption that these might be derived from the same (mesenchymal) stem cell. In this study, we investigated the distribution of extracellular matrix components in 21 adamantinomas by immunohistochemistry, to gain information on the interaction between the epithelial and fibrous parts of the tumor. Collagens I and III, and fibronectin were generally present in the (osteo-)fibrous tissue of adamantinoma but lacked in the epithelial aggregates. There was a clear relation between the identification of the epithelial and fibrous components at the histological level, and the staining for basement membrane proteins collagen IV and laminin. Prominent areas with cohesive epithelial growth were surrounded by continuous basement membranes, whereas less distinct epithelial islands contained membrane interruptions or had no surrounding basement membrane at all. Tenascin stained intensely surrounding demarcated epithelial aggregates, but weakly or absent more distantly. Osteofibrous dysplasia (OFD)-like tumors displayed local spicular density or pericellular staining of basement membrane factors in fields of isolated keratin-positive cells. These findings suggest that in adamantinoma individual epithelial cells transform from the osteofibrous tissue and thereafter form clusters of epithelium, as can be recognized in classic adamantinoma. This is in analogy to the development of the glandular component of biphasic synovial sarcoma. The fibrous part of adamantinoma is, however, believed to be of benign nature. These results further substantiate the hypothesis of osteofibrous dysplasia being a potential precursor lesion of adamantinoma.

DNA aberrations in the epithelial cell component of adamantinoma of long bones.

Adamantinoma of long bones is a rare malignant tumor composed of cells with epithelial characteristics in various differentiation patterns surrounded by fibrous cells. Evidence as to whether this neoplasm should be designated as an epithelial bone tumor or a biphasic sarcoma with both epithelial and mesenchymal features is lacking. In this study the nature of the mesenchymal and epithelial components of adamantinoma was investigated by DNA flow cytometry, DNA image cytometry, p53 immunohistochemistry, and polymerase chain reaction-based loss of heterozygosity detection at the p53 locus. Specimens from 6 of 15 patients (40%) analyzed by flow cytometry had an aneuploid DNA index. Image cytometry analysis of Feulgen-stained paraffin sections of 6 aneuploid and 2 diploid tumors revealed that aneuploid nuclei were detected in cells with an epithelial phenotype only, whereas all fibrous cells were diploid. Immunohistochemistry for p53 on specimens from 25 patients revealed moderate or strong immunoreactivity in 12 tumors (48%) restricted to the epithelial cells. Loss of heterozygosity at the p53 locus could be confirmed in the epithelial component of an immunohistochemically p53-positive tumor. Additionally, sections of 7 lung metastases were studied histologically. Only keratin-positive epithelial cells, predominantly in the spindle cell pattern, were present in these metastases, whereas the osteofibrous tissue present in the primary tumors was not detected. These results suggest that either adamantinoma consists of a malignant epithelial part with a reactive osteofibrous stroma or that the malignant epithelial cells develop next to a proliferating benign fibrous component. Additional analysis of common genetic abnormalities in the fibrous and epithelial cells of adamantinoma is therefore indicated.

Immunostaining of chain-specific keratins on formalin-fixed, paraffin-embedded tissues: a comparison of various antigen retrieval systems using microwave heating and proteolytic pre-treatments.

The use of chain-specific monoclonal antibodies (MAbs) against keratins in pathology is hampered by their limited staining on formalin-fixed, paraffin-embedded tissue. In the present study, various treatments before immunohistochemistry on paraffin sections were compared, including proteolytic enzymes and microwave antigen retrieval in various solutions. Sections of normal cervical and skin tissue were stained in a three-step immunoperoxidase method, employing a broad panel of MAbs against chain-specific keratins 4, 5, 7, 8, 10, 13, 14, 17, 18, 19 and pankeratin. Using microwave heating, Target Unmasking Fluid (TUF), Antigen Retrieval Solution (ARS), a simple detergent solution (DET), PBS, and distilled water (MiQ) were compared. Microwave heating in PBS or MiQ strongly improved staining results. Moreover, microwave pre-treatment in TUF or DET gave excellent and specific staining with the majority of MAbs tested, comparable with or even better than staining obtained on frozen sections. Using microwave antigen retrieval, tissue morphology remained optimal, and only in a very limited number of MAbs did immunoreactivity on paraffin sections fail to be restored. Proteolytic pre-treatment with trypsin, pepsin, or pronase gave moderate to strong staining with some of the MAbs. Other MAbs, for which microwave pre-treatment was able to restore the loss of immunoreactivity, failed to give appropriate staining with proteolytic pre-treatment. Our results show that microwave heating in either TUF or a simple detergent solution before immunohistochemistry is a reliable method for antigen retrieval of chain-specific keratins in formalin-fixed, paraffin-embedded tissues.

The distribution of cellular adhesion molecules in pigmented skin lesions.

BACKGROUND: The process of multistep tumor development has been studied thoroughly in the development of malignant melanomas. The authors investigated the expression of cellular adhesion molecules in nevomelanocytic lesions to explore a postulated role of adhesion molecules in cell-cell and cell-matrix interactions during tumor development. METHODS: Sections of 20 nevocellular nevi, 35 dysplastic nevi, 6 melanomas in situ, and 20 malignant melanomas were investigated with respect to their expression of intercellular adhesion molecule-1 (ICAM-1), inducible cell adhesion molecule-110 (INCAM-110)/vascular cell adhesion molecule-1 (VCAM-1), E-selectin, lymphocyte function-associated antigen-1 (LFA-1), and the integrins for very late antigen-(VLA) alpha-(alpha) 2 and VLA-alpha 6; for these studies, monoclonal antibodies were used and indirect immunoperoxidase and immunofluorescence staining methods were performed. RESULTS: In the transformation from benign to malignant neoplasms, the expression of ICAM-1 was upregulated strongly. The expression of VLA-alpha 2 on tumor cells increased whereas that of VLA-alpha 6 decreased; these alterations corresponded to changes previously observed in their ligands within the extracellular matrix. These results were statistically significant. In addition, ICAM-1, INCAM-110/VCAM-1, and E-selectin were detected in activated endothelial cells, probably as a result of cytokine activation. The ligand for ICAM-1, LFA-1, was confined to mononuclear cells. CONCLUSIONS: The increase in ICAM-1 and VLA-alpha 2 expression and the decrease of VLA-alpha 6 expression may, in combination with specific matrix alterations, lead to a change in cell-cell and cell-matrix interaction, thereby contributing to the invasive property of melanocytic tumor cells. The neoexpression of INCAM-110/VCAM-1 and E-selectin in pigmented skin lesions may play a role in both infiltrative growth and the generation of a host reaction toward these tumors.

Pathogenesis of experimental lupus nephritis: a role for anti-basement membrane and anti-tubular brush border antibodies in murine chronic graft-versus-host disease.

The pathogenesis of renal involvement was studied in murine chronic graft-versus-host disease (GVHD), which is a model for human systemic lupus erythematosus. GVHD was induced by four i.v. injections of lymphocytes from DBA/2 donor mice into (C57BL/10 x DBA/2)F1 hybrids at 3-4-day intervals. Two weeks after the first injection, antibodies were found to have been deposited in the mesangium and along the glomerular basement membrane (GBM) in a linear arrangement, which changed to a granular pattern after 6-8 weeks. In this stage, large electron-dense complexes were present both subepithelially and subendothelially along the GBM. Proteinuria increased up to 11,300 +/- 2140 micrograms/18 h. Indirect immunofluorescence studies and ELISA showed that sera and kidney eluates contained autoantibodies directed against nuclear antigens and GBM component laminin as well as against renal tubular epithelial antigens (RTE). The specificity of the anti-RTE antibodies was further characterized by the use of absorption techniques as well as immunoblotting. The early linear immunofluorescence pattern seems to be associated with glomerular binding of anti-GBM antibodies, while electron-dense complex formation in later stages may be induced by the superimposed deposition of anti-RTE antibodies. Similar phenomena were recently described in Heymann's nephritis in the rat, a model for human membranous nephropathy.

Development of progressive glomerulosclerosis in experimental chronic serum sickness.

A rat model of chronic serum sickness was used to study the pathogenesis of progressive glomerulosclerosis complicating experimental immune-complex glomerulonephritis. Chronic serum sickness was induced by immunising rats with bovine serum albumin followed by intraperitoneal administration of the antigen. Early lesions consisted of mesangial deposits of rat immunoglobulins, followed later by transient subendothelial and persistent subepithelial immune aggregates. On the basis of the peak level of proteinuria around day 80, three groups of rats were distinguished: I physiological proteinuria; II 50-500 mg/24 h; and III greater than 500 mg/24 h. The animals were killed at day 220 and the presence of mesangial proliferation, epithelial proliferation, and synechiae, as well as focal glomerulosclerosis was scored. It appeared that all and only proteinuric animals developed progressive glomerulosclerosis, although all three groups of animals passed through a phase with mesangial and subendothelial immune deposits. A strong correlation was found between the degree of proteinuria and the proportion of glomeruli affected. We conclude that the combination of mesangial and subendothelial deposits on the one hand and subepithelial deposits associated with increased protein loss on the other constitute a conditio sine qua non for the development of progressive glomerulosclerosis in this model. The use of specific antibodies to investigate the composition of the sclerotic lesions showed the presence of laminin and type IV collagen, but not of types I and III collagen in sclerotic areas of glomeruli. This indicates that the development of progressive glomerulosclerosis in this model is due to an increased production of glomerular basement membrane components by presumably solely glomerular cells after the occurrence of immunological glomerular injury.

Neuroendocrine cells in colorectal adenomas.

A consecutive series of 218 endoscopically resected colorectal adenomas was investigated for the occurrence of neuroendocrine cells. In 59 per cent of these adenomas argyrophil cells were detected. In 8 per cent of the adenomas these cells were numerous and so intricately blended in with the other cell types that they were regarded as an intrinsic part of the tumour. In these adenomas subsequently immunocytochemistry revealed the presence of the neuro-hormonal peptides glucagon, pancreatic polypeptide and somatostatin as well as serotonin, in a pattern similar to that seen in normal colorectal mucosa. The presence of neuroendocrine cells did not correlate with any clinical or pathological parameter. The occurrence of neuroendocrine cells in colorectal adenomas is in agreement with the unitarian theory of the development of the various epithelial cell types in large bowel mucosa.