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To evaluate interrelationships among epithelial cells, and between morphology and function in the microenvironment, we studied the ultrastructural morphology of epithelial cells in sections of human thymus from donors aged 2 months to 31 years. Six types of epithelial cells were observed: "subcapsular-perivascular" (type 1); "pale" (type 2); "intermediate" (type 3); "dark" (type 4); "undifferentiated" (type 5); and "large-medullary" (type 6). Cells of types 2, 3 and 4 were found throughout the organ. The type-2 to -4 epithelial cells may represent various stages in a differentiation process. In this, type-2 cells are very active and type-4 cells are possibly degenerating elements. Type-4 cells can also contribute to Hassall's corpuscles. Type-5 cells were located mainly in the cortico-medullary region and showed the morphological characteristics of undifferentiated elements. Type-6 cells were located exclusively in the medulla and displayed characteristics of cellular activity. Small Hassall's corpuscles consisted of type-6 epithelial cells; in larger corpuscles many nuclei of type-6 cells were found. Cells of types 2 and 6 contained tubular structures (diameter approximately 20 nm). Concerning the function of thymus epithelial cells, the features associated with protein synthesis observed in cellular types 2 and 6 make them likely candidates for humoral factor-producing and/or secreting elements. In addition, type-2 and -3 cells in the cortex appear to contribute to a special pattern of epithelium-lymphocyte interaction ("thymic nurse cells"), as demonstrated by the intracytoplasmic location of lymphocytes in the epithelial cells. The various steps in intrathymic T-cell maturation occur at locations in a microenvironment composed of morphologically distinct epithelial cells.

The tranquil ambience of the former monastery ‘Rolduc’, in the deep south of the Netherlands, provided an ideal venue for nearly 100 thymologists to gather together for three days to discuss recent research. All participants were actively working on the thymus, but came from such a wide range of different areas — histology, cell biology, immunology, molecular biology, clinical medicine, toxicology and pathology — that are refreshingly broad view, crossing both species and discipline carriers, was achieved. This was enhanced by the friendly and informal atmosphere that encouraged open discussions and exhange of ideas.

Three cases of primary malignant lymphoma of the maxilla are reported. The primary intraosseous origin of these tumors was demonstrated by x-ray examination and surgical exploration. The initial interpretation as odontogenic infection led to a delay in starting therapy of 9 months in one case. Biopsies of two cases were initially interpreted as sarcoma because of a dense reactive fibrosis between the tumor cells. Subsequently, hemimaxillectomy was performed in one case. Histologically and ultrastructurally the tumor cells showed marked nuclear abnormalities with cleavage, folding, and lobulation. Immune histochemical studies of two cases showed a monoclonal immunoglobulin expression, IgG-K; T-lymphocyte-associated antigens were not detected on the tumor cells. The findings indicate the existence of a primary B-cell malignant lymphoma of bone with multilobated nuclei. The lymphoid nature may be masked by a dense proliferation of connective tissue. The relation of these tumors to the classifications for malignant lymphoma of lymph node is discussed.

Rabbits were hyperimmunized with Micrococcus Pysodeiticus, leading to homogeneous antibody responses. Peripheral blood lymphocytes were taken from the rabbits before and monthly (during 3 months) after the start of the immunization. The cells were stored frozen. Lymphocytes were tested with anti‐idiotypic conjugates for the presence of surface idiotypic structures. The nature of the idiotype‐positive cells was determined with respect to the presence of IgM or T‐cell antigenic determinants on their surface. A sharp rise and fall in the percentage of idiotypic lymphocytes was found, ranging between 1/40,000 and 1/1,000. Initially almost all idiotypic lymphocytes were IgM‐positive. In the blood taken 2 months after the start of the immunization 20% of the idiotypic cells belonged to the T‐cell population and 10% were negative for both IgM and T‐cell antigenic determinants. Copyright © 1980, Wiley Blackwell. All rights reserved

To evaluate whether the expression of T-cell receptor (TCR) V beta families in eight cases of malignant T-cell lymphomas took place in a preferential manner, we analyzed four cases of mycosis fungoides (MF), the most common form of primary cutaneous T-cell non-Hodgkin's lymphomas (NHL), and four cases of primary nodal T-cell NHL. The usage of V beta families in T-cell populations was investigated on mRNA that was transcribed to cDNA using a C beta primer and reverse transcriptase. Subsequently, the specific usage of the families was analyzed by polymerase chain reaction (PCR) using combinations of the selected C beta-oligonucleotide primer and one of the family-specific V beta primers. Peripheral blood lymphocytes from four healthy volunteers and 1 "reactive" lymph node served as a control and expressed all 20 V beta families tested for. In T-cell lines, with restricted V beta expression, and in three patients with advanced MF, only one or two V beta families were expressed at the mRNA level. In an early MF lesion this monoclonal expression was absent: several V beta families were expressed with a weak intensity. This may indicate either a polyclonal origin of MF, or that too few monoclonal neoplastic cells were present in the tissue specimen. In the four nodal T-cell NHL, only one family could be clearly distinguished, whereas some of the other V beta families showed only a weak expression. These latter families represent the reactive T-cell component in the nodal T-cell NHL. Both in nodal T-cell NHL and in MF there was no preferential expression of a particular V beta family. There was a good correlation between PCR data and the expression of V beta-family protein products observed by immunohistochemistry on tissue sections of the T-cell lymphomas. All T-cell lines, three cases of MF, and three cases of nodal T-cell NHL showed a rearrangement of the TCR beta chain on DNA level.

Culture of small thymic expiants yields fragments depleted of lymphocytes which consist of epithelial-like cells and connective tissue components (1). Such cultured thymic fragments (CTF) induce the development of thymus-dependent immunity when transplanted under the kidney capsule of congenitally athymic animals (1–3). After implantation, CTF become populated with lymphoid elements and regain their original thymus architecture. We (3) and others (2,4) have documented that both syngeneic and allogeneic CTF are effective in this respect. This phenomenon enables to study the impact of the MHC haplotype of CTF on T-cell immunity generated after implantation, especially aspects as allo-antigen recognition repertoire, self-MHC restriction specificity, and self-MHC tolerance. In this respect, the role of distinct stromal components in the thymus is subject of continuing discussion, especially the discrimination between the epithelial reticulum and medullary dendritic cells (5–9).

Immunohistochemical and submicroscopic analyses of human cholesteatoma matrices reveal the presence of Langerhans' cells and T lymphocytes. Through cell-to-cell interaction, Langerhans' cells probably play a key role in skin-related disorders, including cholesteatomas. They originate from a mobile cell population of monocyte origin and migrate into and out of the body's lining. Their custodial function is always carried out in close relation with T lymphocytes. Various monoclonal antibodies directed against Langerhans' cell and T lymphocyte membrane receptors reveal the presence of these cell populations in cholesteatoma matrices but not in the tympanic membrane. Langerhans' cell and T cell traffic through cholesteatomas are discussed in relation to the pathogenesis, natural course, and recurrence rate of cholesteatomas. Through immunopathologic evaluation the clinical aggressiveness of a cholesteatoma will probably become predictable. Medical manipulation of Langerhans' cell and T cell functions- as an adjuvant to surgery - may have consequences for the future handling of cholesteatomas.

Alcoholic liver disease (ALD) is characterized by elevated serum IgA concentrations, the presence of circulating immune complexes containing IgA, and IgA deposits along sinusoids in the liver. When combined with the presupposed IgA-clearance function of the liver, a causal association between IgA abnormalities and the liver disease in ALD can be suggested. This prompted us to study the presence and concentration of circulating IgA-containing immune complexes (IgA-CIC) in 41 patients with ALD and 41 patients with other nonalcoholic liver diseases having comparable serum IgA levels. We searched for relationships among IgA-CIC and history of alcohol abuse, liver histopathology, and IgA deposits in the liver. Using an anti-IgA inhibition binding assay, 56% of the patients exhibited IgA-CIC in polyethylene glycol precipitate of serum and 38% showed IgA-CIC in whole serum. The prevalence and concentration of IgA-CIC was lowest in cases with nonspecific changes or steatosis in the liver biopsy and highest in cases with hepatitis or cirrhosis (P < 0.01). The occurrence of IgA-CIC was not related to a history of alcohol abuse or to the presence of IgA deposits along hepatic sinusoids (which occurred in 78% of ALD and 20% of non-ALD cases). A skin biopsy was available from 34 patients (19 with ALD and 15 with non-ALD). In 68% of these biopsies, IgA deposits were observed in superficial blood capillaries. The presence of skin IgA deposits was related to that of IgA-CIC detected in whole serum (P < 0.05): there was no significant relationship with liver histopathology, alcohol abuse, or the presence of IgA deposits in the liver. We conclude that the presence of circulating IgA-CIC is directly related to the severity of liver parenchymal damage, irrespective of an alcohol etiology. This conclusion substantiates the pivotal role of the liver in the clearance of circulating IgA, especially of IgA-CIC.

The supporting meshwork of the thymus, which is composed of epithelial cells (epithelial-reticular cells), plays a major role in the generation of immunocompetent T lymphocytes. From the characterization and location of lymphocytes in the thymus it can be hypothesized that different microenvironments exist promoting different steps in intrathymic T cell maturation. Our findings on heterogeneity of human thymus epithelial cells synthesizing various thymosin components1 and heterogeneity in antigen expression revealed by monoclonal anti-epithelial cell antibodies (this issue, p 297) gives support to this hypothesis. Also in electron microscopy, variation in ultrastructural characteristics of epithelial cells has been noted.2,3 We studied the ultrastructural morphology of epithelial cells in sections of the human thymus to evaluate whether interrelationships exist between epithelial cell subtypes and between morphology and function in the microenvironment.

The athymic nude mutation was first recorded in 1953 in a colony of outbred hooded rats maintained at the Rowett Research Institute, Bucksburn, Aberdeen, U.K., and the symbol rnu for Rowett nude has been assigned to the recessive mutant gene (1). We have introduced the nude mutant in our institute and backcrossed it into the WAG rat strain for 12 generations. Previous studies (1–3) suggest that the athymic nude rat is in many ways very similar to the nude mouse, but the numbers of animals and parameters investigated were limited. Therefore the morphologic characteristics in the nude rat were further defined (4). We here present a survey of our studies of these nude animals during the last 10 years.

We studied the distribution of IgA1- and IgA2-containing plasma cells in the jejunum of 5 patients with primary IgA nephropathy and of 2 patients with Henoch-Schönlein purpura. The percentage of IgA-containing cells (62.3 +/- 4.6) was below the level found in normal (79.4 +/- 5.1) (p less than 0.001). The percentage of IgA1-containing plasma cells relative to the total IgA-containing cells was too low in 2, normal in 3 and too high in 2 subjects (mean percentage 68.1 +/- 9.6; normal 69.0 +/- 3.8). Our data do not support an increased production of IgA1 in the jejunal mucosa of patients with primary IgA nephropathy or with Henoch-Schönlein purpura.

The proposed role of Epstein-Barr virus (EBV) in salivary gland destruction in Sjogren's syndrome (SS) prompted the authors to study the presence of EBV-DNA (hybridohistochemistry) and EBV-encoded proteins (immunohistochemistry) in sublabial salivary glands taken from eight patients with primary and five with secondary SS and from 16 controls. DNA probes and anti-EBV antibodies were controlled for activity by assessment of human blood B-lymphocytes after in vitro infection with EBV. None of the tissues investigated manifested the presence of EBV proteins (nuclear antigen, early antigen R, membrane antigen, or viral capsid antigen). The salivary gland biopsies of four patients with primary SS and two with secondary SS showed EBV-DNA in epithelial cells of acini and ducts but not in other components. The authors data contrast with those of Fox and colleagues (J Immunol 1986;137:3162-3168), who reported that about half of the patients with SS have EBV early antigen D in epithelium of the sublabial salivary gland. The authors conclude that an active EBV infection associated with EBV protein synthesis does not occur in the diseased salivary gland of patients with SS, but the presence of EBV-DNA in the glands does not exclude a possible role of EBV in the disorder.

The thymic epithelial cell plays an essential role in T cell maturation, either by direct contact with so-called “prethymic” precursor T cells, or by the secretion of biologically active factors (e.g. thymosin) (1). Apart from fetal thymus, transplantation of cultured thymic epithelium (CTE) has become a treatment procedure in patients with deficiency of thymic function, such as di George syndrome and some forms of severe combined immune deficiency. By culturing thymic expiants thymocytes disappear from the tissue (2), whose cells are responsible for graft-versus-host disease which may occur in the recipient. Conditions to get CTE with biological activity of the epithelial cells deprived of thymocytes are rather ill-defined. This prompted us to establish optimal culture conditions of CTE of human and rat origin for transplantation purposes. We looked for morphological criteria, and for the biological activity of CTE both in vitro (synthesis of biologically active factors) and in vivo (induction of thymus dependent immunity in athymic [nude] rats).

Over a three-year-period 105 peripheral arterial reconstructions were performed using a denaturated venous homograft in a group of patients with no suitable autologous vein. A retrospective analysis has been carried out to investigate the potency rate of this graft. After three years 64% of all grafts are functioning well (according to the Life Table Method, Kaplan & Meyer). No significant differences in patency rates were found between reversed autologous veins and the material tested in this study but analysis of grafts removed after failure showed obstruction due to thrombosis or aneurysmal dilatation. No evidence of an immune response to the grafts was seen.

The excessive intake of alcohol is associated with various changes in both cellular and humoral immunity. Especially notable are the effects of alcohol on the IgA immune system. These include an increase of serum IgA with a slight shift towards IgA2 in the IgA1:IgA2 ratio, the presence of IgA containing immune complexes in the circulation, deposition of IgA in various tissues and an increase in the number of IgA producing cells in the circulation. Some of these features are related to the alcohol etiology while others are related to the severity of liver parenchymal damage, underlining the pivotal role of this organ in the IgA metabolism. Alcohol can disturb the integrity of intestinal mucosa resulting in an increased invasion of antigens from the gut, which will lead to a stimulation of the secretory immune system in particular. The characteristic deposition pattern of IgA along the liver sinusoids, seen in alcoholics, is not a reflection of changes in the circulation but the result of a direct effect of alcohol on the liver. This feature can be used for diagnostic purposes. The pathogenetic relevance of most of these changes in the IgA immune system is still unclear

This report describes procedures to quantify IgA responses in the rat sensitized to ovalbumin or infected with the parasite Trichinella spiralis: an ELISPOT detecting specific IgA antibody-producing cells in lymph nodes, and an ELISA demonstrating IgA antibody in serum and gut mucosal scrapings. For this purpose a mouse monoclonal anti-rat IgA antibody was produced. This IgG1-kappa 1 antibody recognized rat IgA but not rat IgM, IgG, or IgE. It proved very suitable in both assays. Using this reagent we could demonstrate large numbers of IgA anti-ovalbumin-producing cells in the mesenteric lymph nodes 15 days after sensitization to ovalbumin via the Peyer's patches. At 28 days after sensitization the numbers were much lower. IgA antibody titres to ovalbumin in serum were maximal between days 14 and 21 after immunization. Maximal numbers of IgA anti-T. spiralis-producing cells were found in the mesenteric lymph nodes 12 days after infection with muscle larvae, followed by a sharp decrease at 15 days. Maximal IgA anti-T. spiralis antibody titres in serum and mucus scrapings of small intestines were found on days 10 and 12 after oral infection with the parasite.

Encapsulated hepatocyte transplantation and encapsulated mesenchymal stem cell transplantation are newly developed potential treatments for acute and chronic liver diseases, respectively. Cells are microencapsulated in biocompatible semi-permeable alginate-based hydrogels. Microspheres protect cells against antibodies and immune cells, while allowing nutrients, small/medium size proteins and drugs to diffuse inside and outside the polymer matrix. Microencapsulated cells are assessed in vitro and designed for experimental transplantation and for future clinical applications. Here, we describe the protocol for microencapsulation of hepatocytes and mesenchymal stem cells within hybrid poly(ethylene glycol)-alginate hydrogels.

Orthotopic DA (RT1a) into Lewis (RT1l) rat kidney allografts and control Lewis-into-Lewis grafts were assessed by magnetic resonance imaging (MRI) and perfusion measurement after intravenous injection of a superparamagnetic contrast agent. MRI anatomical scores (range 1-6) and perfusion rates were compared with graft histology (rank of rejection score 1-6). Not only acute rejection, but also chronic events were monitored after acute rejection was prevented by daily cyclosporine (Sandimmune) treatment during the first 2 weeks after transplantation. In acute allograft rejection (n = 11), MRI scores reached the maximum value of 6 and perfusion rates were severely reduced within 5 days after transplantation; histology showed severe acute rejection (histologic score 5-6). In the chronic phase (100-130 days after transplantation), allografts (n = 5) manifested rejection (in histology cellular rejection and vessel changes), accompanied by MRI scores of around 2-3 and reduced perfusion rates. Both in the acute and chronic phases, the MRI anatomical score correlated significantly with the histological score (Spearman rank correlation coefficient rs 0.89, n = 30, P0.01), and perfusion rates correlated significantly with the MRI score or histological score (rs values between -0.60 and -0.87, n = 23, P0.01). It is concluded that MRI represents an interesting tool for assessing the anatomical and hemodynamical status of a kidney allograft in the acute and chronic phases after transplantation.

• Cultured thymic fragments were implanted in one patient with acquired immunodeficiency syndrome (AIDS)-related complex (ARC) and in eight AIDS patients with opportunistic infections (Ols, four patients), Kaposi’s sarcoma (KS, two patients), or both (two patients). Thereafter, objective clinical improvement was noted in one patient with 01, and a stable symptom-free condition was observed in the ARC patient and in two other patients with Ols. However, the ARC patient and two of the three patients with Ols developed infections three to six months after implantation. A fourth case of 01 and the patients with KS showed progression of the disease. Peripheral blood investigations for counts of total leukocytes, lymphocytes, and T-lymphocyte subsets as well as for lymphocyte stimulation with mitogens showed no changes interpretable as an improvement of the cellular immune deficiency status. We conclude that cultured thymic fragments have no distinct in vivo effect on the course of AIDS, except for a temporary clinical improvement or a period of stable condition in some patients with Ols.