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At least 199 records · Page 11Linked to original sources
PubMed1998

Epstein-Barr virus-induced molecule 1 ligand chemokine is expressed by dendritic cells in lymphoid tissues and strongly attracts naive T cells and activated B cells.

Movement of T and B lymphocytes through secondary lymphoid tissues is likely to involve multiple cues that help the cells navigate to appropriate compartments. Epstein-Barr virus- induced molecule 1 (EBI-1) ligand chemokine (ELC/MIP3beta) is expressed constitutively within lymphoid tissues and may act as such a guidance cue. Here, we have isolated mouse ELC and characterized its expression pattern and chemotactic properties. ELC is expressed constitutively in dendritic cells within the T cell zone of secondary lymphoid tissues. Recombinant ELC was strongly chemotactic for naive (L-selectinhi) CD4 T cells and for CD8 T cells and weakly attractive for resting B cells and memory (L-selectinlo) CD4 T cells. After activation through the B cell receptor, the chemotactic response of B cells was enhanced. Like its human counterpart, murine ELC stimulated cells transfected with EBI-1/CC chemokine receptor 7 (CCR7). Our findings suggest a central role for ELC in promoting encounters between recirculating T cells and dendritic cells and in the migration of activated B cells into the T zone of secondary lymphoid tissues.

Animals↗
PubMed1989

[Lymphoid tissue during phylo- and ontogenesis].

In the process of evolution lymphoid tissue is isolated from the single hemolymphatic system as central and peripheral organs of the immune system. However there remains a close relationship between the lymphoid and myeloid tissues in the forms of perivascular lymphoid accumulations in organs both in the phylo- and ontogenesis. In mammals and man the diffusely disseminated within the body perivascular lymphoid tissue if differentiated in organoid-perivascular lymphoid follicles which are regularly located along the course of links of the hemo- and lymphocirculatory bed.

Animals↗
PubMed1990

Lectin histochemical characterization of the mouse, rat and human lymphoid tissues.

The authors performed a comparative lectin histochemical study on lymphoid organs of three species with 12 different lectins. The T and B cell regions and the accessory cells of lymphoid tissues were studied. The species differences show that the BALB/c mouse can be a valuable tool in modelling human lymphoid tissues, whereas Wistar rats exhibit great differences in lectin binding patterns as compared with human tissues. The positivity of peanut agglutinin binding of cortical and the negativity of medullar thymocytes in mice can be regarded as an indicator of cell differentiation. The focal distribution of peanut agglutinin positivity in the centrocytic region of human and rat germinal centres marks a small B cell subpopulation at the early stage of differentiation, while Bandeira simplicifolia binding is characteristic of a broader B cell lineage, but only in rats and mice. Canavalia ensiformis lectin seems to be a reliable marker of accessory cells (dendritic and interdigitating reticulum cells as well as macrophages) in all species studied.

Adult↗
PubMed2003

Distribution of Toll-like receptor 1 and Toll-like receptor 2 in human lymphoid tissue.

To determine how distinct receptors of the immune system can contribute to innate immunity, we investigated the pattern of Toll-like receptor 1 (TLR1) and TLR2 expression in human lymphoid tissue. We found that TLR1 and TLR2 were co-expressed on cells of the innate immune system, including macrophages and dendritic cells. In addition, TLR1 and TLR2 were expressed in mucosa-associated lymphoid tissue on tonsillar crypt epithelium. Of the lymphoid tissue examined, spleen expressed the highest levels of TLR2. Although TLR1- and TLR2-positive cells were in close proximity to T lymphocytes in vivo, lymphocytes themselves were devoid of TLR1 and TLR2 expression. The co-expression of TLR1 and TLR2 on myeloid cells in lymphoid tissue provides the host with the ability to respond to a variety of microbial ligands at sites conducive to the generation of an immune response.

Dendritic Cells↗
PubMed1995

Localization and identification of granzymes A and B-expressing cells in normal human lymphoid tissue and peripheral blood.

Cytoplasmic granules from activated natural killer (NK) and cytotoxic T lymphocytes (CTL) contain a pore-forming protein, perforin, and several homologous serine proteinases called granzymes. Expression of these proteins correlates with the cytolytic potential of cytotoxic lymphocytes. Using a panel of MoAbs specific for human granzyme A and B, respectively, expression of these proteinases in non-pathological lymphoid tissue and peripheral blood lymphocyte (PBL) subpopulations was investigated. Using immunohistochemistry and double stainings, the phenotype of granzyme-expressing cells in lymphoid tissue was investigated. Granzyme-positive cells were detected in all lymphoid tissues tested. No large differences in the number and distribution between granzyme A- and granzyme B-positive cells were observed. The highest number of positive cells was located in the red pulp of the spleen. Significant numbers were detected in tonsil, lymph nodes, liver and thymus. Low numbers were present in the lamina propria of non-inflamed stomach, small intestine and colon. Phenotypic analysis and cell sorting showed that most of the granzyme-positive cells in lymphoid tissue and PBL consisted of CD3-CD16+CD56+ lymphocytes. Hardly any granzyme-positive CD3+CD8+ CTL were present in peripheral blood. The synthesis of granzyme A as well as B by both CD3+CD16+CD56+ and CD3+CD8+ cells in peripheral blood was increased upon IL-2 stimulation. These results indicate that in normal lymphoid tissue the predominant cytolytic cell population is formed by the NK cells, and activated CTL are rare.

Antibodies, Monoclonal↗
PubMed1976

B and T cells in lymphoid tissues of human appendix.

Human appendix lymphoid cells (HAL) react very strongly to stimulation with concanavalin A, strongly to stimulation with phytohaemagglutinin, and weakly but definitely to stimulation with lipopolysaccharide. From the results of rosette formation assay, cytotoxicity tests with anti-T cell antiserum or anti-B cell antiserum, cell surface or intracellular immunoglobulin staining with fluorescein-conjugated rabbit anti-Fab of human immunoglobulin serum, and plaque-forming cell (PFC) assay, it was concluded that human appendix lymphoid tissue is a B cell pool but includes T cells. However, both direct and indirect PFC could not be significantly demonstrated against sheep red blood cells in a 5-day HAL culture.

Amphotericin B↗
PubMed1982

Complement (C3) receptors on dendritic reticulum cells of normal and malignant lymphoid tissue.

The aim of this study was to investigate whether dendritic reticulum cells (DRC) in normal lymphoid tissue and in malignant non-Hodgkin's lymphomas possess receptors for the third complement component (C3 receptors). For this purpose we studied the in situ expression of C3 receptors in lymphoid tissue by staining frozen tissue sections with an antiserum specific for human C3 receptors (AC3RS), using a modified immunoperoxidase method. The results indicate that DRC of normal and malignant lymphoid tissue express large amounts of C3 receptors. Absorption experiments revealed that the C3 receptors of DRC are identical with, or at least share common antigenic sites with, the C3 receptors expressed by tonsil B cells.

Child↗
PubMed2003

Trafficking of human immunodeficiency virus type 1-specific CD8+ T cells to gut-associated lymphoid tissue during chronic infection.

Gut-associated lymphoid tissue (GALT) is a significant but understudied lymphoid organ, harboring a majority of the body's total lymphocyte population. GALT is also an important portal of entry for human immunodeficiency virus (HIV), a major site of viral replication and CD4(+) T-cell depletion, and a frequent site of AIDS-related opportunistic infections and neoplasms. However, little is known about HIV-specific cell-mediated immune responses in GALT. Using lymphocytes isolated from rectal biopsies, we have determined the frequency and phenotype of HIV-specific CD8(+) T cells in human GALT. GALT CD8(+) T cells were predominantly CD45RO(+) and expressed CXCR4 and CCR5. In 10 clinically stable, chronically infected individuals, the frequency of HIV Gag (SL9)-specific CD8(+) T cells was increased in GALT relative to peripheral blood mononuclear cells by up to 4.6-fold, while that of cytomegalovirus (CMV)-specific CD8(+) T cells was significantly reduced (P = 0.012). Both HIV- and CMV-specific CD8(+) T cells in GALT expressed CCR5, but only HIV-specific CD8(+) T cells expressed alpha E beta 7 integrin, suggesting that mucosal priming may account for their retention in GALT. Chronically infected individuals exhibited striking depletion of GALT CD4(+) T cells expressing CXCR4, CCR5, and alpha E beta 7 integrin, but CD4(+)/CD8(+) T-cell ratios in blood and GALT were similar. The percentage of GALT CD8(+) T cells expressing alpha E beta 7 was significantly decreased in infected individuals, suggesting that HIV infection may perturb lymphocyte retention in GALT. These studies demonstrate the feasibility of using tetramers to assess HIV-specific T cells in GALT and reveal that GALT is the site of an active CD8(+) T-cell response during chronic infection.

Adult↗
PubMed2001

Analysis of HIV-1 reverse transcriptase and protease sequences in paired plasma and lymphoid tissue specimens from HIV-1 infected individuals.

OBJECTIVES: To determine how representative the genotype of HIV-1 circulating in plasma is of the genotype of the virus present in lymphoid tissue. METHODS: Paired plasma and tonsillar tissue samples were prospectively obtained from patients with various levels of plasma HIV-1 RNA who were receiving combination antiretroviral therapy. HIV-1 reverse transcriptase and protease sequences were amplified from plasma and lymphoid tissue specimens by nested polymerase chain reaction and analyzed using an automated sequencing system. Results were compared with consensus HIV-1 sequences to determine whether drug-resistance mutations were present in the regions analyzed. RESULTS: HIV-1 protease sequences were compared in 11 plasma/tissue pairs obtained from eight patients; HIV reverse transcriptase sequences were compared in 12 plasma/tissue pairs obtained from nine patients. Sequence homology between plasma and tissue RNA, tissue RNA and DNA, and plasma and tissue DNA ranged from 97% to 100%. Few discrepancies were found when the percentage of mutant sequences at resistance codons was compared among paired samples. In most instances, tissue RNA or plasma contained a higher percentage of mutant sequences than did tissue DNA. CONCLUSION: The genotype of plasma HIV-1 is similar to the genotype of the virus in lymphoid tissue. Resistance studies using plasma samples should provide accurate information regarding the genotype of HIV-1 in lymphoid tissues.

HIV Infections↗
PubMed1990

CD5-positive B-cells of the fetal and adult spleen lymphoid tissue: an immunophenotypical study.

The lymphoid tissue of the human fetal spleen at various stages of gestation was studied on frozen and paraffin sections and with two-colour flow cytometry. On the sections scattered lymphoid cells and perivascular lymphoid aggregates were found starting from the 15th week of gestation. CD3, CD5, CD19, CD20, CD21, CD22, CD24, CD35, CD38-positive cells were observed. No CD10- and CD23-positive cells were detected. Flow cytometry showed a prevalence of B-lymphocytes. The majority of them expressed CD5 antigen. These cells were also IgM/D, CD19, CD20, CD21, CD22, CD24 and CD35-positive. Only few of them expressed CD10 and CD23. A similar phenotype was found in human cord blood. By contrast, in adult spleens CD5 B-cells never exceeded 8% of the B-cells. The comparison between CD5 B-cells of fetal spleen and CD5 B neoplastic cells of 72 cases of small B-cell lymphomas showed that CD23, which was usually expressed by a high percentage of the neoplastic cells, particularly in B-CLL, was not displayed by the majority of the CD5 non neoplastic cells. The reverse was shown by CD35. These findings suggest that different states of activation distinguish the normal CD5 B-cells from their malignant counterpart.

Adult↗
PubMed1999

Regression of primary gastric B-cell mucosa-associated lymphoid tissue (MALT) lymphoma after eradication of Helicobacter pylori.

OBJECTIVE: primary gastric B-cell lymphoma of the mucosa-associated lymphoid tissue type has been linked to infection of the gastric mucosa with Helicobacter pylori. The eradication of this pathogen with antibiotics can lead to regression of this type of lymphoma. The objective of this study was to describe the clinical, endoscopic and histologic evolution in 6 patients with primary gastric B-cell lymphoma of the mucosa-associated lymphoid tissue type treated with eradication of H. pylori. METHOD: descriptive study of a retrospective case series. Patients with low-grade gastric mucosa-associated lymphoid tissue type lymphoma were initially treated with eradication therapy for H. pylori. We evaluated their clinical, endoscopic and histologic course in sequential follow-up visits after initial therapy. RESULTS: six patients who satisfied all selection criteria were studied. In five of six patients H. pylori was eradicated and the lymphoma showed regression within 6 to 24 months. In one patient transition of low-grade to high-grade gastric lymphoma occurred. CONCLUSIONS: these results, along with similar findings from other studies, suggest eradication of H. pylori should be the initial treatment of choice for low-grade B-cell gastric mucosa-associated lymphoid tissue type lymphoma in the early stages. The most appropriate duration of follow-up is unknown, but prolonged follow-up is indicated to detect recurrences.

Adult↗
PubMed1994

[The influence of subclinical level of graft versus host reaction on reconstitution of host lymphoid tissues].

In this study reconstitution of lymphoid tissues under the influence of subclinical graft versus host reaction (GVHR) was investigated. Lethally irradiated recipient mice (AKR: H-2k, Mls-1a) were reconstituted with donor (B10: H-2b, Mls-1b) bone marrow (BM) cells treated with anti-Thy 1 antibody alone without complement (GVHR chimeras). When their immunological reconstitution was analysed and compared with that of AKR recipients which had been reconstituted with B10 BM treated with anti-Thy 1 and complement (Control chimera), both of these chimeras all survived more than 100 days without showing clinical signs of GVHD. Full donor chimerism was accomplished at an early stage after BM transplantation (BMT) in GVHR chimeras, whereas substantial number of recipient T cells persisted in Control chimeras during the entire observation period. No significant difference was observed in the reconstitution of the thymus and spleen between the Control and GVHR chimeras. By contrast, the reconstitution of lymph nodes (LN) in GVHR chimeras was inhibited. The apparent failure of LN reconstitution was attributed to damage of LN structure involved in homing of lymphocytes, but not attributable to damage of lymphocytes themselves. Since donor CD8+ T cells caused the damage, target antigens of this damage appeared to be H-2 class I molecules in the present system. Furthermore, clonal deletion of V beta 6+T cells that are reactive to recipient Mls-1a antigen was induced in Control chimeras but abrogated in the GVHR chimeras. The latter abrogation of clonal deletion of V beta 6+T cells appeared to result from the early disappearance of recipient T cells in these GVHR chimeras.

Animals↗
PubMed1997

Development of the lymphoid tissues of the tammar wallaby Macropus eugenii.

A study has been made of the development of four lymphoid tissues from birth to maturity in the tammar wallaby Macropus eugenii--the cervical and thoracic thymus, lymph nodes and gut-associated lymphoid tissue (GALT). The development of these tissues in the tammar wallaby is similar to that in two other marsupials, the quokka Setonix brachyurus and the Virginian opossum Didelphis virginiana. Lymphocytes were first detected in the cervical thymus of the tammar at Day 2 post partum and in the thoracic thymus at Day 6. They were subsequently detected in lymph nodes at Day 4 and in the spleen by Day 12 but were not apparent in the GALT until around Day 90 post partum. By Day 21, the cervical thymus had developed distinct areas of cortex and medulla and Hassall's corpuscles were apparent. The maturation of other tissues followed with Hassall's corpuscles in the thoracic thymus by Day 30 and nodules and germinal centres in the lymph nodes by Day 90. Measurement of immunoglobulin G concentrations in the serum of young animals indicated a rise in titre around Day 90 post partum, correlating with the apparent maturation of the lymphoid tissues.

Aging↗
PubMed1998

Multiparametric flow cytometry in the diagnosis and characterization of low-grade pulmonary mucosa-associated lymphoid tissue lymphomas.

Primary mucosa associated lymphoid tissue (MALT) lymphomas are rare neoplasms that seem to have a better prognosis than nodal lymphomas. Morphologic diagnosis of these lesions may be difficult because of features that overlap with those of benign lymphoid infiltrates. In this study, we assessed the contribution of multi-parametric flow cytometry in demonstrating clonality and further characterizing pulmonary MALT lymphomas. Based on a clinical or pathologic suspicion of MALT-lymphoma, 3 transbronchial biopsies, 4 fine needle aspirates, 1 core needle biopsy, and 13 wedge excisions of lung were submitted fresh (unfixed) to our laboratory for evaluation. Among the 13 cases diagnosed as MALT lymphomas, B-cell monoclonality was established by identifying expression of a single immunoglobulin light chain on CD20 or CD19-positive cells in 12 cases. One case lacked expression of both light chains on B-cells. Of 11 lymphoma cases in which CD5 and CD10 surface antigens were assessed, no cases expressed CD10, and 1 case demonstrated weak CD5 expression. Nine of 10 cases studied were diploid and 1 case was hyperdiploid. All of the lymphomas displayed low (< or = 3%) S-phase fractions consistent with low grade processes. In 10 patients with short follow-up, none died of their disease and the majority had no evidence of lymphoma dissemination. In seven of the remaining eight cases, B-cells were polyclonal consistent with reactive processes. In one morphologically reactive case, flow cytometric analysis was unsuccessful because of poor cell viability. The pulmonary MALT lymphomas in this study represent a group of B-cell tumors with distinctive morphologic, immunophenotypic, and cell kinetic characteristics. Multi-parametric flow cytometry is useful for confirming B-cell monoclonality and illustrating an antigenic profile compatible with this diagnosis. Flow cytometry can be particularly helpful when working with small biopsies and cytologic samples with limited diagnostic material and may abrogate the need for more aggressive surgical procedures.

Adult↗
PubMed2006

Macrophage entry mediated by HIV Envs from brain and lymphoid tissues is determined by the capacity to use low CD4 levels and overall efficiency of fusion.

HIV infects macrophages and microglia in the central nervous system (CNS), which express lower levels of CD4 than CD4+ T cells in peripheral blood. To investigate mechanisms of HIV neurotropism, full-length env genes were cloned from autopsy brain and lymphoid tissues from 4 AIDS patients with HIV-associated dementia (HAD). Characterization of 55 functional Env clones demonstrated that Envs with reduced dependence on CD4 for fusion and viral entry are more frequent in brain compared to lymphoid tissue. Envs that mediated efficient entry into macrophages were frequent in brain but were also present in lymphoid tissue. For most Envs, entry into macrophages correlated with overall fusion activity at all levels of CD4 and CCR5. gp160 nucleotide sequences were compartmentalized in brain versus lymphoid tissue within each patient. Proline at position 308 in the V3 loop of gp120 was associated with brain compartmentalization in 3 patients, but mutagenesis studies suggested that P308 alone does not contribute to reduced CD4 dependence or macrophage-tropism. These results suggest that HIV adaptation to replicate in the CNS selects for Envs with reduced CD4 dependence and increased fusion activity. Macrophage-tropic Envs are frequent in brain but are also present in lymphoid tissues of AIDS patients with HAD, and entry into macrophages in the CNS and other tissues is dependent on the ability to use low receptor levels and overall efficiency of fusion.

AIDS Dementia Complex↗
PubMed1986

Storage and transportation of lymphoid tissue for immunophenotyping.

Immunoperoxidase staining of frozen sections is a cost-effective technic for immunophenotyping cells of lymphoid tissue. Because this procedure is not performed in many institutions, a simple method to transport fresh tissue to centers performing these studies is required. Tissues in saline at refrigerator temperature may be successfully transported. In addition, in order to minimize laboratory expenses, lymphoid tissue can be kept refrigerated in saline until permanent sections are examined and immunodiagnostic procedures become necessary. In this study reproducible immunophenotyping of 12 samples of lymphoid tissue stored up to seven days was achieved.

Antibodies, Monoclonal↗
PubMed1990

Flow cytometric and immunohistochemical characterization of the gamma/delta T-lymphocyte population in normal human lymphoid tissue and peripheral blood.

We determined the quantitative and topographic distribution of gamma/delta lymphocytes in normal human lymphoid tissue and peripheral blood using a monoclonal antibody that detects a framework determinant on delta molecules and delineated the immunophenotypic characteristics of the gamma/delta lymphocyte population by one- and/or two-color immunohistochemical and two- and/or three-color flow cytometric analysis. Variable, but generally small, numbers of gamma/delta lymphocytes are present in peripheral blood and in all lymphoid tissues. The vast majority, greater than or equal to 90%, of lymphoid tissue delta lymphocytes reside in interfollicular (T-cell) zones. Approximately 90% of delta thymocytes are present in the thymic medulla. The percentage of CD3-positive T cells that express delta are: spleen 12.5 +/- 8.1%, peripheral blood 4.0 +/- 3.1%, appendix 2.9 +/- 1%, lymph node 2.2 +/- 1%, thymus 1.4 +/- 0.5%, and tonsil 0.7 +/- 0.5%. We further demonstrated that 1) gamma/delta-thymocytes and gamma/delta peripheral lymphocytes express T-cell lineage restricted antigens CD3 and CD2 but only a variable subset, 30% to 90%, express T-cell lineage associated antigens CD5 and/or CD8; (2) approximately 60% of gamma/delta thymocytes express low-density CD4 while all gamma/delta peripheral lymphocytes lack detectable CD4; 3) gamma/delta lymphocytes lack natural killer (NK), macrophage, and B-cell associated antigens CD16, CD14, and CD20, respectively, but greater than or equal to 70% of gamma/delta T lymphocytes express CD11b, Leu7, and NKH-1, antigens, which are also expressed by suppressor/cytotoxic and NK cells; and 4) a large subpopulation, approximately 25%, of gamma/delta thymocytes are in S1-G2 phase, while greater than or equal to 98% of gamma/delta peripheral lymphocytes are small lymphocytes in G0-G1 phase and lack activation/proliferation markers. Together these results indicate that gamma/delta lymphocytes are resting, mature T cells that probably play a primary role in suppressor/cytotoxic phenomena. They also indicate that gamma/delta lymphocytes variably express multiple-cell surface antigens associated with various cell lineages, suggesting that gamma/delta lymphocytes represent a considerably more heterogeneous cell population than previously appreciated and that they may actually subserve multiple functions.

Animals↗
PubMed2003

Region-specific immunological response of the different laryngeal compartments: significance of larynx-associated lymphoid tissue.

The occurrence of primary extranodal marginal-zone B-cell lymphoma [of the mucosa-associated lymphoid tissue (MALT) type] has only been described in the supraglottic region, implying that preexistent organized lymphoid tissue is present at that site only. To date, studies have not established clearly whether organized MALT shows a site-related distribution in the larynx. The supraglottic region of the false vocal folds and the subglottis from 87 unselected cadavers with no known history of nasal, oral, pharyngeal, laryngeal, tracheal, or esophageal disease were examined for the presence of organized MALT. Organized lymphoid tissue was found with the cytomorphological and immunophenotypic features of MALT in 100% of false vocal folds of children and in more than 90% of adolescents, decreasing to 7.1% in persons in their sixth decade, whereas MALT was completely absent in the subglottis in all age groups. The results explain why primary extranodal marginal-zone B-cell lymphoma has only been described in the supraglottic region but is absent in the subglottis. Moreover, the results suggest a region-specific immunological response of the different laryngeal areas as reflected in clinical observations and animal studies. However, the impact on presence or absence of laryngeal MALT awaits clarification.

Adolescent↗