Mycotoxicosis caused by aerosolized T-2 toxin administered to female mice

Thymus, spleen, adrenal glands, and small intestine of female mice exposed to aerosolized T-2 mycotoxin were examined at postexposure hours (PEH) 0.25, 1, 2, 4, 6, 9, 12, and 24. Lymphocyte necrosis was observed at PEH 1 in the thymus, spleen, and lamina propria and Peyer patches of the small intestine. Necrosis of small intestinal crypt epithelial cells was observed at PEH 2, and necrosis of parenchymal cells and increased number of neutrophils were seen in sinusoids of the adrenal cortex at PEH 4. These results indicated that the earliest microscopic evidence of T-2 mycotoxicosis after aerosol exposure was necrosis of lymphocytes in the thymus, spleen, and lamina propria and Peyer patches of the small intestine.

Single and mixed infections of neonatal pigs with rotaviruses and enteroviruses: clinical signs and microscopic lesions

Neonatal colostrum-deprived pigs were inoculated with cell-culture preparations of three rotaviruses and three enteroviruses, singly or in combination. The three enteroviruses established intestinal and systemic infection but did not induce diarrhea or intestinal lesions. The three rotaviruses produced severe enteric disease characterized by profuse watery diarrhea, dehydration and death. Villi were severely stunted. All three isolates were equally virulent. Inoculation with three different rotavirus-enterovirus combinations resulted in disease less severe than that produced by the rotaviruses alone. Intestinal lesions were less extensive and fewer pigs became moribund or died.

T cell localization in rabbit models of acute and chronic experimental hypersensitivity pneumonitis

Cell-mediated hypersensitivity has been increasingly implicated in immunologic diseases of the lung, including hypersensitivity pneumonitis (HSP) (extrinsic allergic alveolitis). We used a T cell-specific monoclonal antibody (L11/135) to localize T cells in the parenchyma and bronchus-associated lymphoid tissue of ethanol-fixed, paraffin-embedded lung sections in rabbit models of experimental HSP to define further their possible role in pathogenesis. T cells appeared within 4 hours in early lesions of rabbit models of acute HSP and heavily infiltrated alveolitis lesions at 8 and 24 hours after aerosol challenge. T cells were also present in lesions of rabbit models with chronic alveolitis and occurred peripherally in granulomas. Variable aggregate and follicular forms of bronchus-associated lymphoid tissue rich in T cells occurred in both experimental and control animals. Our findings document early and continuing presence of T cells in lesions in rabbit models of experimental HSP.

Successive changes of the cellular composition in lymphoid organs of MRL-Mp/lpr-lpr mice during the development of lymphoproliferative disease as investigated in cryosections

To analyze the tissue distribution of lymphocyte subsets of autoimmune MRL/Mp-lpr/lpr mice, we have studied cryostat sections of the lymphoid organs at different stages of the disease using monoclonal antibodies directed against Ly 1 (MAb 53-7.3), Ly 2 (MAb 53-6.7), B 220 (MAb 14.8), and mu heavy chain (MAb b.7.6). We have observed an increase of a characteristic subpopulation of lymphocytes (Ly 1+ (dull), Ly 2-, B 220+, sIgM-), first seen at age of 8 weeks. In lymph nodes, these cells are first organized follicle-like with sIgM+ cells in the center. Later (20th-29th weeks), mu+ cells are found almost exclusively in small areas between the follicles. In the spleen, the cells first appear in the outer periarteriolar lymphatic sheath. Later, they are distributed within the follicles. sIgM+ cells disappear from the follicles; few remain within the marginal zone. In the thymus, some mice show a highly increased number of mu+ cells in the medulla. In Peyer's Patches, these Ly 1+ (dull) B 220+ cells are found predominantly in the interfollicular zone.

Immunoregulation in the Peyer's patch microenvironment. Cellular basis for the enhanced responses by the B cells of X-linked immunodeficient CBA/N mice

The Peyer's patches (PP) of X-linked immunodeficient (xid) CBA/N and hemizygous (CBA/N X DBA/2)F1 (CDF1) male mice contain a B cell subpopulation that expresses the Lyb-5 maturational marker and is responsive to type 2 and T cell-dependent antigens in vitro, a B cell phenotype which is absent from the spleens of xid mice. Experiments reported here show that xid spleen B cells co-cultured with B cell-depleted PP cells from xid mice differentiated into specific plaque-forming cells in response to trinitrophenyl-Ficoll (type 2) and sheep erythrocytes (T cell-dependent). Two cell types were involved in this normalization of xid B cell responses. An accessory cell activity present in the PP, but not the spleens, of both CDF1 male (xid) and CDF1 female (normal) mice was required for the response to either the type 2 or T cell-dependent antigens. In the presence of this PP accessory cell, T cells from the PP of either xid or normal mice supported responses to both classes of antigens. In contrast, T cells from the spleens of xid mice did not support the response to trinitrophenyl-Ficoll, although the splenic T cells from normal mice did synergize with PP accessory cells in allowing plaque-forming cell development by xid B cells to this type 2 antigen. The xid PP T cell activity required for the type 2 response by xid B cells was present in the Ly-1+, Lyt-2- subpopulation, and the xid PP accessory cell activity was provided by an enriched population of dendritic accessory cells. These results demonstrate the the lymphoreticular cells comprising the PP microenvironment provide effective support for the differentiation of xid B cells in response to type 2 and T cell-dependent antigens.

Cryptosporidiosis and the follicle-associated epithelium over the ileal Peyer's patch in calves

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.

Experimental disease in infant goats induced by a Mycobacterium isolated from a patient with Crohn's disease. A preliminary report

Pilot studies were done to assess the pathogenicity of a Mycobacterium which had been recovered from the diseased ileum of a patient with Crohn's disease. In four separate studies, pairs of infant goats served as subjects. One of each pair received an oral inoculum of freshly harvested Mycobacterium species strain Linda suspended in cream. A littermate or stablemate which received only cream served as control. Necropsies were done at three, five, six, and 10 months postinoculation. Each of the four inoculated animals developed segmental granulomatous disease of the ileum or ileum and more proximal segments of small intestine, and regional lymph nodes. The earliest lesion occurred in Peyer's patches of the ileum and consisted of granulomatous clusters of epithelioid cells and giant cells, without caseation, which often occurred in a mantle of lymphocytes between the germinal centers and the muscularis mucosae. Nine of 10 such granulomas were free of acid-fast bacilli. In more advanced lesions, there was confluence of granulomas and ulceration of the mucosal surface. Two of the four inoculated animals also had lymphocytic lymphangitis in affected segments. Although the Mycobacterium Linda was recovered from intestinal segments of all four animals, acid-fast bacteria were not demonstrable in the intestines in two of them. Control animals remained free of lesions and acid-fast bacilli and were negative by bacteriologic culture. The Mycobacterium species strain Linda represents an enteric pathogen capable of inducing granulomas of the distal small intestine of susceptible species. The lesions produced have distinct similarities to those occurring in Crohn's disease.

Gut-associated lymphoid tissue and 1,2-dimethylhydrazine intestinal tumors in the rat: an histological and immunoenzymatic study

The association between chemically-induced intestinal carcinoma and gut lymphoid patches was studied in 20 male Sprague-Dawley rats 7 months after the first of 16 weekly injections of 1,2 dimethylhydrazine (DMH). The lymphoid patches of DMH-treated rats and of 14 untreated control animals were systematically studied histologically on sections of "swiss-rolled" whole intestine. It was found that 78% of the small-intestine carcinomas and 73% of the colorectal carcinomas were associated with intestinal lymphoid patches. Furthermore, misplaced and often atypical glandular crypts were often found in the parafollicular or interfollicular areas of lymphoid patches, in treated as well as in control animals. These glands could be the origin of the lymphoid-patch-associated carcinoma. Immunohistological staining with monoclonal antibodies (MAbs) against T-lymphocyte antigens or anti-IgM serum labelling B lymphocytes clearly localized early carcinoma and atypical glands in the T-dependent, interfollicular and parafollicular area of lymphoid follicles. An MAb directed against la-antigen stained some well-differentiated carcinomas and some atypical glands found in control rats. On the other hand, lymphoid patches, when not invaded by a carcinoma, were not modified in their number, size, morphology or cellular composition in DMH-treated rats as compared to control animals.

Ileal Peyer's patches in experimental infections of calves with rotaviruses and enterotoxigenic Escherichia coli: a light and electron microscopic and enzyme histochemical study

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.

Response of Peyer's patch lymphocyte subsets to Giardia muris infection in BALB/c mice. I. T-cell subsets

Initial cellular events in the intestinal immune response occur within Peyer's patches and are subject to complex regulation by T cells. The aim of this study was to analyze the response of murine Peyer's patch T, T-helper (Th), and T-suppressor (Ts) cells to Giardia muris infection. Immunocompetent BALB/c mice were infected with G. muris cysts and, at serial times during the infection, Peyer's patch leukocyte suspensions were incubated with fluorescent monoclonal antibodies that identified murine leukocytes, T, Th, or Ts lymphocytes. These suspensions were examined by flow cytometry to quantify each T-cell subset as a percentage of total leukocytes. Total Peyer's patch leukocytes more than doubled in number during the course of G. muris infection and returned to control levels as the infection was cleared. The percentages of Peyer's patch Th and Ts lymphocytes were 34.1 +/- 0.8% (mean +/- SEM) and 6.2 +/- 0.3%, respectively, in the absence of infection, and did not change significantly during Giardia infection. The Th/Ts ratio in Peyer's patches was 5.6 +/- 0.2 in uninfected BALB/c mice and also did not change significantly during clearance of G. muris. We conclude that Peyer's patch leukocytes double in number in response to G. muris infection in immunocompetent mice, G. muris infection does not lead to altered percentages of Peyer's patch T, Th, or Ts lymphocytes, and clearance of G. muris infection is associated with a Peyer's patch Th/Ts ratio of greater than 5.

Response of Peyer's patch lymphocyte subsets to Giardia muris infection in BALB/c mice. II. B-cell subsets: enteric antigen exposure is associated with immunoglobulin isotype switching by Peyer's patch B cells

The aim of this study was to quantify the response of Peyer's patch B cells, surface IgA-bearing (sIgA) B cells, and surface IgM-bearing (sIgM) B cells to Giardia muris infection. Following infection of a cohort of immunocompetent BALB/c mice with G. muris cysts, Peyer's patch cell suspensions were prepared at serial time points during the infection, incubated with fluorescein-conjugated monoclonal antibodies directed against murine leukocytes, B cells, sIgA B cells, sIgM B cells, or T cells, and analyzed by flow cytometry. Of total Peyer's patch leukocytes, the percentages of B cells, sIgA B cells, and sIgM B cells in uninfected BALB/c mice were 64.7 +/- 2.0% (mean +/- SEM), 30.3 +/- 1.5%, and 52.5 +/- 2.4%, respectively. The total number of Peyer's patch leukocytes increased significantly (1.8 X) during G. muris infection, and returned to control levels as the infection was cleared. The percentages of Peyer's patch T and total B cells did not change significantly during Giardia infection. However, sequential changes were observed in the percentages and numbers of sIgM and sIgA B cells during the infection. Peyer's patch sIgM B cells rapidly increased in percentage and number, reaching maximum levels 1 week after cyst inoculation. After remaining constant the first week, the number of Peyer's patch sIgA B cells increased during the second week of G. muris infection, reaching a maximum level 11-14 days after cyst inoculation. The data support the hypothesis that immunoglobulin isotype switching in Peyer's patches is induced by antigen exposure.

Experimental pneumococcal otitis media: longitudinal studies in the gerbil model

In order to ascertain that the Mongolian gerbil, Meriones unguiculatus, is an acceptable model for studying the development of chronic from acute otitis media, we used previously published methods for experimental otitis media in a longitudinal study of the acute disease and sequellae. The gerbil was found to be susceptible to as few as 30 viable Streptococcus pneumoniae type 3 cells, indicating that only a few viable pathogens are able to cause the disease. Untreated experimental infections with S. pneumoniae type 23 resulted in a mild, self-limiting disease with little permanent sequellae, while S. pneumoniae type 3 produced severe disease characterized by an acute phase of from 2 to 3 weeks, followed by the development of new bone formation and a vascularized granulation tissue which persisted throughout the 13-week study. Viable pneumococci could be recovered from the middle ears for only two weeks. We conclude that the gerbil is a useful model for otitis media.

Alterations of the intestinal mucosal block in ulcerative colitis and Crohn's disease--immunological and ultrastructural findings, and considerations of the pathogenesis

The intestinal mucosa is the very site of the chronic inflammatory lesion in ulcerative colitis (UC) and in Crohn's disease (CD). The lamina mucosa together with its own and associated cellular and humoral protective properties can be described as the mucosal block which is functionally related to the intestinal and systemic immune system. Deteriorations of this mucosal block probably are of pathogenetic significance in UC and CD. This paper will summarize observations on the systemic immune system and local immune phenomena and their possible relations to the tissue injury in the gut. An immunopathogenetic concept intends to explain the chronicity of the diseases: epithelial insufficiencies of the mucosal block are followed by strong antigenic intrusion and stimulation of the local immune system with disturbance of the local immune homeostasis and the formation of immune complexes. The interactions of phagocytes with immune complexes cause the release of degrading lysosomal enzymes, which leads to continuous injury of the mucosal block and therefore to a perpetuation of the disease.

The shedding of viable cells into the local lymph by tumours growing in the gut of rats

Suspensions of syngeneic sarcoma cells were injected into the Peyer's patches of rats from which the mesenteric nodes had been removed. By later cannulating the thoracic duct of such rats it was possible to collect peripheral intestinal lymph that had come directly from the tumour bearing area without being filtered through a regional node. The number of viable tumour cells in the lymph coming from the tumours was monitored by culturing the whole lymph cells in a limiting dilution assay. The tumours grew to a diameter of approximately 1 cm in 25 days and during this time tumour cells were present in the lymph at a ratio of approximately 1 tumour cell per 10(5) lymph cells. In euthymic rats this number declined as the immune response developed. In athymic rats the number increased by approximately 10 fold during the experiments. It was concluded that the shedding of viable cells parallels the linear, not the volumetric dimensions of the tumour.

Acute lethal graft-versus-host disease stimulates cellular proliferation in Peyer's Patches and follicle associated ileal epithelium of adult rats

In this study cell proliferation in Peyer's Patches (PP) and the crypts of Lieberkuhn of the follicle-associated ileal epithelium was analyzed during the development of acute lethal graft-versus-host disease (GVHD) in adult rats. In addition, the effect of thymectomy on GVHD-induced lymphoproliferation was determined by analyzing the 3H-thymidine labeling index in neonatally thymectomized-control and thymectomized-GVHD rats. A significant increase in the 3H-thymidine-labeling index was found in interfollicular (days 2-7), dome (days 5-10), and follicular (days 5-12) regions of PP as well as in associated ileal crypts (days 5-12) of GVHD rats as compared with controls. Thymectomy altered the proliferative response in PP of GVHD rats in that incorporation of 3H-thymidine by follicular and interfollicular cells was significantly lower than in sham-thymectomized GVHD controls during the later stages of the disease. The results suggest a possible role for host thymus-dependent cells in stimulation of or participation in cell proliferation within follicular and interfollicular areas of PP.

Stress related involution of lymphoid tissues in Australian marsupial mice

Involution of the thoracic thymus in two species of marsupial mouse, Antechinus swainsonii (Waterhouse) and Antechinus stuartii (Macleay) was shown to be unrelated to corticosteroid action and to be complete before puberty. A stress response in male marsupial mice is caused by an androgen related drop in the plasma corticosteroid binding globulin concentration which gives rise to an increase in the plasma free glucocorticoid concentration. The high concentrations of free glucocorticoids in the plasma just prior to the breeding season causes a rapid involution of the spleen and lymph nodes while the gut associated lymphoid tissues remain unaffected. The concentration of free glucocorticoids also rises in females, but it never attains the high concentrations observed in males. Nevertheless, the spleen and lymph nodes do involute to some extent in some females and the degree of involution appears to be related to the relative concentration of plasma free glucocorticoids. At the conclusion of the breeding season, there is a complete mortality in males of the population, due to a stress response in which the compromised immune system clearly plays a role.

Effect of rotavirus and/or Escherichia coli infection on the aggregated lymphoid follicles in the small intestine of neonatal gnotobiotic calves

The effect of rotavirus and/or Escherichia coli infections on the follicle-associated epithelium (FAE or M cells) of the domes of the aggregated lymphoid follicles (ALF, or Peyer's patches) of gnotobiotic calves was evaluated by light, scanning electron, transmission electron, and immunofluorescence microscopies. Calf rotavirus (CRV) infection produced loss of FAE cell microvilli, and virions were observed in cytoplasmic vacuoles of FAE cells, as well as in intercellular spaces between FAE cells and lymphoid cells migrating through the dome epithelium. The CRV particles appeared to have entered the FAE cells by phagocytosis, with no subsequent cytoplasmic replication. Enterotoxigenic E coli (ETEC) induced more severe alterations including marked microvilli loss and ballooning in the FAE cells. There was no adhesion to, or colonization of FAE cells by ETEC, but bacteria were observed free or phagocytized within the dome and the germinal centers of the ALF. There were no ETEC observed in the cytoplasm of FAE cells. The presence of nonenterotoxigenic E coli (NETEC) in the intestine of calves had no effect on the intestinal FAE cells. The addition of NETEC to CRV infections did not enhance or modify in any way the response of FAE cells to the viral infection; however, the combination of CRV + ETEC produced severe necrosis of the FAE cells, and loss of dome epithelium of ALF.

Pathology of ochratoxicosis A in young broiler chicks

Ochratoxin A (OA), a potent nephrotoxin, was fed in the diet in sublethal concentrations (2 and 4 ppm) to broiler chicks for 20 days from hatch. Its effects on growth, relative organ size and histology of the liver, kidney and lymphoid organs were investigated. In young broiler chicks, OA caused a significant enlargement of the kidney, liver and proventriculus, whereas the thymus and bursa of Fabricius were reduced in size. It principally affected the proximal convoluted tubules of the kidney causing severe distension, enlargement and hypertrophy, and it also resulted in thickening of the glomerular basement membrane. In the liver, vacuolation and glycogen accumulation in the hepatocytes were seen. The toxin also caused regression of and a drastic reduction in the lymphoid cell population in the immunological organs. The toxicity of OA was found to be dose related.

Enteral and parenteral responses in mice after primary infection with Trichinella spiralis (Nematoda)

Enteral and enteral-parenteral infections were produced with T. spiralis in albino, Swiss Webster, outbred mice. Primary enteral infections abbreviated with thiabendazole stimulated inflammatory changes in Peyer's patches and the lamina propria of the small intestine of mice. These changes were accompanied by increased IgA in the intestinal luminal wash. Primary enteral-parenteral infections similarly stimulated the gut, and, in addition, the spleen. Splenic stimulation resulted in production of IgG1, and IgG2 antibodies specific for T. spiralis L3.

[Experience with double-contrast examination of the small intestine]

Experiences and results of 600 small bowel examinations in double-contrast technique are reported. Pathologic lesions were found in 40%. The double-contrast technique has proved to be an efficient method in detecting small bowel pathology. Its specific value lies in precise delineation of pattern, extent and intensity of disease.

The pathology of experimental Corynebacterium equi infection in foals following intragastric challenge

The intragastric inoculation of a suspension of Corynebacterium equi on five consecutive days induced severe ulcerative colitis, typhlitis, and lymphadenitis of colonic and cecal nodes in two ponies necropsied three weeks after infection. No gross lesions were observed in two ponies necropsied ten days after infection. A single inoculum of equivalent size failed to induce gross lesions in four ponies killed at ten or 20 days after infection. Microscopic lesions consistent with early C. equi infection of Peyer's patches were seen in two of the ponies killed ten days after infection. Only one small pulmonary abscess occurred in one foal, suggesting that intestinal lesions are not likely the usual precursor of pulmonary disease in naturally infected foals. The gross and microscopic lesions in the experimentally infected ponies were typical of the intestinal form of naturally occurring C. equi associated disease in foals.

[State of the small intestine in rabbits with salmonella infections]

The paper is concerned with the results of morphological and biochemical studies of the duodenum and ileum in young rabbits with salmonellosis. It was shown that all the parts of the small intestine were involved into the pathological process. Enzymopathy developed in the presence of acute catarrhal inflammation and erosive enteritis accompanied by ulceration of necrotized lymph follicles of Peyer's patches of the small intestine. The activity of maltase and alkaline phosphatase was found to be most vulnerable. Of crucial significance in the development of diarrhea in experimental young rabbits were pronounced morphological alterations and derangement of enzyme-forming function in the small intestine.

Pathology and diagnosis of mousepox

The pathologic changes of mousepox were studied during an outbreak at the National Institutes of Health in 1979. The most consistent lesions were necrosis of lymphatic tissues, especially the spleen, lymph nodes, and Peyer's patches. Hepatic necrosis and jejunal hemorrhage also were found. In two transmission studies, the disease was experimentally induced in BALB/cAnN and C3H/HeN-nu mice. Athymic mice were found to be highly susceptible, and they developed fulminant disease. The diagnosis was confirmed by demonstration of pox virions in infected tissues by electron microscopy, staining of viral antigen by immunoperoxidase methods, and by isolation of the virus in chorioallantoic membranes of hen's eggs and in cultures of chick embryonic cells.

Characterization of the (rnunz) nude rat. Morphological characteristics of the lymphoid system

A nude mutant (rnunz) arose spontaneously in a colony of Wistar albino rats (the wild-type strain) in Wellington, New Zealand. On gross examination no thymus could be found in the mediastina of young animals, whereas in older mutants lobules of fatty tissue mimicked the appearance of the thymus of the wild-type strain. Lymph nodes from the rnunz strain showed a marked lymphocyte depletion in the thymus-dependent para-cortical region of the node. Peyer's patches from the nude animals also showed a reduced density of small lymphocytes in the interfollicular zones. In the spleen, tissue from the reticular framework surrounding individual arterioles was sometimes completely empty of lymphocytes but the degree of depletion varied. Total leucocyte numbers in the rnunz strain were 28% lower than the wild-type strain. In 10 out of 13 animals T cells were less than 3% of the lymphocytes present (wild-type 35% T cells). The findings are in agreement with studies of the Rowett nude rat (rnu) and the nude mouse.

Globule leucocytes and Peyer's patches in lambs infected with coccidia

In a study of intestinal tissues from worm-free lambs experimentally infected with coccidia, the population of globule leucocytes was on average nine times higher in the mucosa overlying Peyer's patches than in the adjacent mucosa. Mucosal mast cell populations in the two areas were not significantly different. There was evidence of increased migration of globule leucocytes into the villus epithelium in response to coccidial infection.

[Features of the morphofunctional response of Peyer's patches in rats during the course of traumatic shock and the early post-shock period]

The reaction of Peyer's patches to trauma manifests in: 1) vascular changes; 2) primary or stressor cells shifts recordable in traumatic shock, characterized by depletion of patch follicles by minor lymphocytes; 3) secondary changes associated with the onset of reparative processes; 4) the increased macrophagal activity detectable during the entire period of the traumatic shock and in the early post-shock period. It is suggested that changes seen may be due to endotoxin that penetrates from the intestine.

Peyer's patches and the follicle-associated epithelium in diarrheic calves. Pathomorphology, morphometry and acid phosphatase histochemistry

Twelve 2–5-week-old calves affected with a spontaneous intestinal disorder were examined; 8 had diarrhea and 4 were convalescents. In all the affected calves the “pseudovilli” (syn. domes or lymphoid villi) over Peyer’s patches seemed atrophic and appeared enclosed within the mucosa, owing to fusion of ordinary villi with “pseudovilli”. Morphometric examination showed a decrease of lymphoid follicle length in the affected calves as compared with controls (P < 0.01). Convalescents showed longer follicles than diarrheic calves (P<0.05). Often cytoplasmic acid phosphatase of the follicle-associated epithelium (FAE) in affected calves did not show the marked basal-apical decrease along “pseudovillus”, typical of the controls. Scanning electron microscopy revealed sparse development of concentric folds in the luminal plasma membrane of the enclosed FAE, contrasting with their abundance in the normal FAE. Transmission electron microscopy showed that the “pseudovilli” had increased numbers of ordinary villous epithelial cells. Affinity of chlamydia for FAE was shown. It is suggested that the sparse occurrence of surface folds in the FAE and the change in acid phosphatase distribution indicate diminished endocytosis of antigenic material, probably resulting from the enclosure of “pseudovilli”. The atrophy of lymphoid follicles may be another expression of the probable decreased contact with the intestinal contents.

Ulcerative enterocolitis in dogs induced by drugs

An ulcerative enterocolitis was induced in dogs by two drugs; cinchophen given intravenously or indomethacin given orally. Ulcers were closely associated with Peyer's patches with either drug. Granulomata were occasionally seen in the mucosa and adjacent mesenteric nodes of dogs who received cinchophen. Transmural inflammation was seen only in some dogs who received indomethacin. A skip-like distribution of mucosal lesions was seen, induced by either drug and corresponding to the skip-like collections of lymphoid follicles. An explanation of the pathogenesis of these lesions is offered in the light of recent advances in the understanding of the immune response of gut-associated lymphoid tissue.

Cellular depletion in Peyer's patches after cyclophosphamide treatment in mice

The cytotoxic effects of cyclophosphamide (CY) in mice given by the intravenous route at the dose of 200 mg per kg of body weight, were investigated in Peyer's patches comparatively with peripheral blood and mesenteric lymph node as well as changes in the spleen weight. Peyer's patches are the sites of a more intense and durable cellular depletion than the mesenteric lymph node, observed as soon as day 1. A partial restauration of cell populations was observed from the 9th day, but even at day 21 their number remained lower than in control mice. Histological studies failed to show any germinal centre throughout the experiment; just a few cells were observed, 2 days after CY injection, in the interfollicular areas in which cells in mitosis were only seen at day 7. This preliminary results allow to study the role of the Peyer's patches as first barrier against penetration of an enteropathogenic bacteria able to invade the host tissues through the intestinal wall components after local or general acquired immunodeficiency.

Alterations of the thymus and peripheral lymphoid tissues in fatal measles. A review of 14 autopsy cases

As a result of re-examining 14 autopsy cases of fatal measles, neither aplastic nor hypoplastic thymuses were found even in a case with giant cell pneumonia, but there were degenerative and/or necrotic changes with giant cells mostly in the thymus and less in the peripheral lymphoid organs such as spleen, lymph nodes, Peyer's patches and tonsils. This damage of the lymphoid system was associated with the occurrence of complications, particularly of giant cell pneumonia and encephalitis. The lymphoid cell damage, which might be primarily due to virulence of the infected measles virus, seemed to prolong the viremia. Involvement of viremia in the process of complication is discussed.

Immunotherapeutic trials of murine and guinea-pig solid tumors by oral administration of BCG

Efficacy of oral administration of BCG on the growth of various tumors in mice and guinea pigs was studied. The growth-inhibitory effect varied depending on the tumor systems and the experimental conditions. Weekly oral administrations with 5-mg doses of BCG to mice or 80-mg doses of BCG to guinea pigs were ineffective on syngeneic mouse melanoma B16 or syngeneic guinea pig hepatocarcinoma line-10 but effective on syngeneic mouse carcinoma IMC and syngeneic guinea-pig fibrosarcoma H9A. Oral BCG seemed effective also on allogeneic mouse carcinoma Ehrlich, developed with a relatively small size of tumor cell inoculum, and on guinea-pig syngeneic liposarcoma H10. On Ehrlich tumors, oral BCG given once a week seemed to have better effects than did oral BCG given twice a week or subcutaneously once or repeatedly; heat-killed BCG given orally showed no effect. However, it seems premature to draw a definite conclusion on the efficacy of oral BCG on Ehrlich and H10 tumors, because some of these tumors regressed spontaneously even in nontreated control animals. The host responses to oral BCG were studied with the following results. Weekly oral administration with 80-mg doses of BCG to guinea pigs elicited positive skin reactions to 25 TU PPD in about 65 days after the first BCG, while a single sc injection of 8 mg of BCG did so within 10 days. Orally administered BCG organisms were recovered largely from Peyer's patches, a little from the mesenteric lymph nodes, and very little from the liver and the spleen. The BCG distributive pattern was in reverse order when BCG was given subcutaneously. Histologic examinations of Peyer's patches indicated enlargement of germinal centers, in which primitive reticular cells proliferated prominently and the macrophages with tingible bodies scattered frequently.

Relationship between lymphocyte emigration and vascular endothelium in chronic inflammation

Small blood vessels within areas of chronic inflammation which contain large numbers of lymphocytes develop unusually thick walls. Combined histological and electron microscope study shows that the thickening is due to hypertrophy of endothelial cells which come to resemble the endothelium of post-capillary venules in lymphoid tissue. Vessels of this type have been found in experimental granulomas induced by injection of Freund's adjuvant or killed tubercle bacilli and in human biopsy material from cases of rheumatoid arthritis and Hashimoto's disease of the thyroid. Comparison with the developing Peyer's patch in young rats shows that the unusual vessels in granulomas are very similar in endothelial cell size, pattern of distribution, extent of lymphocyte migration and degree of carbon leakage to post-capillary venules of the immature Peyer's patch. Study of the time at which lymphocytes appear in large numbers within the granuloma or developing Peyer's patch and the time at which thickened vessels are first seen suggest tha the endothelial changes are a consequence and not a cause of lymphocyte emigration. The stimulus to endothelial hyperthrophy appears to be massive sustained migration of lymphocytes, but the functional significance of this change in vascular structure is not clear.

Corynebacterium equi enteritis in foals

Corynebacterium equi is a pathogen associated with respiratory disease in the foal. This paper discusses two cases of Corynebacterium equi infection, one acute and one chronic, in which the major damage was intestinal. Necrosis of Peyer's patches was the only lesion seen in the small intestine of both foals. The foal with acute disease had distinct green-tan focal necrosis and thickened mucosa of the large intestine. In the foal with chronic disease, the mucosa of the large intestine was thickened, rugose, and mottled red-tan. Histologically, the predominant lesions were villous atrophy, mucosal necrosis, mesenteric lymph node necrosis and large numbers of periodic acid Schiff (PAS)-positive macrophages filled with gram-positive pleomorphic bacilli. Electron microscopy of intestinal mucosa showed bacilli undergoing binary fission in macrophages and bacilli free in the lamina propria.

Feline Panleukopenia. I. Pathogenesis in germfree and specific pathogen-free cats

Germfree and specific pathogen-free cats were inoculated panleukopenia vivus. Total leucocyte counts decreased significantly in both germfree and specific pathogen-free cats. Clinical illness was not seen in any germfree cat. Specific pathogen-free cats had anorexia and slight diarrhea 5-6 days after inoculation. None of the cats died. Both germfree and specific pathogen-free cats had thymic involution. No other gross lesions were seen. Tissues for histological virus isolation and immunofluorescence studies were taken daily from days 2 through 6 after inoculation. Virus-infected cells and lesions of panleukopenia were seen in the small intestine of both germfree and specific pathogen-free cats. The incidence of virus-infected cells and lesions was greater in specific pathogen-free cats than in germfree cats.

Lymphoid depletion in ileal loops: mechanism and clinical implications

Recent long-term follow-up studies of children undergoing ileal loop urinary diversion have shown a number of complications arising in these patients: recurrent urinary tract infections, deteriorating renal function, and late midloop stricture. We suggest that all three may be related to the same underlying problem, namely, a severe depletion of lymphoid elements in the intestine. In both clinical and animal studies urine exposure to intestinal segments resulted in a marked depletion of lymphoid elements from the Peyer's patches and from beneath the intestinal villi in the intestine. In addition there was an associated hypertrophy of the lymph nodes in the ileal loop mesentery. When the intestine was no longer exposed to urine, there was a prompt regeneration and reappearance of the lymphoid elements. The lymphocytes seemed to "home in" on the submucosal areas and reform Peyer's patches once the urine was removed. The hyperplastic lymph nodes in the ileal loop mesentery regressed when urine exposure was removed. Conventional treatment of ileal loop infections focuses on the upper urinary tracts. Mid-loop stenoses are treated by resection and creation of a new ileal loop conduit. Local therapy in the form of antibiotics and/or steroid enemas may relieve some late midloop obstruction and prevent further damage to renal parenchyma.

Non-endemic Burkitt's lymphoma. A B-cell tumor related to germinal centers

To investigate the nature of non-endemic Burkitt's lymphoma, we examined neoplastic cells from eight American patients for receptors for sheep erythrocytes (E), complement (EAC), and Fc fragment of lgG (igGEA), and for surface immunoglobulins (Slg) and hydrolytic enzymes. In addition, we reviewed 47 biopsies and 17 autopsies from American patients to ascertain patterns of involvement by tumor in lymph nodes, spleens and Peyer's patches. Neoplastic cells in all cases studies bore monoclonal surface immunoglobulins of the igM class. Receptors for EAC and igGEA were identified on a minority of the cells. Little or no hydrolytic enzyme activity was demonstrable. These results indicate that, like Burkitt's lymphoma in Africans, this histologically identical tumor in American patients consists of B lymphocytes. In 10 biopsies and two autopsies, germinal centers were selectively involved by tumor, suggesting that these neoplastic cells may be related to some B lymphocytes of normal germinal centers.

Lymphoid tissue and lymphoid-glandular complexes of the colon: relation to diverticulosis

The lymphoid tissue of the normal colon is compared with that of colons with diverticular disease. Colons with diverticular disease show a significant increase in the number of lymphoid nodules in areas not containing diverticula. Lymphoid-glandular complexes of the colon were studied in relation to diverticular disease. It is suggested that the lymphoid nodules and the lymphoid-glandular complexes of the colon constitute weak points in the bowel wall and may play a part in the pathogenesis of diverticula.

Swine dysentery: pathogenicity of Treponema hyodysenteriae

When pure cultures of Treponema hyodysenteriae were orally inoculated into pigs, severe disease characteristic of swine dysentery developed. Less severe lesions were produced by oral inoculation of infective minced colon. Noninoculated pigs were used as controls. Inoculations of surgically isolated porcine colonic loops with either pure cultures or infective minced colon produced lesions only in the injected loop; the adjacent noninjected colon remained normal. Pigs and other experimental animals, including rabbits, guinea pigs, and mice, inoculated with washed cultures by various parenteral routes remained normal.

Lymphoid cell necrosis, thymic atrophy, and growth retardation in newborn mice inoculated with murine cytomegalovirus

During studies on the effect of murine cytomegalovirus on the developing retina, virus was inoculated into the eyes of newborn Swiss mice, and the animals were sacrificed at various times thereafter. Controls consisted of mice inoculated with ultraviolet-inactivated murine cytomegalovirus and uninjected mice. Marked lymphoid cell necrosis, thymic atrophy, pronounced growth retardation, bacteremia, and death occurred in the animals inoculated with live virus. this virus-induced injury resulted in a marked depletion of lymphocytes in the subcapsular and cortical areas of the thymus as well as in the spleen, lymph nodes, and Peyer's patches. Areas of necrosis with viral inclusions were present at the site of inoculation and in various other organs including the spleen and bone marrow. Since growth retardation has been associated with thymic atrophy due to other causes, the observed abnormal physical development in the present study was interpreted as a sequel to the thymic injury. An implication of this study is that some human infants with concomitant immune deficiency and viral infection may have a primary viral disease with resultant secondary lymphoid tissue alterations, rather than a thymic disorder with a subsequent viral infection.

Virus-initiated septic shock. Acute death of Venezuelan encephalitis virus-infected hamsters

Hamster hematopoietic and lymphatic organs were studied sequentially by light and electron microscopy following Venezuelan encephalitis virus inoculation. In addition to extensive marrow and splenic necrosis nearly transmural necrosis of the ileum in Peyer's patch areas, with concomitant bacterial overgrowth, was noted. Viruses were observed ultrastructurally in reticular cells of Peyer's patches. In addition, bacterial blood cultures, consistent with an enteric origin, were generally positive in late stages of the infection. Reticuloendothelial function, measured by clearance of colloidal carbon, was significantly depressed in Venezuelan encephalitis virus-infected hamsters. It is proposed that the acute death of hamsters infected with Venezuelan encephalitis virus may be determined by the development of an endotoxic shock syndrome mediated by the extensive ileal lesions, coupled with impaired reticuloendothelial detoxifying function.

Pathogenecity of Yersinia enterocolitica for mice

A laboratory infection of Yersinia enterocolitica in mice which closely resembles the naturally acquired human infection is described Intravenous inoculation of mice with small numbers of Y. enterocolitica gives rise to a systemic, pyogenic infection involving primarily the spleen, liver, and lungs. Massive neutrophil infiltration of these organs occurs early in the infection, eventually leading to large abscesses and pulmonary consolidation. Mice infected intragastrically show neutophil infiltration in the Peyer's patches of the distal ileum less than 24h postinfection. The Peyer's patches are unable to contain the infection which spreads to the mesenteric lymph node, causing large abscesses in the medullary regions. Soon after, the infection becomes systemic with abscesses forming in the liver, spleen, and lungs, and the total peripheral leukocyte count rises dramatically to over 30,000/mm2. A serological response, in the form of agglutinating antibody, begins to appear 2 weeks after infection. Possible causes of death and the usefulness of this infectious disease model are discussed.