Embryonal development of grouped lymphoid nodules (Peyer's patches) in the human ileum]

Embryogenesis of Payer's patches (PP) of the ileum, has been studied in 183 human fetuses 8-40-week-old. Their anlages appear on the 8th-9th week as an accumulation of atypical villi. At first the PP are localized in the cranial part of the ileum, and then spread caudally. Their most active increase in amount takes place from the 15th up to 17th weeks of development. From the 8th up to the 40th weeks the PP amount increase from 10 up to 37. During the same time their length develops from 0.7 up to 8.3 mm, their width--from 0.3 up to 2.2. The first lymphoid nodules++ in the PP are detected on the 14th week, then their number rises from 200 up to 3,500. The superficial area of all the PP, turning into the lumen of the ileum widens from 1.4 up to 620 mm2. Their predominate form is ellipsoid. During the whole prenatal period in the lymphoid nodules++ no germinative centers are revealed. Lymphocytes in the PP are identified in 8-9-week-old fetuses. By the 29th week the whole amount of lymphocytes in them increase up to 9.6 x 10(6) cells. Lymphocytic suspension of the PP of 8-9-week-old fetuses contains 1.7% of T-lymphocytes (E = POK) and 0.1% of B-lymphocytes (EAC = POK). By the 29th week their amount increases up to 9% and 7%, respectively, but by birth it does not reach their amount in the PP of mature organisms.     

Absence of Peyer's patches and abnormal lymphoid architecture in chronic proliferative dermatitis (cpdm/cpdm) mice

The chronic proliferative dermatitis (cpdm) mutation causes inflammation in multiple organs, most prominently in the skin. Examination of the immune system revealed severe abnormalities in the architecture of lymphoid tissues. Peyer's patches were absent. In contrast, the spleen, lymph nodes, and nasal-associated lymphoid tissues were present. The spleen had normal numbers of T and B cells, but the spleen, lymph nodes, and nasal-associated lymphoid tissues had poorly defined follicles and lacked germinal centers and follicular dendritic cells. The marginal zone in the spleen was absent. The total concentration of serum IgG, IgA, and IgE in cpdm/cpdm mice was significantly decreased, whereas serum IgM was normal. Fecal IgA was low to undetectable in mutant mice, and the concentration of fecal IgM was increased. The titer of DNP-specific Abs following immunization with DNP-keyhole limpet hemocyanin was significantly decreased for all IgG subclasses. In contrast, T cell function appeared normal as assessed by evaluation of the contact hypersensitivity response in cpdm/cpdm mice. The cpdm mutation causes a complex phenotype that is characterized by multiorgan inflammation and the defective development of lymphoid tissues. The cpdm/cpdm mouse may be a useful model to study the factors that control the development of lymphoid tissues, in particular the Peyer's patches, and the mechanisms that control the humoral immune response.     

Lymphotoxin-independent expression of TNF-related activation-induced cytokine by stromal cells in cryptopatches, isolated lymphoid follicles, and Peyer's patches

Stromal cells play a crucial role in the organogenesis of lymphoid tissues. We previously identified VCAM-1(+) stromal cells in cryptopatches (CP) and isolated lymphoid follicles (ILF) in the small intestine of C57BL/6 mice. Nonhemopoietic stromal cell networks in CP and ILF of adult mice also expressed FDC-M1, CD157 (BP-3), and TNF-related activation-induced cytokine (TRANCE). Individual stromal cells were heterogeneous in their expression of these markers, with not all stromal cells expressing the entire set of stromal cell markers. Expression of VCAM-1, FDC-M1, and CD157 on CP stromal cells was absent in alymphoplasia mice deficient in NF-kappaB-inducing kinase (NIK) and NIK knockout mice. Administration of lymphotoxin beta receptor (LTbetaR)-Ig to wild-type mice on day 13 resulted in the absence of CP on day 20; delaying administration of LTbetaR-Ig until day 18 resulted in an 80% decrease in the number of CP on day 22 and diminished expression of VCAM-1, FDC-M1, and CD157 on the remaining CP. In sharp contrast, TRANCE expression by stromal cells was completely independent of NIK and LTbetaR. In addition, expression of TRANCE in ILF was concentrated just beneath the follicle-associated epithelium, a pattern of polarization that was also observed in Peyer's patches. These findings suggest that TRANCE on stromal cells contributes to the differentiation and maintenance of organized lymphoid aggregates in the small intestine.     

Selective emigration of suppressor T cells from Peyer's patches

The emigration of Peyer's patch lymphocytes to mesenteric lymph nodes was studied by injecting fluorescein isothiocyanate (FITC) directly into Peyer's patches. Using double immunofluorescence it was demonstrated that at 2 and 4 hr after FITC injection 70% of the labeled cells that migrated to mesenteric lymph nodes were T lymphocytes, although rat Peyer's patches contain only 15-20% T lymphocytes. At later time points after FITC injection this percentage of T cells derived from Peyer's patches gradually declined, most likely caused by selective interaction and/or retention inside the mesenteric lymph node. Determination of helper and suppressor T-cell subsets within this emigrating population showed an increased number of T suppressor cells migrating into mesenteric lymph nodes. The putative role of suppressor T cells in inducing systemic tolerance after oral antigen administration was discussed.     

Vi-Suppressed wild strain Salmonella typhi cultured in high osmolarity is hyperinvasive toward epithelial cells and destructive of Peyer's patches

Salmonella typhi GIFU10007-3 which lost a viaB locus on its chromosome became highly invasive in our previous study. To investigate the phenomenon, we controlled Vi expression in wild strain S. typhi GIFU10007, and studied the invasive phenotype both in vitro and in vivo. When the wild strain of S. typhi was cultured in 300 mM NaCl containing Luria-Bertani broth (LBH), the expression of Vi antigen was suppressed, but secretion of invasion proteins (SipC, SipB and SipA) was increased. In this condition, wild strain S. typhi became highly invasive toward both epithelial cells and M cells of rat Peyer's patches. When GIFU10007 was cultured under conditions of high osmolarity, the bacteria disrupted Peyer's patches and induced massive bleeding in these structures only 20 min after inoculation into the ileal loop. In contrast, Vi-encapsulated wild strain GIFU10007 cultured under low osmolarity was not destructive, even after 60 min. To understand the role of the type III secretion system under conditions of high osmolarity, we knocked out the invA and sipC genes of both GIFU10007 and GIFU10007-3. Neither invA nor sipC mutants could invade epithelial cells or M cells in a high osmolarity environment. Our data show that the highly invasive phenotype was only expressed when the wild strain S. typhi was cultured under high osmolarity, which induced a state of Vi suppression, and in the presence of the type III secretion system.     

Somatic generation of diversity in a mammalian primary lymphoid organ: the sheep ileal Peyer's patches

Ileal Peyer's patches (IPPs) in the sheep are composed of tightly packed follicles in which surface IgM-positive B cells proliferate and can be exported to the periphery. We report that the light chain rearrangement pattern in a single IPP follicle is much more restricted than in the entire tissue, which indicates that, as in the chicken bursa, ongoing rearrangement does not take place in this organ. Moreover, we show that B cells extensively diversify their antigen receptor while proliferating in IPP follicles. Sequencing of part of the V lambda locus indicates that this diversification is not achieved by gene conversion, but rather by untemplated somatic mutation and intense selective pressure. These results strongly imply that sheep IPPs behave as a bursa-equivalent, primary lymphoid organ of diversification and that somatic point hypermutation, which is known to proceed during secondary immune responses, can also generate an antibody repertoire.     

Particles and macrophages in murine Peyer's patches

Mice were given 1% suspensions of 5 insoluble particles (chrysotile asbestos, quartz, carmine, carbon, and iron oxide) in drinking water for 3 months. The particles were subsequently sought in intestinal Peyer's patches by light microscopy. Carbon and iron oxide particles were visible in Peyer's patch macrophages, particularly in the subepithelial region, but the other particles could not be detected. The findings suggest that particle surface properties as well as particle size govern accumulation in Peyer's patches. The cytochemistry of subepithelial, mid-dome, tingible-body, and serosal macrophages of control mice indicated diversity of macrophages within the patch. Macrophages of asbestos-fed mice contained more lysosomes than macrophages of controls. Macrophage abundance in the dome apex was not significantly altered by asbestos ingestion. The other particles did not produce detectable alterations in macrophage morphology.     

Intestinal gamma delta T cells develop in mice lacking thymus, all lymph nodes, Peyer's patches, and isolated lymphoid follicles

Through analysis of athymic (nu/nu) mice carrying a transgenic gene encoding GFP instead of RAG-2 product, it has recently been reported that, in the absence of thymopoiesis, mesenteric lymph nodes and Peyer's patches (PP) but not gut cryptopatches are pivotal birthplace of mature T cells such as the thymus-independent intestinal intraepithelial T cells (IEL). To explore and evaluate this important issue, we generated nu/nu mice lacking all lymph nodes (LN) and PP by administration of lymphotoxin-beta receptor-Ig and TNF receptor 55-Ig fusion proteins into the timed pregnant nu/+ mice that had been mated with male nu/nu mice (nu/nu LNP- mice). We also generated nu/nu aly/aly (aly, alymphoplasia) double-mutant mice that inherently lacked all LN, PP, and isolated lymphoid follicles. Although gammadelta-IEL were slightly smaller in number than those in nu/nu mice, substantial colonization of gammadelta-IEL was found to take place in the intestinal epithelia of nu/nu LNP- and nu/nu aly/aly mice. Notably, the population size of a major CD8alphaalpha+ gammadelta-IEL subset was maintained, the use of TCR-gamma-chain variable gene segments by these gammadelta-IEL was unaltered, and the development of cryptopatches remained intact in these nu/nu LNP- and nu/nu aly/aly mice. These findings indicate that all LN, including mesenteric LN, PP, and isolated lymphoid follicles, are not an absolute requirement for the development of gammadelta-IEL in athymic nu/nu mice.     

Natural cytotoxic T cells (NCTC) that differ from natural killer (NK) and natural cytotoxic (NC) cells are present in Peyer's patches of mice

We have examined noninduced cytotoxicity of mouse gut associated and peripheral lymphoid tissues for a wide variety of syngeneic as well as allogeneic cell lines and lymphoblasts. Lymphoid cells from Peyer's patches were found to lyse these targets in a 3-hr chromium release assay whereas lymphoid cells from intestinal mucosa, mesenteric or peripheral lymph nodes, spleen, and thymus did not. The variety of targets toward which Peyer's patch cells were cytotoxic established the latter as nonspecific and H-2 unrestricted. The cell responsible for the lytic event was identified as possessing Thy 1.2 and Ia surface antigens. This naturally cytotoxic T cell (NCTC) was found to be adherent to nylon-wool but not to plastic plates. Although both natural killer cell (NK) and non-NK targets served as targets for the NCTC, the latter were further differentiable from NK cells by lack of asialo GM1 surface marker, which is present on NK cells. In addition, NCTC remained fully functional in mice given either of the drugs cyclophosphamide or cortisone. Each of these drugs, in the doses used, markedly reduced poly(I:C)-induced NK activity. Thus, NCTC differs from NK on the basis of the spectrum of targets against which it is functional, phenotypic surface markers, insusceptibility to stimulation with poly(I:C), and insensitivity to diminution by the immunosuppressive drugs cyclophosphamide and hydrocortisone. Since NCTC is a Thy 1.2 antigen-bearing cell and is detectable in a 3-hr cytotoxic assay, it also differs from the natural cytotoxic (NC) cell. NC lacks the Thy 1.2 marker and becomes detectable only in an 18-hr cytotoxic assay. Thus, NCTC is neither an NK nor an NC cell. We have discussed the possibility that the three naturally occurring cells may be related by being dedifferentiated descendants of an antigen-specific cytotoxic T lymphocyte (CTL). Alternatively, since NCTC is confined to an anatomical site prone to ample antigenic exposure and is still identifiable as a T cell, it may be in linear transition from the CTL to the NK or NC stages.     

Immunohistochemical examination of Peyer's patches in autoimmune mice

The distribution of T-cells and B-cells in Peyer's patches was examined in three autoimmune model mice, MRL/Mp-lpr/lpr, BXSB, NZBWF1/J mice and normal BALB/c mice, between one and ten months old. A multiple layering technique was used for immunohistochemical detection of lymphocyte surface antigens of T-cells (Thy1.2, Lyt1, Lyt2) and B-cells (surface IgM) and peanut agglutinin receptor for germinal center cells. The T-cell population of female MRL/Mp-lpr/lpr mice increased markedly with age, and the B-cell population of the male BXSB mouse tended to increase. However, little change was observed with age in the NZBWF1/J mice. The immunohistochemical properties of the Peyer's patches in the three autoimmune model mice were different.     

Immune cells associated with M cells in the follicle-associated epithelium of Peyer's patches in the rat

Summary Follicle-associated epithelium of Peyer's patches can be differentiated from nearby villous epithelium by the presence of M cells which are antigen-sampling epithelial cells, and by an increase in intraepithelial lymphocytes that are in close contact with M cells. The phenotype of the immune cells close to the M cells of the follicle-associated epithelium of rat Peyer's patches was determined by immunohistochemistry and compared with that of the intra-epithelial lymphocytes of the villous epithelium. Lymphoid T cells, predominantly of the cytotoxic/suppressor phenotype, were observed both in follicle-associated epithelium and in villous epithelium. Lymphoid B cells, mainly immunoblasts and plasma cells containing intracytoplasmic IgM, were present only in the follicle-associated epithelium, near M cells. Macrophages were also present, in contact with M cells, in follicle-associated epithelium, but not in villous epithelium. In addition, M cells bore Ia molecules on their apical membranes. These findings reinforce the concept of immune specialization of the follicle-associated epithelium, by demonstrating that this epithelium contains all the effector cells of immune responses.     

Identification of M cells and their distribution in rabbit intestinal Peyer's patches and appendix

The distribution of intestinal membranous (M) cells has been studied within the follicle-associated epithelium of rabbit Peyer's patches and appendix. Vimentin expression has been assessed as a primary criterion to identify rabbit M cells in tissue sections and in whole tissue preparations. This criterion has been compared to the use of the absence of alkaline phosphatase which, due to its heterogeneous distribution within the enterocyte population, is less reliable than vimentin expression as a marker for rabbit M cells. The pattern of vimentin immunostaining revealed that the majority of M cells are located in the periphery of the follicle-associated epithelium, the dome apex being largely free of M cells. This distribution was confirmed by scanning electron microscopy. Vimentin is also expressed by follicle-associated epithelial cells in the vicinity of crypts which lack the typical lymphocyte-containing pocket of M cells. Cytoplasmic peanut agglutinin binding coincides with vimentin-expression throughout the follicle-associated epithelium but is absent from vimentin-negative enterocytes. The co-localisation of these two phenotypic markers in both M cells and epithelial cells adjacent to crypts, which lack the typical morphology of fully developed rabbit M cells, suggests that they correspond to immature M cells which by their location appear to derive directly from undifferentiated crypt stem cells and not from mature columnar enterocytes.     

Differential surface characteristics of M cells from mouse intestinal Peyer's and caecal patches

Summary The mouse caecal patch is located near the blind end of the caecum, and consists of a group of lymphoid follicles. In common with the Peyer's patches, the follicle-associated epithelium overlying these follicles is largely composed of enterocytes, goblet cells and membranous epithelial (M) cells. Each of these types of cell was readily identified by electron microscopy, although caecal patch enterocytes and M cells were morphologically distinct from those of the Peyer's patches. Staining for alkaline phosphatase activity demonstrated that the majority of caecal follicle-associated epithelial cells were alkaline phosphatase-negative, positive cells consisting of a mixture of enterocytes and M cells. In contrast, it has previously been found that Peyer's patch enterocytes are positive for alkaline phosphatase while the M cells are relatively lacking in alkaline phosphatase activity. Lectin histochemistry revealed that surface glycoconjugate expression differs between the caecal and Peyer's patch follicle-associated epithelial cells; in particular, the characteristic staining of Peyer's patch M cells by Ulex europaeus agglutinin 1 was absent on the caecal patch follicle-associated epithelium. These altered surface characteristics indicate that the development of the caecal patch follicle-associated epithelial cells is influenced by the local environment, and these altered properties may be indicative of modified functional roles for the cells at this site.