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 721 records · Page 40Linked to original sources

PubMedDate not supplied

Particle uptake by conjunctiva-associated lymphoid tissue (CALT) in turkeys.

Uptake of tracer particles was assessed in lower eyelid conjunctiva-associated lymphoid tissue (CALT) of 3-week-old turkeys. Tracer particle suspensions, including carbon, iron oxide, or three sizes of latex beads (0.81 micron, 1.7 microns, and 2.9 microns), were placed into the experimentally sealed conjunctival space. After 5, 15, or 30 minutes, eyelids were removed and CALT was examined by light microscopy. Uptake was confirmed for all tracers and occurred within the lymphoepithelium of CALT. The uptake of latex beads was not as frequent as for carbon and iron. Tracers were increasingly evident in lymphoepithelium and subepithelial macrophage clusters as contact time increased. These findings provide additional evidence that CALT is capable of antigen uptake and may play a role in paraocular and upper respiratory immunity in turkeys.

Animals↗

PubMed1984

Phenotypic expression of B-lymphocytes. 1. Identification with monoclonal antibodies in normal lymphoid tissues.

Marker expression is highly variable among different stages of B-cell activation. In peripheral lymphoid tissues, architecturally and cytologically three or four types of B cells can be identified, thus allowing an investigation of cellular surface or cytoplasmic phenotypes. Mantle zone lymphocytes of follicles are phenotypically similar, if not identical, to peripheral blood B-lymphocytes and express the following markers: B1, B2, BA-1, HLA-DR, Leu 10, A1G3, Leu 8, and T200. The germinal center is composed of two main populations, centroblasts and centrocytes which express the following markers: B1, BA-2, J5, OKT9, HLA-DR, Leu 10, and T200. This phenotype is similar to that of activated B cells or pre-B cells. Although membranous OKT10 is present in cortical thymocytes, the presence of cytoplasmic OKT10 appears to be a useful marker for plasma cells, terminally differentiated B cells, which also express A1G3 and T200. This study also revealed that a subpopulation of T cells in the germinal center express different markers (A1G3-/Leu 8-) as compared with that of most T cells in the T-dependent zone (A1G3+/Leu 8+).

Animals↗

PubMedDate not supplied

IL-12 secreting dendritic cells are required for optimum activation of human secondary lymphoid tissue T cells.

Successful immunization requires that mature dendritic cells (mDCs) prime T cells in secondary lymphoid tissue (LT). Previously, the authors have shown that LT T cell activation has an increased costimulatory threshold for a proliferative response as compared with peripheral blood (PB) T cells. Therefore, to optimize mDC immunogenicity, DC maturation was studied using LT T cells as responders. While mDCs obtained with soluble CD40Ligand (sCD40L) or a sCD40L/IFNgamma combination similarly expressed the CD83 and CCR7 molecules on their membrane, only the latter secreted IL-12. sCD40L/IFNgamma mDCs, as compared with sCD40L mDCs, enhanced allogeneic LT T cell proliferation, LT CD4+ cell IFNgamma production and LT CD8+ cell cytotoxicity. Enhancement could be predominantly ascribed to IL-12 secreted by sCD40L/IFNgamma mDCs and to additional costimulatory signals as shown remarkably in the IFNgamma response when IL-12 was neutralized. Therefore, in addition to their membrane phenotype, mDCs to be used in immunization protocols should be assessed for IL-12 secretion as a surrogate marker for an optimum costimulatory potential.

Animals↗

PubMed2001

T cell proliferation and apoptosis in HIV-1-infected lymphoid tissue: impact of highly active antiretroviral therapy.

T cell turnover was studied in situ in tonsillar lymphoid tissue (LT) from HIV-1-infected individuals during 48 weeks of highly active antiretroviral therapy (HAART) and compared to that of HIV-1-negative controls. Prior to therapy, CD4 cell proliferation (%CD4+ Ki67+) and apoptosis (%CD4+ TUNEL+) were increased in HIV-1-infected LT and both parameters correlated with tonsillar viral load. CD8 cell proliferation (%CD8+ Ki67+) was increased 4- to 10-fold, mainly in the germinal centers. Apoptotic CD8+ T cell levels (%CD8+ TUNEL+) were raised preferentially in the tonsillar T cell zone. The frequency of CD8+ Ki67+ and CD8+ TUNEL+ T cells correlated with tonsillar viral load and with the fraction of CD8(+) T cells expressing activation markers. During HAART, CD4 cell turnover normalized while CD8 cell turnover was dramatically reduced. However, low level viral replication concomitant with slightly elevated levels of CD8 cell turnover indicated a persistent cellular immune response in LT. In conclusion, enhanced T cell turnover may reflect effector cells related to HIV-1 infection.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Aging effect on the immune functions of murine gut-associated lymphoid tissues.

Immune functions generally decline with aging. However, the onset and the rate of the functional decline may be different in each lymphoid compartment. We studied the effect of aging on the murine Peyer's patch (PP) cells, and mesenteric lymph node (MLN) cells, which are a part of gut-associated lymphoid tissues (GALT). The capacity of proliferative responses to mitogens of lymphoid cells from GALT decreased with aging. However, the rate of the decrease was much slower than that in the spleen cells. Production of interleukin-2 (IL-2) and interleukin-3 (IL-3) in aged T cells was also studied. IL-2 production of T cells from PP, MLN, spleen cells decreased with age. The age-related decrease was observed at 21 months of age in spleen and at 24 months of age in PP and MLN cells. In contrast, IL-3 production of PP, MLN, spleen cells didn't decrease at 21 months of age, but decreased only in spleen cells at 24 months of age. Therefore, it is suggested that the onset and the rate of age-related functional decline of GALT are much later and slower than those of systemic immune system. GALT seems to maintain the immune functions longer than systemic immune system.

Aging↗

PubMed2005

Complement dependent trapping of infectious HIV in human lymphoid tissues.

OBJECTIVES: HIV-1 bound extracellularly to follicular dendritic cells (FDC) in germinal centers (GC) of lymphoid tissues (LT) represents the largest viral reservoir in HIV-infected individuals; however there is no direct evidence as to whether HIV trapped in human GC remains infectious. In the GC, complement receptors and Fc gamma receptors have been suggested to participate in trapping of HIV; therefore, the relative contribution of complement- and Fc gamma receptors in binding HIV on LT was investigated and the infectivity of this virus was tested. DESIGN: As it is difficult to isolate FDC without contaminations of productively infected cells, HIV was detached from LT of HIV positive individuals using antibodies blocking complement- and Fc gamma receptors. Isolated virus was tested in an infectivity assay. METHODS: HIV detached from LT was quantified by HIV p24 ELISA, PCR and in an in vitro infectivity assay. Presence and accessibility of viral envelope proteins, complement factors and immunoglobulins on the surface of detached viral particles were evaluated through viral capture by respective antibodies. RESULTS: Although both C3d-fragments and IgG molecules were identified on the surface of HIV detached from LT, trapping of HIV was mediated solely by CR2-C3d interactions, whereas contribution of Fc gamma receptors was not detectable. Infectivity assays with HIV stripped from LT of HIV positive individuals revealed that in four out of ten patients HIV particles were infectious. CONCLUSIONS: These findings indicate that in the GC infectious virus is trapped on CR2-expressing FDC (or B cells). Reduction of this pool of HIV could be a therapeutic goal.

Cells, Cultured↗

PubMed1998

Clinical and pathologic characterization of mucosa-associated lymphoid tissue lymphoma of the head and neck.

Mucosa-associated lymphoid tissue (MALT) has recently been recognized as a possible site of origin for low-grade lymphomas of the B-cell type. Though relatively rare, these MALT lymphomas may arise within several sites in the head and neck, and often present diagnostic and therapeutic challenges. We review 4 cases of primary MALT lymphoma of the head and neck, treated with surgical excision (3 cases), irradiation (2 cases), and chemotherapy (1 case), to further characterize this new subtype of head and neck malignancy. The mean time from onset of symptoms to histologic diagnosis was 15 months. Fine needle aspiration identified an atypical lymphoid infiltrate in only 1 of 3 patients. Immunohistochemical analysis was essential in establishing the diagnosis of MALT lymphoma in all 4 of the cases, and demonstrated characteristic negative staining for CD3, CD5, and CD43, positive staining for CD20, and monotypic staining for either kappa or lambda light chain immunoglobulin markers. All patients achieved complete remission after primary therapy, and all remain free of disease with follow-up ranging from 6 to 54 months (mean 33 months). The diagnosis of MALT lymphoma should be considered in cases of atypical lymphoid infiltrates in the head and neck, and increased awareness coupled with detailed immunohistochemical analysis is essential to securing an accurate diagnosis. Clinical remission of MALT lymphoma may be achieved with several modalities, but further study will be required to determine the long-term response to treatment.

Adult↗

PubMed2004

HLA-DR, ICAM-1, CD40, CD40L, and CD86 are incorporated to a similar degree into clinical human immunodeficiency virus type 1 variants expanded in natural reservoirs such as peripheral blood mononuclear cells and human lymphoid tissue cultured ex vivo.

To provide additional information on the acquisition of host cell membrane proteins by human immunodeficiency virus type 1 (HIV-1) produced by natural cellular reservoirs, two different field isolates were used to infect ex vivo expanded peripheral blood mononuclear cells (PBMCs) and human lymphoid tissue histocultures. The insertion of host-derived HLA-DR, intercellular adhesion molecule-1 (ICAM-1), CD40, CD40L, and CD86 within HIV-1 particles was evaluated by using specific antibodies linked to a solid matrix to capture ultrafiltrated viral progeny. Overall, our data indicate that neither the HIV-1 co-receptor usage (i.e., T-tropic or macrophage-tropic) nor the cellular source of HIV-1 has an impact on the incorporation process but it was found to be under the influence of the donor source. Given that most viral replication is thought to occur in lymphoid tissues and previous works have shown that HIV-1 life cycle is affected by several virus-anchored host proteins, our results suggest that this phenomenon is likely to contribute to the pathogenesis of this retroviral infection.

Animals↗

PubMed1986

Bronchus associated lymphoid tissue in the lungs of cattle: relationship to age.

The occurrence and morphological features of bronchus associated lymphoid tissue (BALT) were examined by light and electron microscopy in the non-pneumonic left lungs of five age groups of cattle from neonate to aged adult. The amount of BALT was correlated with age. It was absent in neonatal lungs and increased progressively with age until it declined in aged adult cattle. Within age groups the occurrence and morphology of BALT was variable. Widely scattered lymphoid aggregates were the predominant morphological type of BALT in the bovine lung. Follicular development in BALT foci was less frequent and quite variable within individual lungs. Morphologically distinct lymphoepithelium overlying BALT foci could not be demonstrated in non-pneumonic bovine lungs.

Aging↗

PubMed2000

HIV-infected human Langerhans cells transmit infection to human lymphoid tissue ex vivo.

OBJECTIVES: To create a novel ex vivo model for early biologic events involved in sexual transmission of HIV and to demonstrate that Langerhans cells (LC), the purported initial mucosal target cells for HIV, play a critical role in this process. METHODS: Epidermal cells containing LC were isolated from normal-appearing skin of healthy volunteers and exposed to a panel of primary and laboratory-adapted R5- and X4-HIV isolates, washed and applied to the surfaces of allogeneic tonsil tissue blocks. Viral replication was followed by measuring HIV p24 protein in culture supernatants by ELISA. RESULTS: Both R5- and X4-HIV isolates could be transmitted by LC and established high levels of infection in lymphoid tissue (p24 > 10 ng/ml). Depletion of LC within epidermal cell suspensions abrogated the ability of HIV-exposed suspensions to transmit virus to tonsil histocultures. CONCLUSIONS: Using a novel ex vivo model, human LC are shown for the first time to be the major epidermal cell type that is involved in transmission of HIV infection to human lymphoid tissue. Importantly, this system could prove useful in further understanding LC trafficking and other early biological events involved in primary HIV infection.

Cells, Cultured↗

PubMed1992

In vitro preactivated human T cells engraft in SCID mice and migrate to murine lymphoid tissues.

Mice with severe combined immunodeficiency (SCID) accept grafts of human T and B lymphocytes derived from resting peripheral blood mononuclear cells (PBMC). We wished to determine whether activated human T cells engraft and migrate into lymphoid tissues in SCID mice. PBMC (50 x 10(6)) activated in vitro in a 4-day mixed lymphocyte culture (MLC) were injected into the peritoneum of 12 SCID mice. In 11 of 12 animals killed at 3 or 4 weeks after injection, human cells were detected in cells pooled from lymphoid organs by flow cytometry and by immunohistochemical staining of frozen tissue sections. The percentage of CD45+ cells in the 11 mice ranged from 2% to 45% and the absolute numbers of CD45+ cells recovered from lymphoid organs ranged from 4 x 10(6) to 90 x 10(6). Up to 93% of the human cells expressed the CD3 antigen together with either CD4 or CD8. Human T cells were localized in periarteriolar areas in murine spleens, whereas in the lymph nodes and gut mucosa, the T cells did not show the pattern for T-dependent areas found in human lymphoid tissue. Numerous human plasma cells were detected in the spleen and gut mucosal crypts of engrafted SCID mice. Human IgG was detected in the serum of all 11 engrafted SCID mice. The functional activity of human T cells recovered from murine splenic tissue was very low 3-4 weeks after engraftment.

Animals↗

PubMed2002

Increased expression of the inflammatory chemokine CXC chemokine ligand 9/monokine induced by interferon-gamma in lymphoid tissues of rhesus macaques during simian immunodeficiency virus infection and acquired immunodeficiency syndrome.

Chemokines are important mediators of cell trafficking during immune inductive and effector activities, and dysregulation of their expression might contribute to the pathogenesis of human immunodeficiency virus type 1 and the related simian immunodeficiency virus (SIV). To understand better the effects of SIV infection on lymphoid tissues in rhesus macaques, we examined chemokine messenger RNA (mRNA) expression patterns by using DNA filter array hybridization. Of the 34 chemokines examined, the interferon gamma (IFN-gamma)-inducible chemokine CXC chemokine ligand 9/monokine induced by interferon-gamma (CXCL9/Mig) was one of the most highly up-regulated chemokines in rhesus macaque spleen tissue early after infection with pathogenic SIV. The relative levels of expression of CXCL9/Mig mRNA in spleen and lymph nodes were significantly increased after infection with SIV in both quantitative image capture and analysis and real-time reverse transcriptase-polymerase chain reaction assays. In addition, in situ hybridization for CXCL9/Mig mRNA revealed that the patterns of expression were altered after SIV infection. Associated with the increased expression of CXCL9/Mig were increased numbers of IFN-gamma mRNA-positive cells in tissues and reduced percentages of CXC chemokine receptor (CXCR) 3(+)/CD3(+) and CXCR3(+)/CD8(+) lymphocytes in peripheral blood. We propose that SIV replication in vivo initiates IFN-gamma-driven positive-feedback loops in lymphoid tissues that disrupt the trafficking of effector T lymphocytes and lead to chronic local inflammation, thereby contributing to immunopathogenesis.

Animals↗

PubMed2000

Histological grading with clinical relevance in gastric mucosa-associated lymphoid tissue (MALT) lymphoma.

Treatment choice in gastric mucosa-associated lymphoid tissue (MALT) lymphoma is dependent on the stage and biological rate of progression and transformation as reflected by grade. In pre-treatment, endoscopic biopsy samples, histological and biological criteria to recognize tumor components with a significantly adverse impact on prognosis have to be defined to select patients who may benefit from Helicobacter pylori (H. pylori) eradication as single modality treatment and those who need "classical" anti-cancer therapy. In a consecutive series of 106 patients with gastric MALT-non-Hodgkin's lymphoma (NHL), it was possible to define criteria to differentiate between low-grade and high-grade (transformed) disease. Moreover, within the low-grade group, a category with a diffuse large cell component of 1-10% with or without non-confluent clusters of blasts could be separated with a significantly worse prognosis (10-year disease-specific survival 90% versus 75%). No clinical parameters of known prognostic significance could account for this difference. In a separate series of 19 patients treated with H. pylori eradication, this morphology was strongly related to the chance of reaching complete remission as an independent risk factor. This suggests that it is possible to define criteria in endoscopic biopsy samples to recognize clinically relevant tumor-progression and that these criteria may serve as a guideline in the choice of therapy.

Adult↗

PubMedDate not supplied

Bilateral cystic parotid masses and a hypopharyngeal mass: a case report and review of mucosa-associated lymphoid tissue lymphoma in the head and neck.

Mucosa-associated lymphoid tissue (MALT) lymphoma is a low-grade B-cell lymphoma that was first described in gastric mucosa. Although presentation in the parotid gland is not unusual, bilateral cystic masses and associated hypopharyngeal involvement are rare. We describe an 83-year-old man with a large painless facial swelling; he was otherwise asymptomatic. On examination, bilateral parotid masses and a mass in the hypopharynx were found. Biopsy of the hypopharynx was consistent with MALT lymphoma. The patient was treated with single-agent chemotherapy and had a good initial response. MALT lymphoma occasionally originates within the salivary glands and other sites in the head and neck region. This disease should be considered in the differential diagnosis of cystic or bilateral parotid masses and hypopharyngeal masses.

Aged↗

PubMed2006

[MALT (Mucosal Associated Lymphoid Tissue) lymphoma of the palpebral conjunctiva].

BACKGROUND: MALT (Mucosal Associated Lymphoid Tissue) lymphomas of the conjunctiva belong to the extranodal marginal zone B-cell lymphomas. This site, while standard, is uncommon. CASE-REPORT: A pink papular tumor developed on the lower eyelid of a 59-year-old woman. Sarcoidosis was diagnosed 9 years earlier associated with mediastinal lymphadenopathy and erythema nodosum not requiring treatment. Histological examination yielded a diagnosis of conjunctival MALT lymphoma. No visceral involvement was demonstrated. Radiotherapy (30 Gy) induced a complete response. A remote lesion developed on the patient's arm 18 months later. No other sites were found. Further radiotherapy (26 Gy) again induced complete remission. No new lesions were seen after 24 months of follow-up. DISCUSSION: This case is interesting because of the association of a MALT lymphoma and previous sarcoidosis, described in the literature as "sarcoidosis-lymphoma syndrome". Association of sarcoidosis with MALT lymphoma is infrequent. Treatment of conjunctival MALT lymphoma is standardized. Radiotherapy offers excellent efficacy and is well tolerated at this site. Regular and long-term follow-up is required. Local and distant relapse can occur.

Biopsy↗

PubMed2006

Spontaneous regression of intraoral mucosa-associated lymphoid tissue lymphoma: molecular study of a case.

Mucosa-associated lymphoid tissue (MALT) lymphoma presentation in the oral cavity is very rare. Reported herein is a case of intraoral MALT lymphoma of the minor salivary gland in a 70-year-old woman with Sjogren's syndrome. Unexpectedly, a spontaneous clinically and histologically confirmed regression occurred 1 month after the tumor biopsy for diagnosis. Considering that salivary MALT lymphoma is associated with Sjogren's syndrome and that the chronic inflammation caused by Sjogren's syndrome persisted, it is hypothesized that the tumor clone might be present in the regressed lesion. Minimal residual tumor clone identical with the primary lesion was detected using the polymerase chain reaction (PCR) clonality assay for immunoglobulin heavy chain gene (IgH) rearrangement. No recurrence was clinically evident 38 months after the diagnosis. Spontaneous regression of MALT lymphoma should be examined at the molecular level in addition to clinical and histological evaluations. When minimal residual disease is detected, close follow up is necessary for early detection of the tumor relapse.

Aged↗

PubMed1995

Expression of the bcl-2 protein in B cell lymphomas arising from mucosa associated lymphoid tissue.

AIM: To determine whether lymphomas arising from mucosa associated lymphoid tissue (MALT) express the bcl-2 protein. METHODS: Forty two cases of MALT B cell lymphomas, 20 low grade neoplasms and 22 high grade tumours, were studied. Immunohistological staining was performed on paraffin wax embedded tissue using a monoclonal antibody specific for the bcl-2 protein. RESULTS: All of the low grade lymphomas gave positive results on staining, with clear cytoplasmic labelling for bcl-2 protein in the small neoplastic cells, some of which formed characteristic lympho-epithelial lesions. A striking feature was that larger bcl-2 negative cells were observed in nine of these tumours. They were either scattered singly among the small neoplastic cells or formed small clusters, suggesting that they could represent early areas of transformation to high grade neoplasia. Germinal centres in the vicinity of the tumours lacked bcl-2 protein and hence contrasted clearly with the neoplastic cells. In some cases this permitted germinal centres, which were not obvious on conventional histological staining, to be recognised. In 20 of the 22 cases of high grade B cell lymphoma the large neoplastic cells were bcl-2 negative; the remaining two cases, however, contained a proportion of large neoplastic bcl-2 positive cells. In four of the 22 cases of high grade tumours a low grade component was found which expressed bcl-2 in all cases. CONCLUSION: Bcl-2 protein is expressed in low grade, but not in most high grade, MALT lymphomas. In view of recent data indicating that most high grade nodal lymphomas express bcl-2, these findings suggest that MALT lymphomas may regulate bcl-2 gene expression differently to nodal lymphomas.

Antibodies, Monoclonal↗

PubMed2001

Changes in pattern of immunoglobulin heavy chain gene rearrangement and MIB-1 staining before and after eradication of Helicobacter pylori in gastric mucosa-associated lymphoid tissue (MALT) lymphoma.

Gastric low-grade mucosa-associated lymphoid tissue (MALT) lymphomas are strongly associated with infection by Helicobacter pylori (H. pylori). Antibiotic treatment for H. pylori induces a sustained remission in a significant number of patients. We report here the outcome in 13 patients with gastric low-grade MALT lymphomas or suspected gastric lesions, treated for eradication of H. pylori. Patients were followed closely with sequential histological studies, polymerase chain reaction (PCR) amplification of the immunoglobulin heavy chain (IgH) gene and immunohistochemistry for MIB-1. Antibiotic therapy resulted in eradication of H. pylori in all but one case, as assessed histologically. In 12 cases with successful eradication, complete regression was observed histologically in 9 cases (75%) and no regression in 3 (25%). In 7 of 9 (78%) patients who had a complete remission, clonal bands of IgH gene detected on PCR before therapy disappeared after therapy. All 9 patients with complete regression showed a reduced number of MIB-1 positive cells, while 4 cases with no change or disease progression showed no change or increased number of MIB-1 positive cells. There was a strong relationship between density of MIB-1-positive cells and histological score. These results indicate that combination analysis of PCR of IgH and MIB-1 seems to represent a very good current approach for the diagnosis of gastric low-grade MALT lymphoma and to assess the effects of chemotherapy, especially in problematic cases.

Aged↗