PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Lymphoid Tissue”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38Linked to original sources

Lymphotoxin plays a crucial role in the development and function of nasal-associated lymphoid tissue through regulation of chemokines and peripheral node addressin.

The mechanism of nasal-associated lymphoid tissue (NALT) development is incompletely understood with regard to the roles of cytokines, chemokines, and vascular addressins. Development of the wild-type NALT continued in the immediate postnatal period with gradual increases in cellularity, compartmentalization into T- and B-cell zones, and expression of lymphotoxin (LT)-alpha, LT-beta, and lymphoid chemokines (CCL21, CCL19, CXCL13). High endothelial venules (HEVs) developed that expressed GlyCAM-1, HEC-6ST [an enzyme crucial for expression of luminal peripheral node addressin (PNAd)], and PNAd itself. LT-beta(-/-) and LT-alpha(-/-) NALTs had fewer cells than those of wild-type mice, reduced (LT-beta(-/-)) or absent (LT-alpha(-/-)) lymphoid chemokines, and no T- and B-cell compartmentalization. LT-beta(-/-) HEVs expressed only abluminal PNAd and no HEC-6ST or GlyCAM-1. LT-alpha(-/-) HEVs had no PNAd, HEC-6ST, or GlyCAM-1. Because intranasal immunization gives rise to vaginal IgA, immunization of LT-beta(-/-) mice, which retain cervical lymph nodes, might generate such a response. Intranasal immunization with ovalbumin and cholera toxin revealed lower cytokine levels in the LT-alpha(-/-) and LT-beta(-/-) NALTs, and undetectable vaginal IgA. In contrast, splenic cytokines and serum IgG titers, although reduced, were detectable. These data indicate that LT-alpha(3) and LT-alpha(1)beta(2) cooperatively contribute to NALT development and function through regulation of lymphoid chemokines and adhesion molecules; they are the first to implicate LT-alpha(1)beta(2) in GlyCAM-1 regulation in NALT HEV development.

Animals↗

Dendritic cell subsets in blood and lymphoid tissue of rhesus monkeys and their mobilization with Flt3 ligand.

We provide phenotypic and functional evidence of premonocytoid dendritic cells (DCs) and preplasmacytoid DCs in blood and of corresponding DC subsets in secondary lymphoid tissue of rhesus monkeys. Subsets were identified and sorted by 4-color flow cytometry using antihuman monoclonal antibodies cross-reactive with rhesus monkey. To mobilize pre-DC subsets, fms-like tyrosine 3 kinase ligand (Flt3L; 100 microg/kg subcutaneously) was administered for 10 days. Presumptive pre-DC subsets were identified within the lineage- (Lin-) major histocompatibility complex (MHC) class II+ fraction of blood mononuclear cells. Premonocytoid DCs were CD11c+CD123- (interleukin-3Ralpha- [IL-3Ralpha-]). Preplasmacytoid DCs were characterized as CD11c-CD123++ Flt3L increased the CD11c+ pre-DC (7-fold) and CD123++ pre-DC subsets (3-fold) in blood. The freshly isolated CD11c+ pre-DC subset induced modest proliferation of naive allogeneic T cells. After overnight culture with granulocyte macro-phage-colony-stimulating factor (GMCSF) and CD40L, both subsets up-regulated surface costimulatory molecules, and CD11c+ pre-DCs became potent allostimulators. Freshly isolated CD123++ pre-DCs showed typical plasmacytoid morphology and, when cultured with IL-3 and CD40L for 72 hours, developed mature DC morphology. Following stimulation with CD40L, CD11c+ pre-DCs secreted increased levels of IL-12p40. Importantly, herpes simplex virus-stimulated CD123++ pre-DCs, but not CD11c+ pre-DCs, secreted interferon-alpha (IFN-alpha). Corresponding DC subsets were identified by flow analysis and immunohistochemistry in lymph nodes wherein both populations were increased 2- to 3-fold by Flt3L administration. CD123+ pre-DCs produced IFN-alpha in response to in vivo viral infection. Thus, rhesus monkeys exhibit 2 distinct DC precursor populations that closely resemble those of humans. Both are mobilized into blood and lymphoid tissue by Flt3L, offering potential for their further characterization and possible therapeutic application.

Animals↗

Diffuse large B-cell lymphoma with anaplastic features and focal low-grade mucosa-associated lymphoid tissue lymphoma component of the stomach.

We describe an 83-year-old man diagnosed as having diffuse, large B-cell lymphoma with anaplastic features and CD30 expression of the stomach. Focally, the tumor showed typical low-grade mucosa-associated lymphoid tissue lymphoma. We are not aware of a previous report on the transformation of low-grade gastric lymphoma of mucosa-associated lymphoid tissue type into an "anaplastic," large B-cell tumor.

Aged↗

T cell regulation of IgA immunoglobulin production in gut-associated lymphoid tissues.

To explore mechanisms of gut-mucosal IgA immune response, we have established Con A-induced cloned T cell lines originating from PP and spleen. These cloned cells expressed Thy-1.2+, Lyt-1+2-, Ia (I-A and I-E) and H-2 (K/D) surface antigens. Cloned T cells derived from PP were found to suppress LPS-induced IgM and IgG synthesis and secretion of co-cultured PP B cells; in addition, whereas the PP cloned T cells did not bring about IgA production, they did cause the appearance of large numbers of cells expressing sIgA. In contrast, cloned T cells derived from spleen had little or no effect on LPS-induced IgM synthesis and secretion by PP B cells; in addition, whereas they did suppress IgG production, they neither brought about IgA production nor the appearance of cells expressing sIgA. These studies provide evidence for the existence of a new type of T cell in PP, a switch T cell, which is able to induce B cells to undergo class-specific switches from IgM to IgA; the PP switch T cells appear to govern the pathway of DNA recombination (or RNA splicing) rather than cellular events resulting in terminal differentiation. Thus, these switch T cells are probably responsible for the fact that PP are a major source of mucosal IgA B cells. In additional studies, we show that post-switch IgA B cells, i.e. cells precultured with PP cloned T cells, have the capacity to undergo terminal differentiation into IgA producing plasma cells. provided they are exposed to helper T cells (uncloned) and an appropriate mitogenic stimulus (staphylococcal protein A). We can conclude, therefore, that the development of PP B cells into IgA-producing plasma cells in gut-associated lymphoid tissues (GALT) appears to require at least two steps: one which involves heavy chain switching to IgA and which is governed by IgA class-specific switch T cells in PP, and one which involves differentiation of post-switch B cells and which is governed by helper T cells in lymphoid tissues outside of PP (such as MLN and spleen).

Animals↗

Gut-associated lymphoid tissue in the chicken. I. Morphology, ontogeny, and some functional characteristics of Peyer's patches.

Lymphoid aggregates with many of the characteristics of mammalian Peyer's patches (PP) were identified in the chicken intestine. These chicken PP could not be seen with the naked eye at the time of hatching, but by 10 days of age, 1 or 2 PP were identified in 50% of the birds. Up to 16 wk of age, the numbers of PP increased to a maximum of 5 per animal and they were widely scattered in the intestine, apart from one that was regularly found about 5 to 10 cm anterior to the ileocecal junction. As the birds aged, the number of PP declined so that in older birds (58 wk) only a single PP was evident near the ileocecal junction. Chicken PP possess: a distinct lymphoepithelium with M cells and strong pinocytotic activity; follicles and a subepithelium zone and central zone similar to those of the cecal tonsil (CT). Studies with in ovo hormonal bursectomy and age-associated involution of PP suggested that the subepithelial zone is a B-dependent area and the central zone a T, or thymus-dependent region. These observations extend our knowledge of gut-associated lymphoid tissue (GALT) in the bird to include the bursa of Fabricius, CT, PP, and aggregates in the urodeum and proctodeum. They raise issues about the roles of chicken PP that may aid our understanding of the functions of mammalian GALT.

Animals↗

Encephalitis, lymphoid tissue depletion and secondary diseases associated with bovine immunodeficiency virus in a dairy herd.

Encephalitis, lymphoid tissue depletion and secondary infections occurred over a 5-yr-period in Holstein cows infected with bovine immunodeficiency virus (BIV). There were 59 cattle studied, the majority during 1991, when a severe environmental stress occurred, each with one or more primary causes of death, natural or by euthanasia, and most with several secondary diseases. The encephalitis was characterized by meningeal, perivascular and parenchymal infiltration with lymphocytes, occasional plasma cells and macrophages with perivascular edema in some cows. Affected areas included the cerebrum, cerebellum, and spinal cord with no particular distribution pattern recognized. The lymphoid depletion was primarily an absence of follicular development in nodes draining regions with secondary infections such as chronic mastitis and chronic suppurative pododermatitis. Paucity of lymphocytes in thymic-dependent regions of lymph nodes and the spleen suggested a primary depletion of T cells. Secondary infections were often multiple with each cow having several minor conditions, usually considered short-term and treatable. These included mastitis and pododermatitis, with many cows having non-responding abscesses, cellulitis and myositis attributed to injection site infections. A large number of the cattle had parturition difficulties such as dystocia, obturator paralysis, and metritis. Pulmonary, cardiovascular, and intestinal disease were recognized as both primary and secondary disease conditions. There was a high level of infection with bovine leukemia virus with 4 of the 59 cattle having lymphosarcoma. Under practical conditions, the infection with BIV has a different effect on the host than has been observed under experimental conditions. The presence of BIV combined with the stresses associated with parturition and a modern dairy production system were considered causal for the development of untreatable secondary diseases in immunocompromised cattle. The peak incidence in 1991 was attributed to increased environmental stress during renovation of the barn facility. During this time the cattle were kept on open pasture, exposed to an extremely wet winter, and spring weather conditions. The effect of co-infection with bovine leukemia virus, the influence of immunocompromise on the chronicity of mastitis, the relationship with laminitis and pododermatitis, and several questions related to viral transmission, complementarism with bovine leukemia virus, viral reactivation and immunoprophylaxis all remain as viable avenues for future investigations.

Animals↗

Structure and function of bronchus-associated lymphoid tissue (BALT).

This article deals with the ontogeny, morphology, and function of bronchus-associated lymphoid tissue (BALT). The surface epithelium of the respiratory tract, including the lymphoepithelium of BALT, is described, with emphasis on infiltrated nonepithelial cells (lymphocytes, macrophages). Special attention is given to antigen handling by the lymphoepithelium and the interaction with BALT and lung macrophages. The structure and function of the diverse types of BALT nonlymphoid cells are discussed. The local immune responses (cellular and humoral reactions), the relationships between local and systemic immune reactions, and the role of BALT in the common mucosal immune system are reviewed. The BALT is compared with Peyer's patches in terms of antigen processing, local immune responses, cell populations, and migration of lymphoid and nonlymphoid cells.

Animals↗

Postnatal development of bronchus-associated lymphoid tissue (BALT) in the rat, Rattus norvegicus.

The pattern of development of bronchus-associated lymphoid tissue (BALT) in specified-pathogen-free and conventional (non-barrier maintained) rats over the initial 4 weeks of life appeared to be similar. BALT first appeared around the 2nd week of life and increased in amount over the following 2 weeks. Overlying large nodules of BALT the bronchial epithelium becomes infiltrated by lymphocytes to form a lymphoepithelium. This transformation occurs earlier in conventional rats, possibly because of the differing antigen levels to which they are exposed.

Animals↗

Bronchus-associated lymphoid tissue and the source of immunoglobulin-containing cells in the mucosa.

Bronchus-associated lymphoid tissue has major morphologic and functional similarities to Peyer's patches found in the gut. Both possess a lymphoepithelium with selective antigen sampling properties, both appear in the apparent absence of direct antigen stimulation, both contain a high percentage of cells bearing IgA sdurface immunoglobulin and both can repopulate the bronchial and gut lamina propria with IgA containing cells. Good evidence now exists (and will be reviewed) in support of the concept of a common mucosal immunologic system. Cells potentially sensitized at or in a mucosal tissue such as the gut or lung would then migrate to the draining lymph node, thence into the circulation and localize in a variety of mucosal tissues. Factors involved but not essential for such localization include antigen. Lymphoblasts derived from the lung tend to go back to the lung. Similarly, gut derived lymphoblasts have a predilection for the gut. However, available evidence supports the concept of integrated systemic and mucosal immune systems. Several factors must be taken into account in analysis of the products of local mucosal immune reactions and in developing approaches to achieve optimal humoral immunity at any mucosal surface.

Animals↗

Molecular cytogenetic delineation of the breakpoint at 18q21.1 in low-grade B-cell lymphoma of mucosa-associated lymphoid tissue.

Extranodal malignant non-Hodgkin lymphoma of mucosa-associated lymphoid tissue type (MALT lymphoma) represents a subtype of B-cell lymphoid malignancies with distinct clinicopathological features and is often associated with a favorable prognosis. Recent cytogenetic studies have revealed that t(11;18)(q21;q21) is a characteristic chromosomal aberration in low-grade B-cell MALT-type lymphoma. In the present study, we employed florescence in situ hybridization analysis using contiguous YAC clones mapped to the 18q21.1 region to identify a YAC clone, y789F3, encompassing the breakpoint of t(11;18)(q21;q21) in a MALT lymphoma. PI artificial chromosome (PAC) contigs constructed on this YAC clone were used to analyze the breakpoint region. PAC clone 264m4 was observed on normal chromosome 18 and on der(18), and PAC clone 879n 10 on normal chromosome 18 and on der(II), confirming that the breakpoint is located between these two PAC clones. We also found that a region of approximately 500 kb between the two PAC clones was deleted. These results indicate that the locus between PAC clones 264m4 and 879n 10 at 18q21.1 involved in t(11;18) translocation or associated deletion plays an important role in the development of MALT lymphoma.

Chromosome Mapping↗

Importance of extensive staging in patients with mucosa-associated lymphoid tissue (MALT)-type lymphoma.

Lymphoma of the mucosa-associated lymphoid tissue (MALT) type usually arises in MALT acquired through chronic antigenic stimulation triggered by persistent infection and/or autoimmune processes. Due to specific ligand-receptor interactions between lymphoid cells and high-endothelial venules of MALT, both normal and neoplastic lymphoid cells display a pronounced homing tendency to MALT throughout the body. In the case of neoplastic disease these homing properties may be responsible for lymphoma dissemination among various MALT-sites. According to this concept, we have standardized staging procedures in all patients diagnosed with MALT-type lymphoma. All patients with MALT-type lymphoma underwent standardized staging procedures before treatment. Staging included ophthalmologic examination, otolaryngologic investigation, gastroscopy with multiple biopsies, endosonography of the upper gastrointestinal tract, enteroclysis, colonoscopy, computed tomography of thorax and abdomen and bone marrow biopsy. Biopsy was performed in all lesions suggestive for lymphomatous involvement, and evaluation of all biopsy specimens was performed by a reference pathologist. 35 consecutive patients with histologically verified MALT-type lymphoma were admitted to our department. Twenty-four patients (68%) had primary involvement of the stomach, five (15%) had lymphoma of the ocular adnexa, three (8.5%) had lymphoma of the parotid, and three (8,5%) of the lung. Lymph-node involvement corresponding to stage EII disease was found in 13 patients (37%), only one patient with primary gastric lymphoma had local and supradiaphragmatic lymph-node involvement (stage EIII). Bone marrow biopsies were negative in all patients. Overall, eight of 35 patients (23%) had simultaneous biopsy-proven involvement of two MALT-sites: one patient each had lymphoma of parotid and lacrimal gland, conjunctiva and hypopharynx, conjunctiva and skin, lacrimal gland and lung, stomach and colon, and stomach and lung. The remaining two patients had bilateral parotideal lymphoma. Staging work-up was negative for lymph-node involvement in all of these eight patients. The importance of extensive staging in MALT-type lymphoma is emphasized by the demonstration of multiorgan involvement in almost a quarter of patients. In addition, our data suggest that extra-gastrointestinal MALT-type lymphoma more frequently occurs simultaneously at different anatomic sites than MALT-type lymphoma involving the GI-tract.

Eye Neoplasms↗

A survey of Epstein-Barr virus DNA in lymphoid tissue. Frequent detection in Hodgkin's disease.

A total of 151 unselected malignant and nonmalignant lymphoid tissue samples were surveyed by Southern blotting for the presence of Epstein-Barr virus (EBV) DNA. Eight of 28 Hodgkin's disease (HD) samples (29%) had detectable EBV DNA. Both nodular sclerosis and mixed cellularity histologic results were positive. The tumor type with the next highest frequency, 8%, was diffuse large cell lymphoma. The presence of EBV DNA in some HD biopsies suggests that EBV may be a factor in the pathogenesis of this disease. Alternatively, its presence may be secondary to the immune deficiency characteristic of HD. The clonal B-lymphocyte expansions reported in some cases of HD may result from EBV infection.

Blotting, Southern↗

Migration of donor leukocytes from limb allografts into host lymphoid tissues.

This study was undertaken in an initial effort to characterize the immunology of extremity transplantation by examining the pattern and kinetics of leukocyte migration from rat limb transplants. Migration of donor leukocytes was evaluated by examining recipient lymphoid tissues with a donor-specific, anti-major histocompatibility complex, class I monoclonal antibody. Double-antibody, two-color labeling was used to localize donor cells to specific regions within these tissues. Donor leukocytes, with dendritic cell morphology, were found in the T-cell-rich areas of lymph nodes draining the allograft and spleen. The donor cells were present on postoperative days 1 through 3 but were not present on days 5 to 7. Donor leukocytes were not present in distant lymph nodes or liver. These findings indicate a migration of leukocytes, most likely the highly immunogenic dendritic cell, from rat limb transplants to the draining lymphoid tissues. Migration occurs shortly after transplantation and may lead to the sensitization of alloreactive T-cells.

Animals↗

[Seasonal involution of the lymphoid tissue of the spleen of the European suslik (Citellus citellus L.)].

The spleen of male immature ground squirrels has been studied throughout the year using histological, histochemical and cytochemical methods. Histo-architectonical and cytological changes in the splenic lymphoid tissue within the annual cycle have been established. They consist of its gradual hypertrophy up to the midsummer, followed by involution at the summer end and the beginning of the autumn. The deepest involutive changes in the structure and cell composition have been established during the first stage of hibernation--November--December. An obvious proliferation and hypertrophy of the lymphoid tissue during the second stage of hibernation (January--March) is observed.

Animals↗

Development of dome epithelium in gut-associated lymphoid tissues: association of IgA with M cells.

The dome epithelium (DE), which covers gut-associated lymphoid tissues (GALT) and provides both a protective barrier over lymphoid follicles and a route for antigen uptake from the gut, develops in rabbit appendix (caecum) during the first week of neonatal life. To determine if secretory immunoglobulins from maternal milk interact with this developing tissue, their interrelationships in neonatal rabbit appendix were examined by use of immunocytochemical techniques. The glycoprotein, secretory component, was not produced by neonatal rabbits less than 15 days old, since neither the membranous nor the free, secreted forms of maternal secretory component were associated with villi or DE of neonates. Immunoglobulin A (IgA), but neither IgG nor IgM, were noted on DE by light microscopy, even though IgG was abundant in the villus lamina propria and vascular spaces. The epithelial IgA was distributed, in a patchy pattern, across the upper dome surface of some two-day-old, and all five-and ten-day old nursing animals, but IgA was not on DE of rabbits prevented from nursing. Immuno-electron microscopy of appendix from nursed rabbits revealed IgA directly over the apical surface of M cells, where it formed a continuous, thick coating without binding to adjacent immature absorptive cells; it was also within apical vacuoles of M cell cytoplasm. The distribution of IgA on the DE of rabbit appendices indicated that in differentiating GALT, maternal IgA reacted preferentially with M cells or pre-M cells, leading to speculation concerning a role for IgA in the development of GALT and in establishment of mucosal immune responses in neonates.

Aging↗

Early reduction of immune activation in lymphoid tissue following highly active HIV therapy.

OBJECTIVE: To evaluate immune reconstitution within HIV-infected lymphoid tissue during highly active antiretroviral therapy (HAART). DESIGN AND METHODS: In situ cellular responses were studied in sequential tonsillar biopsies in three asymptomatic HIV-infected (CD4 cells greater than 400 x 10(6)/l) antiretroviral treatment-naive volunteers enrolled in a clinical trial to determine the early effect of HAART. Computerized image analysis was used to study immunohistochemically stained sequential tonsil sections for the patterns of local cytokine production, chemokine receptor expression and cellular distribution. Replicate quantitative assessments of samples before and after 4 weeks of therapy were used for the evaluation of drug effects and compared with four uninfected controls. Tonsillar HIV proviral-DNA was determined by fluorescent in situ 5'-nuclease assay. RESULTS: HIV-infected tonsil tissue was characterized by extensive pro-inflammatory and type 1 cytokine expression. A five- to 15-fold elevation of interleukin (IL)-1 alpha, IL-12, IL-2 and interferon (IFN)-gamma protein expression was found compared with controls, and each encompassed a mean of at least 4.5% of the tissue compartment. This was reduced by 20-90% in all individuals after 4 weeks of HAART. In contrast, type 2 cytokine expression (IL-4, IL-10), plus tumour necrosis factor (TNF)-alpha, remained low throughout the study. HAART reduced, by 40%, the expression of HIV co-receptors, CCR5 and CXCR4, which initially were elevated four to six times over the control values. In addition, the myelomonocytic inflammatory proteins, CD68 and calprotectin, diminished by 26-83% after therapy. The HIV RNA was reduced to undetectable levels in plasma by HAART. However, a large pool of tonsil cells (2-7%), remained HIV DNA positive after 4 weeks of therapy. CONCLUSIONS: Although immune activation may be the direct consequence of HIV replication, HAART-associated reconstitution begins with a reduction in inflammatory cytokine production which precedes the elimination of local proviral reservoirs.

Anti-HIV Agents↗

Virologic and immunologic effect of antiretroviral therapy on HIV-1 in gut-associated lymphoid tissue.

OBJECTIVES: We evaluated virologic and immunologic responses to antiretroviral therapy in gut-associated lymphoid tissue (GALT) compared with those found in peripheral blood. METHODS: Eight HIV-1-infected individuals were treated with three reverse transcriptase inhibitors and one protease inhibitor. Endoscopic biopsies were performed at baseline, and at months 1, 2, and 6. We measured the level of cell-associated multiply spliced and unspliced HIV-1 mRNA in GALT and in peripheral blood mononuclear cells. Immunologic responses were assessed by flow cytometry. RESULTS: Levels of multiply spliced HIV-1 mRNA declined in parallel fashion both in peripheral blood and GALT. After 6 months of therapy, unspliced HIV-1 mRNA in the GALT was below assay detection although it persisted in peripheral blood mononuclear cells in 4 study subjects. Although the percentage of CD4+ lymphocytes increased significantly in peripheral blood, only modest increases occurred in GALT. The percentage of activated CD8+ T cells decreased significantly in peripheral blood whereas only modest reductions occurred in GALT. CONCLUSIONS: Antiretroviral therapy effectively suppressed HIV-1 replication in GALT. The percentage of CD4+ T cells in peripheral blood uniformly increased in all study subjects, whereas it was more variable in the GALT.

Adult↗

Stimulation of bronchus-associated lymphoid tissue in rats by repeated inhalation of aerosolized lipopeptide MALP-2.

OBJECTIVE: Bronchus-associated lymphoid tissue (BALT) is a part of the integrated mucosal immune system. It may play an important functional role for antigen uptake and induction of specific immune reactions. The aim of this study was to investigate whether it is possible to induce or modulate BALT by the repetitive inhalation of the synthetic lipopeptide MALP-2. METHODS: Female Lewis rats (245 +/- 19 g) inhaled 25 microg of MALP-2 six times at intervals of 1 week. One week after the last inhalation, they were sacrificed. Cells of the bronchoalveolar lavage and the left lung were investigated by flow cytometry. The middle lobe of the right lung was embedded in paraffin. BALT was semiquantitatively measured in 15 serial cross sections per animal. RESULTS: After repetitive inhalation of the diluent as well as MALP-2, BALT was found. The total area was increased after repetitive treatment with MALP-2. In addition, the preferential incidence of BALT was higher after MALP-2 application, in association with a bronchial diameter of 0.6-1 mm. The cellular analysis revealed no differences in the number of leukocyte subsets between the control and MALP-2 group. CONCLUSION: MALP-2 is a potent local stimulator and can be used to modulate BALT by repetitive inhalant treatment. The functional significance of enlarged or activated BALT has to be elucidated in future studies.

Adjuvants, Immunologic↗