Presence Of High Endothelial Venules Research Articles

LTβR Agonism Promotes Anti-Tumor Immune Responses via Modulation of the Tumor Microenvironment.

The presence of high endothelial venules (HEV) and tertiary lymphoid structures (TLS) in solid tumors is correlated with favorable prognosis and better responses to immune-checkpoint blockade (ICB) in many cancer types. Elucidation of the molecular mechanisms underlying intratumoral HEV and TLS formation and their contribution to anti-tumor responses may facilitate development of improved treatment strategies. Lymphotoxin beta receptor (LTβR) signaling is a critical regulator of lymph node organogenesis and can cooperate with antiangiogenic and ICB treatment to augment tumor-associated HEV formation. Here, we demonstrated that LTβR signaling modulates the tumor microenvironment via multiple mechanisms to promote anti-tumor T cell responses. Systemic activation of the LTβR pathway via agonistic antibody treatment induced tumor-specific HEV formation, upregulated the expression of TLS-related chemokines, and enhanced dendritic cell (DC) and T cell infiltration and activation in syngeneic tumor models. In vitro studies confirmed direct effects of LTβR agonism on DC activation and maturation and associated DC-mediated T cell activation. Single agent LTβR agonist treatment inhibited syngeneic tumor growth in a CD8+ T cell- and HEV-dependent manner, and the LTβR agonist enhanced anti-tumor effects of anti-PD-1 and CAR T cell therapies. An in vivo tumor screen for TLS-inducing cytokines revealed that the combination of LTβR agonism and lymphotoxin alpha (LT⍺) expression promoted robust intratumoral TLS induction and enhanced tumor responses to anti-CTLA-4 treatment. Collectively, this study highlights crucial functions of LTβR signaling in modulating the tumor microenvironment and could inform future HEV/TLS-based strategies for cancer treatments.

Gene co-expression regulatory analysis associated with tertiary lymphoid structures and endometrial cancer progression

Abstract Endometrial cancer (EC) is the most common cancer diagnosis of the reproductive organs among women in the United States. Previous studies have shown the chemokine CXCL13 was correlated with forming B-cell and other immune cell aggregates in the presence of high endothelial venules (HEV). These ectopic lymphoid formations are referred to as tertiary lymphoid structures (TLS). Some studies have shown that TLS are associated with a reduced risk of recurrence and improved immune response in cancers, while others have described negative cancer outcomes associated with TLS. Few studies have focused on the role of TLS in EC and the pathways involved in tumorigenesis. In this project, we identify chemokine-mediated gene networks associated with TLS formation and EC pathogenicity. We obtained RNA-Seq EC samples (n=643), which included Type I Uterine Corpus Endometrial Cancer (UCEC, n=587) and Type II Uterine Carcinosarcoma (UCS, n= 56) from the Cancer Genome Atlas (TCGA). Hierarchically clustered genes were correlated, functionally annotated for mRNA, and evaluated using a weighted gene network co-expression analysis (WGCNA). Functional enrichment analysis, such as Gene Ontology (GO) and the database for annotation, visualization, and integrated discovery (DAVID), were used to identify and visualize biological functions associated with the hub genes overrepresented in significant modules. Modules associated with metastasis and survival are representative of novel and known pathways. The analysis reveals that CXCL13 may be involved in cell cycle progression and apoptosis pathways. This study provides novel insights into the biological pathways associated with TLS, EC tumorigenesis, and patient survival risks. Supported by Frederick National Laboratory for Cancer Research subcontract IDIQ NCI (75N91019D00024) and MSM/TU/UABCCC Partnership NCI (U54CA118638)

Light and Electron-Microscopic Studies on the Paraepiglottic Tonsil of the Buffalo (Bubalus bubalis)

The paraepiglottic tonsil present on either side of the base of the epiglottis constitutes a small portion of the mucosa-associated lymphoid tissue. The present study was conducted on the paraepiglottic tonsils of 12 adult buffaloes of the local mixed breed to explore its basic histomorphological, histochemical, and ultrastructural characteristics and to compare with other tonsils of the oral region to ascribe immunological function. The tonsil mucosa was lined by partly stratified squamous keratinised epithelium towards the outer surface and a stratified squamous non-keratinised epithelium towards the shallow crypts. The non-keratinised epithelium modified into reticular type due to infiltration of underlying lymphoid tissue was characterised by the predominance of the lymphoid cells, interrupting basement membrane and indistinct strata. The reticular epithelium at places presented a spongy appearance. The loose irregular connective tissue of propria-submucosa was mainly comprised of glandular and lymphoid tissue. The lymphoid tissue was mainly in the form of isolated lymphocytes, diffuse aggregations, and lymphoid follicles. The inter-follicular areas showed the presence of high endothelial venules. The sero-mucous type of glandular acini presented a strong reaction for glycogen, acidic mucosubstances, weakly sulfated mucosubstances, mucin, and the presence of more than 4% cysteine in their secretions. The tonsils under scanning electron microscopy presented an undulating appearance due to the presence of crest and folds. Higher magnification revealed squamous cells having various patterns and arrangements of microplicae. Small pits visualised on the mucosal surface represented openings of the glandular ducts. The cells towards the lumen of some glandular ducts appeared whorl-like where typical microplicae were absent. The transmission electron microscopy of different strata of different types of epithelia showed varying cell organelles, especially the mitochondria, endoplasmic reticulum, Golgi apparatus, and few filaments. The structural features of the tonsil were similar to those of other oral tonsils and suggested their immunological role, which might be of importance to local immunity.

Identification and characterisation of tertiary lymphoid organs in human type 1 diabetes

Aims/hypothesisWe and others previously reported the presence of tertiary lymphoid organs (TLOs) in the pancreas of NOD mice, where they play a role in the development of type 1 diabetes. Our aims here are to investigate whether TLOs are present in the pancreas of individuals with type 1 diabetes and to characterise their distinctive features, in comparison with TLOs present in NOD mouse pancreases, in order to interpret their functional significance.MethodsUsing immunofluorescence confocal microscopy, we examined the extracellular matrix (ECM) and cellular constituents of pancreatic TLOs from individuals with ongoing islet autoimmunity in three distinct clinical settings of type 1 diabetes: at risk of diabetes; at/after diagnosis; and in the transplanted pancreas with recurrent diabetes. Comparisons were made with TLOs from 14-week-old NOD mice, which contain islets exhibiting mild to heavy leucocyte infiltration. We determined the frequency of the TLOs in human type 1diabetes with insulitis and investigated the presence of TLOs in relation to age of onset, disease duration and disease severity.ResultsTLOs were identified in preclinical and clinical settings of human type 1 diabetes. The main characteristics of these TLOs, including the cellular and ECM composition of reticular fibres (RFs), the presence of high endothelial venules and immune cell subtypes detected, were similar to those observed for TLOs from NOD mouse pancreases. Among 21 donors with clinical type 1 diabetes who exhibited insulitis, 12 had TLOs and had developed disease at younger age compared with those lacking TLOs. Compartmentalised TLOs with distinct T cell and B cell zones were detected in donors with short disease duration. Overall, TLOs were mainly associated with insulin-containing islets and their frequency decreased with increasing severity of beta cell loss. Parallel studies in NOD mice further revealed some differences in so far as regulatory T cells were essentially absent from human pancreatic TLOs and CCL21 was not associated with RFs.Conclusions/interpretationWe demonstrate a novel feature of pancreas pathology in type 1 diabetes. TLOs represent a potential site of autoreactive effector T cell generation in islet autoimmunity and our data from mouse and human tissues suggest that they disappear once the destructive process has run its course. Thus, TLOs may be important for type 1 diabetes progression.Graphical abstract

High endothelial venules are present in pharyngeal and laryngeal carcinomas and they are associated with better prognosis

BackgroundTumors lymphocytic infiltration has prognostic and predictive value. However, the mechanisms involved in lymphocyte recruitment remain poorly characterized. High endothelial venules (HEV) are blood vessels specialized in lymphocyte recruitment, recently showing prognostic significance in some types of cancer. Their implications in laryngeal or pharyngeal cancer is largely unknown. Aim of the studyTo investigate the possible presence of HEVs in head and neck cancer. Material and MethodsOropharyngeal (n = 61), hypopharyngeal (n = 53) and laryngeal (n = 21) squamous cell carcinomas were immunohistochemically studied with the MECA-79 antibody, which specifically recognizes HEVs. Histological and clinical factors were correlated with HEVs’ presence. ResultsHEVs were present in 34% of tumors, showing significant correlations with oropharyngeal localization, higher lymphocytic response, lower tumor budding, lower T status, absence of distant metastases and better overall and progression-free survival. ConclusionHEVs represent an important prognostic factor in head and neck cancer.

Abstract A137: The innate/adaptive immune response triggered in response to local immunotherapy of orthotopically growing bladder cancer tumors

Abstract The mouse bladder 49 (MB49) syngeneic tumors respond to various immunotherapies, both stimulatory immunotherapies and check-point blockers; when tumors are cured it is often an antitumor memory response established (previous publications by our group and others). Herein we present data suggesting that bladders of orthotopic MB49 tumor-bearing mice hold a reservoir of lymphocytes surrounding the tumor, wherein they migrate rapidly upon immune adjuvant stimulation. The tumors appear to form an accessible immune microenvironment rich in vessels that mediate the homing of leukocytes to the tumor site. This is in contrast to MB49 tumors that grow subcutaneously and do not appear to provide the same rapid immune cell infiltration capacity. Herein we further examined the immune cell populations of tumors locally treated with CpG ODN 1668, a type B CpG and a strong immunostimulatory agent or dilution buffer, as a control. Interestingly, we identified markers of high-endothelial venules (HEVs) in the vessels present in tumors from both untreated and treated animals. Thus we conclude that HEVs develop naturally in the orthotopic MB49 model and we wished to explore whether manipulation of the tumor microenvironment (TME) can induce HEVs and how this stimuli affect the infiltration of immune cells. Immunohistochemical profiling revealed that CD11c+ dendritic cells, CCL21+ cells along with B and T lymphocytes are present in various ways in different zones of the tumor with HEVs and CD31+ vessels. A correlation with vessel density and the presence of HEVs was identified in untreated animals. In immune-stimulated tumors, this correlation was lost in the early phase post stimuli. We could also identify that CpG treated bladder displayed increased vascularization around the tumor 24 hours post treatment. Interestingly, it appeared as CCL21 expression intratumorally aligned with increased recruitment of CD11c+ DCs in the TME. Intratumorally it was a clear correlation between CCL21 expression with both CD11c+ and CD8+ cell infiltration. As CD11c+ dendritic cells migrate towards gradients of CCL21 via their CCR7 receptor, enabling antigen presentation, it is plausible that antigen-presentation takes place in the TME in relation to this finding. By these preliminary data we conclude that in the orthotopic MB49 tumor model, CCL21 appears to play a role in the induction of adaptive immune responses through the CCL21/CCR7 axis. The role of HEVs, or alternatively lymphatic vessels, for this recruitment is yet to be determined. Currently we are investigating multiplex analyses on bladder tumors, urine and blood from tumor-bearing animals to identify cytokines in the TME or systemically that are correlated the formation of an adaptive immune response. Our future goal is to examine what is the key to raise an effective immune response to the so called immune "hot" orthotopic MB49 tumor. Citation Format: Iliana Kyriaki, Sara M. Mangsbo. The innate/adaptive immune response triggered in response to local immunotherapy of orthotopically growing bladder cancer tumors [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A137.

Aggressive Angioimmunoblastic T Cell Lymphomas (AITL) with Soft Tissue Extranodal Mass Varied Histopathological Patterns with Peripheral Blood, Bone Marrow, and Splenic Involvement and Review of Literature.

Angioimmunoblastic T cell lymphoma (AITL) is a peripheral T cell non-Hodgkin lymphoma with an aggressive fatal course and it has varied clinical presentation with an uncommon presentation when they present as soft tissue masses or when there is spill in the peripheral blood or there are composite lymphomas that are rare presentations. Common presentations include lymphadenopathy, fever and systemic symptoms, hemolytic anemias, skin rashes, and rheumatoid arthritis. The classical histopathology is absence of follicles in lymph nodes with presence of high endothelial venules and the tumor cells of small to medium-sized lymphocytes with pale cytoplasm mixed with reactive T cells. On immunohistochemistry, the cells are positive for CD3, CD4, CD10, BCL2, and CXCL13. In this observational study, the clinicopathologic presentation and the immunohistochemical profile of five cases who initially presented with a soft tissue mass which is an extremely rare presentation of this rare type of non-Hodgkin lymphoma that was diagnosed at our center with peripheral blood and bone marrow involvement and the clinicopathologic presentation, immunohistochemical profile, and response to treatment on follow-up are correlated with the literature review. One case had a fulminant and aggressive course and was fatal within 2months of diagnosis. The rest of the four cases are on regular chemotherapy and follow-up. Our five cases had presented with soft tissue masses, two in the axillary regio,n two in the hand, and one in the scapular region with an extranodal presentation, and there was associated lymphadenopathy which developed subsequently with classic histomorphology and immunohistochemical findings. The age range was 46-54years and all five cases were males. Three cases were with anemia (hemoglobin range 6.5-8.0mg/dl) and all five cases were having peripheral blood plasmacytosis. Histopathology was classic with paracortical involvement with polymorphous population of cells with neoplastic lymphocytes of small and large sizes with numerous arborizing blood vessels which correspond to high endothelial venules. Microscopically, three architectural patterns; pattern I was seen in three cases (60%) and then pattern II and III in one case each (20% each). Immunohistochemistry revealed CD4+, CD8-, CXCL13+, CD10+, BCL6+, CD19, CD20, CD1a, Tdt, CD21, and CD23+ in follicular dendritic cells. AITL is a rare and aggressive non-Hodgkin lymphoma with varied clinical presentation with classic histomorphology with various patterns which may cause diagnostic dilemma and immunophenotypic findings, and prompt and early diagnosis is mandatory for institution of therapy.

A Unique Cellular and Molecular Microenvironment Is Present in Tertiary Lymphoid Organs of Patients with Spontaneous Prostate Cancer Regression.

Multiple solid cancers contain tertiary lymphoid organs (TLO). However, it is unclear whether they promote tumor rejection, facilitate tumor evasion, or simply whether they are a byproduct of chronic inflammation. We hypothesize that although chronic inflammation induces TLO formation, the tumor milieu can modulate TLO organization and functions in prostate cancer. Therefore, our study seeks to elucidate the cellular and molecular signatures in unique prostatectomy specimens from evanescent carcinoma patients to identify markers of cancer regression, which could be harnessed to modulate local immunosuppression or potentially enhance TLO function. We used multicolor immunofluorescence to stain prostate tissues, collected at different stages of cancer progression (prostatic intraepithelial neoplasia, intermediate and advanced cancer) or from patients with evanescent prostate carcinoma. Tissues were stained with antibodies specific for pro-inflammatory molecules (cyclooxygenase 2, CXCL10, IL17), tumor-infiltrating immune cells (mature DC-LAMP+ dendritic cells, CD3+ T cells, CD3+Foxp3+ regulatory T cells (Treg), T bet+ Th1 cells, granzyme B+ cytotoxic cells), and stromal cell populations (lymphatic vessels, tumor neovessels, high endothelial venules (HEV), stromal cells), which promote prostate tumor growth or are critical components of tumor-associated TLO. Generally, inflammatory cells are located at the margins of tumors. Unexpectedly, we found TLO within prostate tumors from patients at different stages of cancer and in unique samples from patients with spontaneous cancer remission. In evanescent prostate carcinomas, accumulation of Treg was compromised, while Tbet+ T cells and CD8 T cells were abundant in tumor-associated TLO. In addition, we found a global decrease in tumor neovascularization and the coverage by cells positive for cyclooxygenase 2 (COX2). Finally, consistent with tumor regression, prostate stem cell antigen was considerably reduced in TLO and tumor areas from evanescent carcinoma patients. Collectively, our results suggest that COX2 and Treg are attractive therapeutic targets that can be harnessed to enhance TLO-driven tumor immunity against prostate cancer. Specially, the presence of HEV and lymphatics indicate that TLO can be used as a platform for delivery of cell-based and/or COX2 blocking therapies to improve control of tumor growth in prostate cancer.

High endothelial venules associated with T cell subsets in the inflamed gut of newly diagnosed inflammatory bowel disease patients.

Naive and central memory T lymphocytes (TN and TCM ) can infiltrate the inflamed gut mucosa in inflammatory bowel disease (IBD) patients. Homing of these subsets to the gut might be explained by ectopic formation of tertiary lymphoid organs (TLOs), containing high endothelial venules (HEVs). We aimed to evaluate the presence of HEVs and TLOs in inflamed intestinal mucosa of newly diagnosed, untreated IBD patients in relation to the presence of TN and TCM lymphocytes. IBD patients (n = 39) and healthy controls (n = 8) were included prospectively. Biopsy samples of inflamed and normal intestine, respectively, were analysed by immunohistochemistry for lymphocytes (CD3/CD20), blood vessels (CD31) and peripheral lymph node addressin (PNAd) expression (MECA-79). TN and TCM lymphocyte subsets were identified by flow cytometric immunophenotyping. A higher number of HEVs was found in the inflamed colon of patients with ulcerative colitis [median 3·05 HEV/mm2 ; interquartile range (IQR) = 0-6·39] and ileum of Crohn's disease patients (1·40; 0-4·34) compared to healthy controls (both 0; P = 0·033). A high density of colonic HEVs (HEVhigh ) was associated with increased infiltration of TN and TCM in the inflamed gut (median 87%; IQR = 82-93% of T cell population), compared to HEVlow patients (58%; 38-81%; P = 0·003). The number of colonic follicles was higher in HEVhigh patients (median 0·54/mm2 ; IQR 0·28-0·84) compared to HEVlow patients (0·25/mm2 ; 0·08-0·45; P = 0·031) and controls (0·31/mm2 ; 0·23-0·45; P = 0·043). Increased homing of TN and TCM lymphocytes to inflamed gut tissue in IBD patients might be facilitated by ectopic formation of extrafollicular HEVs and TLOs in a subgroup of patients.

The development of tertiary lymphoid organs in the central nervous system facilitates determinant spreading of the MP4-specific T cell response (P4164)

Abstract Accumulating evidence indicates that B cells aggregate into tertiary lymphoid organs (TLOs) in the central nervous system (CNS) in the human autoimmune disease multiple sclerosis (MS). In patients with secondary-progressive MS the presence of ectopic B cell aggregates has been linked to more severe clinical disease and cortical pathology. Here we demonstrate the formation of TLOs in myelin basic protein (MBP)-proteolipid protein (PLP) fusion protein MP4-induced experimental autoimmune encephalomyelitis (EAE) of C57BL/6 mice. TLOs were a characteristic feature of the chronic disease stage and most prevalent in the cerebellum, while also being present in the spinal cord and cerebrum, but absent in the brain stem. TLOs were characterized by B and T cell compartmentalization, the presence of high endothelial venules and germinal center formation. An association with TH17, but not TH1 cells was evident. In addition, results obtained from ELISPOT analysis of the antigen-specific T cell response suggest that TLOs facilitate determinant spreading of the MP4-specific T cell response to myelin oligodendrocyte glycoprotein (MOG). Our data add novel insights into the contribution of TLOs to disease progression in the context of CNS autoimmunity. We suggest that the blockade of TLO development is a therapeutic strategy that needs to be carefully considered in future studies.

T-Cell Trafficking Facilitated by High Endothelial Venules Is Required for Tumor Control after Regulatory T-Cell Depletion

The evolution of immune blockades in tumors limits successful antitumor immunity, but the mechanisms underlying this process are not fully understood. Depletion of regulatory T cells (Treg), a T-cell subset that dampens excessive inflammatory and autoreactive responses, can allow activation of tumor-specific T cells. However, cancer immunotherapy studies have shown that a persistent failure of activated lymphocytes to infiltrate tumors remains a fundamental problem. In evaluating this issue, we found that despite an increase in T-cell activation and proliferation following Treg depletion, there was no significant association with tumor growth rate. In contrast, there was a highly significant association between low tumor growth rate and the extent of T-cell infiltration. Further analyses revealed a total concordance between low tumor growth rate, high T-cell infiltration, and the presence of high endothelial venules (HEV). HEV are blood vessels normally found in secondary lymphoid tissue where they are specialized for lymphocyte recruitment. Thus, our findings suggest that Treg depletion may promote HEV neogenesis, facilitating increased lymphocyte infiltration and destruction of the tumor tissue. These findings are important as they point to a hitherto unidentified role of Tregs, the manipulation of which may refine strategies for more effective cancer immunotherapy.

Human Conjunctiva Contains High Endothelial Venules That Express Lymphocyte Homing Receptors

Lymphocyte trafficking into tissues has been shown to occur across vessels with specialized endothelial cells called high endothelial venules. High endothelial venules naturally occur in lymph nodes and mucosal lymphoid tissues. The presence of high endothelial venules in the conjunctiva has not been demonstrated previously and the purpose of this study was to determine whether there is such a specialized vasculature to facilitate lymphocyte trafficking in conjunctiva associated lymphoid tissue.Samples of conjunctiva from four different individuals were analysed morphometrically for the presence of high endothelial venules by light and electron microscopy, and by immunohistochemistry using antibodies specific for high endothelial venules and for two adhesion molecules namely, Vascular Adhesion Protein-1 and Mucosal Addressin Cell Adhesion Molecule-1, expressed on high endothelial venules found in other tissues.Blood vessels with anatomical features of high endothelial venules were demonstrated in relation to conjunctival follicles and in the lamina propria. Immunohistochemical studies showed positive staining of vessels with anti-high endothelial venule antibodies, and with antibody against Vascular Adhesion Protein-1 but not with antibody against Mucosal Addressin Cell Adhesion Molecule-1.This study reveals that some of the blood vessels associated with conjunctival follicles and lamina propria have features of high endothelial venules. These vessels may play a significant role in lymphocyte homing to the conjunctiva and Vascular Adhesion Protein-1 (but not Mucosal Addressin Cell Adhesion Molecule-1) is one of the vascular addressin/adhesion molecules.

High endothelial venules. Kinetics of the expression in IRBP-induced experimental autoimmune uveitis

Experimental autoimmune uveitis (EAU) is a T-cell-mediated disease expressing high endothelial venules (HEVs) in the retina. HEVs could be responsible for the absorption of activated T-cells. The purpose of this study was to investigate the kinetics of HEV expression in the murine IRBP (interphotoreceptor retinoid binding protein) induced EAU. B10. A mice were immunized subcutaneously with IRBP. The eyes were analysed on days 10, 18, 24 and 28 (n = 5 for each time point). While HEVs were identified with the mAb MECA 325, the control mAb MECA 20 stained all endothelial cells. HEVs were detectable in the intact retina from day 10. Presence of HEVs peaked on day 18 and decreased by day 28, when maximal inflammation and retinal destruction was detectable. HEV expression could play a central role in the onset of EAU, allowing homing and migration of inflammatory cells into the eye.

High Endothelial Venules in Extranodal Lymphomas with Emphasis on Their Prognostic Significance

In the present study, the frequency of occurrence of high endothelial venules (HEVs) in extranodal lymphomas at various sites was examined, and its prognostic implication subsequently estimated. The presence of HEVs was tested for by an immunohistochemical method using the monoclonal antibody, HECA-452, known to be specific for HEVs. The number of cases at each extranodal site were 13 in the thyroid, three in the salivary gland, 15 in the gastrointestinal(GI) tract, 20 in the brain, six in the lung, 12 in the pleura, nine in the testis, 10 in the bone, 19 in the skin and seven in the breast. Histologically, 26 of the 114 cases (23%) were of high grade malignancy according to the Working Formulation. Immunohistochemistry revealed 89 cases (78%) to be of B-cell type, eight (7%) T-cell type and 17 (15%) others. HEVs were observed frequently among the cases of lymphoma of the salivary gland (100%), thyroid (77%), GI tract (53%), lung (50%) and breast (43%). Evident were a preponderance of female patients (P less than 0.02) and those with histologically favorable lymphoma types (P less than 0.001), and a more favorable prognosis (P less than 0.001) for cases with HEVs over those without. There were no significant differences in age and immunologic type distributions between cases with and without HEVs. The findings suggest that the presence of HEVs could be used as an indicator for a favorable prognosis in cases of extranodal lymphoma.

Tannic-acid staining material on high endothelial venules and lymphocytes in skin and peripheral lymph nodes in Staphylococcus aureus-associated erythroderma

The recognition and binding of glycoprotein receptors on lymphocytes to specific antigens present on high endothelial venules (HEV) precedes the egress of lymphocytes from the blood stream into the tissues. In this paper, we report the presence of HEVs with tannic-acid staining material (TASM+ HEVs) in Staphylococcus aureus-associated erythroderma, which allow the migration of CD8+ lymphocytes from the bloodstream into the epidermis. TASM positivity is also expressed on lymphocytes within the regional lymph nodes, and by intravascular lymphocytes prior to leaving the TASM+ HEV. It is proposed that TASM positivity may represent a molecule, which may function in binding lymphocytes to HEVs prior to egress from the HEV. (TASM is lost from lymphocytes after leaving the HEVs). The expression of TASM positivity may form an essential part of the CD8+ lymphocyte-HEV recognition system, and may be the means whereby CD8+ lymphocytes generated in the regional lymph nodes by various mitogens (in this case by staphylococcal mitogens) may 'home' to specific sites within the epidermis. TASM positivity on both the HEVs and lymphocytes may serve as a convenient marker of such a system.

The localization of macrophage subsets and dendritic cells in the gastrointestinal tract of the mouse with special reference to the presence of high endothelial venules

This study concerns the distribution of macrophages and dendritic cells (DC) in the gastrointestinal tract of the mouse. Heterogeneity of macrophage population was found by using the MOMA-1, MOMA-2, ERTR-9, Mac-1 and F4/80 monoclonal antibodies. MOMA-1, ERTR-9, Mac-1 and F4/80+ cells were detected mostly at the villous cores in the lamina propria of the villi, whereas MOMA-2+ cells were primarily found around the crypts at the base of the villi. These MOMA-2+ cells revealed a granular appearance throughout the cytoplasm and displayed a strong acid phosphatase (AcPh) activity. Few MOMA-2+ cells were seen at the top of the villi in the epithelium. Although MOMA-1 and ERTR-9+ cells have similar morphology and the same distribution patterns in the lamina propria, they are likely different populations, because in Peyer's patches (PP), MOMA-1+ cells were present, whereas ERTR-9+ cells could not be detected. Both populations displayed AcPh activity. Strongly stained Mac-1+ cells were abundantly seen in the lamina propria of the small intestine. F4/80+ cells were rare. NLDC-145+ cells with AcPh activity and weak Ia staining were also found. In the PP-associated villi and in the T-dependent area of PP, dendritic NLDC-145+ cells, which were strongly Ia positive, were detected. MIDC-8+ cells were found only in the T-dependent area. Few NLDC-145+ cells (dendritic cells) were found in the upper part of the oesophagus. These cells were also stained with the MIDC-8 antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocytes in the Lung: Should We Continue to Exalt Only BALT?

Few lymphocytes are found in the normal human lung. Those cells that are present are found in four locations: (1) the pulmonary and hilar lymph nodes; (2) lymphoreticular aggregates in the parenchymal interstitium; (3) in the airway mucosa; and (4) within the airways (1). In certain disease states, such as influenza virus infection, sarcoidosis, or transplantation rejection, the number of lymphocytes in airways and lung increases dramatically. This influx of cells may be partly mediated by clonal expansion of resident lymphocytes, but it may also result from recruitment of lymphocytes from the blood. The mode of entry oflymphocytes into the lung has not been established, but it is thought to be similar to other tissues, involving the adherence of blood lymphocytes to specialized endothelium known as high endothelial venules (HEV). HEV express defined adhesion molecules known as addressins which bind to complementary adhesion molecules on lymphocytes. HEV are found only in defined sites in organized lymphoid tissue such as the lymph nodes and Peyer's patches in the gut (reviewed in reference 2). Bronchus-associated lymphoid tissue, or BALT, is a term coined by Bienenstock and associates (reviewed in references 3 and 4) to describe organized lymphoid tissue found in the submucosal region of large airways, which appeared analogous to that seen in other mucosal tissues, especially Peyer's patches (gut-associated lymphoid tissue, GALT). Like GALT, BALT contains HEV and is the site of homing for IgA-committed B cells, though both T and B cells have been found in BALT. In addition to containing a meshwork of lymphocytes and antigen-presenting cells, BALT is covered with a specialized epithelium which facilitates transport and processing of antigen from the airway lumen. Because of the presence of HEV, and because of studies showing translocation of blood lymphocytes into BALT (3), BALT is assumed to be important in the immune response to inhaled antigens and has been proposed to be the normal pathway for lymphocyte movement from blood to lung. BALThas been found in many mammalian species. BALT has been observed in normal human airways (1) and has been reported to be hyperplastic in patients with chronic respira-

High endothelial venules in involved and uninvolved psoriatic skin: recognition by homing receptors on cytotoxic T lymphocytes

We report the presence of tannic acid staining material in the intercellular spaces between adjacent endothelial cells of the high endothelial venules (HEVs) in psoriatic skin, which appears to be recognized by T8 (cytotoxic/suppressor) lymphocytes, as the presence of HEVs was found to be related to the presence of T8 lymphocytes in the epidermis. As HEVs with similar tannic acid staining material were also observed in peripheral lymph nodes, we suggest that this material may serve as a marker for HEVs recognized by the T8 lymphocyte subset. T8 + lymphocytes were found in the epidermis at 5 min and I h after tape-stripping of uninvolved skin of psoriatic patients with active disease, but not until 24 h in a psoriatic patient in remission. The prior existence of HEVs in uninvolved psoriatic skin could account for the rapid egress of T8 lymphocytes from the vasculature to the epidermis in response to trauma.

Architecture of associations of minor salivary gland ducts and lymphoid follicles in Macaca fascicularis. An ultrastructural study.

Previous light-microscopic and ultra-immunohistochemical tracer studies revealed the existence of an independent local immune response of the simian oral mucosa. This local response is attributed to the presence of minor salivary gland (MSG) duct-related lymphoid tissue. Semithin sections from a total of 263 Epon-embedded tissue blocks from the labial and buccal mucosae of seven monkeys, Macaca fascicularis, were analysed light-microscopically, and 10 suitable MSG duct/follicle assemblies were investigated ultrastructurally. These duct/follicle assemblies include follicular and parafollicular compartments with distinct fine-structural elements. The follicular area or germinal centre contains numerous small and large lymphoid cells, mitotic figures, plasmablasts, macrophages, and cells resembling the follicular dendritic cells with distinct desmosomal junctions. The parafollicular area, which includes the heavily infiltrated duct wall, contains numerous small lymphocytes, T-lymphoblasts, plasma cells and reticular cells resembling fibroblasts. A distinct feature of this compartment is the presence of high endothelial venules (HEV). The presence of HEV and numerous blast cells, resembling blast-forming T-lymphocytes activated in vitro, in a specific area of the duct/follicle assembly strongly suggests that this area is structurally and physiologically identical to the thymus-dependent area of other lymphoid tissues. In other words, the duct/follicle assemblies of simian MSG contain the various specific fine-structural elements that are suitable for antigen recognition and processing. These elements are distributed in discrete compartments comparable to the B- and T-cell areas of "classical" lymphoid tissue.