SEARCH · PubMed Health
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.
The evidence on the changes detectable in remote periods (at 1, 3, and 6 months) is presented. It shows that the quantitative and functional defects are retained in the hemopoietic and lymphoid tissues within 3-6 months after exposure to the effects of various cytostatic agents. These defects may be corrected by means of immunomodulators.
Long-term (greater than 2 years) topical, conjunctival application of fluoresceinyl ovalbumin (FL-OA) induced allergic conjunctivitis-like lesions and hyperplasia of conjunctival-associated lymphoid tissue (CALT) in guinea pigs. Single-cell suspensions of CALT and spleen were prepared by collagenase digestion and cultured with or without FL-OA or lipopolysaccharide; the culture supernatants were assayed for IgG, IgA, IgM, and IgE antibody. Absolute values (ng Ab protein/ml) of anti-FL-OA IgG subclasses (IgG1 and IgG2) were measured using purified preparations of IgG1 and IgG2 anti-FL-OA antibody standards in an enzyme-linked immunosorbent assay. Immunohistochemical studies were performed using frozen sectioned CALT tissues as well as cultured single cells. IgG1, IgG2, IgA, IgM, but not IgE, anti-FL-OA antibodies were detected in the culture supernatants of both CALT and spleen. IgG- and IgA-secreting plasma cells were demonstrated in immunoperoxidase-stained CALT and single-cell cultures. The ratio of IgG1 to IgG2 isotypes produced by CALT in vitro was significantly higher than that produced by spleen and also that found in serum. These findings indicated that a site-specific regulation of antibody isotypes may exist within the hyperplastic CALT induced by the long-term topical exposure to FL-OA.
The nasal cavity of a rodent is lined by an epithelium organized into distinct regional domains responsible for specific physiological functions. Aggregates of nasal lymphoid tissue (NALT) located at the base of the nasal cavity are believed to be sites of induction of mucosal immune responses to airborne antigens. The epithelium overlying NALT contains M cells which are specialized for the transcytosis of immunogens, as demonstrated in other mucosal tissues. We hypothesized that NALT M cells are characterized by distinct glycoconjugate receptors which influence antigen uptake and immune responses to transcytosed antigens. To identify glycoconjugates that may distinguish NALT M cells from other cells of the respiratory epithelium (RE), we performed lectin histochemistry on sections of the hamster nasal cavity with a panel of lectins. Many classes of glycoconjugates were found on epithelial cells in this region. While most lectins bound to sites on both the RE and M cells, probes capable of recognizing alpha-linked galactose were found to label the follicle-associated epithelium (FAE) almost exclusively. By morphological criteria, the FAE contains >90% M cells. To determine if apical glycoconjugates on M cells were accessible from the nasal cavity, an M-cell-selective lectin and a control lectin in parallel were administered intranasally to hamsters. The M-cell-selective lectin was found to specifically target the FAE, while the control lectin did not. Lectin bound to M cells in vivo was efficiently endocytosed, consistent with the role of M cells in antigen transport. Intranasal immunization with lectin-test antigen conjugates without adjuvant stimulated induction of specific serum immunoglobulin G, whereas antigen alone or admixed with lectin did not. The selective recognition of NALT M cells by a lectin in vivo provides a model for microbial adhesin-host cell receptor interactions on M cells and the targeted delivery of immunogens to NALT following intranasal administration.
Explore the source record for details and available documents.
The nasal mucosal is the first site of contact with inhaled antigens. However, the nature of local immune responses and the role of nasal-associated lymphoid tissue (NALT) in those responses have rarely been studied. To characterize the cells involved in mucosally derived immune responses, NALT and Peyer's patch (PP) cells from normal mice, and mice immunized intragastrically or intranasally with cholera toxin (CT), were isolated and analyzed. Compared with PP cells, unstimulated NALT cells contained a higher proportion of T-cells. The CD4:CD8 ratio in NALT cell preparations was less than that observed in PP and more closely resembled that seen in spleen. Additionally, the total B-cell frequency in NALT cell isolates was 20% lower than that observed in PP cell preparations. Although NALT and PP cell isolates contained both mature B-cells and cells undergoing activation to express surface IgA, unlike PP, NALT showed no significant frequency of IgA-switched cells. After intranasal immunization with CT, toxin-specific IgA antibody-forming cells (AFCs) were detected in NALT cell preparations. The numbers of these cells correlated with CT-specific IgA in nasal, but not in gut washes or sera, thus suggesting local nasal production of antigen-specific mucosal antibodies. There was no evidence of anti-CT AFCs in NALT or CT-specific antibody in nasal washes after intragastric CT administration. These results support the notion that nasal mucosal antibody production is best achieved via direct stimulation of IgA-committed, NALT-derived B-cells.
Alpha-Naphthyl acetate esterase (ANAE) and fluoride resistant alpha-naphthyl acetate esterase (FRANAE) have been compared as histochemical methods to identify T lymphocytes in sections of normal and pathological human lymphoid tissues. In addition, the FRANAE method was combined with alkaline phosphatase (ALP) in order to simultaneously evaluate the relationship between T lymphocytes and fibroblastic reticular cells (ALP) positive). The "dot like" esterase positivity of T lymphocyte was better evaluated by using FRANAE when compared to ANAE because of fluoride inhibitor of the strong esterase activity of dendritic cells and most macrophages. The combined ALP-FRANAE method clearly demonstrated a large number of fibroblastic reticular cells within the T-areas in various normal and pathological tissues such as hyperplastic lymph nodes and especially in the lymph nodes and spleens from patients with Hodgkin's disease.
BACKGROUND: It is still unclear which patients with gastric mucosa-associated lymphoid tissue (MALT) lymphoma will benefit from the eradication of Helicobacter pylori. METHODS: The authors studied a total of 34 patients. Twenty-three patients had primary gastric lymphoma and underwent gastric resection as initial treatment. Eleven patients with gastric MALT lymphoma who received antibiotics against H. pylori as initial treatment were also included. In all 34 patients, the presence of H. pylori, endoscopic findings, and pathologic features were evaluated. Immunohistochemical expression of Bcl-2, p53, and proliferating cell nuclear antigen (PCNA) was classified as follows: (-), no reactive cells; (+), scattered positive cells; (2+), nests of positive cells; (3+), diffuse positive cells. RESULTS: Patients with low grade MALT lymphoma (LG) tended to be positive for H. pylori (6 of 9), to localize within the submucosa (7 of 9), not to have lymph node involvement (7 of 8), and to have lower tumor stage compared with patients with high grade MALT components (HG). Bcl-2 protein was expressed with high frequency by LG (7 of 9). Strong expression of p 53 was more common in the HG tumors (4 of 14), and strong expression of PCNA showed a significant difference between LG (1 of 8) and HG patients (12 of 13). Investigation of the patients with long term follow-up (n = 4) revealed that LG remained superficial for a long time and showed gradual progression. Most of these tumors were Bcl-2+/p53-approximately+/-/ PCNA- approximately +. There were two patients whose superficial LG (sm/Bcl-2+/p53-/PCNA- approximately +) regressed after the disappearance of H. pylori. On the other hand, one patient developed ulcerated LG (sm/Bcl-2 /p53+/PCNA3+) after disappearance of H. pylori. The authors found complete regression of MALT lymphoma in 9 of 11 patients after H. pylori eradication. Initial tumors of these 9 patients were superficial/sm/n(-)/low grade/Bcl-2+approximately +/-/p53-approximately+ (n = 9), /PCNA-approximately+(n = 6), /PCNA 2+ (n = 3). Two local recurrence and one non-Hodgkin lymphoma in other sites were observed after initial therapy. CONCLUSIONS: Gastric MALT lymphoma with (H. pylori positive/superficial/sm/low grade/Bcl-2 +/p53- approximately +/PCNA- approximately +) pattern will disappear after a patient is cured of H. pylori infection.
Previous studies have suggested that the gut-associated lymphoid tissue (GALT) of man is distinct from that of laboratory animals, but it is not clear whether this is due to environmental or true species difference. We have made a comparative study of rats and baboons because, like rats, baboons are herbivorous and relatively unhygienic but they are phylogenetically much more closely related to man. The Peyer's patches of rats, baboons and man are morphologically very similar in all three species but phenotypically those of man and baboons are different to those of rats. Cells with irregular nuclei ("centrocyte-like" cells) surround the mantle zone in all three species. While these cells express surface IgD and IgM in rats, in man and baboons they express surface IgM or IgA. A population of immunoblasts which express cytoplasmic IgA are present in association with the high endothelial venules of rat Peyer's patches. These cells are not present to the same extent in man or baboons. This suggests that the events between the antigenic stimulation of Peyer's patches and the ultimate seeding of the lamina propria with IgA secreting plasma cells may be different in rodents and primates.
BACKGROUND & AIMS: The growth of gastric mucosa-associated lymphoid tissue lymphoma (MALToma) seems to depend on the stimulation of Helicobacter pylori. We attempted to identify specific antigen(s) from H. pylori strains associated with MALToma. METHODS: Membranous and secreted proteins of H. pylori were compared on sodium dodecyl sulfate-polyacrylamide gel electrophoresis by Western blot using sera from patients with MALToma. RESULTS: A 19-kilodalton protein was seen in all strains isolated from patients with MALToma but uncommonly in other strains. The protein was purified and sequenced. Amino acid sequence comparison showed it was an FldA homologue, a putative flavodoxin protein. DNA sequencing in 26 strains revealed that a nucleotide G insertion at position 481 of the fldA gene was more frequently observed in strains associated with MALToma than other strains (9/9 vs. 6/17; P = 0.002). The mutation caused a short truncation. A recombinant protein with this truncation was expressed and tested. Sera of 12 (70.6%) of 17 patients with MALToma were positive for the antibody to the recombinant protein, and 7 (16.7%) of 42 control patients were positive (12/17 vs. 7/42; P < 0.0001). CONCLUSIONS: Truncated FldA of H. pylori is associated with gastric MALToma. It may be involved in the pathogenesis of gastric MALToma. Antibody to this antigen could be used as a serological marker of the disease.
20-30% of gastric mucosa-associated lymphoid tissue (MALT) lymphoma associated with Helicobacter pylori do not regress after antibiotic therapy. Regression can be assessed only by extended follow-up. To assess whether t(11;18, q21;q21), which results in a chimeric transcript between the AP12 and MLT genes, predicts lymphoma resistance to antibiotic therapy, we screened for the fusion transcript with RT-PCR in ten responsive and 12 non-responsive gastric MALT lymphomas. The AP12-MLT transcript was detected in nine (75%) of 12 patients non-responsive to antibiotic therapy but not in responsive patients. Most H pylori-associated gastric MALT lymphomas that do not respond to antibiotic therapy are associated with t(11;18, q21;q21).
Non Hodgkin Malignant lymphomas (NHML) of mucosa associated lymphoid tissue (MALT) are known to have multiple involvement of the digestive tract. We report one case, presenting with an infiltrative process of the jejuno-ileum, associating lymphoplasmacytoid proliferating cells and amyloidosis. The plasmacytoid cells expressed Alpha and scarce Mu heavy chains, and lambda light chain. Lympho-epithelial lesions were more obvious at the second site of involvement, in the gastric mucosa. The amyloid substance was negative with the Amyloid A component antibody and gave a background noise with Alpha, Mu and lambda chains. No similar report of amyloidosis associated with MALT NHML has been found in the literature.
Extranodal marginal zone B-cell lymphomas of mucosal-associated lymphoid tissue (MALT)-type occur in a number of anatomic sites, but share overlapping morphological and immunophenotypic features. Helicobacter pylori infection has been identified as an etiological factor in gastric MALT lymphoma, but the cause of MALT lymphomas at other sites remains a matter of speculation. Despite these limitations in understanding the etiology of MALT lymphoma, standard cytogenetic analysis has proved useful by demonstrating similar alterations in MALT lymphomas from different anatomic sites. The common cytogenetic alterations that characterize MALT lymphomas include t(11:18)(q21:q21), t(1;14)(p22;q32) and, more recently, t(14;18)(q32;q21). The apparent complexity of the cytogenetic alterations that have now been implicated in the pathogenesis of extranodal MALT lymphoma serves as a paradigm for molecular cross talk in neoplastic disease. Recent data have shown that these very disparate translocations affect a common signaling mechanism, and thus unify all three under a common pathogenesis, resulting in the constitutive activation of the NF-kappaB pathway.
Mucosa-associated lymphoid tissue (MALT) lymphomas are increasingly recognized as a distinct clinical-pathologic entity among the non-Hodgkin's lymphomas. It usually presents as a localized disease process in extranodal tissues or organs such as stomach, salivary gland, thyroid gland, and not infrequently in orbital adnexa. Radiotherapy has an important role in the management, although long-term clinical results specifically addressing localized MALT lymphomas are lacking. We report a case of localized MALT lymphoma of the lacrimal gland, with successful treatment by radiation therapy (total dose 25 Gy) with 3 years of clinical follow-up. A review of the published literature was undertaken to assess the role of radiotherapy in the treatment of this disease involving orbital tissues, specifically, the lacrimal gland. Based on previous reports of patients with orbital lymphomas (low grade) and pseudolymphomas, of which many will now be recognized as MALT lymphomas, radiotherapy has an excellent local control rate and would be the treatment of choice. However, long-term results of pathologically confirmed cases of MALT lymphomas need further study because occasional relapses at distant sites can occur.
BACKGROUND: Extranodal marginal zone B cell lymphoma of the mucosa-associated lymphoid tissue (MALT) is a relatively common type of lymphoma. Owing to its B cell lineage, it appears to be a potential target for treatment with the CD20 antibody rituximab. We present an analysis of our experience with rituximab for treatment of patients with advanced MALT lymphoma. PATIENTS AND METHODS: A retrospective analysis of patients with histologically verified MALT lymphoma undergoing treatment with rituximab was done. After reassessment of histological samples for the presence of MALT lymphoma, patients were evaluated as regards date of diagnosis, prior therapy for MALT lymphoma, sites of involvement upon treatment with rituximab, clinical response in terms of complete remission (CR), partial response (PR), stable disease (SD) and progressive disease as well as symptomatic response, duration of response and survival. RESULTS: A total of 9 patients with advanced MALT lymphoma undergoing therapy with single-agent rituximab were identified. All patients received treatment at a dose of 375 mg/m(2) once weekly x4. One patient each had relapsed after chemotherapy and radiation, respectively, while none of the other 7 patients had received prior cytotoxic treatment or radiation. Three patients achieved a CR, 2 patients had PR for 6 and 14 months, while the remaining patients had SD between 8 and 18+ months. One patient died of progressive disease in spite of the initiation of chemotherapy and 1 patient succumbed to a cardiovascular event while having been in ongoing PR for 11 months. The other 7 patients are currently alive with disease 10-27 months after initiation of therapy. Follow-up biopsies for histological assessment were available in 5 patients with gastric lymphoma. In 1 patient with SD, however, persistence of CD20-positive cells within lymphoepithelial lesions was noted in spite of almost complete depletion of B lymphocytes from the normal gastric mucosa, suggesting either recirculation of MALT lymphoma cells to these lesions or defining lymphoepithelial lesions as a sanctuary site from rituximab penetration. CONCLUSION: Rituximab had only moderate activity in terms of inducing objective responses in our unselected and heterogeneous cohort of patients with disseminated MALT lymphoma. Long-term disease stabilization, however, along with a symptomatic benefit was seen in all patients. Our data nevertheless indicate that rituximab might not optimally penetrate into the gastric mucosa in all patients.
Low-grade B-cell mucosa associated lymphoid tissue (MALT) lymphoma can rarely present primarily in extranodal sites other than stomach, which is the most common site for it. Until now only four cases of primary prostatic MALTomas have been described in the literature and we report the fifth. We describe a case of primary prostatic MALToma in a 67-year-old man and the diagnosis was made on the trans-urethral resection specimen of the prostate. As the disease was limited to prostate (stage IEA), the patient was treated with external beam radiation therapy to a total dose of 4400cGy in 22 fractions. The patient achieved completed remission and has remained free of disease in the following 36 months.
Gastric adenocarcinoma developing concomitantly with a gastric lymphoma of the mucosa-associated lymphoid tissue (MALT) type is rare. Herein, we report a case with a synchronous primary gastric MALT lymphoma and an early adenocarcinoma of the stomach. A 72-year-old patient with initial presentation of weight loss was found with endoscopy to have a large tumor mass in the gastric body. Pathologic examination of biopsies revealed a low-grade MALT lymphoma for which chemotherapy with cyclophosphamide, vincristine, and prednisolone was administered. A gastric adenocarcinoma was found at a different site in the of stomach 3 months after cessation of chemotherapy when there was still residual MALT lymphoma in the stomach. The presence of double neoplasms was established preoperatively. The patient underwent a proximal gastrectomy. Infection with Helicobacter pylori (H. pylori) was detected once in the repeated endoscopic gastric biopsies. The occurrence of both gastric MALT lymphoma and gastric adenocarcinoma was reviewed and the association of H. pylori infection with both malignancies is discussed.
We investigated the metastatic process to the lungs from subcutaneous transplants of R3327-MatLyLu tumor, a rat model for anaplastic prostatic carcinoma. Considerable metastasis of tumor cells to bronchus associated lymphoid tissue (BALT) was observed with time. Immunocytochemistry clearly showed the presence of the epithelial type of intermediate filaments (cytokeratin) in these cells, confirming their carcinomatous origin. No positive staining for cytokeratin could be observed in the BALT in controls. Localization of tumor cells within the BALT was mainly confined to the region near the adjacent artery. After intravenous injection of monodispersed tumor cells, an influx of tumor cells was observed within minutes in this same region of the BALT. These observations suggest that BALT is involved in the metastatic process of tumor cells to the lungs. Its role in controlling metastasis and in tumor cell kill, if any, remains to be elucidated.
BACKGROUND: Clinically, in the absence of enteral nutrition, the morbidity of infectious complication is high. Although experiments using mice have shown alterations in gut-associated lymphoid tissue (GALT) to be an important mechanism underlying impaired host defense, there are no clinical studies on the effects of nutritional routes on GALT. METHODS: A total of 27 colon cancer cases who underwent right colectomy or hemicolectomy were reviewed. Six patients did not receive enteral nutrition for 4 to 28 days before surgery because of bowel obstruction (parenteral nutrition [PNI group). Twenty-one patients were enterally fed before surgery (enteral nutrition [EN] group). The terminal ileum from resected specimens was examined microscopically. T-cell numbers in intraepithelial spaces (IE) and the lamina propria (LP) were determined immunohistochemically in blinded fashion. RESULTS: There were no significant differences in baseline characteristics between the 2 groups. T-cell number in the LP was significantly lower in the PN group than in the EN group, with no difference in IE cell numbers. CONCLUSIONS: Lack of enteral delivery of nutrients reduces GALT cell number in patients with colon cancer, as is the case in mice.