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1.
Unlike the Peyer's patches of rats and mice, which are considered to be secondary lymphoid organs, the ileal Peyer's patch of sheep is thought to be responsible for the primary generation of B cells, like the bursa of Fabricius of birds. The ileal Peyer's patch of sheep shows prenatal maturation, antigen-independent lymphopoiesis, a rate of lymphocyte production larger than that of the thymus, and involution at a young age. Follicles contain few T cells and have an IgM+, relatively immature B lymphocyte population, as judged by B-cell differentiation markers. The follicle-associated epithelium of the ileal Peyer's patch is of a special type that sheds carbonic anhydrase-rich, 50-nanometer membrane-bounded particles (carbonic anhydrase-reactive particles; CAP) into the intercellular spaces. The CAP filter into the follicle centre and are taken up by lymphocytes. They represent the epithelial (bursa-like) element in an otherwise mesenchymal stroma of reticular cells embedding the follicle lymphocytes. Transepithelial transport of macromolecules, with the formation of multivesicular body-like cytoplasmic vacuoles, appears to be the basis for CAP formation. The jejunal Peyer's patches are devoid of CAP, persist in the adult animal, contain M cells with clusters of B cells in the follicle-associated epithelium, and have many CD4+ lymphocytes in the follicles and in the interfollicular areas. Aggregates of lymphoid follicles in the large intestine resemble the jejunal Peyer's patches with respect to their lymphocyte population and the ileal Peyer's patch with respect to their follicle-associated epithelium.  相似文献   

2.
Immunoperoxidase (IPX) labelling for CD4, CD8, TCR-gammadelta, WC1, CD1b, IFN-gamma, CD45R, CD56 and lysozyme was used to investigate changes in cell mediated immune effector cell populations in the intestinal Peyer's patches (PP) and mesenteric lymph nodes of lambs, 2 and 4 months after experimental infection with low doses of sheep strain Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis). The organism was cultured from the tissues of each infected lamb, but histological lesions were not present. This infection model was considered to be more representative of natural M. a. paratuberculosis infection than previous studies. Infected sheep had significantly more CD4+ cells in the mucosa, domes and interfollicular areas of the terminal ileum, and in the interfollicular areas of the jejunal Peyer's patch. Infected sheep also had significantly increased numbers of TCR-gammadelta+ cells in the mucosa and interfollicular areas of the jejunal Peyer's patch, and increased numbers of WC1+ cells in the ileal Peyer's patch. These findings are consistent with previous findings in sheep given higher doses of cattle strain M. a. paratuberculosis. Significantly fewer CD1b+ cells were present in the paracortical areas of the mesenteric lymph nodes of infected sheep, and the reduction was greater in sheep infected for 4 months compared to sheep infected for only 2 months. Down-regulation of CD1b expression may be important for the continued survival and multiplication of M. a. paratuberculosis as specific adaptive immunity develops. Across all sheep, jejunal Peyer's patches had higher numbers of CD4+, CD8+, TCR-gammadelta+, WC1+ and CD45R+ cells, and lower numbers of CD56+ fibres compared to ileal Peyer's patches. These findings confirm and extend the peculiarities of the terminal ileal Peyer's patch in the young ruminant, with possible implications for the early establishment of M. a. paratuberculosis infection.  相似文献   

3.
The dome epithelium of Peyer's patches from different parts of the intestine of four dogs was examined by scanning and transmission electron-microscopy and by alkaline phosphatase histochemistry on glycol-methacrylate embedded sections. M cells were scattered among more numerous enterocytes in duodenal and jejunal Peyer's patches, but constituted the major cellular component of dome epithelia of the ileal Peyer's patches. Alkaline phosphatase histochemistry demonstrated low enzyme activity in the brush border of M cells, as compared to enterocytes, in the duodenum and jejunum, allowing identification of M cells at the light microscopic level. Alkaline phosphatase activity was too low in ileal enterocytes to permit visualization of M cells. The presence of intrafollicular invaginations of dome epithelium is a consistent finding in duodenal Peyer's patches of the dog and these invaginations were characterized by few M cells, many intraepithelial lymphocytes and strong alkaline phosphatase activity.  相似文献   

4.
The morphology of the gut-associated lymphoid tissue of the small and large intestine in three gnotobiotic calves was examined by scanning and transmission electron microscopy, and the distribution of specialized membranous cells present in the follicle associated epithelium was defined. Isolated follicles remaining in the ileum of a cow after involution of the continuous Peyer's patch were examined by scanning electron microscopy. The presence of membrane-bound particles, reported to be exclusively associated with the continuous Peyer's patch, was investigated in other gut-associated tissue of the small and large intestine of the calf. The presence of two types of follicle associated epithelium in the small intestine of the calf was confirmed, and the follicle associated epithelium of the large intestine proved to be a homogeneous population of specialized membranous cells, similar to that of the continuous Peyer's patch of the small intestine. In the discrete Peyer's patches, some specialized membranous cells were completely hidden by adjacent enterocytes and could only be identified by cytoplasmic extensions into the intestinal lumen. In the proximal part of the continuous Peyer's patch, a transitional zone was detected where the follicle associated epithelium of some doomed villi was composed of a homogeneous population of specialized membranous cells, while the epithelium covering other doomed villi consisted of a mixture of absorptive and specialized membranous cells, usually only found in the discrete Peyer's patches. Membrane-bound particles were observed associated with gut-associated lymphoid tissue in the small and large intestine.  相似文献   

5.
Various pathogens gain access to the intestinal wall via specialized cells, the M cells, found among the follicle-associated epithelial cells overlying the domes of the Peyer's patches. The present study was undertaken to examine the uptake of live Mycobacterium avium subsp. paratuberculosis in the distal small intestine of goat kids. Following laparotomy, distal small intestinal segments of five goats were ligated and injected with bacterial suspension. After 1 hour, the intestinal segments were excised and fixed for light and electron microscopic studies. M. a. paratuberculosis organisms were observed by transmission electron microscopy at locations in the intestinal wall, suggesting transcellular transportation through the M cells. The organisms were present both in the cytoplasm of the M cells and in the cytoplasm of intraepithelial leukocytes found in M-cell pockets. Intercellular bacteria between M cells were occasionally seen. Bacteria were not observed in association with the absorptive epithelium. This study indicates that in goat kids, M. a. paratuberculosis enters the intestinal wall primarily through the M cells in the follicle-associated epithelium of the Peyer's patches.  相似文献   

6.
In contrast to rodents, all compartments of the porcine small intestine contain lymphoid cells at birth. During the first few days of life maternal antibodies and leukocytes are taken up by the intestinal epithelium. The number of intraepithelial lymphocytes (IEL) increases by a factor of 12 from Day 1 to Day 60, but in germfree pigs only a minor increase is observed. Immediately after birth, low numbers of T cells are present in the small intestinal lamina propria (LP), and many of these express neither CD4 nor CD8 on their surface. This type of subset composition is still present in germfree pigs at an age of 1.5 months. The appearance of IgA+ and IgM+ lymphocytes in the LP differs. Many more of these B cells are found in the LP of the crypts than of the villi. The development of the discrete jejunal Peyer's patches (PP) differs from that of the continuous PP in the terminal ileum. The lymphocyte subset composition shows the most obvious differences between conventional and germfree piglets and between the jejunal and ileal PP at an age of 1.5 months. Several markers, e.g. for antigen-presenting cells, memory T cells, M cells in the domes of PP, have recently become available for the pig. These should now be applied in experiments on pigs in the early postnatal period to study the mechanisms of the development of tolerance and protective immune reactions.  相似文献   

7.
An enzymatic technique for isolating bovine Peyer's patch leukocytes was developed. Enzymatic dissociation of Peyer's patches yielded a cell population rich in T and B lymphocytes containing 6-10% adherent accessory cells, as defined by morphology and nonspecific esterase staining. Analysis of Peyer's patch lymphocytes, using sheep erythrocyte rosetting and immunofluorescence with conventional antisera and monoclonal antibodies, showed that leukocytes were approximately 45% T cells and 25% Ig-positive B cells. The cell population contained functionally active T and B lymphocytes which proliferated in response to T and B cell mitogens and to exogenous human recombinant interleukin-2. The observed differences in patterns of Peyer's patch leukocyte responsiveness to these mitogens suggest some cellular heterogeneity of the bovine Peyer's patch.  相似文献   

8.
The main lesions of paratuberculosis in ruminants are in the small intestine. Previous studies have shown that the bacterium enters the small intestine through M cells found in the follicle-associated epithelium lining the domes of the Peyer's patches. The everted sleeve method, devised for the in vitro study of intestinal absorption, was used in this study to investigate the uptake of Mycobacterium avium subsp. paratuberculosis in goat intestine. Everted small intestinal sleeves of goat kids, prepared from areas with and without Peyer's patches, were incubated for 60 min in 3H-labeled bacterial solution. The results of this study imply that the bacteria can enter the intestinal mucosa of the jejunum, both in areas with and without Peyer's patches. These findings indicate, therefore, that M. avium subsp. paratuberculosis bacteria not only enter through M cells but also through enterocytes.  相似文献   

9.
The objective of this study was to develop an intestinal model of Mycobacterium avium subspecies paratuberculosis (Map) infection in the calf for evaluation of mucosal pathology and local and systemic immunologic responses. Map was inoculated into Peyer's patches of young calves using a right flank surgical approach in standing calves to exteriorize the ileocecal junction. Inoculum doses ranging from 10(3) to 10(9) colony-forming units of strain K10 Map were injected through the serosal surface into Peyer's patches of the distal ileum near the ileocecal valve. Fecal samples were collected for culture from each calf weekly until termination of the study. Calves were necropsied at 7, 30, 60, and 90 days after infection, when inoculation sites, lymph nodes, spleen, and peripheral blood were collected for evaluation. Ileocecal lymph nodes were consistently colonized by Map in the 10(5) to 10(9) groups. The ileocecal valve was also colonized in 10(7) and 10(9) groups. This correlated with fecal culture results as infected calves intermittently shed Map in their feces throughout the study. Granulomatous lesions with giant cells and acid-fast bacilli at the ileocecal junction, ileocecal lymph nodes, and lamina propria of high-dose animals (10(7) and 10(9)) were identified from each time point. Flow cytometry was used to detect antigen-specific production of interferon-γ and interleukin-4 locally (ileocecal lymph node) and systemically (peripheral blood mononuclear cells), which defined distinct immunologic profiles in low-dose and high-dose calves. This study demonstrates intestinal Map infection via Peyer's patch inoculation, a novel model with many shared features of natural Map infection.  相似文献   

10.
The distribution and diameter of the pores of epithelial basement membrane in the intestinal villi and the lymph nodules of ileal Peyer's patches were investigated in the rat small intestine by scanning electron microscopy after the removal of the overlying epithelial cells with OsO(4) maceration. In the duodenum, jejunum and ileum, the pores were mainly distributed at the upper three fourths of the villi, but were scarce around the top of the villi. The diameter of some of the pores in the upper three fourths of the villi was larger than that of those in the lower portion. The protrusion of lymphocytes and the cytoplasmic processes of macrophages were also seen at the orifices of the pores. In ileal Peyer's patches, in contrast, pores were densely distributed in the lower one third of the follicle-associated epithelium (FAE) where M cells were mainly seen. Furthermore, these pores were larger than those found in the upper two thirds. Lymphocytes or cytoplasmic processes of macrophages were frequently seen in the lower one third of FAE. These results suggest that the pores at the basement membrane correspond to the passage of the immunocompetent cells which are in contact with M cells or villous columnar epithelial cells and that the abundance of pores is a sign of aggressive interaction between the particular epithelial cells and the immunocompetent cells at the upper three fourths of intestinal villi and the lower one third of FAE in the rat small intestine.  相似文献   

11.
The distribution of B cells in the lymphoid organs of the goat was studied using a panel of 13 monoclonal antibodies (mAbs) developed against different markers for bovine B cells. Samples of mesenteric lymph nodes, jejunal and ileal Peyer's patches, duodenum, jejunum, ileum, colon, caecum and rectum were taken from four 7-month-old male Murciano-granadina goats using the avidin-biotin-peroxidase (ABC) method on frozen sections as described by Hsu et al. (1981). The mAbs against immunoglobulins (Ig) recognized a large number of cells, particularly in the light zones of the germinative centres of the lymphoid follicles, regardless of the isotype against which they were directed. However, the greatest numbers of B cells in the germinative centres and outer coronas of the lymphoid follicles of the lymph node, spleen and Peyer's patches were recognized by mAbs against the L lambda chain of Ig and against IgM. This was also the case in other locations where B cells were abundant, such as the medulla of the lymph node and the dome of the Peyer's patches. These mAbs recognized not only B lymphocytes but also plasma cells, showing an intracytoplasmatic reaction (numerous in the spleen red pulp and the intestinal lamina propria when mAbs were used against the L lambda chain of the Ig, scarce in the intestinal lamina propria when used against IgM and scarce in spleen red pulp and numerous in the intestinal lamina propria when mAbs against IgA were used). The mAbs BAQ44 A, GC65 A and GB25 A are of interest because, besides marking cells in the B areas where lymphocytes show surface Ig, they give a positive reaction in areas where there are Ig-cells (the dark zone of the germinative centre) and do not immunostain plasma cells. Thus, these mAbs recognize a surface marker which is not an Ig.  相似文献   

12.
Structure and function of Peyer's patches in man and animals are compared reviewing reports of recent years. Differences exist regarding number and distribution of Peyer's patches along the small intestine and regarding distribution of m-cells of dome epithelium. M-cells trigger the contact between infectious organisms and intestinal epithelium. Several different ways of interaction are possible: 1. Selective uptake of organisms by m-cells. 2. Paracellular transport of organisms between m-cells. 3. Multiplication of organisms above dome epithelial areas. 4. Restriction of interaction between organism and mucosa to absorptive enterocytes. 5. Specific damage of organisms to lymphatic areas of Peyer's patches.  相似文献   

13.
Three calves were studied in stages of spontaneous cryptosporidial infection with particular reference to the relation of the cryptosporidia to the follicle-associated epithelium (FAE) over the ileal Peyer's patch (IPP). In early infection scanning electron microscopy and streptavidin immunoperoxidase staining showed marked predilection of cryptosporidia for the FAE. Cryptosporidial antigen was also found in subepithelial tissue, both in the domes over the IPP and in villi, apparently in macrophages, where the parasites seemed to be progressively degraded. The FAE showed long tightly spaced microvilli, replacing normal low folds and protrusions, particularly in late infection. Endocytosis of indian ink was restricted to the cell periphery in late infection, contrasting the normal, more even distribution of endocytosis in the FAE apical cytoplasm. Few parasites were seen in the intestinal mucosa at this stage. At convalescence the FAE was normal, but all stages of infection were characterised by elongation of microvilli in absorptive cells.  相似文献   

14.
The effect of rotaviruses and enterotoxigenic Escherichia coli administered in various sequences to cesarean-derived, colostrum-deprived calves was studied using light and electron microscopy. The structure of the lymphoid tissue in the ileum, the number of mitoses in the crypts, number of intraepithelial lymphocytes, and enzyme histochemistry (alkaline phosphatase, acid phosphatase, succinic dehydrogenase, beta-galactosidase, and leucinaminopeptidase) of the ileal dome epithelium were evaluated. The area of lymphoid follicles in Peyer's patches of the ileum was investigated morphometrically. Monoinfections with either rotavirus or enterotoxigenic E. coli induced a significant increase in lymphoid follicle area, but did not affect dome epithelial cells. Dual infections did not consistently affect the follicle area, but the number of intraepithelial lymphocytes and the mitotic indices exceeded those of comparable monoinfections. Changes in activity of enzymes in the ileal dome epithelial area were minor.  相似文献   

15.
The present study was made to know the morphology of the initial invasion and lesions involved in the intestinal colonization of Yersinia enterocolitica serovar O3 in the epithelium of Peyer's patches of mice. Microfold (M) cells formed a specific structure like a pseudopodium and the bacteria were observed on the surface of the pseudopodium-like structure 4 hr after oral administration of serovar O3. The colonies of serovar O3 were observed in the epithelium and the lamina propria of the Peyer's patches dome region, and the bacteria grown in the Peyer's patches were in direct contact with the lumen without covered with the host tissue 24 hr after the administration.  相似文献   

16.
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17.
The follicle-associated epithelium (FAE) of Peyer''s patches (PPs) contains M cells that are important for reducing mucosal immune responses by transporting antigens into the underlying lymphoid tissue. We generated a monoclonal antibody (C6) that reacted with the FAE of calf ileal PPs, and analyzed the characteristics of C6 using immunohistochemistry and Western blotting. FAE of the ileal PP was stained with C6 during both late fetal developmental and postnatal stages. Neither the villous epithelial cell nor intestinal crypt basal cells were stained at any developmental stage. During the prenatal stages, FAE of the jejunal PP was C6-negative. However, a few C6-positive cells were distributed diffusely in some FAE of the jejunal PPs during the postnatal stages. The protein molecular weight of the antigen recognized by C6 was approximately 45 kDa. These data show that C6 is useful for identifying the FAE in ileal PPs and further suggest that differentiation of the FAE in these areas is independent of external antigens.  相似文献   

18.
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19.
Cells were isolated from canine Peyer's patches (PPs) and their phenotype and capacity to secrete immunoglobulins in vitro were determined. Cells isolated from duodenal and jejunal PPs of adult dogs consisted of 91.4% lymphocytes and 1.6% macrophages with 55.4% mIg(+)-cells and 35.6% Thy-1(+)-cells. In vitro IgA secretion by pokeweed mitogen (PWM)-stimulated PP cells exceeded that by cells from other lymphoid tissues and was specifically increased by concanavalin A, suggesting a role for isotype-specific T-cells. Comparison of duodenal and jejunal (proximal) PPs and the ileal PP revealed that the ileal PP contained fewer T-cells, fewer mIgA(+)-cells and more mIgM(+)-cells. Cells from the ileal PP produced very little IgA and IgG, but abundant IgM in vitro. These data suggest that the proximal PPs of dogs are important in the generation of IgA B-cells, similar to PPs of rodents. The ileal PP of dogs may have a function in the early development of the B-cell system of the dog.  相似文献   

20.
It is well established that glucocorticoids are key regulators of the immune system and act as immunosuppressive agents in high concentrations. In the pig, effects on the gut immune system and trafficking of lymphocytes between tissues and blood plasma were not investigated so far. Twelve pigs of 70 kg were fed 0.4 mg portions of dexamethasone (Dexa) twice daily for 9 days or remained untreated (controls) and were sacrificed for tissue collection at the end of Dexa treatment. Another six pigs with jugular vein catheters were left untreated for 7 days (control period) and then received Dexa for 9 days. Blood was drawn twice during the control period and at days 3, 6 and 9 of the Dexa period for characterization of peripheral blood leukocytes. Cells were obtained from thymus, mesenteric lymph nodes, jejunal mucosa and Peyer's patches. Lymphoid cells from gut tissue were isolated from two fractions: the EDTA-fraction, containing the intraepithelial lymphocytes (IEL), and the Collagenase-fraction, containing the lamina propria lymphocytes (LPL). In all samples, cell counts and phenotypic characterization of cells by flow cytometry (FCM) were performed. In thymus, Dexa led to a more than 90% reduction of the absolute cell number, which was mainly found in the CD4+CD8+ subpopulation. Dexa effects on lymphocytes from mesenteric lymph nodes were less severe (50%) and led mainly to a decrease (71%) of B-lymphocytes. The number of lymphocytes in the EDTA-fraction (IEL) of the jejunal mucosa decreased significantly by 56% in the Dexa-treated animals compared to the controls, whereas the number of lymphocytes in the Collagenase-fraction (LPL) decreased only moderately. In the Peyer's patches, a decreasing tendency in the number of lymphocytes in the EDTA-fraction was observed which, however, was not significant. In blood, monocytes and granulocytes were significantly increased in an order of 60%. The data show that supraphysiological amounts of Dexa remarkably reduce cell numbers in thymus and also in the intraepithelial compartment of the jejunal mucosa and ileal Peyer's patches. In blood, a notable homeostasis was observed for several leukocyte populations whereas both monocytes and granulocytes increased.  相似文献   

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