Expression of gamma delta T cell receptor on caprine globule leukocytes

Globule Leukocytes and Other Mast Cells in the Mouse Intestine

Only 2 major mast cell (MC) subtypes are commonly recognized in the mouse: the large connective tissue mast cells (CTMCs) and the mucosal mast cells (MMCs). Interepithelial mucosal inflammatory cells, most commonly identified as globule leukocytes (GLs), represent a third MC subtype in mice, which we term interepithelial mucosal mast cells (ieMMCs). This term clearly distinguishes ieMMCs from lamina proprial MMCs (lpMMCs) while clearly communicating their common MC lineage. Both lpMMCs and ieMMCs are rare in normal mouse intestinal mucosa, but increased numbers of ieMMCs are seen as part of type 2 immune responses to intestinal helminth infections and in food allergies. Interestingly, we found that increased ieMMCs were consistently associated with decreased mucosal inflammation and damage, suggesting that they might have a role in controlling helminth-induced immunopathology. We also found that ieMMC hyperplasia can develop in the absence of helminth infections, for example, in Treg-deficient mice, Arf null mice, some nude mice, and certain graft-vs-host responses. Since tuft cell hyperplasia plays a critical role in type 2 immune responses to intestinal helminths, we looked for (but did not find) any direct relationship between ieMMC and tuft cell numbers in the intestinal mucosa. Much remains to be learned about the differing functions of ieMMCs and lpMMCs in the intestinal mucosa, but an essential step in deciphering their roles in mucosal immune responses will be to apply immunohistochemistry methods to consistently and accurately identify them in tissue sections.

Granule exocytosis of granulysin and granzyme B as a potential key mechanism in vaccine-induced immunity in cattle against the nematode Ostertagia ostertagi

Ostertagia ostertagi is considered one of the most economically important bovine parasites. As an alternative to anthelmintic treatment, an experimental host-protective vaccine was previously developed on the basis of ASP proteins derived from adult worms. Intramuscular injection of this vaccine, combined with QuilA as an adjuvant, significantly reduced fecal egg counts by 59%. However, the immunological mechanisms triggered by the vaccine are still unclear. Therefore, in this study, the differences in immune responses at the site of infection, i.e., the abomasal mucosa, between ASP-QuilA-vaccinated animals and QuilA-vaccinated control animals were investigated on a transcriptomic level by using a whole-genome bovine microarray combined with histological analysis. Sixty-nine genes were significantly impacted in animals protected by the vaccine, 48 of which were upregulated. A correlation study between the parasitological parameters and gene transcription levels showed that the transcription levels of two of the upregulated genes, those for granulysin (GNLY) and granzyme B (GZMB), were negatively correlated with cumulative fecal egg counts and total worm counts, respectively. Both genes were also positively correlated with each other and with another upregulated gene, that for the IgE receptor subunit (FCER1A). Surprisingly, these three genes were also correlated significantly with CMA1, which encodes a mast cell marker, and with counts of mast cells and cells previously described as globule leukocytes. Furthermore, immunohistochemical data showed that GNLY was present in the granules of globule leukocytes and that it was secreted in mucus. Overall, the results suggest a potential role for granule exocytosis by globule leukocytes, potentially IgE mediated, in vaccine-induced protection against O. ostertagi.

Mast cell sarcoma with megakaryocytic differentiation in a calf

A case of mast cell sarcoma in a 5-month-old Holstein female calf is described. Macroscopically, enlargement of the spleen, lymph nodes, tonsils and kidneys was noted, and there were tumor masses in the neck region and on the pleura and peritoneum. The pericardium and uterine and ureter walls were also involved by tumor. Most neoplastic cells had eosinophilic granules, which were metachromatic and positive for naphthol AS-D chloroacetate esterase and tryptase, whereas smaller numbers of cells were positive for factor VIII-related antigen, a marker of megakaryocytes. Some of the predominant type of these tumor cells were found within the epithelia of the lungs, tonsils, gastrointestinal tract, liver, ureters, urinary bladder and uterus. Their normal counterparts were considered to be globule leukocytes.

Characterization of local immune response against lungworms in naturally infected sheep

This study describes the immunohistochemical and histochemical phenotypes of inflammatory cells in sheep lungs infected with lungworms. A total of 20 naturally infected sheep lungs were used. Protostrongylus spp., Muellerius capillaris, Neostrongylus linearis, and Cystocaulus ocreatus were the chief organisms determined from such lesions, which were of a chronic nature. All the lungs had many developmental stages of the parasites and a similar inflammatory response, which included numerous mast cells, eosinophils, T cells, B cells, dendritic cells, and macrophages. In the bronchial and interstitial tissues, the inflammatory cells were dominated by MHCII, CD1, CD4, CD5, CD14, CD21, IgM, and CD172a positive cells, whereas CD2 and WC1 positive cells were detected less. The data provided additional evidence that subsets of inflammatory cells were included within ovine lungs infected with lungworms; however, understanding the entire immune-response process and development of resistance to lungworms in sheep remain to be clearly elucidated.

T-cell mediated immune responses in calves primary-infected or re-infected with Cooperia oncophora: similar effector cells but different timing

Cooperia oncophora is the most prevalent intestinal nematode of cattle occurring in Western Europe. Primary infection with 100000 third stage infective larvae (L3) induces acquired immunity in a high proportion of the animals but there is little information on immunity against re-infection. In the current experiment, the contribution of the T-cell mediated immunity in protection against re-infection with C. oncophora was investigated in detail. Priming elicited long-lasting protective immunity that was evidenced by a significantly decreased worm burden and egg excretion in primed animals compared to challenge control animals. Lymphocyte proliferation tests with excretory/secretory products (ESP) of C. oncophora and with three distinct ESP fractions indicated an enhanced reactivity in primed animals and suggested that by fractionating of ESP we selected for proteins involved in protective immunity against re-infection with C. oncophora. Phenotypic analysis of T cell subsets at diverse anatomical locations revealed that the enhanced reactivity of lymphocytes from peripheral blood and lymph nodes of the infected animals coincided with a significantly increased frequency of CD4(+) cells at these locations but a deceased frequency of CD4(+) cells in the lamina propria. These findings were independent of the immune status of the animals but more pronounced in the primed animals than in the challenge control animals. In addition we demonstrated that primary and secondary infections with C. oncophora were associated with two waves of eosinophils and that the kinetics of this cell population differed as a result of priming. Based on the observed correlations we propose that the early increase of eosinophils is T cell independent and merely a consequence of inflammation in the parasitised gut. In contrast, the second wave of eosinophils depends upon CD4(+) cells and correlations with parasitological parameters at this time point support a role of eosinophils as effector cells against adult stages of C. oncophora.

Large granular lymphocytes in the oviduct of developing and hormone-treated chickens

1. In the present study the distribution of large granular lymphocytes (LGLs) and influence of oestrogen on these cells was investigated in the oviduct of chickens by the observation of H and E stained sections. 2. The LGLs first appeared in the oviduct at 9 weeks and their frequency of occurrence increased with age and was highest in the infundibulum and vagina from 21 to 32 weeks of age. The frequency of occurrence of LGLs from magnum to uterus (glandular part) was low. These cells were located at the base, middle and apical parts of the lining epithelium as well as in the sperm-storage glandular epithelium. 3. When chickens of 21 weeks were treated with DES, LGLs abundantly infiltrated in the oviducal epithelium in comparison to the control. 4. These results suggested that the development of LGLs in the oviduct of chickens correlates with oestrogen secretion.

Small intestine large granular lymphoma in a horse

A 12-year-old Appaloosa gelding was referred to the Texas Veterinary Medical Center with a history of chronic diarrhea and weight loss. At necropsy, numerous oval, craterlike ulcers were observed throughout the small intestine. Histologically, these lesions were composed of a neoplastic proliferation of round cells with intracytoplasmic phosphotungstic acid-hematoxylin-positive granules. The tumor cells stained positively for the CD3 antigen and negatively for a B-cell marker. A diagnosis of large granular lymphoma was based on the morphologic and immunohistochemical characteristics of the neoplasm. The postmortem presentation of this case depicted unusual multifocal, ulcerative lymphomatous lesions throughout the small intestine without involvement of the regional lymph nodes. The histologic and ultrastructural morphology of the neoplastic lymphocytes was similar to that in previously reported cases of abdominal equine large granular lymphomas, but in this case the neoplasm was restricted to the small intestine.

Kinetics of IL-2 receptor expression on lymphocyte subsets from goats infected with Mycobacterium avium subsp. paratuberculosis after specific in vitro stimulation

Quantification of surface IL-2R expression on activated lymphocytes by flow cytometry have recently been reported to be useful in measuring cellular immunity against Mycobacterium avium subsp. paratuberculosis in goats (Whist et al., 2000, Vet. Immunol. Immunopathol. 73, 207-218). To characterise the phenotype of the peripheral lymphocytes expressing IL-2R after in vitro stimulation with purified protein derivative (PPD) from M. a. paratuberculosis, cells were processed for dual or triple colour analysis by flow cytometry (CD4 and IL-2R or CD8, gammadelta-TcR and IL-2R). To distinguish the response of antigen-specific T cells from non-specific stimulation, we performed a time-course study of proliferating cells in a group of M. a. paratuberculosis-infected animals and a control group. Following in vitro stimulation with PPD of whole blood for three different periods of time, IL-2R expression was detected mainly not only in gammadelta-T cells, but also in CD4+ and CD8+ T cells. We found a specific response of gammadelta-T cells from infected animals after 24h of stimulation. Following 120h of stimulation, however, gammadelta-T cells from control animals up-regulated IL-2R to the same level as those from infected animals, indicating either a non-specific stimulation or activation due to a first line of defence against Mycobacterium antigens. The CD4+ cells showed a specific response to PPD stimulation at all three time points. A minor population of antigen reactive gammadelta+ cells also expressed CD8. The proliferative responses differed between alphabeta and gammadelta-T cells; the IL-2R+ alphabeta T cell population mainly comprised proliferating cells, while the gammadelta+ population showed less expansion.

The immunobiology of gastrointestinal nematode infections in ruminants

The major gastrointestinal nematode parasites of ruminants all belong to the Order Strongylida and the family Trichostrongyloidea. Despite this close evolutionary relationship, distinct differences exist in the microenvironmental niches occupied by the developmental stages of the various parasites, which may account for the variable susceptibility of the different parasite species to the immune effector mechanisms generated by the host. In addition, different manifestations of resistance have been observed against the adult and larval stages of the same parasite species, and even against the same parasite stage. In particular, both rapid and delayed rejection of infective larval stages of gastrointestinal nematode parasites has been documented. This review will give an overview of the various manifestations of resistance to gastrointestinal nematode parasites of ruminants, as well as the immune mechanisms and antigens associated with the generation of immunity by the ruminant hosts to these parasites. In addition, a working model is provided aimed at reconciling most of the present knowledge on the different immune responses generated during infection with the various parasite rejection profiles. Extrapolation of these results to field conditions will need to take into account the variability imposed by seasonal changes and management practices, as well as the individual variability in immune responsiveness present in outbred animal populations.

Helicobacter pylori gastritis in cats with long-term natural infection as a model of human disease

A natural infection with Helicobacter pylori (H. pylori) in domestic cats (Felis cattus) less than 2 years of age has been well described in a closed colony of animals. Six cats from this colony that were serially evaluated by culture, polymerase chain reaction, and light and electron microscopy for a period of 3 years demonstrated persistent gastric colonization with a single cag(-) vac(+) strain of H. pylori. In these cats, as well as five other 5- to 6-year-old cats that were examined, a long-term infection resulted in chronic diffuse lymphofollicular atrophic gastritis with areas of mucosal dysplasia in the antrum and predominantly midsuperficial gastritis in the body and cardia. Topographically, the distribution of lesions was similar in both young and older cats and closely resembled that found in humans, with the most severe changes occurring in the gastric antrum. Few granulocytes and no significant elevation in mast cells were seen in older H. pylori-infected cats compared with uninfected controls; however, marked increases in interepithelial globule leukocytes and numerous active mucosal lymphoid follicles were present in infected animals. Indices of gastritis were significantly greater in older infected cats when compared with uninfected controls and younger cats (P < 0.05). The antral cell proliferation index of infected older cats was significantly (P = 0.021) greater than that of uninfected controls. Apoptotic indices of the gastric antrum and body of infected cats were significantly (P = 0.01) increased versus controls. Chronic infection with H. pylori in cats shares many features of long-term H. pylori infection in humans, including the development of preneoplastic processes. This similarity provides useful, comparative insights into host-pathogen interactions.

Eosinophilic gastroenterocolitis in iron lactate-overloaded rats

Eosinophilic gastroenterocolitis with peripheral eosinophilia was induced in rats fed a diet containing 2.5% or 5.0% iron lactate for 3 mo. Additional findings consistent with iron overload were also observed. Microscopically, the lesions consisted of eosinophilic infiltrations in the mucosa and submucosa along the whole length of the gastrointestinal tracts, increased surface area of the gastric mucosal propria covered with mucous cells, and increased apoptotic bodies in the gastric glandular neck of rats in the 2.5% and 5.0% groups. An increased number of intraepithelial globule leukocytes in the gastric and intestinal lamina propria was also observed in the 5.0% group. Globule leukocytes in the gastric mucosa contained obviously enlarged granules in their cytoplasm in these rats. The granules of the globule leukocytes were positive for rat mast cell protease II, suggesting the mastocyte origin of these cells. Although severe infiltration of eosinophils and globule leukocytes suggested a type-1 hypersensitivity reaction, other features such as an increasing vascular permeability were not detected. Serum IgE levels in the 5.0% and control groups were < 3 ng/ml. Final body weights of male and female rats of the 5.0% group were suppressed to 70% and 90%, respectively, of those of the control rats, whereas food consumption was comparable to that of the control group. The morphologic characteristics of the gastrointestinal lesions and peripheral eosinophilia induced in rats fed iron lactate were very similar to those in some cases of eosinophilic gastroenterocolitis in humans and other animals.

Perforin-like immunoreactivity in four cases of lymphoma of large granular lymphocytes in the cat

Tumors composed of discrete round cells with large eosinophilic granules in their cytoplasm were observed in four cats. These cats were presented with severe gastrointestinal signs, including anorexia, vomiting, and diarrhea. The exploratory laparotomy in two cats and necropsy in the other two revealed thickening and perforation of the intestinal walls, enlargement of the mesenteric, ileocolic, and/or colic lymph nodes, and splenomegaly. Histologically, there was severe and disseminated infiltration of the tumor cells in the affected organs. In the two cats necropsied, the spleen and the jejunal mucosa appeared to be the primary organs involved. The tumor cells of all the cats showed the pore-forming protein (perforin)-like immunoreactivity unique to the cytotoxic lymphocytes but failed to show histamine immunoreactivity. These results indicate that the tumor cells were derived from large granular lymphocytes and that perforinlike immunoreactivity may be a useful marker for histologic diagnosis of feline large granular lymphoma.

Lymphocyte subpopulations in the mammary gland of the goat

Mammary glands of pregnant, lactating and resting goats were studied by immunohistochemistry for lymphocyte subpopulations using a panel of monoclonal antibodies. All T lymphocyte subpopulations that may have a role in the immune response, CD2+, CD4+, CD8+ and gamma delta T cells and subsets, were present in the mammary gland and were noted to increase in number progressively during pregnancy, decrease significantly during lactation, and then moderately increase during the resting period. CD4+ cells, the predominant cell type in the mammary gland, were located mainly in the connective tissue, whereas CD2+, CD8+ and TcR1-N24+ cells were predominant in the intraepithelial areas. TcR1-N6+ cells were detected almost exclusively during pregnancy, being localized mainly in the connective tissue. Their proportion decreased markedly following parturition. Very few WC1-N3+ and -N4+ cells were detected in the mammary gland. It is suggested that the majority of gamma delta T lymphocytes in the mammary gland of the goat are CD2+ CD8+ WCl-, a distinctive subset from that of the WCl+ subset in peripheral blood.