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PubMed2006

Histopathological and immunohistochemical findings in lymphoid tissues of the endangered Iberian lynx (Lynx pardinus).

The Iberian lynx (Lynx pardinus) is the most threatened wild feline in the world. Little is known about the diseases and pathology that affect this animal. The aim of this study was to evaluate the histopathological status of the peripheral lymphoid tissues and thymus of Iberian lynxes necropsied between 1998 and 2003. Seventeen animals including females (n=8) and males (n=9), age range of 10 months to 16 years, with different causes of death were histopathologically and immunohistochemically (anti-CD3, CD79, MAC387, CD68) studied. Feline immunosuppressive virus laboratorial tests were negative. Five individuals presented neoplasia and/or tuberculosis. All animals presented some degree of both B and T cells depletion in peripheral lymphoid tissues and follicular hyalinosis in the center of depleted follicles. A viral origin of the lymphoid depletion is postulated although other causes (inbreeding, stress, toxic) are not ruled out. The loss of the effectiveness of the immune system increases the vulnerability of the critically endangered Iberian lynx to pathogens.

Animals↗
PubMed2004

Increased lymphoid tissue apoptosis in baboons with bacteremic shock.

The molecular mechanisms of immune cell apoptosis during sepsis remain unclear. Two young adult baboons (Papio sp.) received a lethal dose of live Escherichia coli and were sacrificed at either 16 (for animal welfare concerns) or 24 h post-septic shock. An additional baboon, which received no bacteria, served as a control. Necropsy was performed immediately with subsequent immunohistochemical staining of lymphoid tissue. Immunohistologic analysis of tissues from the septic baboons revealed marked systemic lymphocyte apoptosis occurring in all lymphoid tissues examined. Focally, pyknotic and karyorrhectic lymphocytes demonstrated activation of a mitochondrial-dependent cell death pathway (active caspase 9 and apoptosis-inducing factor). Other regions demonstrated apoptotic lymphocytes with activation of a death receptor-dependent cell pathway (Fas ligand). Thus, we have demonstrated for the first time in primates that overwhelming gram-negative bacteremia produces an early and profound lymphocyte death that occurs through multiple cell death pathways. Bacteremic shock in the baboon may be an appropriate model for studying experimental therapies aimed at blocking lymphocyte apoptosis because their response appears comparable to humans dying from sepsis.

Animals↗
PubMed1982

Ultrastructure of gut-associated lymphoid tissue (GALT) in the amphibian urodele, Pleurodeles waltlii.

The ultrastructure of gut-associated lymphoid tissue (GALT) has been studied in the salamander, Pleurodeles waltlii. Lymphoid accumulations appear as true infiltrates scattered throughout the lamina propria cell elements. The most important components of these infiltrates are small and medium sized lymphocytes, and, in lesser amounts, developing and mature plasma cells, macrophages and granulocytes. Migrating lymphoid cells massively invade the intestinal epithelium inducing noticeable modifications, such as the disappearance of the basement membrane and decreased numbers of mucous cells. Thus, in its organization and cell composition, the GALT of P. waltlii appears to represent a primitive phylogenetic precursor of the mammalian "intestinal-immunologic" barrier.

Animals↗
PubMed1999

Pulmonary mucosa-associated lymphoid tissue lymphoma: CT and pathologic findings.

OBJECTIVE: The objective of this study was to determine the CT findings in pulmonary mucosa-associated lymphoid tissue lymphoma and to correlate these CT findings with histologic specimens. CONCLUSION: In the 11 patients reviewed, the most common CT appearance of pulmonary mucosa-associated lymphoid tissue lymphoma was consolidation with air bronchograms, correlating histologically with a cellular lymphocytic infiltrate expanding the interstitium and compressing adjacent alveoli, producing air bronchograms.

Female↗
PubMed1995

Immunohistologic analysis of ineffective CD40-CD40 ligand interaction in lymphoid tissues from patients with X-linked immunodeficiency with hyper-IgM. Abortive germinal center cell reaction and severe depletion of follicular dendritic cells.

The CD40 ligand (CD40L) is an activation-induced surface membrane protein expressed by CD4+ T helper cells in lymphoid follicles, and is involved in the contact-dependent signaling-mediated activation, proliferation, and differentiation of CD40+ B cells. Using immunohistochemistry, the present study analyzes the cell microenvironment of lymphoid tissues in two cases of X-linked hyper-IgM syndrome, a congenital immunodeficiency caused by mutations of the CD40L gene, and which represents a unique model to dissect the functional and morphologic consequences of disrupted CD40/CD40L interactions. Prominent primary B follicles are identified in the lymph nodes and in the extranodal lymphoid tissues from both cases, but tiny collections of Bcl-2-, MIB1/Ki67+ centroblasts are also found in one case. Despite the CD40L defect, intrafollicular CD4+CD57+ T helper cells, identified by anti-parvalbumin mAb, are normally present. However, a severe depletion of follicular dendritic cells, recognized by Abs against NGFR, CD21 and CD23, and lack of expression of the Ag recognized by KiM4p on these cells, are noticed. Finally, no major alterations of the architecture and cellular composition of the paracortical T cell area are found. A large number of plasma cells exclusively expressing IgM were detected in the colon lamina propria in one of the patients, who also had extremely elevated IgM serum levels. Taken together, these data support the idea that ineffective CD40/CD40L interactions determine both abortive germinal center cell reaction as well as severe depletion and phenotypical abnormalities of follicular dendritic cells, thus impairing the functional development of B follicles. Recurrent or persisting antigenic stimulation in mucosal tissues is likely to play a major role in determining and maintaining elevated IgM serum levels.

Adult↗
PubMedDate not supplied

Significance of S-100 protein immunostaining in the immunohistological analysis of normal and neoplastic lymphoid tissues--an appraisal.

S-100 protein is a heterogeneous fraction of dimeric polypeptides (alpha and beta subunits) that can exist in different combination forms within the various tissues. Concerning the S-100 protein immunodetection within lymphoid tissue, the heterogeneity of the S-100 antigen, the tissue quality (frozen or paraffin-embedded after treatment with different fixatives) and the treatment of the tissue with different immunostaining methods and antibodies of different nature, all make for inconsistent results obtained in the immunohistological studies reported in the literature. Most of the S-100-positive cells of the lymphoreticular system are dendritic cells involved in the immune response (interdigitating reticulum cells, Langerhans cells, and follicular dendritic reticulum cells), other S-100-positive cells belonging to the mononuclear/phagocytic system. S-100 protein immunostaining may be used as a helpful immunohistological diagnostic clue to certain malignancies of the immune system (follicular center cell lymphomas) on the basis of their specifically related dendritic cell microenvironment. In addition to monoclonal antibodies for the immunophenotypic characterization of dendritic cells and macrophages and to enzyme reactions, the combined use of anti-S-100 antibodies specific for each of the S-100 protein subunits, tested with sensitive procedures, would be a very useful tool in the attempt to classify the proliferative disorders of dendritic cells and macrophages.

Biomarkers, Tumor↗
PubMed2006

In situ replication of immediate dendritic cell (DC) precursors contributes to conventional DC homeostasis in lymphoid tissue.

The developmental biology of dendritic cells (DC) under physiological conditions remains unclear. In this study, we show that mouse CD11c(+) MHC class II(-)lineage(-) cells are immediate precursors of conventional DC and are widely distributed in both bone marrow and lymphoid tissues. These precursors have a high clonal efficiency, and when cocultured on a supportive stromal monolayer or adoptively transferred in vivo, generate a population CD11c(+)MHC class II(+) DC that retain limited proliferation capacity. During steady state conditions, a small proportion of immediate DC precursors (DCp) and DCs are dividing actively in bone marrow and spleen. Cytokines that initiate and support proliferation of immediate DCp were defined. Collectively, our findings provide evidence of a distinct development pathway for conventional DC in both bone marrow and lymphoid tissues and highlight the importance of in situ replication of immediate DCp and DC in maintaining conventional DC populations.

Animals↗
PubMed2000

Immunohistological and flow cytometric analysis of glycosphingolipid expression in mouse lymphoid tissues.

Expression of neutral glycosphingolipids (GSLs) and gangliosides in normal lymphoid tissues and cells has been studied mostly by biochemical and immunochemical analysis of lipid extracts separated by thin-layer chromatography. GSLs and gangliosides involved in the GM1b biosynthetic pathway were assigned to T-lymphocytes, whereas B-cell gangliosides and GSLs have been poorly characterized in former publications. We used specific polyclonal antibodies in immunohistochemistry and flow cytometry to analyze the distribution of globotriaosylceramide (Gb(3)Cer), globoside (Gb(4)Cer), gangliotriaosylceramide (Gg(3)Cer), gangliotetraosylceramide (Gg(4)Cer), and gangliosides GM3 and GalNAc-GM1b in the mouse thymus, spleen, and lymph node. Immature thymocytes expressed epitopes recognized by all antibodies, except for anti-Gb(4)Cer. Mature thymocytes bound only antibodies to GalNAc-GM1b, Gg(4)Cer, and Gb(4)Cer. In secondary lymphoid organs, antibodies to globo-series GSLs bound to vascular spaces of secondary lymphoid organs, whereas the ganglio-series GSL antibodies recognized lymphocyte-containing regions. In a Western blotting analysis, only GalNAc-GM1b antibody recognized a specific protein band in all three organs. Flow cytometric analysis of spleen and lymph node cells revealed that B-cells carried epitopes recognized by all antibodies, whereas the T-cell GSL repertoire was mostly oriented to ganglio-series-neutral GSLs and GM1b-type gangliosides. The results of immunohistochemistry and flow cytometry were not always identical, possibly because of crossreactivity to glycoprotein-linked oligosaccharides and/or differences between cell surface carbohydrate profiles of isolated cells and cells in a tissue environment.

Animals↗
PubMed1998

Aggressive non-Hodgkin's lymphoma after successful eradication of Helicobacter pylori and regression of gastric lymphoma of mucosa-associated lymphoid tissue.

A 57-year-old woman presented to our clinic with low-grade gastric lymphoma of mucosa-associated lymphoid tissue (stage IE) and Helicobacter pylori infection. She received a 2-week course of omeprazole and clarithromycin, resulting in eradication of H. pylori and histological disappearance of the lymphoma. However, 9 months later (May 1996), multiple mass lesions were found around the pancreas and hepato-duodenal ligament on abdominal computed tomography. Inguinal lymph node biopsy revealed aggressive nodal type B-cell non-Hodgkin's lymphoma, diffuse large cell type. She received chemotherapy with cyclophosphamide, adriamycin, vincristine, and prednisolone, but failed to achieve remission and died in December 1996. There was no evidence of recurrent gastric lymphoma. This case emphasizes the importance of performing follow-up examinations to detect other neoplasms in patients with gastric lymphoma of mucosa-associated lymphoid tissue.

Diagnosis, Differential↗
PubMed1979

Morphologic study of the action of lymphoid tissue extracts in peroxidase arthritis.

By means of modelling arthritis by horseradish peroxidase it was possible to reproduce a process corresponding to immune synovitis. A considerable reduction of immunomorphological phenomena in joints, lymphoid tissue, heart, liver and kidneys was favoured by application of lymphoid tissue extracts. Comparison between the extracts of spleen and lymph nodes showed a more pronounced effect of spleen extract.

Animals↗
PubMed1986

Selective chemotaxis of subsets of B lymphocytes from gut-associated lymphoid tissue and its implications for the recruitment of mucosal plasma cells.

As they differentiate, precursor cells from the gut-associated lymphoid tissue are known to travel via the lymphatic system to the blood and then preferentially to home to various mucosal and exocrine sites such as the lamina propria of the gut and the lactating mammary gland, where they give rise to IgA-secreting plasma cells. The present study, directed at the mechanism by which the circulating precursors of mucosal IgA plasma cells selectively lodge in characteristic locations, explored the hypothesis that such homing is due to a locally produced chemotactic factor and that milk might be a source of such a factor. Subsets of lymphocytes bearing particular surface markers and purified by panning from lymph nodes of mice were examined in a micropore chemotaxis assay to search for the presence of chemotactic activity in mouse milk. The globulin fraction of whey was shown to contain a nondialyzable factor that is chemotactic for IgA (and also IgG)-positive lymphocytes when these are obtained from mesenteric lymph nodes as a source of mucosal-associated lymphoid tissue. Lymphocytes from peripheral lymph nodes, nonmucosal associated, were unaffected as were surface IgM-positive lymphocytes and T lymphocytes obtained from mesenteric nodes. Chemotactic activity for IgA lymphocytes was undetectable in mouse serum. The data are consistent with the idea that precursors of mucosal IgA plasma cells home to mucosal and exocrine sites in response to a specific chemotactic factor elaborated by local differentiated epithelial cells.

Animals↗
PubMed2003

Bystander CD4+ T lymphocytes survive in HIV-infected human lymphoid tissue.

HIV infection is associated with depletion of CD4(+) T cells. The mechanisms of this phenomenon remain to be understood. In particular, it remains controversial whether and to what extent uninfected ("bystander") CD4(+) T cells die in HIV-infected individuals. We address this question using a system of human lymphoid tissue ex vivo. Tissue blocks were inoculated with HIV-1. After productive infection was established, they were treated with the reverse transcriptase inhibitor nevirapine to protect from infection those CD4(+) T cells that had not yet been infected. These CD4(+) T cells residing in HIV-infected tissue are by definition bystanders. Our results demonstrate that after nevirapine application the number of bystander CD4(+) T cells is conserved. Thus, in the context of HIV-infected human lymphoid tissue, productive HIV infection kills infected cells but is not sufficient to cause the death of a significant number of uninfected CD4(+) T cells.

Apoptosis↗
PubMed1992

Expression of nerve growth factor receptor immunoreactivity on follicular dendritic cells from human mucosa associated lymphoid tissues.

Nerve growth factor (NGF) was originally considered as a trophic factor for peripheral sympathetic and sensory neurones; however, recent reports indicate that NGF may induce proliferation of immune and haematopoietic cells. Histochemical studies conducted in human spleen and lymph nodes have suggested the presence of NGF receptor (NGF-R) immunoreactive elements in secondary follicles; however the nature of the cells bearing the NGF-R in lymphoid tissue has not been determined. In this paper we report the results of an immunohistochemical study conducted on mucosa associated lymphoid tissue. Using a specific monoclonal antibody to human NGF-R (mAb 20.4) we observed an NGF-R-immunoreactive population in all secondary lymphoid follicles examined. Double immunostaining revealed that this population was composed of follicular dendritic cells (FDC); lymphoid cells within the germinal centres did not appear to be 20.4 immunoreactive. Cell suspensions from tonsillar follicles also contained NGF-R immunopositive dendritic cells which were enriched by a 20.4 labelled magnetic bead procedure, revealing cells with the morphological characteristics of FDC. Mononuclear cells from human peripheral blood did not contain any NGF-R-immunoreactive elements using our techniques.

Adolescent↗
PubMed1988

Lymphoid tissue responses to perfluorocarbon emulsion in rats: time course effects relative to immune challenge.

1. The effects of either intraperitoneal (i.p.) or intravenous (i.v.) injection of low doses (10 ml/kg) of the commercial emulsion, Fluosol-DA 20% (F-DA), on lymphoid tissues and antibody production against sheep red blood cells (SRBC) have been studied relative to the timing of immunization in rats. 2. Spleen and liver weights were significantly increased in response to injection of F-DA although no consistent pattern was observed. 3. Thymus weight was decreased following F-DA injection in some experimental groups whereas mesenteric lymph node (MLN) weights were unchanged throughout. 4. The mean plasma antibody titre to SRBC was significantly increased in some groups of animals injected with F-DA both before or after immunization; maximum titres were observed following injection of emulsion simultaneously with SRBC. 5. These results show that lymphoid tissue weights and plasma antibody titres in rats immunized with SRBC vary according to the timing and route of a previous or subsequent injection of F-DA.

Animals↗
PubMed1998

A previously unrecognized site of local accumulation of mononuclear cells. The vascular-associated lymphoid tissue.

In recent years our laboratory has developed an immunological hypothesis for the pathogenesis of atherosclerosis. We have shown that cellular and humoral immune reactions against heat shock proteins (Hsps) 60/65 expressed on the surface of stressed endothelial cells comprise the initial event in the pathogenesis of this disease. In the course of these studies, we also investigated normal, unaffected arteries for control purposes (carotid bifurcations from children aged 8 weeks to 10 years). This investigation led to the unexpected and previously unknown finding that mononuclear cells pre-exist in the intima at bifurcation sites. Our findings can be summarized as follows: Mononuclear cells are always found in the intima, primarily at sites subjected to major hemodynamic stress. Although the proportion of macrophages vs CD3(+) T-cells differs, overall the latter clearly predominate. Most of the T-cells express the T-cell receptor (TCR)alpha/beta, but TCRgamma/delta cells are also present. We also identified dendritic cells and mast cells in the intima. Analogous to the mucosa-associated lymphoid tissue (MALT) we coined the designation "vascular-associated lymphoid tissue" (VALT) for these newly discovered cellular aggregates in the arterial intima.

Antigens, CD↗
PubMed1994

Evaluation of cellular proliferation in human biopsy samples of lymphoid tissue according to the expression of AgNORs.

The proportions of cells with a high expression of AgNORs, as directly assessed under the light microscope, and those of Ki-67-immunoreactive cells were divided into three categories (low, < 25%; intermediate, 25-50%; high, > 50%) and compared to a series of 41 human biopsy samples of lymphoid tissue. Irrespective of histological features a strong correlation was found between both variables (contingency coefficient = 0.8; P < 0.001). It is concluded that direct evaluation of cells with a high expression of AgNORs may serve as an index of proliferative activity in biopsy samples of lymphoid tissue.

Biopsy↗
PubMed2003

[Eye-associated lymphoid tissue (EALT) is continuously spread throughout the ocular surface from the lacrimal gland to the lacrimal drainage system].

INTRODUCTION: Components of the mucosal immune system (MALT) have been identified in the conjunctiva (as CALT) and the lacrimal drainage system (as LDALT). Their structural and functional relation with the established immune protection by the lacrimal gland is unclear. MATERIAL AND METHODS: Macroscopically normal and complete tissues of the conjunctiva, lacrimal drainage system and lacrimal gland from human body donors were investigated by analysis of translucent whole mounts, and using histology, immunohistology as well as scanning and transmission electron microscopy. RESULTS: A typical diffuse lymphoid tissue, composed of effector cells of the immune system (T-lymphocytes and IgA producing plasma cells) under an epithelium that contains the IgA transporter SC, is not isolated in the conjunctiva and lacrimal drainage system. It is anatomically continuous from the lacrimal gland along its excretory ducts into the conjunctiva and from there via the lacrimal canaliculi into the lacrimal drainage system. Lymphoid follicles occur in a majority (about 60%) and with bilateral symmetry. The topography of CALT corresponds to the position of the cornea in the closed eye. CONCLUSION: These results show that the MALT of the lacrimal gland, conjunctiva and lacrimal drainage system constitute an anatomical and functional unit for immune protection of the ocular surface. Therefore it should be integrated as an "eye-associated lymphoid tissue" (EALT) into the MALT system of the body. EALT can detect ocular surface antigens by the lymphoid follicles and can supply other organs and the ocular surface including the lacrimal gland with specific effector cells via the regulated recirculation of lymphoid cells.

Aged↗