Lymphoid tissues of the ileum in young horses: distribution, structure, and epithelium

Lymphoid tissues in the ileum of young horses form raised plaques that are macroscopically visible from the mucosal surface. These are termed ileal lymphoid patches. These patches are variable in size, shape and position within the ileal wall, occasionally lying along the site of mesenteric attachment. Within lymphoid patches, follicles exist in three different morphological forms: follicle/dome structures, proprial follicles, and lymphoglandular complexes (LGCs). In follicle/dome structures, the majority of the follicle lies in the submucosa and merges with a dome in the lamina propria through a gap in the muscularis mucosae. In proprial follicles, the majority, or all, of the follicle is found in the lamina propria, and in LGCs, the follicles lie in the submucosa and communicate with the intestinal lumen via a central invagination of epithelium that extends vertically through a gap in the muscularis mucosae. Follicle-associated epithelium covers the follicle/dome structures and proprial follicles. It consists of enterocytes, cells morphologically resembling M cells, intraepithelial lymphocytes, goblet cells, and amine-precursor uptake and decarboxylation (APUD) cells. The epithelium of LGCs is mainly populated by immature enterocytes, intraepithelial lymphocytes and goblet cells. Cells with coarse, long microvilli are also present. Information regarding the presence of LGCs in the small intestine is scant, but LGCs have been well described in the large intestine of many species. Further investigation will be required to determine if factors exist that are common to both the ileum of the horse and the large intestine of other species to influence the development of LGCs at these specific sites.     

Splenic stromal cells mediate IL‐7 independent adult lymphoid tissue inducer cell survival

Lymphoid tissue inducer cells (LTi) play an important role in the development of lymphoid tissue in embryos. Adult CD4⁺CD3^? LTi‐like cells present a similar phenotype and gene expression to their embryonic counterpart and have important roles in CD4⁺ T‐cell memory and lymphoid tissue recovery following viral infection. However, adult LTi‐like cells are heterogeneous populations and the factors that regulate their survival and accumulation within secondary lymphoid organs remain unclear, in particular whether the T‐zone stroma is involved. Here we report the identification and characterization of a distinct subset of podoplanin⁺ murine splenic stromal cells that support adult LTi‐like cell survival. We have identified and isolated CD45^?podoplanin⁺ stromal cell populations which have a similar but distinct phenotype to T‐zone reticular cells in LN. CD45^?podoplanin⁺ fibroblast‐like cells mediate LTi‐like cell survival in vitro; surprisingly this was not dependent upon IL‐7 as revealed through blocking Ab experiments and studies using LTi‐like cells unable to respond to γ chain cytokines. Our findings show that adult LTi‐like cells require extrinsic signals from podoplanin⁺ splenic stromal cells to survive and suggest that IL‐7 is not necessary to mediate their survival in the adult spleen.     

Proteasome composition in immune cells implies special immune-cell-specific immunoproteasome function

Immunoproteasomes are a special class of proteasomes, which can be induced with IFN-γ in an inflammatory environment. In recent years, it became evident that certain immune cell types constitutively express high levels of immunoproteasomes. However, information regarding the basal expression of proteolytically active immunoproteasome subunits in different types of immune cells is still rare. Hence, we quantified standard proteasome subunits (β1c, β2c, β5c) and immunoproteasome subunits (LMP2, MECL-1, LMP7) in the major murine (CD4⁺ T cells, CD8⁺ T cells, CD19⁺ B cells, CD11c⁺ dendritic cells, CD49d⁺ natural killer cells, Ly-6G⁺ neutrophils) and human immune cell (CD4⁺ T cells, CD8⁺ T cells, CD19⁺ B cells, CD1c⁺CD141⁺ myeloid dendritic cells, CD56⁺ natural killer cells, granulocytes) subsets. The different human immune cell types were isolated from peripheral blood and the murine immune cell subsets from spleen. We found that proteasomes of most immune cell subsets mainly consist of immunoproteasome subunits. Our data will serve as a reference and guideline for immunoproteasome expression and imply a special role of immunoproteasomes in immune cells.     

The pericyte and stromal cell marker CD248 (endosialin) is required for efficient lymph node expansion

CD248 is a cell surface receptor that specifically identifies fibroblasts and pericytes during development and in association with cancer and inflammation. However, its function is poorly defined and its role in lymphoid organs not studied. Here, we used (4‐hydroxy‐3‐nitrophenyl)acetyl chicken γ‐globulin immunisation and mice lacking CD248 to study whether CD248 modulates popliteal LN (pLN) expansion and subsequent immune responses. We have found that CD248 is required for complete pLN expansion but not for co‐ordination of B and T cell compartmentalisation or antibody production following (4‐hydroxy‐3‐nitrophenyl)acetyl chicken γ‐globulin immunisation. In vitro, we show that CD248 expression in human MG63 stromal cells and mouse embryonic fibroblasts leads to a pro‐proliferative and pro‐migratory phenotype. This correlates with a proliferating CD248⁺ population observed in vivo during pLN expansion. Taken together, these data highlight a role for CD248 in secondary lymphoid organ remodelling during adaptive immune responses.     

Hepatocellular carcinoma with massive lymphoid infiltration: A regressing phenomenon?

Spontaneous regression of hepatocellular carcinoma (HCC) is extremely rare. Among the numerous proposed mechanisms of spontaneous regression for HCC, immunological factors, which have yet to be fully understood, may have the most important roles in this rare phenomenon. A regressing HCC with lymphoid stroma is reported. A hepatic mass was detected in a 57-year-old man by abdominal computed tomography during a follow-up health check. The resected tumor was 2.7×2.4 cm² in size, and was composed of two distinct nodules with a complete rim of fibrous tissue separating the tumor from the adjacent liver parenchyma. Microscopically, one nodule was replaced by a remarkable infiltration of inflammatory cells with insignificant amounts of vital tumor cells. The other nodule demonstrated a small portion of well- to moderately-differentiated hepatocellular carcinoma cells forming 2–3 thick trabeculae with massive inflammatory infiltrates. Infiltrating inflammatory cells were composed of T cells (CD4+>CD8+), macrophages, B cells, and other cells in order of prevalence. Epstein-Barr virus was not detected. After 60 months of follow-up, the patient is in good health without evidence of tumor recurrence.     

Comparative anatomy of mammalian conjunctival lymphoid tissue: a putative mucosal immune site

Organized mucosa-associated lymphoid tissue (O-MALT) is defined by mucosal lymphoid follicles with unique overlying lymphoepithelia, and classically appears in tissues with a simple columnar epithelium. Within follicle-associated epithelium, goblet cells are characteristically absent, replaced by ultrastructurally distinct antigen-absorptive cells, termed M cells (or microfold cells) for the appearance of their apical cell membranes. To determine if mammalian conjunctiva, with its stratified squamous epithelium, can be considered as a site of O-MALT, we compared the light and electron microscopic anatomy of conjunctiva from fourteen species of non-human adult mammals, and the conjunctiva of human adults harvested at autopsy. Lymphoid follicles in the conjunctiva were demonstrated in all mammals studied except for mice and rats. In those mammals with conjunctival lymphoid follicles, the follicle-associated conjunctival epithelium was notable for an absence of goblet cells. Transmission electron microscopy demonstrated an intimate association of lymphocytes with surface epithelial cells, but epithelial cell morphology was uniform overlying the follicle, and other ultrastructural features of M cells were absent. Therefore, conjunctival lymphoid follicle-associated stratified squamous epithelium demonstrates some but not all features of O-MALT lymphoepithelia. Further studies are necessary to determine what role conjunctival lymphoid tissue may play in mucosal immunity.     

Distribution of lymphoid tissue in the caecal mucosa of chickens

In order to clarify the fundamental structure of the host defence mechanism in chicken caeca, a detailed analysis of the distribution of lymphoid nodules (LNs) was carried out on longitudinal sections of both the mesenteric (side of the ileocaecal ligament) and the antimesenteric mucosa. An overwhelming majority of solitary or aggregated LNs were located in the mesenteric mucosa, although a few were also found in the antimesenteric mucosa. Of the total LNs, 45.7% were detected at the proximal 7.8% section in the caecal tonsil. LNs (21.4%) were also concentrated in the distal 22.0% section corresponding to the apex. A moderate concentration of LNs (13.1%) was found at the transitional 20.0% region between the base and body. Approximately 80.2% of total LNs were found at the above 3 regions in the mesenteric mucosa. In many cases, the frequency of LNs in the caecal tonsils was opposite to that at the apices. Aggregated LNs were mainly found in the caecal tonsils, transitional region and apex. Almost all aggregated LNs consisted of fundamental nodular units possessing M cells in their follicle associated epithelia. The aggregated LNs in the above 3 regions therefore could provide immunological surveillance against caecal luminal contents. In particular, the cooperative function between LNs of the caecal tonsil and apex might be highly important in maintaining the caecal microenvironment.     

Plasmacytoid dendritic cells are dispensable for noninfectious intestinal IgA responses in vivo

Intestinal DCs orchestrate gut immune homeostasis by dampening proinflammatory T‐cell responses and inducing anti‐inflammatory IgA responses. Although no specific DC subset has been strictly assigned so far to govern IgA response, some candidate subsets emerge. In particular, plasmacytoid DCs (pDCs), which notoriously promote anti‐viral immunity and T‐cell tolerance to innocuous antigens (Ags), contribute to IgA induction in response to intestinal viral infection and promote T‐cell‐independent IgA responses in vitro. Here, using two transgenic mouse models, we show that neither short‐term nor long‐term pDC depletion alters IgA class switch recombination in Peyer's patches and frequency of IgA plasma cells in intestinal mucosa at steady state, even in the absence of T‐cell help. In addition, pDCs are dispensable for induction of intestinal IgA plasma cells in response to oral immunization with T‐cell‐dependent or T‐cell‐independent Ags, and are not required for proliferation and IgA switch of Ag‐specific B cells in GALT. These results show that pDCs are dispensable for noninfectious IgA responses, and suggest that various DC subsets may play redundant roles in the control of intestinal IgA responses.     

Cellular origins of human polymeric and monomeric IgA: enumeration of single cells secreting polymeric IgA1 and IgA2 in peripheral blood, bone marrow, spleen, gingiva and synovial tissue

Using modified ELISA and spot-ELISA, which permit the parallel determination of heavy chain subclass and the presence of covalently linked J chain, we analysed IgA found in cell culture supernatants or secreted by individual cells from peripheral blood, spleen, bone marrow, gingiva and synovial tissue, with respect to its polymeric or monomeric IgA form (pIgA, mIgA) and IgA1 or IgA2 subclass. The ELISA for determination of J chain in tissue culture supernatants was specific and highly sensitive (detection limit in pg). The results demonstrated that IgA1-producing cells predominated in the tissues examined, and that J chain could be detected in association with the majority of IgA1 and IgA2 secreted by individual cells. With respect to the frequency of cells secreting polymeric, J chain-containing IgA, only 20-30% of cells from the bone marrow were engaged in the synthesis of PIgA. In other tissues the frequency of cells secreting pIgA1 and pIgA2 was considerably higher. Peripheral blood mononuclear cells secreting pIgA2 were easily inducible during stimulation with T cell-dependent pokeweed mitogen, whereas Epstein-Barr virus-transformed cells secreted preferentially mIgA1. When the frequencies of pIgA-, pIgA1- or pIgA2-secreting cells (determined by spot-ELISA technique) from different tissues were correlated with the proportion of pIgA to mIgA (and IgA subclasses) secreted in tissue culture supernatants, data obtained suggest that many individual IgA-producing cells could be engaged in simultaneous secretion of mIgA and pIgA.     

Gastrointestinal stromal tumors: a contemporary review

The literature on gastrointestinal stromal tumors (GISTs) has rapidly expanded and has demonstrated how scientific advancements in diagnosis can revolutionize the understanding of disease, while paving the way for effective treatment. While KIT (CD117) immunohistochemistry has established our definition of GISTs, molecular genetics continue to refine it. Elucidation of the aberrant receptor tyrosine kinase (RTK) model of GIST pathogenesis through mutations in c-kit and platelet-derived growth factor alpha PDGFR proto-oncogenes has been prerequisite to the use of imatinib mesylate (STI571, Gleevec; Novartis, Switzerland), a molecular inhibitor of several tyrosine kinases, in the treatment of GISTs. In addition to providing a means for effective treatment, clarification of the molecular pathology of GISTs may potentially offer a new classification of these tumors by correlating genotype with histological, immunohistochemical, and clinical phenotype. This article seeks to review current knowledge of GISTs, offering a practical guide to their diagnosis and describing current epidemiological, molecular biological, and therapeutic aspects.     

Profile of autoantibody to basement membrane zone proteins in patients with mucous membrane pemphigoid: long-term follow up and influence of therapy

Mucous membrane pemphigoid (MMP) is an autoimmune mucocutaneous blistering disease characterized by autoantibodies to components within the basement membrane zone. In this study, we report the titers of autoantibodies to antigens in the BMZ, in the sera of 13 patients, treated with intravenous immunoglobulin as monotherapy over a consecutive 18-month period. Using bovine gingiva lysate as substrate in an immunoblot assay, autoantibodies to human bullous pemphigoid antigens (BPAg1 and BPAg2), human beta4 integrin, and laminin 5 were measured. A statistically significant (P < 0.05) decline in the autoantibody titers to beta4-integrin was observed after 3.42 months of initiating the IVIg therapy. These titers were undetectable after 13 months of therapy. The titers of antibodies to BPAg1 and BPAg2 did not correlate with disease activity or response to therapy. Antibodies to laminins were not detected. In patients with MMP, autoantibody titers to beta4-integrin correlate with disease activity and response to therapy.     

A method for the isolation of human gastric mucous epithelial cells for primary cell culture: A comparison of biopsy vs surgical tissue

We have developed a method for the isolation and growth of normal human gastric mucous epithelial cells using biopsies or surgically resected tissues as the source of the cells. The attachment and growth of cells were dependent upon: (1) cell planting density, 50,000 cells/cm²; (2) extracellular matrix (fibronectin); and (3) and the use of a porous filter. In all experiments we found better cells attachment and growth of human gastric mucous cells isolated from surgical specimens compared with those gastric mucous cells isolated from gastric biopsies. The initial cell viability (as measured by Trypan-blue) was the same in both populations of gastric mucous epithelial cells isolated from either gastric biopsies or surgical specimens. After 4–5 days in culture one could detect various amounts of mucin in all the cells using either periodic acid Schiff (PAS) staining or a specific anti-mucin antibody. A similar pattern of much straining was also found in primary cultures of guinea pig gastric mucous epithelial cells. Immunohistochemical staining for chief cells (anti-pepsinogen) or parietal cells (anti-H⁺/K⁺ ATPasc) in the gastric mucous cuboidal-like epithelial cells with tight junctions, desmosomes,short microvilli, a filamentous terminal web, mucous granules, and basal lamina-like structure. We could not detect the presence of fibroblasts during the 7–9 days that the primary cells were in culture. This cell culture method will prove useful in the isolation of normal human gastric mucous epithelial cells for in vitro studies of gastric mucosal injury and repair.     

Dynamic changes in intrathymic ILC populations during murine neonatal development

Members of the innate lymphoid cell (ILC) family have been implicated in the development of thymic microenvironments and the recovery of this architecture after damage. However, a detailed characterization of this family in the thymus is lacking. To better understand the thymic ILC compartment, we have utilized multiple in vivo models including the fate mapping of inhibitor of DNA binding‐2 (Id2) expression and the use of Id2 reporter mice. Our data demonstrate that ILCs are more prominent immediately after birth, but were rapidly diluted as the T‐cell development program increased. As observed in the embryonic thymus, CCR6⁺NKp46^? lymphoid tissue inducer (LTi) cells were the main ILC3 population present, but numbers of these cells swiftly declined in the neonate and ILC3 were barely detectable in adult thymus. This loss of ILC3 means ILC2 are the dominant ILC population in the thymus. Thymic ILC2 were able to produce IL‐5 and IL‐13, were located within the medulla, and did not result from ILC3 plasticity. Furthermore, in WT mice, thymic ILC2 express little RANKL (receptor activator of nuclear factor kappa‐B ligand) arguing that functionally, these cells provide different signals to LTi cells in the thymus. Collectively, these data reveal a dynamic switch in the ILC populations of the thymus during neonatal development.     

EXPERIMENTAL GLOMERULAR TISSUE INJURY INDUCED BY IMMUNIZATION WITH CULTURED ENDOTHELIAL CELL PLASMA MEMBRANE

Damage to glomerular endothelial cells, which are the constituents of the size-dependent and charge-dependent glomerular barrier, may result in proteinuria. Brain endothelial cell plasma membrane possesses an Intrinsic potential antigenicity which is capable of injuring the blood-brain barrier and causing widespread demyelination in the brain. To examine the pathogenetic effect on the glomerulus of plasma membrane sensitization, we injected guinea pigs with a single dose of plasma membrane products derived from cultured endothelial cells from the brain and umbilical cord, and observed the resulting effects both clinically and by histological, immunofluorescence and ultra-structural examinations of renal tissues. The animals immunized with plasma membrane products showed clinically mild proteinuria. Proliferative changes in the mesangial matrix with mild mononuclear cell infiltration was observed in the glomeruli of all experimental animals. Immunofluorescence studies showed finely granular, peripheral capillary loop and mesangial staining for IgG and C₃. Electron microscopy revealed fine, electron-dense deposits in the subendothelial region. In addition, titers of anti-endothelial cell antibodies and circulating immune complexes were significantly high. It was suggested that antibody-mediated immune mechanisms might play a role in the pathogenesis of this glomerular tissue injury induced by immunization with cultured endothelial cell plasma membrane products. ACTA PATHOL JPN 38: 823∼839, 1988.     

Working formulation of the non-Hodgkin's lymphomas: a study of cell size and mitotic indices in cytologic subtypes

Cell size and mitotic indices were studied in 243 non-Hodgkin's lymphomas (NHL) diagnosed cytologically and classified according to the Working Formulation. Low-, intermediate-, and high-grade lymphomas constituted 14.8%, 18.9%, and 61.7% of the cases, respectively. Measurement of the diameter of 100 lymphoid cells in each case showed that in most of the low-grade malignant lymphomas, 50-80% of the cells were small (less than 10 microns). A majority of the cells (an average of 45-60%) in intermediate- and high-grade lymphomas were in the range of 11-15 microns. Only the intermediate-grade large noncleaved and high-grade immunoblastic lymphomas had a majority of their cells (greater than 50%) larger than 15 microns. The mitotic indices (number of mitotic figures per 500 lymphoid cells) showed a highly significant difference between low- (0.7 +/- 1.14), intermediate- (3.0 +/- 2.67), and high-grade (5.4 +/- 3.40) lymphomas using the Wilcoxon's signed rank test (P less than 0.0001). Nearly two-thirds of the cases in each grade were within specific ranges of mitotic indices, i.e., less than 1 for low-, 1-3 for intermediate-, and greater than 3 for high-grade lymphomas.     

Normal Uterine Cervix: Characterization of Isolated Lymphocyte Phenotypes and Immunoglobulin Secretion

PROBLEM : Isolation of viable cervical lymphocyte populations and characterization of their function in healthy tissue is necessary to understand immunity in the genital tract. METHODS : Normal, cervical tissue was digested using a multi-enzymatic digestion procedure. Lymphocytes were characterized using FACS analysis and ELISPOT analysis for immunoglobulin secreting cells. RESULTS : Following the digestion procedure, 0.16 × 10⁶ ± 0.8 cells/g of tissue with a viability of 90–98% were isolated from normal cervical tissue. FACS analysis determined that B lymphocytes were the predominant cell type in normal cervical tissue representing a significantly higher percentage than that found in peripheral blood (P=0.015). T lymphocytes and NK cells represented a significantly lower percentage than that found in peripheral blood (P=0.0001 and 0.026, respectively). The largest percentage of immunoglobulin secreting cells isolated were secreting IgG followed by IgA. A limited number of IgM secreting cells were detected. IgA2 secreting cells represented 34.46 ± 4.6% of the total number of IgA plasma cells. CONCLUSION : These studies represent the first analysis of viable mononuclear cells isolated from normal cervical tissue. The results form a baseline from which it will now be possible to compare changes that occur at the cervical squamocolumnar junction in response to infection or neoplasia.     

骨髓间充质干细胞在鸡蛋膜为支架材料上复合培养的实验研究

目的探讨鸡蛋膜作为组织工程支架材料同大鼠骨髓间充质干细胞（bone marrow mesenchymal stem cells．BMSCs）复合培养的可行性。方法利用材料试验机对鸡蛋膜进行力学性能评价；用浓度0．1mol／L HCl预制鸡蛋膜支架材料且复合Ⅰ型胶原后，采用梯度离心法分离大鼠骨髓间充质干细胞；将第2代的BMSCs同鸡蛋膜支架材料复合培养，连续培养7、14d后分别用扫描电镜观察。结果鸡蛋膜具有一定的力学强度；细胞同鸡蛋膜复合培养后容易贴附生长，7d后鸡蛋膜表面有大量的细胞生长，14d后细胞连接成片且鸡蛋膜网状孔隙中有大量的细胞生长。结论鸡蛋膜具有良好的力学特性，同时又具有空间网状结构，适合细胞生长、增殖，是作为组织工程的理想支架材料之一。     

Myeloid derived suppressor cells in tumor microenvironment: Interaction with innate lymphoid cells

Human myeloid-derived suppressor cells (MDSC) represent a stage of immature myeloid cells and two main subsets can be identified: monocytic and polymorphonuclear. MDSC contribute to the establishment of an immunosuppressive tumor microenvironment (TME). The presence and the activity of MDSC in patients with different tumors correlate with poor prognosis. As previously reported, MDSC promote tumor growth and use different mechanisms to suppress the immune cell-mediated anti-tumor activity. Immunosuppression mechanisms used by MDSC are broad and depend on their differentiation stage and on the pathological context. It is known that some effector cells of the immune system can play an important role in the control of tumor progression and metastatic spread. In particular, innate lymphoid cells (ILC) contribute to control tumor growth representing a potential, versatile and, immunotherapeutic tool. Despite promising results obtained by using new cellular immunotherapeutic approaches, a relevant proportion of patients do not benefit from these therapies. Novel strategies have been investigated to overcome the detrimental effect exerted by the immunosuppressive component of TME (i.e. MDSC). In this review, we summarized the characteristics and the interactions occurring between MDSC and ILC in different tumors discussing how a deeper knowledge on MDSC biology could represent an important target for tumor immunotherapy capable of decreasing immunosuppression and enhancing anti-tumor activity exerted by immune cells.