Distribution of fibronectin and laminin in normal and pathological lymphoid tissue

Histopathological Evaluation of Angiogenic Markers in Non-Hodgkin's Lymphoma

Background Angiogenesis plays a key role in the development, maintenance, and progression of tumor. The incidence of non-Hodgkin's lymphoma (NHL) is increasing from the past three decades.

Materials and Methods The aim of the study is to evaluate microvessel density (MVD) using CD34 monoclonal antibody and vascular endothelial growth factor (VEGF) using monoclonal antibody that were studied in pretreatment paraffin-embedded tissue samples of 60 cases.

Results MVD was found to be increased in parallel with increasing grade of tumor. B-NHL had a mean MVD of 79.5 ± 8.8 (no./mm2), while T-NHL had a mean MVD of 183 ± 37.6 (no./mm2). VEGF expression was seen in 42 cases (70%), 20 cases (33.3%) showed strong VEGF expression, and the remainder showed either weak (36.6%) or no (30%) staining. Strong VEGF expression is seen in 100% cases of T-NHL and 77.7% cases of B-NHL. Mean MVD and VEGF expression was found to be correlated significantly with the histological grade of NHL (p = 0.001 and p = 0.000, respectively). Average microvessel counts were 53, 82.9, and 130.8 vessels (no./mm2) for negative, weak, and strong VEGF staining, respectively. These differences were statistically significant (p = 0.005 for strong vs. negative and p = 0.091 for strong vs. weak VEGF staining individually).

Conclusion As the grade of tumor progresses, the angiogenic potential also advances which seems to depend on VEGF. The presence of higher MVD in high-grade lymphomas can be utilized for antiangiogenic drugs.

Leukaemia: a model metastatic disease

In contrast to solid cancers, which often require genetic modifications and complex cellular reprogramming for effective metastatic dissemination, leukaemic cells uniquely possess the innate ability for migration and invasion. Dedifferentiated, malignant leukocytes retain the benign leukocytes' capacity for cell motility and survival in the circulation, while acquiring the potential for rapid and uncontrolled cell division. For these reasons, leukaemias, although not traditionally considered as metastatic diseases, are in fact models of highly efficient metastatic spread. Accordingly, they are often aggressive and challenging diseases to treat. In this Perspective, we discuss the key molecular processes that facilitate metastasis in a variety of leukaemic subtypes, the clinical significance of leukaemic invasion into specific tissues and the current pipeline of treatments targeting leukaemia metastasis.

Fibronectin in the palatine tonsil as a susceptibility marker in Egyptian rheumatic families: histological and immunohistochemical studies

Rheumatic fever (RF) and rheumatic heart disease (RHD) are the multisystem autoimmune sequel of group A streptococci (GAS) infection of the upper respiratory passages, mainly tonsillopharyngitis. The major receptor on the surface of human palatine tonsil for GAS is fibronectin (FN; adhesin receptor). Early detection of RF susceptibility is considered as an important aim of this study. Therefore, the present study aimed to use FN immunoreactivity (FN-ir) as a marker for early detection of rheumatic susceptible children with palatine tonsil crypts surface epithelium. A total of 30 palatine tonsillar specimens were obtained from children aged from 3 to 15 years. Histological studies showed moderate vascular changes and more than four apparent epithelial disruptions in the crypt epithelium. FN-ir showed a significant increase in FN in the basal layers of surface epithelium, subepithelial connective tissue and interfollicular areas. Tonsils of children in rheumatic families showed significant increase in FN in subepithelial connective tissue areas with more than one apparent crypt epithelial disruption compared to normal children. We can conclude that FN plays a central role in the RF and differentially distributed in the functional compartments of the palatine tonsil in children with RHD, so FN-ir can be used as a marker for rheumatic susceptibility.

Angiogenesis in Non-Hodgkin's Lymphoma: An Intercategory Comparison of Microvessel Density

Background. This study was aimed at comparing angiogenesis, seen as microvessel density (MVD) in subtypes of non-Hodgkin's lymphoma (NHL). Methods. In this study, 64 cases of NHL diagnosed over a three-year period were included along with 15 lymph node biopsies of reactive hyperplasia. NHLs were classified using REAL classification, and immunohistochemistry was performed for CD34 in all cases. CD34-stained sections were evaluated for “hot spots,” where MVD was assessed and expressed as per mm². Appropriate statistical methods were applied. Results. There were 6 cases of well-differentiated lymphocytic lymphoma (SLL), 21 diffuse large B-cell lymphoma (DLBCL), 15 follicular lymphoma, 10 lymphoblastic lymphoma, 7 MALToma, and 5 peripheral T-cell lymphoma (PTCL). Mean MVD was highest in reactive hyperplasia (191.92 ± 12.16 per mm²) compared to all NHLs. Among NHLs, PTCL demonstrated the highest MVD (183.42 ± 8.24) followed by DLBCL (149.91 ± 13.68). A significant difference was found in MVD between reactive and individual lymphoma groups. SLL had significantly lower MVD than other lymphoma subtypes. Conclusion. Angiogenesis, assessed by MVD, showed significant differences among subtypes of NHL, especially the indolent types like SLL. The higher MVD in aggressive lymphomas like PTCL and DLBCL can potentially be utilized in targeted therapy with antiangiogenic drugs.

Endothelial and virgultar cell formations in the mammalian lymph node sinus: endothelial differentiation morphotypes characterized by a special kind of junction (complexus adhaerens)

The lymph node sinus are channel structures of unquestionable importance in immunology and pathology, specifically in the filtering of the lymph, the transport and processing of antigens, the adhesion and migration of immune cells, and the spread of metastatic cancer cells. Our knowledge of the cell and molecular biology of the sinus-forming cells is still limited, and the origin and biological nature of these cells have long been a matter of debate. Here, we review the relevant literature and present our own experimental results, in particular concerning molecular markers of intercellular junctions and cell differentiation. We show that both the monolayer cells lining the sinus walls and the intraluminal virgultar cell meshwork are indeed different morphotypes of the same basic endothelial cell character, as demonstrated by the presence of a distinct spectrum of general and lymphatic endothelial markers, and we therefore refer to these cells as sinus endothelial/virgultar cells (SEVCs). These cells are connected by unique adhering junctions, termed complexus adhaerentes, characterized by the transmembrane glycoprotein VE-cadherin, combined with the desmosomal plaque protein desmoplakin, several adherens junction plaque proteins including alpha- and beta-catenin and p120 catenin, and components of the tight junction ensemble, specifically claudin-5 and JAM-A, and the plaque protein ZO-1. We show that complexus adhaerentes are involved in the tight three-dimensional integration of the virgultar network of SEVC processes along extracellular guidance structures composed of paracrystalline collagen bundle "stays". Overall, the SEVC system might be considered as a local and specific modification of the general lymphatic vasculature system. Finally, physiological and pathological alterations of the SEVC system will be presented, and the possible value of the molecular markers described in histological diagnoses of autochthonous lymph node tumors will be discussed.

Lectin histochemistry of the rat lymph node: visualisation of stroma, blood vessels, sinuses, and macrophages. A contribution to the concept of an immune accessory role of sinus-lining endothelia

The lectin Chelidonium majus agglutinin (CMA) was previously shown to visualise endothelia of all blood vessels and those lining sinuses of red pulp, stromal reticular meshwok (RM) and dendritic cells of lymphatic follicles in white pulp of the spleen in rats. The aim of the present study was the analysis of CMA and some other lectins in labelling RM, vascular structures and macrophages in lymph nodes of rats. It appeared that CMA stained the entire RM, dendritic cells, lining cells of sinuses and all types of blood vessels. Sinus-lining cells of lymph nodes were labelled with CMA and mannose-, GalNac-, and sialic acid-specific lectins. Moreover, lymph node macrophages were labelled above all by mannose specific lectins. The broad lectin-binding pattern of sinuses--not observed in rat spleen- and CMA-reactivity of both sinus-lining and dendritic cells corroborates the hypothesis that lymph node sinus-lining endothelia are precursors or a special type of immune accessory cells.

Growth and dissemination of a newly-established murine B-cell lymphoma cell line is inhibited by multimeric YIGSR peptide

B-cell lymphoma frequently shows simultaneous dissemination to multiple organs. It also occasionally involves bone and causes osteolytic lesions. To study the mechanisms responsible for this capacity of lymphoma cells to grow in different tissue microenvironments and search for effective therapeutic interventions for this hematological malignancy, we established a new murine B-cell lymphoma cell line named MH-95. The tumor disseminated to multiple organs including the lung, liver, kidney, spleen and lymph nodes within 2 weeks after subcutaneous inoculation in nude mice. In addition, the tumor also grew in bone and caused osteoclastic osteolytic lesions. Thus, this tumor model mimics the behavior in many ways of B-cell lymphoma in humans. We studied the role of laminin, a major component of the basement membrane, in this model, since although it has been implicated in solid tumor metastasis, little is known about the involvement of laminin in the growth of B-cell lymphoma in bone and other organs. Immunohistochemical examination showed strong laminin expression in the stroma of the primary subcutaneous tumor and tumors in the bone and other organs. Systemic administration of the antagonistic laminin peptide YIGSR decreased primary tumor growth and tumor cell deposit in the bone, liver and kidney. In addition, the peptide also decreased apparent neovascularization in the tumor, suggesting that the peptide suppressed angiogenesis presumably due to inhibition of laminin binding to its receptors. These results demonstrate that the MH-95 B-cell lymphoma cells express laminin and suggest that laminin plays a critical role in the growth and simultaneous dissemination of tumor cells to multiple organs, similar to what has been described in solid tumors. The results also suggest that suppression of angiogenesis through interfering with laminin actions may be a useful adjuvant therapy for B-cell lymphoma.

Adhesion molecules in haemopoiesis

In the adult mammal, haemopoiesis is restricted to the extravascular compartment of the bone marrow (BM) where primitive haemopoietic stem cells (HSC) and their clonogenic progeny develop in intimate contiguity with a heterogeneous population of stromal cells that comprise the haemopoietic micro-environment (HM). Although the importance of cellular interactions between primitive haemopoietic progenitor cells (HPC) and marrow stromal cells is well established, precise definition of the nature of many of these interactions at the molecular level is lacking and remains an objective of fundamental importance to understanding of haemopoietic regulation. Current data suggest that a wide variety of cell surface molecules representing several adhesion molecule superfamilies, including integrins, selectins, sialomucins and the immunoglobulin gene superfamily, are involved in supporting cell-cell and cell-extracellular matrix (ECM) interactions. These diverse CAM-ligand interactions, rather than simply serving to initiate and maintain contact between HPC and stromal cells and ECM components, also have an additional, more direct role in controlling the growth and development of primitive haemopoietic cells.

Reed-Sternberg Cells of Classical Hodgkin's Disease React With the Plasma Cell-Specific Monoclonal Antibody B-B4 and Express Human Syndecan-1

Although the cellular origin of Reed-Sternberg (RS) cells of classical Hodgkin's disease (HD) has been a controversial issue for many years, recent immunophenotypic and molecular studies have suggested that RS cells of a subset of classical HD cases may be related to B cells. To further define the immunophenotypic features and the differentiation stage of RS cells, a series of 56 HD samples, including both nodular lymphocyte predominance (LP) (eight cases) and classical HD (nodular sclerosis [NS], 32 cases; mixed cellularity [MC], 16 cases) with a non-T–cell phenotype, were evaluated for the immunohistochemical expression of the B-B4 antigen, a specific marker for terminally differentiated B cells. Because the cDNA of the B-B4 antigen encodes syndecan-1, a member of a family of transmembrane heparan sulfate proteoglycans thought to be involved in binding cells of the B lineage to the interstitial matrix, the B-B4 immunoreactivity was correlated with the expression of syndecan-1 in HD-derived cell lines (L428, KM-H2), as detected by both reverse transcriptase polymerase chain reaction (RT-PCR) studies and Western blotting. Our results show that B-B4 reacts with RS cells and their morphological variants of all cases of classical HD, irrespective of their antigenic phenotype (B, undetermined), albeit at a varying degree of cellular expression. Notably, a high reactivity and staining intensity for the B-B4 monoclonal antibody (MoAb) was restricted to tumor cells from NS HD. In cases of the latter subtype, B-B4 positivity was also found in sclerosis-trapped spindle cells (fibrocytes/fibroblasts). Conversely, the putative tumor cells of nodular LP HD were consistently unreactive with the B-B4 MoAb. Finally, we have demonstrated by RT-PCR, flow cytometry, and Western blotting that cultured RS cells, of B and undetermined phenotype, express syndecan-1 mRNA and produce a form of syndecan-1, recognized by the B-B4 MoAb, which is predominantly associated with glycosaminoglycans and is present at the cell surface. Our detection of the plasma cell-specific antigen B-B4 (syndecan-1) on tumor cells of classical HD further supports that RS cell progenitors may be related to germinal/postgerminal center mature B cells and suggests that expression of syndecan-1 may contribute to some of the typical biologic and histopathologic features of classical HD, with a special regard to the NS subtype.

Reed-Sternberg Cells of Classical Hodgkin's Disease React With the Plasma Cell-Specific Monoclonal Antibody B-B4 and Express Human Syndecan-1

Although the cellular origin of Reed-Sternberg (RS) cells of classical Hodgkin's disease (HD) has been a controversial issue for many years, recent immunophenotypic and molecular studies have suggested that RS cells of a subset of classical HD cases may be related to B cells. To further define the immunophenotypic features and the differentiation stage of RS cells, a series of 56 HD samples, including both nodular lymphocyte predominance (LP) (eight cases) and classical HD (nodular sclerosis [NS], 32 cases; mixed cellularity [MC], 16 cases) with a non-T–cell phenotype, were evaluated for the immunohistochemical expression of the B-B4 antigen, a specific marker for terminally differentiated B cells. Because the cDNA of the B-B4 antigen encodes syndecan-1, a member of a family of transmembrane heparan sulfate proteoglycans thought to be involved in binding cells of the B lineage to the interstitial matrix, the B-B4 immunoreactivity was correlated with the expression of syndecan-1 in HD-derived cell lines (L428, KM-H2), as detected by both reverse transcriptase polymerase chain reaction (RT-PCR) studies and Western blotting. Our results show that B-B4 reacts with RS cells and their morphological variants of all cases of classical HD, irrespective of their antigenic phenotype (B, undetermined), albeit at a varying degree of cellular expression. Notably, a high reactivity and staining intensity for the B-B4 monoclonal antibody (MoAb) was restricted to tumor cells from NS HD. In cases of the latter subtype, B-B4 positivity was also found in sclerosis-trapped spindle cells (fibrocytes/fibroblasts). Conversely, the putative tumor cells of nodular LP HD were consistently unreactive with the B-B4 MoAb. Finally, we have demonstrated by RT-PCR, flow cytometry, and Western blotting that cultured RS cells, of B and undetermined phenotype, express syndecan-1 mRNA and produce a form of syndecan-1, recognized by the B-B4 MoAb, which is predominantly associated with glycosaminoglycans and is present at the cell surface. Our detection of the plasma cell-specific antigen B-B4 (syndecan-1) on tumor cells of classical HD further supports that RS cell progenitors may be related to germinal/postgerminal center mature B cells and suggests that expression of syndecan-1 may contribute to some of the typical biologic and histopathologic features of classical HD, with a special regard to the NS subtype.

Focal hepatic lymphoma: magnetic resonance demonstration using current techniques including gadolinium enhancement

This study demonstrates the appearance of focal hepatic lymphoma using current magnetic resonance techniques including gadolinium enhancement. Fifteen patients with hepatic lymphoma were imaged at 1.5T. T1-weighted, T2-weighted, immediate, and 5-10-min delayed T1-weighted spoiled gradient echo images were acquired in all patients. Determination was made of lesion size, number, morphology, and signal intensity of lesions on all sequences. Seven patients had solitary lesions and 8 patients had multiple lesions. Focal lesions of hepatic lymphoma ranged in size from 5 mm to 15 cm. They were well defined masses with mild to moderate low signal intensity relative to liver on T1-weighted images. Lymphoma lesions in 6 patients were moderately high in signal intensity on T2-weighted images compared with liver (Type I lesions), and enhancement of lesions was intense on early post-gadolinium images in 5 of these patients. Lymphoma lesions in 6 patients were mildly hypointense to mildly hyperintense on T2-weighted images compared to liver (Type II lesions), and lesions in 5 of these patients enhanced minimally on the early post-gadolinium spoiled gradient echo images. The remaining 3 patients had received chemotherapy before the magnetic resonance examination, and the imaging findings varied reflecting presumed differences in treatment responses. Transient ill defined perilesional enhancement on immediate post-gadolinium spoiled gradient echo images was observed in 9 patients including patients with either type of lesion. Focal lesions of hepatic lymphoma are usually low in signal intensity on T1-weighted images but have variable signal intensity on T2-weighted images. In general, lesions that are mildly hypointense to minimally hyperintense in signal intensity on T2-weighted images enhance minimally, and lesions moderately high in signal intensity of T2-weighted images enhance intensely. Transient increased perilesional enhancement is common.

Evolution of Hodgkin's disease

Hodgkin's disease is an oncogenic core disorder characterized by both mitotic and amitotic neoplastic multiplication, and is associated with collateral disorders such as lacunar formation and leukocytic infiltration. Research has demonstrated that Hodgkin's disease progresses stepwise, beginning with a reversible, biological stage during which Hodgkin and Reed-Sternberg cells are formed, followed by constitutive, but reversible Hodgkinogenic medical stage that leads to an irreversible, systemic and fatal proto-oncogenic stage. This disease results from collateral activation of cytokine and archaic oncogenes, suppression of DNA repair genes in multiple chromosomes. The variability of Hodgkin's disease manifestations has required antisynthetic (antimetabolites, radiotherapy), anti-viral (acyclovir) and anti-mitotic (vincristine, vinblastine) for different loci minores of treatment. Continued molecular biological research of the ancestral and prokaryotic oncogenes is recommended.

Angiogenesis spectrum in the stroma of B-cell non-Hodgkin's lymphomas. An immunohistochemical and ultrastructural study

Samples of lymph nodes from 88 patients with B-cell non-Hodgkin's lymphoma (B-NHL) grouped by the Working Formulation (WF) and from 15 patients with benign lymphadenopathies were investigated immunohistochemically and ultrastructurally for changes in angiogenesis and stromal distribution of two subendothelial basement membrane (BM) components, namely laminin and type IV collagen. The microvessel number was usually low in lymphadenopathies, and increased significantly in low-grade B-NHL. Intermediate-grade tumors displayed a further significant increase that was mainly due to their diffuse subtypes rather than to the follicular subtype. High-grade B-NHL showed the highest counts. By contrast with the lymphadenopathies studied, the stroma of B-NHL reacted intensely with both BM components, whose linear co-expression was significantly associated with low-grade and follicular intermediate-grade B-NHL, while expression of laminin alone in a granular pattern was detected in diffuse intermediate-grade and high-grade tumors. Ultrastructural analysis revealed immature vessels more frequently in diffuse intermediate-grade, and in high-grade B-NHL. These in situ data suggest that angiogenesis occurring in B-NHL increases along their progression path, and emphasize the importance of angiogenesis as an epigenetic phenomenon of B-NHL progression.

Extracellular matrix proteins and integrin receptors in reactive and non-reactive lymph nodes

The extracellular matrix (ECM) proteins collagen I, III and IV, laminin, fibronectin, vitronectin, thrombospondin, tenascin and their integrin receptors of the beta 1 and beta 3 subfamilies showed characteristic patterns of distribution in different compartments of non-reactive and reactive lymph nodes (human and monkey). This was particularly evident during development of germinal centres. Thus, ECM proteins (collagens, laminin, fibronectin and tenascin) were abundant in the interfollicular (T-cell rich) compartments of non-reactive as well as reactive lymph nodes. In primary follicles, collagen I, III and fibronectin were expressed but displaced by the expanding germinal centre during the formation of secondary follicles in reactive lymphoid tissues. The integrin subunits were mainly associated with endothelial cells and lymphoid cells in interfollicular areas, but were absent or only poorly expressed in primary as well as secondary follicles. Evidently the expression of ECM components and their integrin receptors is markedly down-regulated in the reactive, highly proliferative germinal centres.

Extracellular matrix of small round cell tumors of childhood: an immunohistochemical study of 67 cases

Sixty-seven childhood tumors were studied immunohistochemically for the extracellular matrix element type IV collagen, laminin, and fibronectin. Tumors included Ewing's sarcoma, primitive neuroectodermal tumor, small cell osteosarcoma, neuroblastoma or ganglioneuroblastoma, rhabdomyosarcoma, and lymphoma. It was found that small cell osteosarcoma was often positive for fibronectin but not type IV collagen or laminin, a new observation. In the lymphomas, matrix proteins were rarely found. Ewing's sarcoma was variably positive for type IV collagen and laminin, but fibronectin was absent. Extracellular laminin and fibronectin were found in one of two cases of primitive neuroectodermal tumor. In neuroblastoma and ganglioneuroblastoma, the matrix components were rarely found. These results, discrepant with findings in cultured cells, may reflect the altered capacity of tumors to produce these proteins in vitro, which suggests that caution should be exercised in drawing conclusions regarding the nature or histogenesis of tumors from data obtained with cultured tumor cells. Embryonal rhabdomyosarcoma frequently contained all matrix elements in the extracellular space and in a dotlike pattern in the cytoplasm; alveolar rhabdomyosarcoma rarely contained these proteins and never exhibited the dotlike pattern. The frequent finding of matrix proteins in embryonal rhabdomyosarcoma but only rarely in alveolar rhabdomyosarcoma and the unique immunostaining pattern in embryonal rhabdomyosarcoma may prove to be a useful adjunct in the diagnosis of childhood tumors.

Localization of beta 1 integrins and their extracellular ligands in human lymphoid tissues

In this study, we describe the immunocytochemical distribution of the beta 1 integrins (alpha 1 to alpha 6) and their extracellular matrix ligands in human peripheral lymphoid tissues. The results show that within these tissues individual beta 1 integrins are differentially expressed by (sub)populations of stromal cells, including reticular cells, endothelial cells, epithelial cells, and sinus lining cells. The extracellular matrix components studied, eg, collagen I, III, and VI, fibronectin, laminin, and vitronectin, were predominantly associated with the stroma of the lymphoid tissues, and a unique distribution pattern was observed for each of them. Except for alpha 4 (and beta 1), low or no expression of the beta 1 integrins was found on lymphocytes, macrophages, interdigitating cells, and follicular dendritic cells. The results suggest that cell-matrix interactions play a major role in the maintenance of the complex spatial organization of the lymphoid tissue.

The nonlymphoid microenvironment of reactive follicles and lymphomas of follicular origin as defined by immunohistology on paraffin-embedded tissues

Twenty-five reactive lymph nodes, 10 palatine tonsils, and 72 B-cell non-Hodgkin's lymphomas (NHLs) of supposed follicular origin were investigated in an immunohistologic study of fixed, paraffin-embedded tissues using a panel of monoclonal antibodies reactive with antigens resistant against fixation and paraffin-embedding techniques together with polyclonal antibodies. The results concerning the microenvironmental organization of reactive lymphoid follicles confirmed that the distribution of CD21+ and CD23+ dendritic reticulum cells, vimentin+ fibroblastic reticulum cells, and CD68+ tingible-body macrophages is heterogeneous with reference to their immunostaining patterns and topographic localization within the germinal center and mantle zone. Moreover, a close microenvironmental similarity between the follicular lymphomas of supposed germinal center or mantle zone origin and their normal counterparts was noted. The study of the microenvironment of the B-zone small lymphocytic lymphoma cases, showing the same distribution patterns for the nonlymphoid cells as seen in mantle zone lymphomas, corroborated the supposed follicular origin of this unusual variant of small lymphocytic lymphoma. In conclusion, this study shows that monoclonal antibodies recognizing CD21, CD23, and CD68 antigens may be valuable additions to vimentin, S-100 protein, laminin, and type IV collagen antibodies for investigating the microenvironmental organization of lymphoid tissues in both normal and neoplastic conditions.

Correlation of extracellular matrix components with the cytoarchitecture of mouse Peyer's patches

The distribution patterns of extracellular matrix elements were determined to ascertain whether they play a role in the localization of lymphocytes in discrete T-cell, B-cell and dome antigen-processing domains within Peyer's patches. Antibodies against collagen types I, III and IV, laminin and fibronectin were applied to cryosections of mouse Peyer's patches and localized by direct or indirect immunoperoxidase methods. T-cell domains were identified with a monoclonal antibody against Thy-1.2. Labeled reticular fibers in distinctive patterns were more numerous in parafollicular and dome areas than within follicles. Germinal centers contained few such fibers. In parafollicular areas, fibers were oriented predominantly toward follicle domes; their distribution corresponded to T-cell zones and lymphocyte traffic areas, with their orientation being parallel to the migration pathways of lymphocytes from high endothelial venules to the antigen-processing domes. Subepithelial and subendothelial basal laminae were immunopositive for type-IV collagen, laminin and fibronectin. The dome subepithelial basal lamina had pore-like discontinuities through which lymphocytes migrated to and from the epithelium. The correspondence of the distribution patterns of extracellular matrix to specific functional domains of Peyer's patches suggests that this matrix provides a structural framework for lymphocyte migration and localization.

Basement membrane components in lymphoid follicles: immunohistochemical demonstration and relationship to the follicular dendritic cell network

We analyzed the distribution of two basement membrane components, laminin and type IV collagen, in human reactive and neoplastic lymphoid follicles by using immunoenzymatic and immunofluorescence methods on serial frozen sections from 11 reactive lymph nodes, three palatine tonsils, and 11 immunophenotypically defined B cell non-Hodgkin's lymphomas. The patterns of distribution of these two antigens were compared with that of follicular dendritic reticulum cells (DRCs) as visualized by anti-DRC-1 and anti-desmoplakin 1 and 2 antibodies. Immunostaining for laminin and type IV collagen produced overlapping results. Germinal centers contained some vascular and fiber-like linear staining, but the most striking feature was the presence of a large amount of punctate-granular staining. This staining was present throughout the entire area of most of the germinal centers, although often more densely in the central areas. The stronger punctate-granular staining for laminin, type IV collagen, and desmoplakin 1 and 2 corresponded to the more densely stained areas for DRC-1. Double immunofluorescence assay demonstrated that there was a close similarity between the punctate-granular staining pattern of laminin and the dendritic network of DRC-1-positive cells. In the nine B cell lymphomas of follicular center origin in which DRCs were present, although distributed in different patterns, immunostaining for laminin and type IV collagen could be observed only in those areas showing immunoreactivity for DRC-1. The results of this study suggest that the punctate-granular staining pattern for laminin and type IV collagen is specific for the follicle. This finding may be strictly related to the follicular microenvironment because the pattern of distribution displayed by laminin and type IV collagen seems to be spatially related to the staining pattern of DRCs, as visualized by the anti-DRC-1 and desmoplakins antibodies, both in reactive and neoplastic conditions.

Vitronectin (serum spreading factor): its localisation in normal and fibrotic tissue

The distribution of vitronectin and fibronectin in normal and fibrotic tissue was directly compared using indirect immunofluorescence. Both glycoproteins were ubiquitiously localised to loose connective tissue. Vitronectin, unlike fibronectin, was not detected in basement membranes, in normal renal glomeruli, or around smooth muscle cells of both musculares mucosae and propria of the gastrointestinal tract. The presence of vitronectin could not be shown in washed permeabilised platelets. Vitronectin was very much increased in reactive and fibrotic tissue, as was fibronectin. This was observed in lymph nodes affected by both nodular sclerosing Hodgkin's disease and by metastatic carcinoma as well as in myelofibrotic bone marrow and sclerotic glomeruli. These findings suggest that vitronectin may have an important role in the processes of inflammation and repair.

Characterization of extracellular matrix in non-Hodgkin's lymphomas

Basement membrane proteins laminin, type IV collagen and aminoterminal propeptide of type III collagen (type III pN-collagen) are important components of extracellular matrix of normal lymph nodes; they are present in reticular fibres and in the walls of blood vessels and sinuses. We have studied the distribution of these proteins in 45 cases of non-Hodgkin's lymphomas representing different types of Kiel classification. Light microscopic immunohistochemistry was used on sections from formalin fixed, paraffin embedded biopsy specimens. Reticular cells were identified by using antibodies against S-100 protein, a marker for dendritic and interdigitating reticulum cells, and against cystatin A for the demonstration of follicular dendritic reticulum cells. The findings of the immunohistochemical stainings were generally similar in the different lymphoma types. Thus the method for the demonstration of extracellular matrix proteins could not give obvious aid for lymphoma classification. BM stainings proved to be efficient in the demonstration of sinuses. Marginal and medullary sinuses of the nodal cases were either totally or partly spared and open also in the cases in which there was extracapsular growth. The fibre content was variable, but generally the distribution of all the three extracellular matrix proteins was comparable with each other and mainly corresponded with the pattern seen in conventional Gomori's reticulin stain. This also holds for the tumor tissue infiltrated through the capsule and for extranodal cases. Areas of sclerosis of some cases contained only type III pN-collagen. Reticular fibres were at places seen to be closely associated with cells of spindle or dendritic shape. A few reticulum cells could be found to show cytoplasmic staining for laminin, type IV collagen and type III pN collagen. This finding suggests that the cells are synthetizing these proteins. The amount of cells staining for cystatin A or S-100 protein did not generally correlate with the amount of fibres, and most of the stained cells were not closely associated with fibres. The results show that in non-Hodgkin's lymphomas basement membrane proteins and type III pN-collagen are important components of reticular fibres. Results also indirectly support the main role of fibroblastic reticulum cells in the production of the fibres.

Laminin: molecular organization and biological function

Laminin, the most abundant glycoprotein molecule found in basement membrane, has multiple functions in eukaryotic tissues. It serves to attach epithelial cells to basement membrane, aids development and migration of specific cell types in growth and maturation, and has been implicated in tumor metastasis and some types of infection. Current concepts of the molecular organization and myriad functions of the laminin molecule are reviewed.

An immunohistochemical study of laminin, type-IV collagen and type-III pN-collagen with relation to reticular fibres in Hodgkin's disease

The distribution of aminoterminal propeptides of type-III procollagen (indicating the presence of type-III pN-collagen, i.e., type-III collagen molecule with a non-cleaved aminoterminal propeptide), laminin and type-IV collagen was studied by immunohistochemical methods. The results were compared with the distribution of reticular fibres using Gomori's reticulin stain. Lymph nodes from 20 cases of Hodgkin's disease (HD) and 3 spleens affected by nodular sclerosis HD were studied. The reticular fibres stained for all the antigens investigated, the strongest reaction being for pN type-III collagen. Thick fibres stained mainly for type-III pN-collagen, the BM proteins being located in a fragmented rim on the surface. The distribution and composition of fibres was similar in both nodal and extranodal infiltrations. The morphological alterations noted in the fibres comprised (1) compression between nodules in the nodular type of lymphocyte-predominant HD, and (2) fragmentation, present in collections of histiocytes in lymphocyte-predominant HD. BM proteins and type-III pN-collagen were present in the walls of the sinuses and vessels. The marginal sinuses were often partially spared in spite of extracapsular invasion. Our results suggest that laminin, type-IV collagen and type-III pN-collagen are important components of reticular fibres in HD and that the composition of the fibres is similar to that seen in the normal lymph node.

Immunohistology of adenolymphoma (Warthin's tumour): evidence for a role of vascularization in the organization of the lympho-epithelial structure

The epithelial, vascular and lymphoid components present in two cases of adenolymphoma (Warthin's tumour) were characterized by immunohistochemistry on frozen sections. Epithelial cells were positive for cytokeratin and keratin and were in close contact with numerous factor VIII related antigen-positive capillary vessels, running parallel to the epithelial basement membrane. The capillary vessels were in communication with high endothelial post-capillary venules which were often lined by HLA-DR-positive endothelial cells. The lymphoid tissue was organized in B-cell and T-cell areas. The B-cell areas consisted of B4+/To15+ B-lymphocytes admixed with DRC-1-positive follicular dendritic reticulum cells. The T-cell areas were mainly populated by T11+/T3+/T4+ lymphocytes admixed with some S-100+/HLA-DR+ interdigitating reticulum cells. Plasma cells and T8+ lymphocytes were more numerous in the proximity of the epithelium. Leu-M3+/PAM-1+ macrophages were scattered singly in the T-cell areas or were arranged in sinus-like structures around the epithelial cysts. The epithelial basement membrane, the vascular membrane and the fibrillar reticular stroma of the lymphoid tissue were immunoreactive for laminin and type IV collagen. The possibility is discussed that the accumulation of lymphoid tissue in Warthin's tumour is modulated by the epithelial cells, perhaps through their ability to organize a peculiar pattern of vascularization.

Plexiform vascularization of lymph nodes: an unusual but distinctive lymphadenopathy in cats

A distinctive lymphadenopathy in nine cats, four of which were of the Longhair breed, was characterized by capillary vasoproliferation and lymphoid atrophy. It occurred in the cervical or inguinal regions. The animals were, apart from local manifestations, healthy at the time and remained so subsequently. In the absence of any clinical or morphological evidence for viral, neoplastic or developmental aetiologies, we postulate an ischaemic pathogenesis for the lesions which may be related to human "vascular transformation of lymph node sinuses". The lesions appear to be by no means a rare cause of non-neoplastic lymphadenopathy in domestic cats, since they constituted over 5 per cent of surgical biopsies of cat lymph nodes seen in the past 5 years. The lesions merit wider recognition and investigation.

Immunohistochemical localization of fibronectin in the human placentas at their different stages of maturation

The distribution of fibronectin in the human placenta was studied by the aid of the immunoperoxidase technique using specific antibodies against it. In the early chorionic tissue, fibronectin was distributed along the trophoblastic basement membrane, on the wall of fetal blood vessels, in the connective tissue core, and in the cytotrophoblastic cell columns. In the term placenta, this glycoprotein was detected mainly on the fetal blood vessels and less intensely in the stroma, but not along the trophoblastic basement membrane. Endothelial cells of the blood vessels, fibroblastic cells in the stroma, and unidentified cells in the cytotrophoblastic cell columns were immunostained positively for fibronectin. These data suggest that fibronectin of the placenta is produced locally and retained in the tissue, if not all.

Contribution of histiocytic cells to sarcomatous development of the gliosarcoma. An immunohistochemical study

The expression of glial fibrillary acidic protein, fibronectin (FN), factor VIII-related antigen (FVIII/RAG), and of three monohistiocytic markers, lysozyme, alpha-1-antitrypsin and alpha-1-antichymotrypsin was examined in five gliosarcomas (GS) by peroxidase-antiperoxidase immunostaining of formalin-fixed and paraffin-embedded specimens, and compared with vascular changes in 16 glioblastomas (GB). In contrast to GB, endothelial proliferations of GS were sheathed by sarcomatous tissue (perivascular sarcoma), which was contiguous with fibrosarcomatous areas. Cells with conspicuous intracytoplasmic FN content (FN+ cells) were seen in the vascular stroma of GB and dominated in the sarcomatous parts of GS. Most FN+ cells of GS were of varying size and shape and clearly neoplastic. Monohistiocytic markers were demonstrable in small infiltrating mononuclear cells as well as in many sarcomatous cells including FN+ cells. FVIII/RAG was restricted to lumen-lining endothelium and was not found in sarcomatous cells. These results suggest that a major part of sarcoma in GS is less likely to develop from proliferated endothelial cells than from histiocytic cells in the perivascular spaces of GB. By FN mediation, histiocytic cells might also guide and promote sarcomatous proliferations of other mesenchymal cells, leading to fibrosarcomatous development. Prominent monstrous giant cells of one GS seemed to be degenerating glioma cells.

S-100 protein, fibronectin, and laminin immunostaining in lymphomas of follicular center cell origin

Forty-nine paraffin-embedded biopsy specimens of involved nodal and extranodal tissue (bone marrow, spleen, and liver) from 13 patients with follicular center cell lymphomas (FCCL) and 14 with small lymphocytic lymphomas (SLL), including 11 cases with chronic lymphocytic leukemia, were tested for S-100 protein immunoreactivity. Analysis for fibronectin and laminin immunoreactivities was limited to the lymph node biopsy specimens. In FCCL, S-100-positive dendritic reticulum cells (DRCs) were found in 23 of the 26 tissue specimens examined, regardless of the involved sites and the growth pattern. Cases with completely or predominantly follicular pattern were usually associated with a spherical meshwork pattern of S-100-positive DRCs; in the FCCL specimens with a diffuse pattern (lymph nodes and bone marrow) as well as in the specimen areas with a minimally follicular tumor pattern, S-100-positive DRCs were consistently fewer in number and composed loosely aggregated nests. No S-100-positive DRCs were found in all the biopsy specimens in SLL. Concerning fibronectin and laminin immunostainings, results showed that no differences were present between areas of follicular and diffuse neoplastic growth and that the neoplastic growth of FCCL maintained for each antiserum the same distribution pattern as that seen in normal follicles. Analysis of the microenvironmental components as revealed with antisera used in the current study--particularly with anti-S-100 protein antiserum--appears to be a useful adjunct for the identification of FCCL in paraffin-embedded biopsy specimens, especially in extranodal sites.

Distribution of basement membrane laminin and type IV collagen in human reactive lymph nodes

The location of two basement membrane components, laminin and the 7-S domain of type IV collagen, was studied in human lymph nodes using the peroxidase-antiperoxidase method. Basement membrane antigens were present on the walls of blood vessels and of marginal, trabecular and medullary sinuses. Thin, fragmented fibre-like staining was present also in parenchyma outside the germinal centres, in a pattern overlapping with reticular fibres as seen on conventional reticulin stains. This finding suggests that basement membrane components are a part of the reticular fibres of lymph nodes, or are closely associated with them.

Development of stroma in malignant lymphomas of the brain compared with epidural lymphomas. An immunohistochemical study

The relation of lymphoma cells to gliomesenchymal stroma within nervous tissue was studied by peroxidase-antiperoxidase immunostaining of formalin-fixed and paraffin-embedded surgical specimens for fibronectin (FN), factor VIII-related antigen and glial fibrillary acidic protein in 17 malignant non-Hodgkin lymphomas of the brain. For comparison, 9 non-Hodgkin lymphomas, 6 Hodgkin lymphomas, and 19 plasmacytomas of the spinal or cranial epidural spaces were studied with the same methods. Lymphoma cells were consistently negative for all markers. All lymphomas of the brain showed conspicuous concentric perivascular circles of immunoreactivity for FN in parts infiltrating brain tissue. Such structures are considered to derive from splitting of basal laminae of preexisting brain vessels; they were not seen in tumors of the epidural space. Cells with conspicuous FN content were found in brain as well as in epidural lymphomas. A monohistiocytic origin of those cells was confirmed by presence of monohistiocytic markers lysozyme and alpha-1-anti-chymotrypsin. Thus, additional immunostaining for FN seems to be useful for detecting monohistiocytes/macrophages in brain tumors.