Maternal cells are widely distributed in murine fetuses in utero

Passage of maternal cells into conceptuses in utero is recognized but poorly defined in species with hemochorial placentation. Despite the potential importance for such a phenomenon in vertical disease transmission, only limited data address the frequency of material to fetal cell trafficking or the developmental stage of its initiation. A murine model system, involving transfer of LacZ-, scid/scid, or wild type (+/+) blastocysts to pseudo-pregnant, LacZ+ transgenic ROSA26 females provided both flow cytometric and in situ information. In 100% of the late-gestation pregnancies studied, nucleated LacZ+ maternal cells crossed to conceptuses. In 90% of scid/scid fetuses, nucleated maternal cells were present in at least one lymphoid organ and often in more than one organ. Thymus was the most frequent site for maternal cell detection while the highest proportions of maternal cells were found in liver. Maternal cells were also visualized in fetal lung, heart, and bone marrow. Maternal cell trafficking into scid/scid fetuses commenced about midgestation, coincident with maturation of a placental circulation. In late-gestation +/+ fetuses, maternal cells were found extensively throughout bone marrow but not in other organs. The presence of maternal cells within primary lymphoid organs of fetuses may influence the repertoire of the developing fetal immune system and may be an underappreciated mechanism for vertical disease transmission.

Development of bronchus-associated lymphoid tissue in goats

Development of bronchus-associated lymphoid tissue (BALT) was studied in clinically healthy and diseased Assam local goats. Animals were sacrificed before term as well as at different postnatal periods to screen lung sections for the presence of BALT. In a retrospective study sections prepared from pneumonic lungs were examined for any alteration of BALT. No BALT-like structure was found in neonatal goats. Bronchial lymphoid structures appeared in half of the animals from 1 month of age onward. The frequency of the BALT/4.5 cm2 of lung section ranged from one to two in 1-month-old and three to six in 1-year-old goats. In pneumonic lungs BALT became hyperplastic, and the size was also increased. The incidence of BALT was increased in lungs with fibrotic pneumonia. The number of BALT/section was high (five to eight/4.5-cm2 area) in mesenchymal cell proliferation. The present study shows that BALT did not develop in prenatal periods. But in the presence of potent antigens lymphoid aggregates appeared in the bronchial lamina propria of normal and diseased lungs.

Interleukin-2 receptor alpha chain regulates the size and content of the peripheral lymphoid compartment

Interleukin-2 receptor alpha chain (IL-2R alpha) expression occurs at specific stages of early T and B lymphocyte development and is induced upon activation of mature lymphocytes. Young mice that lack IL-2R alpha have phenotypically normal development of T and B cells. However, as adults, these mice develop massive enlargement of peripheral lymphoid organs associated with polyclonal T and B cell expansion, which, for T cells, is correlated with impaired activation-induced cell death in vivo. Older IL-2R alpha-deficient mice also develop autoimmune disorders, including hemolytic anemia and inflammatory bowel disease. Thus, IL-2R alpha is essential for regulation of both the size and content of the peripheral lymphoid compartment, probably by influencing the balance between clonal expansion and cell death following lymphocyte activation.

Apoptosis in human immunodeficiency virus-associated nephropathy

Focal segmental glomerulosclerosis associated with human immunodeficiency virus nephropathy (HIVFGS) involves glomeruli, tubules, and interstitium. Its pathogenesis is unknown, but HIV peptides may be critical in its development. Human immunodeficiency virus peptides and peptide-antibody complexes are immunomodulatory, and are associated with apoptosis in lymphoid cells. To determine whether apoptosis is present in HIVFGS, renal biopsy specimens of eight patients with HIVFGS were compared with those of 10 patients with idiopathic focal glomerulosclerosis (FGS) using the Apoptag kit (Oncor, Gaithersburg, MD), which detects single cell apoptosis in formalin-fixed tissue by staining 3' nucleosome fragments with digoxigenin-labeled nucleotides after terminal deoxynucleotidyl transferase enzyme treatment. Apoptosis was scored per glomerulus, in total renal tissue sectioned, and in tubules and interstitium per square millimeter using a computerized digital image analyzer. There was no difference between the number of apoptotic cells per glomerulus or per square millimeter of interstitium in patients with FGS and HIVFGS. There were greater numbers of tubular apoptotic cells per square millimeter (2.1 +/- 0.9 v 0.15 +/- 0.08; P = 0.03) in HIVFGS compared with idiopathic FGS. The difference between apoptotic cells per total square millimeter of renal tissue (2.8 +/- 1.2 v 0.7 +/- 0.3) approached significance (P = 0.066). Apoptosis may be associated with the pathogenesis of HIV nephropathy and may be an important determinant of the tubular disease in HIVFGS.

Dose-dependent systemic human immunodeficiency virus infection of SCID-hu mice after intraperitoneal virus injection

SCID mice were engrafted with human foetal liver, thymus and lung. Human cells were subsequently detected among peripheral blood leukocytes for 81% of tested animals and in tissue implants for 100% of tested animals. SCID-hu mice received intraperitoneal injections of human immunodeficiency virus type 1 (HIV1) at from 20 up to 20,000 median tissue culture infectious doses (TCID5). HIV1 infection was detected by means of cell culture and polymerase chain reaction both in blood and implants, up to 58 days after infection. The rate of infection was dependent upon the inoculated dose: the frequency of thymus infection ranged from 14% with 20-500 TCID50 up to 100% with 20,000 TCID50. HIV1 infection was detected less frequently in blood leukocytes than in thymus. Thymus virus load ranged from 40 to 50,000 HIV1 provirus copies per million cells and was not correlated with either infectious dose or viraemia. Thymus T-cell depletion was observed mainly in the CD1+4+8+ immature thymocyte compartment. The same rate of SCID-hu mouse infection was obtained using three different primary HIV1 isolates, suggesting that infection was not restricted to a few particular virus strains. The systemic infection of SCID-hu mice following intraperitoneal virus injection mimics some traits of human HIV infection and provides a promising, novel approach for future investigations in this field.

Lymphoid expression and regulation of A20, an inhibitor of programmed cell death

A20 is a cytokine-inducible primary response gene that encodes a protein that inhibits apoptosis. We cloned and characterized a murine A20 cDNA and mapped the gene to mouse chromosome 10, 3.5 centimorgans proximal to the c-myb locus. Using the murine cDNA, we conducted in situ hybridization studies to examine patterns of A20 expression in mouse embryos and postnatal tissues. Both temporally restricted and tissue-specific patterns of A20 expression were observed, with strikingly high levels in lymphoid organs, including the thymus, spleen, and gut-associated lymphoid tissue. Northern analysis using purified human lymphocyte populations demonstrated that A20 is constitutively expressed in both immature and mature thymocyte subpopulations, as well as in resting peripheral T cells. Activation leads to a down-regulation of A20 expression in both mature thymocytes and peripheral T cells. This pattern of expression and regulation differs markedly from that observed in prior studies with cell lines in which stimulation led to an induction of A20 expression. Additionally, this is the first demonstration of constitutive expression of A20 in primary cells. The data suggest a role for A20 in the function of the lymphoid system.

CD30 antigen in embryonal carcinoma and embryogenesis and release of the soluble molecule

The expression, serological detection, and possible functional role of the CD30 antigen in Hodgkin's disease and anaplastic large cell lymphoma is well documented. In embryonal carcinoma (EC), the expression of this cytokine receptor has been demonstrated only by immunohistology. Because the CD30 monoclonal antibody Ki-1 was found to cross-react with an unrelated molecule, we examined by in situ hybridization testicular germ cell neoplasms for the presence of CD30-specific transcripts. CD30 mRNA was detectable in the tumor cells of 9 of 9 cases of EC or mixed germ cell tumors with an EC component but in no other nonlymphoid tumors. Thus, the CD30 transcript expression pattern proved to be identical to the immunostaining pattern seen with the CD30-specific monoclonal antibody Ber-H2. By Northern blot analysis, CD30 transcripts could be demonstrated in the EC cell line Tera-2. Employing a highly sensitive second generation sandwich enzyme-linked immunosorbent assay, we could detect the soluble CD30 molecule in 8 of 8 sera from patients with a diagnosis of EC but not in 8 of 10 sera from patients with other testicular germ cell tumors. In fetal tissue, no CD30-expressing germ cells or epithelial cells could be observed. Thus, the cellularly expressed CD30 marker for testicular neoplasms of EC type. Moreover, the serum levels of soluble CD30 antigen seem to be a promising parameter for monitoring patients with EC.

Development of immune responses in early pig ontogeny

Low amounts of immunoglobulins, produced without any known cause of stimulation, can be detected in sera and cells of fetal and colostrum deprived newborn pigs. These immunoglobulins are believed to represent the preimmune antibody repertoire on the basis of their polyspecificity and reactivity against self antigens. In vitro activation of liver and spleen cells with various polyclonal B cell activators (PBA) results in pronounced immunoglobulins synthesis as measured in the culture media by enzyme-linked immunosorbent assay. Intrauterine injection of fetal and germfree pigs with PBA led to increased IgM, IgG and IgA levels in sera. Specific responses during fetal development were studied after intrauterine immunization. Antibodies to the heapten and its carrier flagellin, could be detected 7 days after the immunization of 55-day-old fetuses. Fetal and colostrum germfree pigs may be useful experimental models in which developmental immunity can be studied in the absence of maternal antibodies and environmental antigens.

Impaired immune and acute-phase responses in interleukin-6-deficient mice

Interleukin-6 (IL-6) is a multifunctional cytokine that regulates various aspects of the immune response, acute-phase reaction and haematopoiesis (for reviews see refs 1, 2). In vitro, leukaemia inhibitory factor, oncostatin M, ciliary neurotrophic factor and interleukin-11 display overlapping activities with IL-6. This functional redundancy may be explained by the interactions of specific binding receptors with a common signal-transducing receptor (gp130) (for reviews see refs 3, 4). To elucidate the unique function of IL-6 in vivo, we have disrupted the IL-6 gene by homologous recombination. IL-6-deficient mice develop normally. They fail to control efficiently vaccinia virus and infection with Listeria monocytogenes, a facultative intracellular bacterium. The T-cell-dependent antibody response against vesicular stomatitis virus is impaired. Further, the inflammatory acute-phase response after tissue damage or infection is severely compromised, whereas it is only moderately affected after challenge with lipopolysaccharide. We conclude that IL-6 production induced by injury or infection is an important in vivo SOS signal which coordinates activities of liver cells, macrophages and lymphocytes.

Lymphocyte expression in transgenic trout by mouse immunoglobulin promoter/enhancer

Two groups of transgenic rainbow trout (Oncorhynchus mykiss, Walbaum) have been produced and compared. One group harbored the reporter gene of chloramphenicol acetyltransferase (CAT) associated with mouse immunoglobulin (Ig) promoter/enhancer (pUCL-CAT-E). The other group carried the same reporter gene under the control of the cytomegalovirus promoter/enhancer (pCMV-CAT). Slot blot analysis of DNA from blood cells and other tissues from pUCL-CAT-E fish showed variation of copy number between the major tissues but not between red and white blood cells. Southern blot analysis indicated that multiple copies organized in concatemers were incorporated into the genome. The pCMV-CAT fish had a pronounced expression of CAT in both white and red blood cells. In contrast, activity of CAT was found in the white blood cells of all pUCL-CAT-E fish but not in their red blood cells. Expression in white blood cells was found preferentially in sIg+ cells, indicating that B cells are the major expressors. High expression was also found in spleen and kidney, but the activity found in thymocytes was equal to the background level. Analysis of some major tissues showed high white blood cell expression associated with low tissue expression, except that liver (known to contain lymphoid tissue in fish) was higher. Thus the regulatory elements of the Ig gene from mouse induce a tissue-specific expression in fish.

Brn-3.0: a POU-domain protein expressed in the sensory, immune, and endocrine systems that functions on elements distinct from known octamer motifs

Characterization of Brn-3.0 and identification of a highly related member (Brn-3.1) of the class IV POU-domain family suggest potential roles of Brn-3.0 in the development of retinal ganglion cells and sensory neurons, as well as potential roles in the pituitary gland and the immune system. Brn-3.0 is expressed in the pituitary gland and in a corticotroph cell line. A functional DNA response element has been identified in the proopiomelanocortin promoter. In contrast to previously described mammalian POU-domain proteins, Brn-3.0 binds relatively ineffectively to known octamer DNA motifs, but instead binds with high affinity to a distinct set of DNA elements, functioning as a transcriptional activator. Brn-3.0, Brn-3.1, and the Drosophila tI-POU share an N-terminal region of homology, referred to as the "POU-IV box," which is similar to a conserved functional domain in the c-myc gene family.

Development of the lymphomyeloid system in the dogfish, Scyliorhinus canicula

Previous studies on the morphology of the lymphomyeloid tissues in the dogfish, Scyliorhinus canicula, have been confined to adults. This study was restricted to the structure and functioning of the developing immune system in embryonic and post-hatch dogfish. A major feature of the developing immune system in S. canicula, is the succession of haemopoietic/lymphoid tissues. The liver is the first tissue to contain immunoglobulin positive cells at 2 months, followed by the interstitial kidney at 3 months. The thymus, spleen, and Leydig organ appears at 4 months while the epigonal and gut-associated lymphomyeloid tissues are the last tissues to differentiate. The haemopoietic/lymphoid nature of the kidney and thymus disappear at post-hatch and the other lymphomyeloid tissues persist through adult life. By the time of egg case splitting (ca. 6 months), when embryos receive massive exposure to water-borne antigens, the structural development of most of the lymphomyeloid tissues is well advanced.

Bcl-2-deficient mice demonstrate fulminant lymphoid apoptosis, polycystic kidneys, and hypopigmented hair

bcl-2-/-mice complete embryonic development, but display growth retardation and early mortality postnatally. Hematopoiesis including lymphocyte differentiation is initially normal, but thymus and spleen undergo massive apoptotic involution. Thymocytes require an apoptotic signal to manifest accelerated cell death. Renal failure results from severe polycystic kidney disease characterized by dilated proximal and distal tubular segments and hyperproliferation of epithelium and interstitium. bcl-2-/-mice turn gray with the second hair follicle cycle, implicating a defect in redox-regulated melanin synthesis. The abnormalities in these loss of function mice argue that Bcl-2 is a death repressor molecule functioning in an antioxidant pathway.

Ontogeny of IgM and IgM-bearing cells in rainbow trout

We have studied the ontogenic development of immunoglobulin M (IgM) and of IgM-bearing cells in the rainbow trout, Oncorhynchus mykiss. Lymphocytes showing cytoplasmic IgM were first observed in embryos at 12 days before hatch (14 degrees C). At this stage, no cells positive for surface IgM were present. Lymphocytes bearing surface IgM were observed at 8 days before hatch (14 degrees C). Unfertilized trout eggs contained detectable amounts of IgM (11.2 +/- 2.6 micrograms/g of egg weight), indicating that transfer of IgM from mother to embryo can occur in salmonids. The levels of IgM from whole fish increase slowly after the appearance of intraembryonic cells that express surface IgM. The amount of IgM/g of tissue peaks around hatch, but this parameter shows lower values up to 2 months after hatch.

Expression of relB transcripts during lymphoid organ development: specific expression in dendritic antigen-presenting cells

We have studied the expression of the relB gene during mouse development using in situ hybridization and immunocytochemical analysis. The results show that the expression of the relB gene is highly restricted to a subpopulation of cells that colonize the lymphoid tissues and that appear very late during the process of hematopoietic diversification. RNA transcripts of relB are very low or undetectable in early and late embryos. Low relB expression is observed in the thymus at late stages of embryogenesis but rapidly increases after birth. In adult lymphoid tissues, relB is detected in the medullary region of the thymus, the periarterial lymphatic sheaths of the spleen, and the deep cortex of the lymph nodes, which correspond to the regions where T cells of mature phenotype and interdigitating dendritic cells are present. Using double immunofluorescent labeling of thymic cell suspensions, we have identified the interdigitating dendritic cells as the target of RelB expression. These cells are part of a system of antigen-presenting cells that function in the induction of several immune responses, such as, tolerance, sensitization of MHC-restricted T cells, rejection of organ transplants and formation of T-dependent antibodies. Our observations indicate that RelB may play a particular role in the signal transduction pathway that regulate dendritic cell differentiation and its cellular responses.

Immunohistochemical study of lymphoid tissue in human fetal salivary gland

Immunoreactivity of lysozyme (LY), lactoferrin (LF), alpha 1-antichymotrypsin (alpha 1-ACT), alpha 1-antitrypsin (alpha 1-AT), keratin proteins KL1, PKK1, K8.12, S-100 protein, MAM-3, MAM-6, and epithelial membrane antigen (EMA) were evaluated in lymphoid and glandular tissues of developing salivary gland of human fetus (gestational age ranging from 17 to 40 wk to investigate the role of lymphoid tissue in developing salivary glands. In a total of 79 cases, lymphoid cell aggregations were noted in parotid (57 cases), submandibular (21 cases) and sublingual (5 cases) glands. Mononuclear cells showing intense activity of LY, alpha 1-ACT and alpha 1-AT were present in the lymphoid aggregation. The glandular ducts embedded in lymphoid tissue were negative to MAM-3, MAM-6, EMA and S-100 protein, but showed positive PKK1 and KL1 reaction during early stages of development, and showed degeneration and effacement upon increase in number and LY activity of the mononuclear cells. The lymphoid aggregations progressively emerged as lymph nodes.

Characterization of B-cell phenotypic changes during ileal and jejunal Peyer's patch development in sheep

Changes in B-cell phenotype during development of ileal and jejunal Peyer's patches (PP) of sheep were investigated using flow cytometry and immunoperoxidase-stained cryosections. On Day 104 of gestation (term at 150 days) B-cell clusters were identified in the lamina propria of the ileum. These clusters were composed of cells that expressed surface IgM (sIgM), lambda or kappa light chain, and BAQ44A, a B-cell differentiation molecule. No cells in the clusters stained for terminal deoxynucleotide transferase. On Day 132 gestation, a change was evident in the phenotype of ileal PP B cells. Most B cells expressed a reduced level of sIgM and 20% were BAQ44A-. The B cells in the dome region were BAQ44A+ but few BAQ44A+ cells were present in the follicles. At 6-8 weeks of age BAQ44A+ cells were restricted to the dome region of the ileal PP; flow cytometric analysis confirmed that 25% of B cells isolated from the dome/follicle complex were BAQ44A+. Thus, the primordial PP was populated with B cells that were phenotypically similar to circulating B cells (sIgMhigh, BAQ44A+). After 132 days gestation, the predominant B-cell phenotype in the ileal PP changed to sIgMlow and BAQ44A-. This phenotypic change could be the result of either early immigrant B-cell differentiation or subsequent colonization by sIgMlow BAQ44A- B cells. The phenotypic changes of ileal PP follicular B cells were not complete until after birth and different phenotypic changes were observed in follicles of the jejunal PP of young lambs.

Characterization, specificity, and IgV gene usage of anti-lymphocyte monoclonal antibodies from perinatal mice

Previous studies have shown that CD5+ B cells predominate during development of the immune system and frequently secrete self-reactive antibodies, some of which appear to influence the development of the adult B cell repertoire. In addition, we now show that a high frequency of perinatally derived antibodies react with lymphocytes. Hybridomas derived from perinatal liver and splenic B cells and from spleens of adult BALB/c and C57BL/6 mice were screened by immunofluorescence on thymocytes. Anti-lymphocyte antibodies, all of the IgM isotype, were detected at a high frequency from perinatal fusions, but none were obtained from adult mice. These anti-lymphocyte mAbs were heterogeneous because they stained different subsets of peripheral T and B lymphocytes. Although the antigens recognized by these mAbs were heterogeneous with respect to their sensitivity to a variety of enzymes, 13 of the 19 mAbs recognized epitopes which were modulated by phosphatidylinositol-phospholipase C treatment. Inhibition experiments suggested that six of these 13 mAbs shared the same molecular specificity, and that they recognized the same T cell subset (62% of CD4+ and 98% of CD8+ cells). Furthermore, three of these mAbs immunoprecipitated the same 100 kDa protein from thymocytes (70 kDa in reducing conditions). The related molecular specificity of some anti-lymphocyte mAbs was also reflected by their restricted V gene usage. Three of the five mAbs specific for the 100 kDa protein used very similar or identical germline SM7 VH genes. In addition to using the same germline D and JH genes, they also exhibited identical VH-D-JH joins, despite originating from distinct fusions. Analysis of light chains also showed some restriction by preferential use of germline V kappa 4 and J kappa 5 genes. Together, these results suggest that the restricted antibody repertoire characteristic of mouse fetal and neonatal B cells is also reflected in the production of anti-lymphocyte antibodies. These B cells appear consistently in early development, use germline V genes, and express a characteristic VH-D-JH join.

Development of the B- and T-cell compartments in porcine lymphoid organs from birth to adult life: an immunohistological approach

Using immunohistological techniques, we studied the development over time of B- and T-cell compartments in the lymphoid organs of specific-pathogen-free pigs. Tissue samples were collected at various time-points, starting 2 days before the pigs were born until the pigs were 10 months old. The samples were collected from the spleen, thymus, peripheral lymph node, mesenteric lymph node, duodenum, jejunum, ileum, jejunal Peyer's patch and ileal Peyer's patch. Monoclonal antibodies specific to B- and T-cells were used to identify where the following cells were localized: IgM-B cells (cells positive to surface immunoglobulin), IgM-, IgG- and IgA-containing cells (cells positive to cytoplasmic immunoglobulin), and CD2-, CD4- and CD8-positive cells. The development of the B- and T-cell subpopulations in each organ was analysed. Two days before birth, most organs contained quantities of IgM-B cells. The spleen, lymph nodes, Peyer's patches and, notably, the thymus, contained some immunoglobulin-containing cells (Ig-CC); this finding indicates that pigs have cells that secrete immunoglobulins before birth. Just after birth, the incidence of Ig-CC increased in most organs; first IgM-CC increased, then either IgG- or IgA-CC increased, depending on the organ. T-cell development was observed clearly in spleen and in the lamina propria of the small intestine, in contrast to other organs, in which the T-cell compartments containing various T-cell subpopulations were well developed before birth. Comparison of the incidence of CD4+ and CD8+ cells showed that the CD4:CD8 ratio of these cells in the spleen, lymph nodes, Peyer's patches and small intestine is low, especially in adult pigs, compared with the CD4:CD8 ratio in other species. Weaning had little influence on the incidence of B- and T-cells in lymphoid organs. This study is the first immunohistological survey to describe the development of the major B- and T-cell subpopulations in various lymphoid organs of pigs, and it should be useful for future immunopathological and comparative immunological studies in pigs.

Cell adhesion in the stromal regulation of haemopoiesis

Haemopoiesis occurs in close physical contact with elements of the bone marrow stroma. This review examines some adhesion molecules which are expressed in haemopoietic environments. These molecules may act to maintain cell contact between haemopoietic progenitors and the cellular and extracellular matrix elements of the marrow stroma. A review is undertaken of several families of adhesion molecules and their ligands, including integrins, CD44, LEC-CAMs, CAMs and variant glycosylation patterns expressed by haemopoietic cells. Both CD44 and integrin receptors have been implicated in mediating important cellular interactions within the haemopoietic system and the significance of these and other molecules in haemopoiesis is discussed.

Ontogeny of reticulum cells in the rat intestine and their possible role in the development of the lymphoid microenvironment

Ontogeny of reticulum cells (RC) in the rat intestine in relation to the development of the gut-associated lymphoid tissue (GALT) was studied using a panel of monoclonal antibodies (mab) directed against RC in peripheral lymphoid organs, ED10-ED15. The mab ED10 specific for RC in the spleen T cell area, recognized an epitope on gut RC, which cells seem to be involved in the influx and accumulation of lymphocytes in the lamina propria and in Peyer's patches (PP) and proximal colonic lymphoid tissue (PCLT). The mab ED11 which recognizes RC in the T cell area and B cell follicles of spleen, stained follicular dendritic cells (FEC) in the B cell area of the mesenteric lymph node (MLN), PP and PCLT. The ED11 expression occurs earlier and reveals stronger staining in MLN as compared to those in PP and PCLT, suggesting the prominent role of MLN in the generation and proliferation of B cells in the gut mucosal immune system. The mab ED13 specific for RC in the B cell area of the lymph nodes, stained the basement membrane of the epithelium overlying PP and PCLT, and high endothelial venules (HEV), suggesting that this might be involved in providing the microenvironment for the development and differentiation of follicle-associated epithelium, and facilitating lymphocyte traffic. The mab ED12 specific for RC in the paracortex of peripheral lymph nodes, gave a diffuse nonspecific staining in the gut, whereas mab ED14 and ED15 are markers for common connective tissue cells. We conclude that the gut RC are morphologically and phenotypically heterogenous. ED10+, ED11+, and ED13+ RC are probably involved in the development of the gut lymphoid microenvironment.

Immunohistochemical studies on ontogeny of bovine lymphoid tissues

Developing lymphoid tissues of bovine fetuses ranging from 70 to 270 days of fetal age were examined by histological and immunohistochemical procedures. In the peripheral blood, surface membrane immunoglobulin bearing cells (B-lymphocytes) and sheep red blood cell rosette forming cells (T-lymphocytes) had already appeared by 70 days of fetal age. In the lymph nodes intracytoplasmic IgM positive cells appeared at 90 days of fetal age. The cells positive for IgG appeared at 150 days of fetal age and IgA positive cells appeared at 180 days of fetal age. The spleen contained intracytoplasmic immunoglobulin positive cells at almost the same time as those in the lymph nodes. In the ileocecal region, IgM positive cells and IgG positive cells were present at 180 days of fetal age and IgA positive cells were present at 210 days of fetal age. The tonsils contained IgM positive cells and IgG positive cells at 240 days of fetal age. In the thymus, terminal deoxynucleotidyl transferase positive cells appeared at 90 days of fetal age.

The ontogeny of human lymphocyte recirculation: high endothelial cell antigen (HECA-452) and CD44 homing receptor expression in the development of the immune system

In the present report we have studied the expression of a lymphocyte homing receptor, the CD44 antigen, and of HECA-452, a high endothelial-specific antigen, during the development of the human immune system. We found that prothymocyte immigrants of the thymus already expressed the CD44 antigen. Similarly, the first peripheral T lymphocytes in fetal lymph nodes, tonsils and gut-associated lymphoid tissue were also CD44+. Cortical thymocytes and germinal center cells were CD44-. CD44 antigen expression was, thus, not limited to mature recirculating lymphocytes. This suggests that CD44 may not only be involved in recirculation of mature lymphocytes but also in the migration of prothymocytes to their site of maturation, i.e. the thymus. High endothelial venules (HEV) were not demonstrable at the early onset of lymphocyte immigration into the developing lymphoid organs. However, when large-scale influx of lymphocytes occurred, it paralleled HEV development. HECA-452 antigen expression preceded the morphological transformation of endothelium into a HEV phenotype. Expression of this antigen therefore, independently reflected the specialized nature of high endothelium. In a patient with complete DiGeorge's syndrome normal HEV developed, indicating that the presence of T lymphocytes is not a requirement for HEV development. Interestingly, a subpopulation of venules located in the thymic medulla near the cortico-medullary junction expressed the HECA-452 antigen. These vessels, which had flat or intermediately high endothelium, are probably involved in lymphocyte migration to the thymus.

Development of cytoplasmic CD3+/T cell receptor-negative cells in the peripheral lymphoid tissues of chickens

In a study of T cell ontogeny using monoclonal antibodies specific for chicken T cell receptors (TcR) and associated cell surface molecules, we found a subset of lymphocytes that express cytoplasmic CD3 epitopes in the absence of cell surface CD3/TcR complexes. Approximately half of these cells, which were present in the spleen, bursa and intestine of young chick embryos, expressed surface CD8. None expressed CD4, TcR 1 (gamma/delta), TcR 2 (alpha/beta) or TcR 3 (a third CD3-associated heterodimer in the chicken). These cytoplasmic CD3+CD8 +/- cells, tentatively named TcR 0 cells to denote their lack of surface TcR, appeared first in the spleen of 8-day embryos, 4 days before TcR expression begins in the thymus, and reached a peak frequency of approximately 10% of the splenic cell in 14-day embryos. The TcR 0 cells were also present in adult birds, where they comprised only about 1% of the CD3+ spleen cells and approximately 40% of the lymphocytes in the intestinal epithelium. We conclude that the avian TcR 0 cells represent a thymus-independent lineage of lymphocytes which, like natural killer cells in mammals, may play an important role in body defense.

Ontogenic development of gut-associated lymphoid tissue in the rat. An immunohistochemical study

The development of gut-associated lymphoid tissue (GALT) in the rat was investigated, with special reference to the behavior and ultrastructure of Ia(+) cells during the development of Peyer's patches (PP). At birth, Ia(+) cells were randomly scattered in the lamina propria. From three days, small aggregates of CD4(+), Ia(+), CD5(-) and IL-1(+) cells were observed in the lamina propria. Immunoelectron microscopically, these appeared as mixed populations of dendritic cells, capillary endothelial cells, fibroblast-like spindle cells and lymphocytes. In addition, CD8(+), CD4(-) and IL-1(-) cells were present in the interepithelial space. By seven days, lymphoid follicles were recognizable in the lamina propria, each with an aggregate of IgM-positive small lymphocytes at its center, surrounded by CD4(+) or CD8(+) lymphocytes. Between the 10th and 14th days, these follicles were covered with single-layered, specially differentiated epithelial cells, and structures resembling PP were formed. IgA plasma cells were identified in the lamina propria between the third and the fourth weeks. We speculate that the PP developed from aggregates of Ia(+), IL-1(+) spindle- or dendritic-shaped cells in the lamina propria. The PP were structurally complete by two weeks, although establishment of the characteristic distribution of GALT components evident in the adult took more than six weeks.

The distribution of mucosal lymphoid nodules in the equine respiratory tract

Mucosal lymphoid nodules were identified within the equine respiratory tract by an acetic acid fixation technique. Nodules were identified in foetuses from nine months gestational age, and estimates of total and regional nodule populations were made in foetal, neonatal and adult horses. Nodules occurred at specific sites within the tract, which probably relate to areas where inhaled antigens accumulate. The largest populations of nodules occurred in the nasopharynx and larynx, with smaller numbers in the nasal cavity, trachea and bronchi. There was an age-related change in the size of these nodule populations, with an increase in number from late gestation to the neonatal period to early adulthood (up to 5 years of age), followed by a decrease in older adults.

Diffusely infiltrated lymphoid areas of the bursa of Fabricius (DIA) and of the cloaca: an embryological study with morphological analogies

The aim of the present experiment was to verify whether the origin of the DIA is ectodermal or endodermal. A rabbit serum against the epithelial cells of the final portion of the cloaca was prepared. The indirect immunofluorescence method was applied to strips obtained with a cryostat, carefully cut in such a way as to include a part of the cloaca, the burso-cloacal stalk, the DIA, and the bursal plicae. In this way, it was possible to demonstrate that the epithelium of the cloaca, of the burso-cloacal stalk, and of the DIA exhibited an intense fluorescence that could not be observed at the level of the epithelium of the bursal plicae. These findings would appear to indicate that the DIA, like the cloaca and the burso-cloacal stalk, is ectodermal in origin. Furthermore, histological study revealed that the DIA exhibits close structural analogies with the dorsal wall of the cloaca. In both areas, unorganized lymphoid infiltrations of the tunica propria can be seen, and the epithelium does not show any follicle-associated epithelial cells. The glands often assume the aspect of dilated crypts containing intestinal transit material. The epithelium of these glands reveals lymphoid infiltrations at various points, and it is not uncommon to detect accumulations of cells in their lumina. Several groups of eosinophilic granulocytes can also be observed in the tunica propria of these two areas, with a clear predominance at the level of the DIA. These similarities between the cloaca and the DIA might lead one to suppose the existence of a functional as well as a morphological correspondence.

The ontogeny of various cell populations defined by monoclonal antibodies in the primary lymphoid organs of the sheep

Monoclonal antibodies specific for various cell surface markers in sheep were employed to study the ontogeny of the immune system in this species. The temporal sequence of appearance of various cell populations of hematopoietic origin is described in the course of fetal development of the liver, spleen, thymus, ileal Payer's patches and bone marrow.

Review of studies on the immunological capacity in the bursectomized chick

This paper summarizes data on the immunological capacity in the bursectomized chick. A series of experiments described by Glick and Sadler represented the functional importance of the bursa of Fabricius for the humoral immunity in chicken. Later studies of immune responses in bursaless chickens reported by Lerner et al. contributed to our knowledge of bursa-independent humoral immunity and demonstrated an extra-bursal site for B-cell differentiation. Bursectomy at an early stage of chicken development changes the immune responses after hatching. Here I present my current understanding of embryonic B-cell populations (bursa-dependent and independent) following in ovo bursectomy which may influence B-cell differentiation with reference to our experiments on J chain production.

Identification of somatomedin/insulin-like growth factor immunoreactive cells in the human fetus

Somatomedins/insulin-like growth factors (Sm/IGFs) are present in blood and in extracts from multiple tissues of the human fetus and induce the proliferation of cultured human fetal cells. To identify the cellular location of immunoreactive Sm/IGF in human fetal tissues, we have performed immunocytochemistry in tissues from prostaglandin-induced human fetal abortuses of 12 to 20 wk in gestation. Every tissue studied except the cerebral cortex contains Sm/IGF immunoreactive cells. Cells staining positively include hepatocytes, hepatic hemopoietic cells, columnar epithelia of the pulmonary airways, intestine and kidney tubules, adrenal cortical cells, dermal cells, skeletal and cardiac muscle fibers, and pancreatic islet and acinar cells. Immunostaining was specific for Sm/IGFs, but because of the cross-reactivity of the antibodies it was not possible to determine whether the immunoreactivity represented Sm-C/IGF I, IGF II, or both. Liver contained the greatest proportion of immunoreactive cells, while the thymus and spleen had only a few immunostained cells. With the possible exception of dermal and some adrenal cortical cells, the immunoreactive cells do not appear to be the primary sites of Sm/IGF synthesis, because parallel in situ hybridization histochemical studies using Sm/IGF oligodeoxyribonucleotide probes show that Sm/IGF mRNAs are localized predominantly to fibroblasts and mesenchymal cells. Therefore the immunoreactive cells identified in this study may define sites of action of Sm/IGFs.

IL 1-like activities present in murine amniotic fluid. A significantly larger amount of IL 1 beta-like activity is present in the amniotic fluid of autoimmune NZB mice

Rapid progress in studies of cytokines have clarified their roles in processes of lymphocyte proliferation and differentiation. However, the involvement of these molecules in lymphopoiesis during embryonic development has not yet been well documented. In this study we screened for possible existence of cytokines that influence lymphopoiesis in murine amniotic fluid (AF) obtained from non-autoimmune prone "normal" strains of mice (CBA/J, BALB/c, A/J, SWR, and C57B/6) and autoimmune-prone NZB mice. Significant colony stimulating activity-1 (CSA-1)-like activities were found in AF of all of the strains tested, but relatively low activities were present in AF of NZB mice. No interleukin 2 (IL 2) or interleukin 3 (IL 3)-like activities were detected, Weak IL 1-like activity was found in AF of most of the strains tested; however, the results of the standard thymocyte proliferation assays varied with each AF sample. This variation is probably related to the presence of nonspecific inhibitors including alpha-fetoprotein in murine AF. Therefore, pooled AF from CBA and NZB strains of mice were subjected to several purification procedures to assess the actual amount of IL 1-like activity present in murine AF. After (NH4)2SO4 precipitation and hydrophobic phenyl-Sepharose chromatography, the measurable level of IL 1-like activity could be increased significantly. With lentil-lectin affinity chromatography, IL 1-like activity was completely dissociated from CSA-like activity. Moreover, a significantly larger amount of IL 1-like activity was found in NZB AF fractions (approximately sixfold higher). Apparent pI values estimated by preparative isoelectric focusing (IEF) were 5.9, 7.2, and 7.4 in CBA AF fractions, and 6.5 and 7.3 in NZB AF fractions. The NZB AF fraction with pI of 7.3 showed significantly higher IL 1 activity than the other fractions studied. These partially purified molecules were found to be resistant to pH 2 and the reducing agent, 2-mercaptoethanol, but were inactivated by heat (56 degrees C, 1 hr) or trypsin. None of the fractions showed IL 2-like activity but some that had IL 1-like activity induced IL 2 production in a IL 1-dependent, IL 2-producing B lymphoma cell line. Apparent m.w. of these IL 1-like activities were 14,000, 14,500, 17,000, 18,000, and 21,000 in CBA AF fractions, and 15,000, 19,000, and 21,000 in NZB AF fractions according to SDS-polyacrylamide gel electrophoresis.(ABSTRACT TRUNCATED AT 400 WORDS)

Ontogeny of gut-associated lymphoid tissue (GALT) in the dogfish Scyliorhinus canicula L

Cartilaginous fish occupy a fundamental position in vertebrate phylogeny and it is likely that this group has retained some of the ancestral immune mechanisms. The ontogeny of GALT has received little attention in elasmobranchs and this study correlates this development with morphological differentiation, development of other lymphoid organs, exposure to seawater and transition from yolk dependence to exogenous food as a source of nutrient. GALT was first represented by individual lymphocyte-like and macrophage-like cells in the lamina propria. In later stages accumulations and intraepithelial leucocytes were recorded prior to hatching. The size of accumulations and the number of lymphocyte and macrophage-like cells infiltrating the lamina propria and epithelium increased in fish as they became dependent upon an exogenous diet. Although GALT developed after the thymus and lymphoid-like tissue in the kidney and at approximately the same time as the epigonal, Leydig and spleen, the source of cells populating the gut is unknown. Plasma cells and granulocytes were not observed in the developing fish until 6 months post-hatch after which the fish had a similar GALT distribution and content to the adult fish.

The development of gut associated lymphoid tissue in the terminal ileum of fetal human intestine

Lymphoid tissue in formalin fixed and snap frozen human fetal ileum has been studied using immunohistochemistry. At 11 weeks gestation clusters of cells expressing CD4 (leu-3a positive) are present in fetal ileum but these do not express CD3 (UCHT1 negative) and are probably macrophages. Aggregates of lymphoid tissue are apparent from 14 weeks gestation which contain T cells of helper/inducer and suppressor/cytotoxic phenotype. Both B and T cells are present at 16 weeks but with no cellular zonation. By 19 weeks, distinct follicles of B cells are present surrounded by T cells of helper/inducer and suppressor/cytotoxic phenotype. Follicular dendritic cells are also present within the B cell areas. The B cells at this age express surface IgM and IgD, C3b- and C3d-receptors. They also express the antigen CD5 which has been shown by others to be present on some fetal B cells but which is almost exclusively associated with T cells in the adult. HLA-D region antigens are present on apparently all of the cells within the fetal lymphoid follicles. The antigen on activated B cells, CD23 (recognized by MHM6), was present on some cells scattered within the B cell follicle. This is indicative of antigen independent B cell proliferation.

A hypothesis on the allantoic origin of the distal midgut

No satisfactory explanation for the absence of the ileocecal portion of the digestive system in the newborns with cloacal exstrophy has been offered previously. This is a report of such a case in which the lymphocytes and plasma cells were used as tissue markers to identify the origin of the lymphatic-rich ileocecal portion of the digestive tract. The absence of these cells, in this case demonstrated immunohistochemically, is suggestive of a dual origin of the midgut. Normal embryogenesis of the digestive system is reviewed and the possibility of participation of the allantois, in addition to the yolk sac, in the embryogenesis of the ileocecal segment of the gastrointestinal tract is discussed.

Lymphoglandular complexes of the colon: structure and distribution

The structure and distribution of lymphoglandular complexes of the colon are described. The cellular composition of these complexes, as detailed by immunohistochemistry and electron microscopy, suggests that they are sites of antigen processing. Variations in structure and in the number of complexes that are found in certain colonic diseases are documented.

Divergent expression of HLA-DC/MB, -DR, and -SB region products on normal and pathological tissues as detected by monoclonal antibodies

A group of eight monoclonal antibodies directed against different monomorphic determinants of HLA-class II molecules was used to investigate the distribution of HLA-DC/DS/MB, -DR and -SB-like antigens on normal and pathological lymphoid and nonlymphoid tissues of human adult and fetal donors. HLA-MB/DC/DS-like molecules, as defined by the antibody TU 22, showed the most limited distribution as they were detected on B-lymphocytes, monocyte/macrophage subpopulations and distinct interstitial cells of various organs. HLA-DR and -SB-like antigens characterized by the other anti-HLA-class II reagents (TU34, TU35, TU37, TU39, TU43, TU58) were also present on these cell types. However, selective expression of HLA-DR and/or -SB like molecules was demonstrated with these antibodies on certain vascular endothelia, as well as different B-cell lymphomas and distinct epithelial cells in adults. Exclusive reactivity of the antibody TU39 shown on endothelial cells of fetal liver and kidney suggested specific functions of HLA-SB antigens during ontogeny. Furthermore, HLA-DR and/or -SB like molecules but not TU22+ HLA-DC/MB antigens were found to be inducible on normally Ia-like antigen negative epithelial cells of various diseased organs. Implications of this differential tissue distribution of HLA-DC/MB/DS, -DR and -SB like products in relation to organ transplantation, regulation of immune responses and cell differentiation are discussed.

Interdigitating cells in the lymphoid tissues of bovine fetuses and calves. An electron-microscopic study

Electron-microscopic studies of lymphoid tissues from bovine fetuses and from calves disclosed a non-lymphoid cell type in the thymus-dependent zones of secondary lymphoid tissues and in the thymus that is distinguishable from reticulum cells, epithelial and endothelial cells, and macrophages. Based on morphological and topographical criteria, the cell is identified as the interdigitating cell. In addition, studies of the tissues of normal and virus-challenged fetuses, and of conventionally reared calves, indicated that the interdigitating cells originate from monocytoid cells, which undergo differentiation in the thymus-dependent zones during an immune response.

[Muscle tissue histogenesis of the lymph hearts of chick embryos]

By means of electron microscope autoradiography, the ultrastructure of muscle fibers, and the capacity if muscle of cell nuclei of 3H-thymidine (3H-T) incorporating of were studed in developing lymph hearts of 0-13 day old chick embryos, rather active sarcomerogenesis developing lymph hearts of 9-13 day old chick embryos, a rather active sarcomerogenesis being observed. Filament of intermediate size microtubules, Golgi complexes, centrioles, and numbers free ribosomes and polysomes were observed in the sarcoplasm. The sarcoplasmic reticulum channels were not numerous, their terminal cisterns often formed "subsarcolemmal cisternae". Between muscle fibers, cell junctions of fasciae adherentes type were observed. Two hours after 3H-T administrations, only mononuclear cells without myofilaments were labeled. If fixation was made 70 hours after 3H-T administration, then the label was found in addition on muscle fiber nuclei. These data evidence that the lymph heart muscle tissue histogenesis undergoes the same patterns of development as does the somatic muscle tissue.

The development of transport ability by embryonic follicle-associated epithelium

The development of transport ability by follicle-associated epithelium was studied in embryonic chick bursae. Developing lymphoid follicles were divided into three morphological types to determine the relationship of epithelial function to lymphoid development. Transport ability was first observed on day 13, two days earlier than obvious morphological evidence of follicle-associated epithelial development. Functional differentiation of the epithelium was, however, closely associated with lymphoid development rather than a day-specific developmental event. It is probable that the lymphoid cells have an inductive influence on the development of the overlying epithelium. Evidence of early embryonic transport by relatively undifferentiated epithelium also suggests that lymphoid development in the bursa may be influenced by epithelial transport.

Studies on the differentiation of T lymphocytes in sheep. I. Recognition of a sheep T-lymphocyte differentiation antigen by a monoclonal antibody T-80

The results presented in this paper demonstrate that a mouse IgM monoclonal antibody (T-80) recognizes an antigen on cells of the T-lymphocyte lineage of sheep. However, this antibody does not identify all T cells, as 10-20% of thymocytes and some peripheral-blood T cells are negative. T-80- thymocytes reside in the medulla. The majority of cortical thymocytes are T-80+ and classified as dull cells on the basis of antigen density per cell as measured by flow microfluorometry. In contrast, T-80+ cells in the periphery can be categorized into two populations, i.e., dull cells and bright cells. Suggestive evidence was obtained that bright T-80+ cells are fast recirculating T cells, whereas dull cells are sessile or less easily mobilizable T cells in the periphery. In foetal environment, over 90% of thymocytes and approximately 5% of spleen cells are T-80+ at 54 days of gestation (gestation period = 150 days), which may indicate that T-cell emigration from the thymus commences well before mid-gestation in sheep.

[Development and structure of the lymphoepithelial pharyngeal ring in the Macacus rhesus]

The lymphoepithelial pharyngeal ring has been studied in fetuses and 6-8-month-old monkeys (Macacus rhesus) by means of macro- and microscopical methods. The pharyngeal, palatile and lingual tonsils and a poorly manifested laryngeal tonsil have been revealed. The anlage of the lingual tonsil occurs later than that of the other ones (in fetuses of 60-73 mm of the parietal-coccygeal length), when the palatile and pharyngeal tonsils are already inhabited with lymphocytes. By the end of the embryonal period, the main structural components are already formed in all the tonsils, but their functional activity is not yet manifested. During the postembryonic period certain differences are revealed in the tonsil structure, they are presented as the germinative centers formation, appearance of active macrophages and plasma cells. A close connection between the lingual, pharyngeal and laryngeal tonsils with the glandular tissue is noted.