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At least 19 recordsLinked to original sources
PubMed1995

Intercellular and lymphatic pathways of the canine palatine tonsils.

The palatine tonsils play a key role in initiating immune responses against antigenic material entering the mouth and their lymphatic pathways are important in disseminating immunological information to the lymph nodes and other mucosal surfaces. Scanning and transmission electron microscopy and Mercox casts were used to examine the intercellular and lymphatic pathways of the palatine tonsil in dogs. Intercellular fluid within the intraepithelial passageways of the reticular epithelium flows through pores in the basement membrane and intermingles with that of the subepithelial intercellular spaces. From there, tissue fluid enters initial lymphatics which form a plexus surrounding each follicle. No lymphatic vessels are seen entering or leaving the follicles but intercellular pathways of the follicles are continuous with those of the adjacent initial lymphatics. These pathways appear to provide the only route for lymphocytes leaving the follicles and directly entering the lymphatic pathway. Lymph then flows into sinuses adjacent to, and incompletely surrounding, the base of follicles; or it may enter a network of sinuses between and beneath the lymphoid follicles which convey lymph throughout the parafollicular tissue. Lymphoid cells enter the parafollicular sinuses which may be a major entry site of lymphocytes emigrating from the lymphoid parenchyma. Some lymph may bypass these sinuses by entering septal lymphatic vessels oriented perpendicular to the central connective tissue lamina of the palatine tonsil. All lymph is collected into basal lymphatic vessels where valves prevent retrograde flow. Basal vessels course within the central lamina and converge to form efferent lymphatic vessels which emerge at the caudal region of the palatine tonsil and convey lymph to the medial retropharyngeal lymph node.

Animals↗
PubMed2005

Histology, immunohistochemistry and ultrastructure of the equine palatine tonsil.

The palatine tonsils of five young horses formed 10-12 cm elongated follicular structures extending from the root of the tongue on either side to the base of the epiglottis and lateral to the glossoepiglottic fold. The stratified squamous non-keratinized epithelium of the outer surface was modified into crypts as reticular epithelium by heavy infiltration of lymphoid cells from underlying lymphoid follicles. In places, lymphoid tissue reaching almost to the surface and with only one to two cell layers intact was identified as the lymphoepithelium. Langerhans cells with Birbeck granules were interspersed between epithelial cells. Lymphoid tissue organized in lymphoid follicles constituted the parenchyma of the palatine tonsil. CD4-positive cells were more numerous and CD8-positive lymphocytes less numerous compared with their distribution in the lingual tonsil. B cells and macrophages were also more numerous than in the lingual tonsil and lectins showed a different pattern of attachment. M cells were not observed. High endothelial venules with well-developed vesiculo-vacuolar organelle had structural evidence of transendothelial and interendothelial migration of lymphocytes. Striated muscles as seen in the deeper lamina propria mucosae of the lingual tonsil were absent. The immunohistological and ultrastructural characteristics of the equine palatine tonsil are similar to those of humans but differ from those of the lingual tonsil and are consistent with a role as an effector and inductor immunological organ.

Animals↗
PubMed2005

Determination of in vivo protein synthesis in human palatine tonsil.

The palatine tonsils are constantly exposed to ingested or inhaled antigens which, in turn, lead to a permanent activation of tonsillar immune cells, even in a basic physiological state. The aim of the present study was to investigate if the immunological activation of the human palatine tonsil is reflected by a high metabolic activity, as determined by in vivo measurement of protein synthesis. The protein synthesis rate of the tonsil was also compared with that of the circulating T-lymphocytes, the total blood mononuclear cells and the whole population of blood leucocytes. Phenotypic characterization of immune-competent cells in tonsil tissue and blood was performed by flow cytometry. Pinch tonsil biopsies were taken after induction of anaesthesia in healthy adult patients (n=12) scheduled for ear surgery, uvulopalatopharyngoplasty or nose surgery. Protein synthesis was quantitatively determined during a 90-min period by a flooding-dose technique. The in vivo protein synthesis rate in the palatine tonsils was 22.8+/-5.7%/24 h (mean+/-S.D.), whereas protein synthesis in the circulating T-lymphocytes was 10.7+/-3.4%/24 h, in mononuclear cells was 10.8+/-2.8%/24 h and in leucocytes was 3.2+/-1.2%/24 h. CD3+ lymphocytes were the most abundant cell population in the tonsil. The in vivo protein synthesis rate in human tonsils was higher compared with the circulating immune cells. This high metabolic rate may reflect the permanent immunological activity present in human tonsils, although cell phenotypes and activity markers do not explain the differences.

Adult↗
PubMed1975

[Palatine tonsils and immunity. VI. Effect of thymosin and palatine tonsil extract on the immunologic reactivity of neonatally thymectomized and intact mice].

Experiments were conducted on Wistar rats, intact and neonatally thymectomized CBA mice; a study was made of the immunological activity of the extracts of the thymus and the palatine tonsils of calves obtained by the method of Goldstein et al (1966). The extract of the palatine tonsils obtained proved to contain a small amount of thymosin at whose expense an insignificant restoration of immunological reactivity occurs in its administration neonatally to thymectomized mice.

Animals↗
PubMed2000

Differential cytokeratin and glycoconjugate expression by the surface and crypt epithelia of human palatine tonsils.

Human palatine tonsils are clinically important due to their susceptibility to tonsillitis and association with other local and systemic diseases. Paradoxically, the tonsils function as antigen sampling sites of the mucosal immune system and, consequently, the tonsil epithelia perform both protective and antigen sampling roles. These epithelia are divided into stratified squamous epithelium overlying the tonsil surface and crypt epithelium lining the tonsil crypts, the latter of which includes reticular areas which are infiltrated by lymphocytes and are responsible for antigen sampling. In this study we characterised cytokeratin and glycoconjugate expression by healthy epithelia of human palatine tonsils. We identified pan-epithelial tonsil markers and also demonstrated that the surface and reticular crypt epithelia are differentiated by the expression of multiple cytokeratins. The latter finding supports the hypothesis that these epithelia undergo alternate differentiation pathways and possess different functional roles. In addition, we identified cell subpopulations in the tonsil epithelia which may represent distinct cell subtypes including specialised antigen sampling cells. These findings establish a basis for future studies to investigate histochemical changes in tonsil epithelia that are associated with or predispose to local and/or systemic disease.

Adolescent↗
PubMed1995

The epithelium of canine palatine tonsils.

The palatine tonsil is positioned to play a key role in protecting the body against ingested microorganisms. These microorganisms must traverse the tonsillar epithelium to initiate immune reactions, but no information is available from dogs on the structure of this epithelium. In this study, the morphology and ultrastructure of the epithelium of the palatine tonsil of dogs was examined using light and electron microscopy. The epithelium is of two types: reticular and non-reticular. Reticular epithelium, which is invaded by lymphoid cells, is located over the apices of nodules, separated indistinctly by islands of non-reticular squamous epithelium. The reticular epithelium contains M cells which are more abundant towards the periphery of lymphoid nodules. The apical membrane of the M cells forms folds from which microvilli extend into the lumen of the oropharynx. Abluminally, cytoplasmic processes enfold clusters of lymphocytes. Numerous desmosomes secure the marginal plasma membrane and lateral membranous interdigitations to adjacent epithelial cells, thereby maintaining the integrity of the tonsillar epithelium. Epithelial discontinuities, which are few, occupy similar positions to M cells and appear to contain migrating lymphocytes. A fenestrated basement membrane allows cell transport between the intraepithelial passageways of the reticular epithelium and the subepithelial lymphoid tissues.

Animals↗
PubMed1976

[Palatine tonsils and immunity. VIII. Soluble factors produced by lymphocytes of the palatine tonsils and other lymphoid formations in rabbits].

A comparison was made of the activity of solbule factors produced by thelymphocytes of the palatine tonsils, the appendix, the spleen and thelymph nodes of rabbits in stimulation with a specific antigen (complete antigen of streptococcus, group A) and PHA. The blastogenic factor produced by the lymphoid cells of the spleen and the lymph nodes was highly active. Lymphocytes of the palatine tonsils and of the appendix produced a factor withlow activity after PHA stimulation. A factor intensifying the transformation in the presence of a complete streptococcus antigen was produced by lymphocytes of the spleen and the lymph nodes of the immunized animals. The lymphocytes of the palatine tonsils and the appendix failed to produce this factor.

Animals↗
PubMed1975

[Palatine tonsils and immunity. III. T- and B-lymphocytes in the palatine tonsils of patients with chronic tonsillitis].

Both B- and T-cells are contained in the palatine tonsils of patients suffering from chronic tonsillitis. The former respond by blast-transformation to the in vitro stimulation by the streptococcus and staphylococcus antigens and the latter--to PHA, and produce soluble substances inducing blast-transformation reaction of lymphoid cells of the palatine tonsils under the effect of streptococcus and staphylococcus antigens.

Antigens, Bacterial↗
PubMed2002

Route of lymphocyte migration through the high endothelial venule (HEV) in human palatine tonsil.

Eleven palatine tonsils were collected from subjects who underwent tonsillectomy in Christian Medical College Hospital and the route of migration of lymphocytes through the high endothelial vessel was studied under EM. In the interendothelial route, migration of a lymphocyte through HEV wall began with the adhesion of a lymphocyte to the surface of endothelial cells by means of a short cytoplasmic projection in the vicinity of intercellular space. The projection extended into the cleft between adjacent endothelial cells. The lymphocyte migrated through HEV by diapedesis. After the lymphocyte had traversed the interendothelial space, it occupied the subendothelial space. In the transendothelial route, migration of a lymphocyte through HEV was initiated by adherence of the lymphocyte to the endothelial cell. The adherent lymphocyte compressed or invaginated into the cytoplasm of the endothelial cell, entered the endothelial cell, was completely enclosed within the endothelial cell cytoplasm, and emerged from the endothelial cell to occupy the subendothelial space. Evidence is presented from static transmission electron microscopic pictures for the migration of lymphocytes by both interendothelial and transendothelial routes through the high endothelial venule.

Adolescent↗
PubMed2005

Cytokines locally produced by lymphocytes removed from the hypertrophic nasopharyngeal and palatine tonsils.

OBJECTIVE: Human palatine tonsils and the nasopharyngheal tonsil are the largest components of the Waldeyer's ring. Subepithelial and intraepithelial lymphocytes of human adenoids and tonsils are responsible for the local and the systemic immune response. We studied the cytokine production by lymphoid cells isolated from 16 nasopharyngeal tonsils (adenoid) and 9 palatine tonsils surgically removed by from 25 children (aged from 4 to 15 years) suffering from tonsil hypertrophy. METHODS: We evaluated (by the cytometry method, using BD Bioscience kits, San Diego, CA) the concentration of IL-2, IL-4, IL-5, IL-10, TNF(alpha) and IFN(gamma) released from human peripheral blood mononuclear cells (MC) (activated or not activated by phytohaemagglutinin (PHA)) cultured in vitro during 72 h. The fluorescence-activated cell sorter (FACS) analysis was also performed and the percentage of mononuclear cells (unstimulated or activated by phorbol acetate during 24 h) stained with the monoclonal antibodies anti-CD3 containing the intracellular cytokines was calculated. RESULTS: The increased secretion of IL-2, IL-4, IL-5, TNF(alpha) and IFN(gamma) from PHA activated palatine origin immune cell cultures, as compared to adenoids, was revealed. The higher mobilization (Delta%) of CD3+ T-lymphocytes containing IL-12 in palatine cell cultures (798.5+/-276.29%), in comparison with to the adenoids (298.5+/-49.16%; p< or =0.05), was also noted. CONCLUSION: In palatine tonsils, as compared to adenoids, the cellular immune (Th1) response dominates over humoral immune (Th2) reaction.

Adenoidectomy↗
PubMed1975

[The palatine tonsils and immunity. Report VII. Soluble factors produced by the lymphocytes of the palatine tonsils in vitro].

A study was made of the production of a blastogenic factor and lymphotoxin in the cultures of lymphocytes of the palatine tonsils removed from patients with chronic tonsillitis; the activity of this blastogenic factor and lymphotoxin was studied in the test-cultures of autologous and allogenic lymphocytes and the transplantable HeLa cells. The antigens of the pathogenic streptococcus and staphylococcus induced production of the blastogenic factor and lymphotoxin; as to the antigens of saprophytic bacteria-they produced no such action. The antigen-specific blastogenic factor intensified the immune response to the homologous antigen, whereas the factor obtained in stimulation of lymphocytes with PHA-to all the microbial antigens under study.

Antigens↗
PubMed2004

Expression and function of tight junctions in the crypt epithelium of human palatine tonsils.

The human palatine tonsils have surface and crypt stratified epithelium and may be initiated via the epithelium to mount immune responses to various presenting antigens. Here we investigated the expression and function of tight junctions in the epithelium of human palatine tonsils from patients with tonsillar hypertrophy or recurrent tonsillitis. Occludin, ZO-1, JAM-1, and claudin-1, -3, -4, -7, -8, and -14 mRNAs were detected in tonsillar hypertrophy. Occludin and claudin-14 were expressed in the uppermost layer of the tonsil surface epithelium, whereas ZO-1, JAM-1, and claudin-1, -4, and -7 were found throughout the epithelium. In the crypt epithelium, claudin-4 was preferentially expressed in the upper layers. In freeze-fracture replicas, short fragments of continuous tight junction strands were observed but never formed networks. In the crypt epithelium of recurrent tonsillitis, the tracer was leaked from the surface regions where occludin and claudin-4 disappeared. Occludin, ZO-1, JAM-1, and claudin-1, -3, -4, and -14, but not claudin-7, mRNAs were decreased in recurrent tonsillitis compared with those of tonsillar hypertrophy. These studies suggest unique expression of tight junctions in human palatine tonsillar epithelium, and the crypt epithelium may possess an epithelial barrier different from that of the surface epithelium.

Adolescent↗