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PubMed1986

Duct-associated lymphoid tissue (DALT) of minor salivary glands and mucosal immunity.

Minor salivary glands (MSG) play a substantial role in the secretory immunoglobulin A (sIgA)-mediated immunity of the oral cavity. There are two possibilities for the induction of this immunity: (i) an explicitly local antigenic stimulus, or (ii) a remote stimulus as part of the so-called 'common mucosal immune system'. This communication is an attempt to consolidate available evidence in support of both possibilities and to address the former in detail. Although there is strong circumstantial evidence supporting the feasibility of MSG functioning as a part of the common mucosal immune system, direct experimental evidence is yet to emerge. On the other hand, there is increasing structural and physiological evidence in support of MSG serving as a local immunological organ. The purely local response is attributed to the presence of MSG duct-associated lymphoid tissue (DALT), which is comparable to gut- or bronchial-associated lymphoid tissue (GALT or BALT) in origin, tissue organization and function. DALT is accessible to oral antigens by retrograde passage through MSG ducts. Repeated topical antigenic challenging via the oral mucosa may result in the appearance of interacinar plasma cells carrying specific homologous antibodies in MSG. Gut or enteric priming of the same antigen, by passing the oral mucosa by gastric intubation, need not evoke a remote immune response in MSG. Since DALT is more likely to occur in healthy, young growing individuals, who are less likely to undergo bioptic examination of MSG, it has not yet been documented in humans. The physiologically induced DALT is apt to be confused with focal accumulations of lymphoid tissue in pathologically altered MSG, as a consequence of local and some systemic autoimmune diseases. An attempt is made to demarcaate healthy and pathological MSG on the basis of currently available clinical, serological, immunological and genetic evidence.

Aging↗
PubMed2006

Retinoblastoma gene family expression in lymphoid tissues.

It appears more and more clear that retinoblastoma (RB) family of proteins represents key molecules in tumour suppression. This family consists of pRb/p105, p107 and pRb2/p130, which participate in a gene regulatory network that governs the cellular response to antimitogenic signals, and whose deregulation constitutes one of the hallmarks of cancer. Irrespective of their structural and biochemical similarities, RB proteins carry out different functional tasks. The expression of RB gene family in the reactive lymphoid tissues again confirms the different role of each member in cell cycle control and differentiation of normal cells. These different functional properties appear to be maintained in tumours lymphoid tissues, where alterations of the RB/p105 gene appear to be relatively rare. In this review, we will summarize the current knowledge about the role of the RB proteins in reactive and neoplastic lymphoid tissue.

Cell Cycle↗
PubMed2005

Cryptopatches and isolated lymphoid follicles: dynamic lymphoid tissues dispensable for the generation of intraepithelial lymphocytes.

In comparison to secondary lymphoid organs, gut-associated lymphoid tissues such as isolated lymphoid follicles (ILF) and cryptopatches (CP) have been less intensively studied. To gain a better insight into processes regulating organization and function of these structures, which are believed to participate in immune responses and extrathymic T cell development, we characterized the lymphoid structures of the murine small intestine in more detail. The size and cellular composition of small intestinal lymphoid aggregations were analyzed in C57BL/6 and BALB/c wild-type and lymphotoxin (LT)-deficient mice, by flow cytometry, histology and automated multi-color immunofluorescence microscopy evaluating large coherent areas of the intestine. These evaluations demonstrate that aggregated lymphoid structures in the small intestine vary in size and cellular composition, with a majority of structures not matching the current definitions of CP or ILF. Accordingly, significant variations depending on species, age and mouse strain were observed. Furthermore, small bowel transplantation revealed a rapid exchange of B but not T cells between host and grafted tissue. Moreover, LT-deficient animals lack any intestinal lymphoid aggregations yet possess the complete panel of intraepithelial lymphocytes (IEL). In summary, our observations disclose intestinal lymphoid aggregations as dynamic structures with a great deal of inborn plasticity and demonstrate their dispensability for the generation of IEL.

Animals↗
PubMed1997

Migration of cells with immunoglobulin/c-myc recombinations in lymphoid tissues of mice.

Recombinations between c-myc and immunoglobulin (Ig) sequences that typically occur in pristane-induced mouse plasmacytomas were detected in secondary lymphoid tissues from normal mice, chiefly in the gut-associated lymphoid tissue. Based on the analysis of recombination sequences as clonotypic markers, migration of c-myc recombination-positive cells was observed between Peyer's patches and into the intestine. Treatment of plasmacytoma-susceptible BALB/cAn mice with pristane induced proliferation and migration of these cells into mesenteric lymph node, spleen, and oil granuloma within 7 days. Plasmacytoma-resistant strains of mice (DBA/2N, C3H/HeJ, C57BL/6) differed in that (1) they harbored fewer clones (Ig/c-myc recombinations were detected in 33% of resistant mice versus 91% of BALB/cAn mice after pristane treatment); (2) Ig/c-myc-positive cells were rarely detected in the oil granuloma, and (3) c-myc recombined predominantly with the Ig alpha locus in BALB/cAn mice (72%), but with the Ig mu locus in DBA/2N and in C57BL/6 (67%). The results demonstrate that normal mice generate a large number of lymphocytes with aberrant c-myc in intestinal tissues without developing tumors.

Animals↗
PubMed1999

Insulin-like growth factor (IGF) II induced changes in expression of IGF binding proteins in lymphoid tissues of hIGF-II transgenic mice.

Overexpression of human insulin-like growth factor II (IGF-II) in transgenic mice does not result in increased overall body growth. The IGF-II overexpression, however, specifically causes growth of the thymus and not of the spleen. We address the question whether the observed differences in growth induction in lymphoid tissues by IGF-II can be related to differences in local IGF binding protein (IGFBP) production, using nonradioactive in situ hybridization and Northern blot analysis. IGFBP-2, -4, and -5 are expressed in both lymphoid tissues of normal mice. The spleen additionally expresses IGFBP-3 and IGFBP-6. IGFBP-1 expression was not detected. Although the expression pattern of the IGFBPs did not change upon IGF-II overexpression, the level of expression changed in a specific manner for each IGFBP. In both the thymus and the spleen of transgenic mice, IGFBP-2 and -5 gene expression was slightly increased, whereas the level of IGFBP-4 expression was not altered. In the spleen, IGFBP-6 expression was not altered by IGF-II overexpression, whereas IGFBP-3 expression was strongly increased. The differences in IGFBP expression, and the difference in response of these IGFBPs to IGF-II overexpression in thymus and spleen suggests an important role of these proteins in growth regulation of both lymphoid tissues. We speculate that an increase of IGFBP-3 expression together with changes in expression of other IGFBPs, inhibits IGF-II stimulated growth in the spleen by an autocrine-/paracrine pathway.

Animals↗
PubMed2000

Primary bilateral mucosa-associated lymphoid tissue lymphoma of the breast with atypical ductal hyperplasia and localized amyloidosis. A case report and review of the literature.

Primary non-Hodgkin lymphoma of the breast is a rare disease. Primary mucosa-associated lymphoid tissue lymphoma is even rarer, and bilateral involvement is exceptional. We describe a case of primary bilateral breast mucosa-associated lymphoid tissue lymphoma with bilateral atypical ductal hyperplasia and bilateral localized amyloidosis in a 64-year-old woman with a history of arthritis and systemic lupus erythematosus and its clinical, histologic, and immunohistochemical features. Microscopic examination of the breast lesion showed dense periductal and perilobular small and plasmacytoid lymphocytes with eosinophilic amyloid in the vessels and the stroma. Bilateral single foci of atypical ductal hyperplasia were also noted. Fine needle aspiration showed small and large lymphocytes and plasma cells. Molecular analysis demonstrated a heavy chain immunoglobulin H gene rearrangement. Flow cytometry studies showed an abnormal B-cell population. The combined histologic, paraffin immunohistochemistry, flow cytometry, and molecular results were considered diagnostic for low-grade mucosa-associated lymphoid tissue lymphoma. The patient underwent bilateral local breast radiation without other organ or site involvement.

Amyloidosis↗
PubMed2003

Extranodal lymphoma originating from mucosa-associated lymphoid tissue of the nasopharynx.

Non-Hodgkin's lymphoma originating from mucosa-associated lymphoid tissue has been connected with autoimmune disease. These tumours often arise in gastric mucosa and are extremely rare in airway mucosa. Three cases of mucosa-associated lymphoid tissue lymphoma in the cavum have been reported in the literature. A 52-year-old male with rheumatoid arthritis presented with an 8-month history of nasal obstruction and recurrent nasal blood discharge. On physical examination a bulky mass was observed in the nasopharynx. CT demonstrated a soft tissue lesion in the nasopharynx without bone destruction. MRI showed a contrast-enhanced mass with extension to the left pterygoid muscle. Biopsy revealed a low-grade B-cell lymphoid tumour of the marginal zone. The patient received six cycles of cyclophosphamide, vincristine and prednisone with adriamycin treatment, together with intracranial methrotrexate as a prophylactic measure. After 48 months of follow-up there was no evidence of disease and a control MRI scan was normal. The prognosis of this type of tumour is unpredictable and there are too few cases to enable definitive conclusions to be drawn.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Phosphatidylazidothymidine and phosphatidyl-ddC: assessment of uptake in mouse lymphoid tissues and antiviral activities in human immunodeficiency virus-infected cells and in Rauscher leukemia virus-infected mice.

During the early stages of human immunodeficiency virus (HIV) infection, although symptoms are absent and viral replication in peripheral blood mononuclear cells is low, substantial levels of HIV replication can be documented in lymphoid tissue [G. Pantaleo, C. Graziosi, J.F. Demarest, L. Butini, M. Montroni, C.H. Fox, J.M. Orenstein, D.P. Kotler, and A.S. Fauci, Nature (London) 362:355-358, 1993, and J. Embretsen, M. Zupancic, J.L. Ribas, A. Burke, P. Racz, K. Tenner-Tacz, and A.T. Haase, Nature (London) 362:359-362, 1993]. This observation suggests that earlier treatment of HIV infection may be indicated and that strategies for enhancing drug targeting to the lymphoid tissue reservoris of HIV infection may be beneficial. To address this issue, we synthesized dioleoylphosphatidyl-ddC (DOP-ddC) and dipalmitoylphosphatidyl-3'-azido-3'-deoxythymidine (DPP-AZT), phospholipid prodrugs which form lipid bilayers and which are readily incorporated into liposomes. The anti-HIV activity of DOP-ddC was similar to that of ddC in HIV type 1-infected HT4-6C cells, but DPP-AZT was considerably less active than AZT in HT4-6C cells. Liposomes containing DOP-[3H]ddC or DPP-[3H]AZT administered intraperitoneally to mice produced greater levels of total radioactivity over time in plasma, spleen, and lymphoid tissue relative to the results with [3H]ddC and [3H]AZT, respectively. DPP-AZT administered intraperitoneally in liposomes as a single daily dose to mice infected with Rauscher leukemia virus prevented increased spleen weight and reverse transcriptase levels in serum with a dose-response roughly comparable to that of AZT given continuously in the drinking water. DOP-ddC, DPP-AZT, and lipid conjugates of other antiretroviral nucleosides may provide higher levels of drug over time in plasma and in lymph nodes and spleen, important reservoirs of HIV infection, and may represent an interesting alternative approach to antiviral nucleoside treatment of AIDS.

Animals↗
PubMed1986

Seasonal changes in the humoral immune response and the lymphoid tissues of the marine teleost, Sebastiscus marmoratus.

Seasonal modulation in antibody production in relation to the state of lymphoid tissue development was studied in the ovoviviparous fish, S. marmoratus. Animals were kept in tanks with running seawater at 23 +/- 1 degrees C for a minimum 2 week acclimatization period and then immunized three times at 2 day intervals with 20% SRBC (5 microliters/g body weight) intraperitoneally. Immunized fish were bled 2 weeks after the first injection at the time of peak response and plasma were analyzed for titration. The thymus and pronephros were weighed and the number of leukocytes counted in the cell suspension. Antibody levels in fish immunized in summer were higher than those in fish immunized in winter, even if the environmental temperature was held constant. Furthermore, the reactivity of mature females to SRBC was lower than that of males or immature females in the spawning season (winter). The antibody titre was inversely related to the weight of the thymus with the exception of females during the spawning season, while the weight of the pronephros did not show any significant change throughout the year. In addition, the thymus of pregnant, and especially post-spawning females, was entirely involuted, showing a marked decrease in the number of lymphocytes in both the cortex and medulla. Preliminary experiments to examine the effect of photoperiod on antibody production indicated a slight increase in titre among adult fish under a long photoperiod regimen. The present data show that both the season and stage of sexual maturity affect the humoral immune response and lymphoid tissues, and suggest that the thymus might have a function other than that concerned with immunity.

Animals↗
PubMed1999

Activation of the gut-associated lymphoid tissue with expression of interleukin-2 receptors that peaks during weaning in the rat.

BACKGROUND: Weaning exposes the intestinal mucosa to food and bacterial antigens at an age when the immune system is believed to be immature and functionally defective. The purpose of this study was to investigate changes in activation and phenotype of immune cells of the gut-associated lymphoid tissue during weaning. METHODS: Litters of infant rats were studied from pre- to postweaned life. The activation status, assessed by interleukin-2 receptor (IL-2R) expression, and phenotype of cells in the gut-associated lymphoid tissue were examined by immunostaining. RESULTS: Interleukin-2 receptor expression peaked two to four-fold at midweaning (day 21) in mesenteric lymph nodes, jejunal lamina propria, Peyer's patches, and intraepithelial lymphocytes, compared with adult animals (day 70). CD45+ cells expanded in the lamina propria, epithelium, and lymphocyte-filled villi. With CD45 as the denominator, 10% to 50% of lymphocytes in the lamina propria and epithelium were alphabetaT-cell receptor (TCR)+, but the remaining cells had a null phenotype, because there were low numbers of gammadeltaTCR+ T cells, B cells, and macrophages. Natural killer cells peaked at midweaning in the lamina propria (9%) and epithelium (20%) but were less than 5% of CD45+ cells after weaning. CONCLUSIONS: Rather than being immature or functionally inactive, the gut-associated lymphoid tissue reacts appropriately during weaning with expression of IL-2R and expansion of alphabetaTCR+ T-cells.

Animals↗
PubMed2000

Adenocarcinoma of colon differentiating as dome epithelium of gut-associated lymphoid tissue.

AIMS: An early adenocarcinoma of the ascending colon was confined to a mass of gut-associated lymphoid tissue (GALT). The first description of an adenocarcinoma of colon differentiating as dome epithelium is presented. METHODS AND RESULTS: A plaque-like carcinoma was identified opposite the ileocaecal valve in an asymptomatic 56-year-old man with a family history of colorectal cancer. Malignant epithelium was confined to a mass of GALT filling but limited to the submucosa. Characterization of the neoplasm was undertaken by means of mucin histochemistry, immunohistochemistry, electron microscopy and assessment of DNA microsatellite instability status. The malignant epithelium comprised well differentiated columnar cells with a microvillous brush border and expressing MUC1, but no goblet cells or expression of MUC2. The demonstration of focal clusters of intraepithelial B-lymphocytes supported the presence of functioning M-cells within the malignant neoplasm. The cancer was DNA microsatellite stable despite the finding of tumour infiltrating lymphocytes. CONCLUSIONS: There is evidence for the origin of colorectal neoplasia from dome epithelium in both experimental models and microreconstruction studies of early adenomas in nonpolypotic human colorectal mucosa. It is suggested that the lymphocyte-rich subset of colorectal cancer that expresses MUC1 but not MUC2 may be differentiating as dome epithelium of gut-associated lymphoid tissue.

Adenocarcinoma↗
PubMedDate not supplied

The development and structure of mouse nasal-associated lymphoid tissue: an immuno- and enzyme-histochemical study.

This study deals with the structure and development of Nasal-Associated Lymphoid Tissue (NALT) in the mouse. NALT is present in the nasal cavity on both sides at the entrance of the pharyngeal duct. The lymphocytes are organized in B- and T-cell areas covered by an epithelium in which M-cells are present. Immuno- and enzyme-histochemistry showed that NALT is already present at birth. Before birth, accumulations of Ia-positive dendritic cells and a few B lymphocytes were the first signs of the formation of NALT. These cell accumulations occurred just under the epithelium in the nasal floor. At birth, NALT could be distinguished as an accumulation of mainly B lymphocytes and Ia positive dendritic cells in a network of reticulum cells. The covering simple epithelium showed crypt-like invaginations. B- and T-cell areas appeared at seven days after birth. High endothelial venules (HEV) were observed from day 7 onward; from day 14 they could be stained with the HEV-specific monoclonal antibody MECA-325. Ia-positive dendritic cells increased in number during ontogeny. They occurred both in NALT and between the covering epithelial cells. Also, some epithelial cells expressed the Ia-antigen. The number of acid phosphatase positive macrophages increased steadily during ontogeny. The cells were mainly observed in the connective tissue surrounding NALT and just under the epithelium. They displayed antigenic determinants characteristic of macrophages (Moma-1, Moma-2). The structure and development of NALT are compared with those of other parts of the mucosa-associated lymphoid tissue.

Animals↗
PubMed2005

Donor cell engraftment in recipient lymphoid tissues after rat limb allograft.

BACKGROUND: The movement of cells from a transplanted tissue into the host organs, the so-called systemic chimerism, is a phenomenon known to occur and be associated with the development of immunologic tolerance in allotransplantation cases. The purpose of this study was to identify donor cell engraftment in recipient lymphoid tissues after performing rat hind limb allograft. MATERIALS AND METHODS: Fifty-five whole-limb allotransplantations were performed in sex-mismatched pairs of rats. Syngeneic male Lewis and allogeneic Dark Agouti donors were transplanted to female Lewis recipients. FK506 was used for immunosuppression. Donor male cells could be identified in the recipient female tissues by semiquantitative polymerase chain reaction analysis for a Y chromosome-specific DNA sequence. Chimerism was assessed at 1, 24, and 48 weeks after transplantation. RESULTS: There was no rejection episode in any of the limb grafts. Although levels of chimerism were highly variable in each lymphoid tissue, a gradual increase was noticed in all during the course of time. At 1 week after the transplant period, only intrasplenic chimerism was at high level (1%) in three groups. At 48 weeks after the transplant, all recipients with allografts showed very high level (10%) of chimerism in the bone marrow. Two, two, and two of six recipients showed very high levels in the spleen, lymph node, and liver, respectively, at 48 weeks. Intrathymic chimerism was higher at 24 weeks after transplant rather than at 48 weeks. CONCLUSION: We demonstrated donor cell engraftment into recipient lymphoid tissues after successful whole limb transplantation. We conclude that limb allograft can work as a vascularized carrier for the bone marrow transplantation, provide a continuous source of donor cells and contribute to chimerism in the recipient.

Animals↗
PubMed2004

Does surgical removal of mucosal associated lymphoid tissue protect against adult coeliac disease? A case controlled study.

BACKGROUND AND AIMS: Surgical resection of mucosa associated lymphoid tissue has been suggested as a protective mechanism against the development of inflammatory bowel disease. Mucosal T-cell activity plays a pivotal role in coeliac disease pathogenesis. We aimed to determine if the development of adult coeliac disease is influenced by appendectomy or tonsillectomy. METHODOLOGY: Three hundred patients over 16 years of age with biopsy proven coeliac disease were identified from two hospital databases in South Yorkshire. From these databases, appendectomy and tonsillectomy status was determined and compared with 1033 coeliac disease antibody-negative controls (volunteers recruited from general practice). Logistic regression was performed to correct for the age differences between the two groups; cross-table analysis was performed. RESULTS: Thirteen percent of coeliac disease patients and 12.2% of controls had previous appendectomy (P = 0.71; odds ratio 1.08; 95% confidence interval 0.72-1.62). 20.7% of coeliac disease patients and 24.5% of the controls had previous tonsillectomy (P = 0.17; odds ratio 0.80; 95% confidence interval 0.59-1.10). CONCLUSIONS: No significance was demonstrated in either the appendectomy or tonsillectomy group. Surgical removal of mucosal associated lymphoid tissue does not appear to prevent the development of adult onset coeliac disease.

Adolescent↗
PubMed2003

Lymphoid tissue and emphysema in the lungs of transgenic mice inducibly expressing tumor necrosis factor-alpha.

To develop a model in which the pathogenic effects of the proinflammatory cytokine tumor necrosis factor-alpha (TNF) could be investigated, transgenic mice that express TNF in the lung under the control of a doxycycline-inducible promoter were generated. TNF transgene message was expressed at a low level in the absence of doxycycline treatment and was induced in the lung by administration of the drug. Analysis of lung lavage fluid indicated increases in neutrophils and lymphocytes in doxycycline-treated transgenic mice. Histologic analysis of lungs from adult transgenic mice treated with doxycycline revealed prominent development of lymphoid tissue and increases in airspace size. Genes upregulated in TNF transgenic mice, as identified by oligonucleotide microarray analysis, included a variety of transcripts expressed in lymphoid tissues. Immunohistochemical analysis demonstrated the presence of B lymphocytes and, to a lesser extent, T lymphocytes within lymphoid aggregates in TNF transgenic mice. CD8-positive T cells were absent from lymphocytic nodules, but in the lung parenchyma were more abundant in transgenic than in nontransgenic mice. These results indicate that induction of TNF in adult lung promotes the formation of lymphoid tissue and emphysema, and provides a model in which the pathogenic effects of TNF on the lung can be investigated.

Animals↗
PubMed2001

Collaboration of epithelial cells with organized mucosal lymphoid tissues.

Immune surveillance of mucosal surfaces requires the delivery of intact macromolecules and microorganisms across epithelial barriers to organized mucosal lymphoid tissues. Transport, processing and presentation of foreign antigens, as well as local induction and clonal expansion of antigen-specific effector lymphocytes, involves a close collaboration between organized lymphoid tissues and the specialized follicle-associated epithelium. M cells in the follicle-associated epithelium transport foreign macromolecules and microorganisms to antigen-presenting cells within and under the epithelial barrier. Determination of the earliest cellular interactions that occur in and under the follicle-associated epithelium could greatly facilitate the design of effective mucosal vaccines in the future.

Animals↗
PubMed2003

Localization of lymphocyte apoptosis in murine lymphoid tissues after stimulation of natural killer T cells with alpha-galactosylceramide.

Alpha-galactosylceramide (alpha-GalCer) has been reported to induce activation-induced cell death (AICD) in natural killer T (NKT) cells. We undertook this study to demonstrate the distribution of AICD of NKT cells in the lymphoid tissues and differences in frequency between the central and peripheral lymphoid tissues, histologically and quantitatively analyzing the apoptotic figure in the murine spleen, lymph node, and thymus after alpha-GalCer treatment. Lymphocyte apoptosis was identified as a cluster of nuclei with chromatin condensation in hematoxylin-eosin-stained sections, and was confirmed by TUNEL staining, double staining for TUNEL and CD4, and electron microscopy. In the spleen, it appeared at 12 h after alpha-GalCer administration, increased in number, reaching a peak at 24 h, and then falling to a normal level at 72 h. It was preferentially found in the white pulp, especially in the periarterial lymphoid sheath, but was sparse in the red pulp. Alpha-GalCer-induced lymphocyte apoptosis was seen in tumor-necrosis factor (TNF)-deficient mice as well, but was not in lpr/lpr (Fas-deficient) or gld/gld (Fas ligand-deficient) mice. As for the tissue distribution, lymphocyte apoptosis was frequently seen in the paracortex of the lymph node, whereas it was rare in the thymus. These data indicate that alpha-GalCer-induced AICD of NKT cells takes place in the T-cell area of peripheral lymphoid tissues (i.e., the spleen and lymph node) through the Fas/Fas ligand, but not the TNF pathway.

Animals↗
PubMed2001

Mucosa-associated lymphoid tissue in middle ear and eustachian tube.

The presence of mucosa-associated lymphoid tissue (MALT) was investigated histopathologically in every 20th section from 99 vertically cut, celloidin-embedded temporal bone-eustachian tube (ET) specimens. Among specimens from infants and children between 1 month and 7 years of age, MALT was found in 22 of 44 (50%). However, in 26 adults over 18 years of age, MALT was found in only 2 specimens (7.7%), a significantly lower incidence than that in infants and children. Moreover, MALT did not appear in any of the 21 neonates under the age of 1 month. All 99 specimens were classified into 2 groups: 41 specimens with otitis media (OM) and 58 specimens without OM. The presence of MALT was significantly higher in specimens with OM (43.9%) than in specimens without OM (13.8%). Mucosa-associated lymphoid tissue was found in the ET, middle ear, and mastoid process in 18 specimens (43.9%). 5 specimens (12.2%), and 1 specimen (2.4%) with OM, respectively, and in 8 (13.8%), 0, and 0 specimens without OM. In regard to the distribution of MALT, it occurred more frequently in the pharyngeal half of the cartilaginous portion of the ET than in the rest of the ET, middle ear, and mastoid; the presence was significantly greater in the inferior half of the cartilaginous portion of the ET than in the superior half. Inflammatory cell infiltration in the cartilaginous and bony portions of the ET was significantly greater in specimens with OM than in specimens without OM with no MALT. However, even in some specimens without OM, inflammatory cells were found in the ET, particularly in the pharyngeal half of the cartilaginous portion of the ET. These findings suggest that MALT has a close relationship to OM and that it may be a local response to repeated infection.

Adolescent↗