The involvement of mast cells and mast cell proteinases in the intestinal response to equine cyathostomin infection

Cyathostomins (Cyathostominae) are regarded as the most pathogenic equine nematode worldwide. These nematodes are difficult to control in equine populations due to emerging anthelmintic resistance and evasion of encysted larval cyathostomins to regular modern anthelmintics. Mast cells and their proteinases have been shown to play a role in the mammalian immune response to nematode infections. Involvement of mast cells and mast cell proteinases in the equine immune response to cyathostomin infection is proposed. A technique was established to perform immunohistochemical staining using polyclonal rabbit anti-equine mast cell proteinase-1 (eqMCP-1) and anti-equine tryptase on formalin-fixed large intestinal sections, from horses classified as cyathostomin positive and negative at the time of death based upon larval enumeration. Quantitative analysis of antibody labelled mast cells was used to detect mast cell proteinases in equine large intestinal sections positive and negative for cyathostomin larvae. This demonstrated an increase in equine tryptase labelled mucosal and submucosal mast cells in cyathostomin positive horses. This study has established an immunohistochemical technique to demonstrate mast cell proteinases in formalin-fixed large intestinal sections. This technique may be used to determine possible involvement of mast cells and their proteinases in the equine immune response to cyathostomin larvae. Further studies are required to define a specific role.     

Large intestinal mast cell count and proteinase expression is associated with larval burden in cyathostomin‐infected horses

Reasons for performing study: Cyathostomins are the principal pathogenic nematode of equidae worldwide. In other species mast cell (MC) proteinases, in particular chymases, appear to have protective roles. Knowledge of the equine intestinal immune response to cyathostomins is limited. Objective: To investigate MC numbers and proteinase expression in equine cyathostomin‐infected large intestine. Hypothesis: MC populations in the large intestine are positively associated with cyathostomin burden and predominantly express chymase. Methods: The caecal cyathostomin burden of naturally infected horses (n = 25) was determined by luminal counts and pepsin digest (mural count). MC were identified and enumerated in caecal tissue using toluidine blue (TB). Immunofluorescent labelling with polyclonal rabbit antibodies was used to demonstrate expression of equine tryptase and the chymase equine mast cell proteinase‐1 (eqMCP‐1) in Carnoy's fixed caecal sections. Results: Significant positive linear relationships were found between TB‐stained mucosal and submucosal MC counts and total cyathostomin burden (P<0.001, r²>36%), and both luminal (P<0.010, r²>25%) and mural (P<0.001, r²>36%) larval counts. Similar relationships were found with mucosal and submucosal chymase and tryptase‐labelled MC counts (total: P<0.004, r²>29%; luminal: P<0.004, r²>30%; and mural: P<0.030, r²>19%). With all three MC labels, mean MC counts were higher in the submucosa compared to the mucosa (P<0.001). All caecal MC appeared to express chymase, with a small number of MC expressing both tryptase and chymase. Conclusions and potential relevance: Large intestinal MC counts are significantly associated with cyathostomin burden, with a predominance of chymase‐positive MC. The burden is significantly associated with expression of MC proteinases, supporting their likely involvement in the intestinal immune response to cyathostomin infection. Further work to investigate the kinetics of proteinase expression, the possibility of differential proteinase expression and the role of these MC proteinases is warranted.     

Molecular cloning of canine IL-13 receptor alpha chain (alpha1 and alpha2) cDNAs and detection of corresponding mRNAs in canine tissues

This communication reports the cloning of cDNAs encoding two canine IL-13 receptor alpha chains (caIL-13Ralpha1 and caIL-13Ralpha2). As described for the members of type-I cytokine receptors, both caIL-13Ralpha1 and caIL-13Ralpha2 were found to contain the highly conserved motifs, such as cysteine and tryptophan residues in their N-terminal portion and the WSXWS at C-terminus. The isolated caIL-13Ralpha1 cDNA contains 1547 nucleotides with an open reading frame that encodes 405 amino acid residues. Canine IL-13Ralpha1 is 82.0 and 69.3% identical to human and mouse IL-13Ralpha1s, respectively, at the amino acid level. Canine IL-13Ralpha1 has an almost identical cytoplasmic domain to its human and mouse counterparts. The isolated caIL-13Ralpha2 cDNA contains 1454 nucleotides and encodes an open reading frame of 386 amino acid residues. Canine IL-13Ralpha2 is 62.6 and 47.5% identical to its human and mouse counterparts, respectively, at the amino acid level. Using RT-PCR with caIL-13Ralpha1 and caIL-13Ralpha2 specific primers, mRNAs of caIL-13Ralpha1 and caIL-13Ralpha2 were detected in most dog tissues. In addition, RT-PCR detected caIL-13Ralpha1 mRNA in one of two canine mastocytoma (C2 but not Br) cell lines and in a canine macrophage-derived cell line (DH82). CaIL-13Ralpha2 mRNA was detected in all three canine cell lines.     

Serum antibody responses of cats to soluble whole cell antigens of feline Porphyromonas gingivalis

The whole cell soluble antigens of two strains (VPB 3457 and VPB 3492) of feline Porphyromonas gingivalis were analysed by Western blotting using serum taken from 40 domestic cats with various grades of periodontal disease. Five strongly immunogenic protein bands (70, 34, 27, 24 and 19kDa) from VPB 3457 and seven from VPB 3492 (58, 44, 34, 27, 25, 24 and 21kDa) were selected for further study. A significant positive correlation was found between the serum antibody response to the 70, 34, 27, 24 and 19kDa bands of VPB 3457 and the 58, 44, 25, 24 and 21kDa bands of VPB 3492 and the overall periodontal grade. A significant positive correlation was also found between the serum antibody response to the 24kDa band of VPB 3457 and the total colony forming units of P. gingivalis. N-terminal sequencing of the 44kDa band of VPB 3492 showed 75% identity with the translated amino acids from the hag A (haemagglutinin) gene of a human strain of P. gingivalis and N-terminal amino acid sequence of the 27kDa band of VPB 3457 showed 88% identity with the amino acid sequences translated from DNA of purported genes coding for variously named proteinases of human strains of P. gingivalis.     

Immunohistochemical and histochemical stains for differentiating canine cutaneous round cell tumors

Immunohistochemical and histochemical stains are useful adjunct techniques in the diagnosis of canine cutaneous round cell tumors, which can appear histologically similar. We applied a panel of monoclonal antibodies (recognizing tryptase, chymase, serotonin for mast cells; CD1a, CD18, MHC class II for histiocytes; CD3 for T lymphocytes; CD79a for B lymphocytes and plasma cells) and one histochemical stain (naphthol AS-D chloroacetate for chymase activity) to formalin-fixed, paraffin-embedded sections of canine cutaneous mast cell tumors, histiocytomas, lymphosarcomas, plasmacytomas, and unidentified round cell tumors. Of 21 tumors with a histologic diagnosis of mast cell tumor, 7/7 (100%) grade I, 6/7 (85.7%) grade II, and 3/7 (42.9%) grade III tumors were diagnosed as mast cell tumors based on positive staining for tryptase antigen and chymase activity. Mast cells were positive for both tryptase antigen and chymase activity, indicating equal efficacy of tryptase immunohistochemistry and chymase histochemistry. Chymase was detected immunohistochemically in both tumor and nontumor cells, while serotonin was not detected in most mast cell tumors, and thus, neither was useful in the diagnosis of mast cell tumors. Immunohistochemistry to detect CD18 and MHC class II was equally effective in staining histiocytomas, although lymphosarcoma must be ruled out through the use of CD3 and CD79a immunohistochemistry. Immunohistochemistry using three different monoclonal antibodies to human CD1a showed no cross-reactivity in canine histiocytomas and was not useful. A final diagnosis was obtained for 4/5 (80%) of the unidentified tumors, indicating the usefulness of multiple stains in poorly differentiated round cell tumors.     

Neospora caninum NcSRS2 is a transmembrane protein that contains a glycosylphosphatidylinositol anchor in insect cells

We investigated the terminal location of NcSRS2, a surface antigen of Neospora caninum that has potential use for diagnosis, and demonstrated its importance as a vaccine component against neosporosis, in an insect-baculovirus expression system. To examine the role of the hydrophobic C-terminal tail in NcSRS2, four types of recombinant baculoviruses were constructed. Immunoblotting and N-terminal amino acid analysis revealed cleavage of a 6 kDa of the N-terminal signal peptide in the mature NcSRS2 protein. The recombinant NcSRS2 (rNcSRS2) lacking 25, and 62 amino acids from the termination codon were detected in supernatants from recombinant virus-infected cells, but not in recombinants with truncated 147 amino acids from the termination codon, and intact NcSRS2 gene (401 amino acids). By flow cytometric and confocal laser scanning microscopic analyses, the truncation of the hydrophobic C-terminal tail in NcSRS2 was shown to result in the reduction of protein expression on the cell surface relative to intact rNcSRS2. Except for the recombinant lacking the 147 C-terminal residues, three other rNcSRS2 were detected in the supernatants after treatment with phosphatidylinositol-specific phospholipase C. Our results demonstrate that the N. caninum NcSRS2 is a transmembrane protein that contains a glycosylphosphatidylinositol-anchor molecule in insect cells, and that the hydrophobic C-terminal domain is an essential component for GPI-membrane attachment. We have likewise shown the usefulness of the insect-recombinant baculovirus system in the expression of rNcSRS2.     

Consequences of eicosapentaenoic acid (n-3) and arachidonic acid (n-6) supplementation on mast cell mediators

Mast cells are important players in the pathogenesis of atopic diseases. These cells release immediate-phase and late-phase mediators of inflammation. Fatty acids are incorporated in cellular membranes and therefore seem to influence mediator production and release. A study was conducted to assess the effects of eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (AA, 20:4n-6) on mast cell mediators in a canine mastocytoma cell line (C2). Cells were cultured in a basic medium (Dulbecco's modified Eagle's medium/HAM's F12 1 : 1, DEH), DEH supplemented with 14.0 microm EPA (DEH-EPA) or 14 microm AA (DEH-AA). The DEH-AA cultured cells had increased spontaneous and mastoparan-stimulated PGE2 production and histamine release. Furthermore, the tryptase activity was increased. The DEH-EPA cultured cells rendered elevated levels of PGE2 and histamine release compared with DEH only after stimulation. These levels were significantly lower in comparison to DEH-AA. The increased PGE2 production of C2 cultured in DEH-AA is the consequence of the AA enrichment, because AA is the precursor of PGE2. However, the different effects by AA and EPA on mast cell mediators possibly reflect the higher susceptibility of long chain polyunsaturated fatty acids (PUFA) to undergo lipid peroxidation, because it is known that altered cellular redox state influences mediator production and release.     

Mast cell mediated inflammatory response in chickens after infection with very virulent infectious bursal disease virus

The potential role of the mast cells in the invasion of very virulent infectious bursal disease virus (vvIBDV) is unknown. We evaluated mast cell activity and tryptase production after vvIBDV infection in special pathogen-free (SPF) chickens using cytochemistry and immunohistochemistry analyses. The results were as follows: (1) severe histologic lesions were observed in the thymus, spleen, cloacal bursa, liver, kidney and other tissues. vvIBDV viral antigens were detected and presented extensively in the parenchymatous organs, in particular, the cloacal bursa, liver, kidney, thymus, spleen and pancreas. (2) In the vvIBDV-infected group, the mast cell population increased markedly in the liver, kidney, thymus, glandular stomach, spleen and cloacal bursa on days 1, 2 and 3 after vvIBDV infection (p<0.05). However, very few mast cells were observed in those same tissues in the controls, especially in the bursa of Fabricius. (3) Tryptase, a marker for activated mast cells, has a positive correlation with mast cell distribution. The mast cells identified in the tissues were likely to be activated since they were associated with cell degranulation and the presence of tryptase. Furthermore, the co-localization of mast cells, and presence of vvIBDV antigens suggests that the mast cells were activated by vvIBDV infection. Our results also suggest that tryptase may contribute to the inflammation of acute IBD induced by vvIBDV infection. Our research contributes to the further understanding of inflammatory response mechanisms and the contribution of mast cell activity to this process.     

Molecular cloning and characterization of equine NK-lysin

NK-lysin is an antimicrobial peptide of cytotoxic and NK lymphocytes that has powerful antibacterial properties as well as antitumoral activity. Here we report the full-length cDNA and deduced amino acid sequence for equine NK-lysin. Equine NK-lysin is 67% identical to porcine NK-lysin, 53% identical to bovine NK-lysin and 41% identical to granulysin in amino acid sequence. Complete conservation of cysteine residues between equine, bovine and porcine NK-lysin suggests similar disulfide bonding patterns among these peptides. Equine NK-lysin has the most positive surface charge when compared with other homologues. Similar to expression profiles in other species, equine NK-lysin is constitutively transcribed in various lymphocytes that include CD4+ and CD8+ staining cells. These findings suggest that equine NK-lysin, similar in cDNA sequence to the porcine, bovine and human homologues may play a role in antimicrobial defense.     

Elevated extrahepatic expression and secretion of mammary-associated serum amyloid A 3 (M-SAA3) into colostrum.

Mammary-associated serum amyloid A 3 (M-SAA3) was secreted at highly elevated levels in bovine, equine and ovine colostrum and found at lower levels in milk 4 days postparturition. N-terminal sequencing of the mature M-SAA3 protein from all the three species revealed a conserved four amino acid motif (TFLK) within the first eight residues. This motif has not been reported to be present in any of the hepatically-produced acute phase SAA (A-SAA) isoforms. Cloning of the bovine M-Saa3 cDNA from mammary gland epithelial cells revealed an open reading frame that encoded a precursor protein of 131 amino acids which included an 18 amino acid signal peptide. The predicted 113 residue mature M-SAA3 protein had a theoretical molecular mass of 12,826Da that corresponded with the observed 12.8kDa molecular mass obtained for M-SAA3 in immunoblot analysis. The high abundance of this extrahepatically produced SAA3 isoform in the colostrum of healthy animals suggests that M-SAA3 may play an important functional role associated with newborn adaptation to extrauterine life and possibly mammary tissue remodeling.     

Characterization of mast cell numbers and subtypes in biopsies from the gastrointestinal tract of dogs with lymphocytic-plasmacytic or eosinophilic gastroenterocolitis

It has been suggested but not proven that hypersensitivity type I reactions are involved in the pathogenesis of canine inflammatory bowel disease (IBD). The main effector cells in type I hypersensitivity reactions are mast cells (MCs). Canine MCs, as human MCs, can be subdivided into three subtypes according to their content of mast cell-specific proteases: tryptase (MC_T), chymase (MC_C), or tryptase and chymase bearing MCs (MC_TC). In this study, numbers and subsets of mast cells were investigated in biopsies from the gastrointestinal tract of dogs with histopathologically confirmed lymphocytic-plasmacytic enteritis (LPE) (n = 4), lymphocytic-plasmacytic colitis (LPC) (n = 1) and eosinophilic gastroenterocolitis (EGE) (n = 11). Paraffin sections of formalin-fixed samples from the stomach, small intestine (duodenum, jejunum, ileum) and colon were stained by using a metachromatic staining method (kresylecht-violet; KEV) and a combined enzyme histochemical and immunohistochemical technique for chymase and tryptase. Additionally, immunohistochemistry with antibodies against T cells (CD3), macrophages (myeloid/histiocyte antigen) and IgA, IgG and IgM bearing cells was conducted. Quantitative evaluation of mast cells and semiquantitative scoring of immunohistochemically stained cells were performed. Between the two histopathologically defined groups clear differences concerning mast cell numbers were detected. In most affected intestinal tissue locations of dogs with LPE/LPC a decrease in metachromatically (kresylecht-violet) stained granule-containing MCs and immunohistochemically stained MC_T,C,TC was found. This reduction could be due to mast cell degranulation, a T helper cell 1 dominated reaction pattern or a “thinning out” due to increasing T cells, IgA and IgG bearing cells. Dogs with EGE displayed higher variability in mast cell numbers but most of the affected large and small intestinal locations had increased numbers of MCs. In these cases, T cells, IgA bearing cells and macrophages also increased. Increased numbers of MCs and eosinophils seen in the intestinal mucosa of dogs with EGE could indicate the presence of a type I hypersensitivity reaction (T helper cell 2 pattern) in response to dietary antigens. Changes in cell numbers occurred also in unaffected locations of dogs with LPE/LPC and EGE which showed reduced MC_T,C,TC, increased KEV positive cells and partially increased leucocytes and macrophages.     

Reduced mucosal injury of SPF chickens by mast cell stabilization after infection with very virulent infectious bursal disease virus

Recent studies here have demonstrated that increased mast cell populations and tryptase activity contribute to lesion formation in regions of immune organs in special-pathogen-free chickens after infection with very virulent infectious bursal disease virus (vvIBDV). Mast cells and their mediators have been implicated in acute inflammatory injury after vvIBDV infection, but their precise role in this process remains elusive. In this study, the role of mast cells in the vvIBDV infection process was examined using ketotifen, a mast cell membrane stabilizer. On days 1, 2, and 3 postinfection, the bursa of Fabricius (BFs) were collected to quantify mast cells, tryptase and histamine contents by cytochemistry, immunohistochemistry and fluorospectrophotometry analyses, respectively. The results showed that the mast cell populations, tryptase expression, and histamine released increased significantly in the BFs (p < 0.01) of infected birds compared to controls, and acute inflammatory responses were observed in the former. In contrast, in infected chickens pretreated with ketotifen, mast cells, tryptase, and histamine were markedly decreased (p < 0.01) and probably as a result, the BFs remitted significantly. The overall results suggest that mast cells are positively involved in BF injury induced by vvIBDV infection. Inhibition of mast cell degranulation and concurrent mediator release may represent a novel strategy to modulate this process. This study, thus, advances the understanding of the acute inflammatory injury mechanisms triggered by vvIBDV infection and the contribution of mast cell activity in this process.     

Canine TIMP-2: purification, characterization and molecular detection

Matrix metalloproteinases (MMPs), which degrade tissues in health and disease are under the control of the tissue inhibitors of MMPs, the TIMPs. TIMP-2 is particularly important for control of MMP-2 and both have been implicated in many pathological processes from arthritis to tumour invasion. This study characterized and detected TIMP-2 from canine cells; including synovial fibroblasts and three tumour-derived canine cell lines, K1, K6 and DH82. Gelatin zymography demonstrated that pro-MMP-2 is produced by synovial fibroblasts and the three cells lines. Reverse zymograms showed that all the cell sources tested secrete both TIMP-1 and TIMP-2. The 22 kDa band was purified and n-terminal amino acid sequencing showed it to be highly homologous to equine and human TIMP-2. Analysis of purified canine MMP-2 and MMP-9 showed that TIMP-2 is associated, and co-purifies with MMP-2. Polymerase chain reaction, using consensus primers, was used to detect TIMP-2 mRNA from the cell sources and proved positive in all cases. This work highlights the importance of TIMP-2 as the main inhibitor for MMP-2 and, therefore, opens the possibilities of targeting TIMP-2 for therapeutic intervention against connective amino acid tissue degradation in a range of diseases.     

绒山羊肥大细胞类胰蛋白酶的免疫组化及图像分析研究

[目的]探讨绒山羊肥大细胞中是否存在类胰蛋白酶及不同固定液对其常规染色和免疫组化染色结果的影响。[方法]采用兔抗羊肥大细胞类胰蛋白酶多克隆抗体间接免疫过氧化物酶技术检测由Carnoy液和中性福尔马林液(NBF)固定的绒山羊空肠、瓣胃和肺等组织肥大细胞中是否存在类胰蛋白酶。同时采用Image-ProPlus图像分析软件和人工计数法对结果进行分析,比较经常规染色和免疫组化染色后不同固定液固定组织中肥大细胞的形态及数量,进而判断Carnoy液和中性福尔马林液(NBF)对该检测技术的影响。[结果]兔抗羊多克隆抗体与绒山羊肥大细胞中的类胰蛋白酶具有良好的交叉反应,证实绒山羊肥大细胞胞浆颗粒中存在类胰蛋白酶。同时,与Carnoy液相比较,NBF液固定组织能较好地反映肥大细胞在组织中的数量和形态变化。[结论]绒山羊肥大细胞中存在类胰蛋白酶,且与Carnoy液相比较,NBF液是一种更为适合绒山羊肥大细胞常规染色和免疫组化染色的固定剂。     

Molecular cloning and sequencing of equine cDNA encoding serum amyloid A (SAA)

The serum amyloid A (SAA) protein is a characteristic and sensitive acute phase reactant in all vertebrates investigated. We molecularly cloned the equine cDNA encoding SAA from the liver of a healthy horse by polymerase chain reaction (PCR). The cloned cDNA is 480 bases in length, and contains an open reading frame (ORF) of 387 nucleotides encoding a precursor SAA protein of 128 amino acids. The precursor of horse SAA seems to have an 18-residue signal peptide and differs from the reported amino acid sequences of the horse SAA by substitution of valine at residue 81. It shows high homology with SAA amino acid sequence of other species such as dog (80.6%), mink (77.5%), human (76.9%) and duck (71.9%). An insertion of eight amino acids at residues between 85 and 92, as compared to human SAA, has also been found in horse SAA. The availability of the equine SAA cDNA will provide a useful reagent for studying its role in diseased horses.     

Characteristics of glycoprotein B of equine herpesvirus 1 expressed by a recombinant baculovirus.

A recombinant baculovirus (Bac-EgB) containing the complete open reading frame of equine herpesvirus 1 glycoprotein B (EHV-1 gB) expressed recombinant products of 107-133 kDa, 58-75 kDa and 53-57 kDa, corresponding to EHV-1 gB precursor, large and small subunits respectively. High molecular mass products (>200 kDa) in the Bac-EgB infected insect cells were consistent with oligomerisation of the recombinant EHV-1 gB products, and analysis with tunicamycin and endoglycosidases indicated that the baculovirus-expressed gB contained N-linked sugars with high mannose and hybrid chains. N-terminal amino acid sequence analysis of the gB forms revealed identical signal and endoproteolytic cleavage sites to those of gB in EHV-1 infected mammalian cells, and authenticity of processing and transport was supported by the presence of EHV-1 gB antigen at the surface of infected insect cells. Immunogold labelling and electron microscopy of recombinant baculovirus particles indicated that the recombinant gB was also present in baculovirus envelopes. Bac-EgB infected insect cells were able to induce low levels of complement dependent virus neutralising antibody, and have been shown to evoke protective immune responses in murine models of respiratory disease and abortion.     

Generation and characterization of bone marrow-derived cultured canine mast cells

Disorders of mast cells, particularly mast cell tumors (MCTs), are common in dogs. There now is evidence that many of these disorders exhibit breed predilections, suggesting an underlying heritable component. In comparison to humans and mice, little is known regarding the biology of canine mast cells. To facilitate the study of mast cell biology in other species, bone marrow-derived cultured mast cells (BMCMCs) often are used because these represent a ready source of large numbers of cells. We have developed a protocol to successfully generate canine BMCMCs from purified CD34(+) cells. After 5-7 weeks of culture with recombinant canine stem cell factor (rcSCF), greater than 90% of the cell population consisted of mast cells as evidenced by staining with Wright's-Giemsa, as well as production of chymase, tryptase, IL-8 and MCP-1. These cells expressed cell surface markers typical of mast cells including Kit, Fc epsilonRI, CD44, CD45 and CD18/CD11b. The canine BMCMCs were dependent on rcSCF for survival and proliferation, and migrated in response to rcSCF gradients. Cross-linking of cell surface-bound IgE induced the release of histamine and TNFalpha. Histamine release could also be stimulated by ConA, compound 48/80, and calcium ionophore. In summary, canine BMCMCs possess phenotypic and functional properties similar to mast cells found in vivo. These cells represent a novel, valuable resource for investigating normal canine mast cell biology as well as for identifying factors that lead to mast cell dysregulation in the dog.     

Hematopoietic prostaglandin D2 synthase in the chicken Harderian gland

The Harderian gland (HG), a sero-mucous secreting organ in the eye orbit, has long been recognized as immunologically important in chickens. During experimentation to characterize immune components of the gland, proteomics analysis revealed the presence of hematopoietic prostaglandin D synthase (H-PGDS). Extraction of total RNA followed by RT-PCR produced cDNA of 597 base pairs. DNA sequencing revealed nucleic acid and predicted amino acid sequences that were 99% aligned with the one published sequence for chicken H-PGDS of the spleen. Alignment with murine, rat, and human H-PGDS were 69, 69, and 66%, respectively. Ocular vaccination of chickens with a Newcastle Disease/Infectious Bronchitis vaccine (Mass.-Ark. Strain) induced an increase in H-PGDS expression determined by real-time PCR. Furthermore, immunohistochemistry of frozen HG sections showed positive stained cells for both H-PGDS and mast cell tryptase in the sub-epithelial cell layers of the HG ducts. Based on the potent vasoactive role of PGD(2), it appears that the chicken HG is a site of active mucosal immunity partially mediated by PGD(2) synthesized by H-PGDS in the gland.     

Feline intestinal sclerosing mast cell tumour: 50 cases (1997–2008)

This case series presents a unique and unreported variant of feline intestinal mast cell tumour recognized at the CSU Veterinary Diagnostic Laboratory. Fifty cases of feline intestinal mast cell tumours described as having a significant stromal component were reviewed. Neoplastic cells formed a trabecular pattern admixed with moderate to abundant dense stromal collagen (sclerosis). Neoplastic cells had poorly discernible intracytoplasmic granules which demonstrated metachromasia with special histochemical stains consistent with mast cell granules. Additionally, a subset of cases stained for mast cell-specific tryptase and c-kit demonstrated positive immunoreactivity. Eosinophilic infiltrates were moderate to marked in almost all cases. Lymph node and hepatic metastases were present in 66% of the cases. Treatment and clinical outcome was available in 25/50 cases. Twenty-three of these patients died or were euthanized within 2 months of initial diagnosis. This is the first case series to characterize a sclerosing variant of intestinal mast cell tumour in the cat which appears to have a high propensity for metastasis and a guarded prognosis.