Immunohistochemical localization of immunoglobulins in bovine granulomatous lesions

The immunohistochemical distribution of IgG, IgA and IgM in granulomatous lesions caused by Actinomyces bovis, Actinobacillus lignieresi, Actinomyces (Corynebacterium) pyogenes, Pseudomonas aeruginosa, Staphylococcus aureus and Mycobacterium bovis was studied. Numerous IgG-containing cells (plasma cells) were distributed in the peripheral connective tissue layers, but not in the epithelioid cell layer. A few scattered IgA- and IgM-containing cells were found in all the lesions examined. Mycobacterial granulomas contained fewer IgG-cells than did non-mycobacterial granulomas. Eosinophilic club-shaped bodies were found in A. bovis, A. lignieresi, P. aeruginosa and S. aureus, but they were generally negative for IgG, IgA and IgM.

Serological characterization of viruses isolated from experimental mucosal disease

Four cattle persistently infected with non-cytopathogenic bovine viral diarrhoea-mucosal disease (BVD-MD) virus and 3 normal controls were challenge exposed to cytopathogenic BVD-MD viruses that are antigenically different from the persistent viruses. Two of the persistently infected cattle developed mucosal disease and became moribund on postinoculation days (PID) 28 and 14, respectively; one developed severe and chronic diarrhoea and became moribund on PID 32; and the other remained healthy until the end of the experiment (PID 150). All control cattle showed transient fever, but no diarrhoea, and recovered from infection. Cytopathogenic viruses were isolated from blood of all cattle early in infection (PID 5-10) and from carcasses at necropsy. The former viruses were antigenically identical with the challenge viruses. On the other hand, the antigenicity of the cytopathogenic viruses isolated from carcasses at necropsy were different from that of the challenge viruses but similar to that of the non-cytopathogenic persistent viruses. Three of 4 persistently infected cattle, but not the calf which became moribund on PID 14, produced serum neutralizing (SN) antibodies to the challenge viruses, but not to the persistent viruses and the cytopathogenic viruses isolated from carcasses at necropsy. Control cattle produced SN antibodies to both the challenge and persistent viruses.

The distribution of ferritin, lactoferrin and transferrin in granulomatous lymphadenitis of bovine paratuberculosis

Immunohistochemical examination of iron-binding proteins was carried out in the formalin-fixed mesenteric lymph nodes of normal cattle and of cattle with paratuberculosis. Ferritin (FT) and lactoferrin (LF) were found in the granulomas in ileal lymph nodes from six infected cattle. A weak reaction for transferrin (TF) was found in granulomas of a lymph node from one of the infected cattle. FT was found in the macrophages in the medullary sinuses of normal and infected nodes; however, the reaction in infected nodes was generally stronger than that in normal ones. LF in the macrophages was found in only two infected nodes. Neutrophils in both normal and infected cattle always reacted strongly for LF. The TF was always found in the blood vessels and intracellular space. These results suggest that: (1) FT and LF may be important in vivo sources of iron for Mycobacterium paratuberculosis, since their own iron-binding compounds are considered to acquire iron from FT and LF in vitro; (2) the increase in FT and LF in the granulomas may be related to inflammatory hyposideraemia associated with paratuberculosis and (3) epithelioid and giant cells may have a different iron metabolism, from normal macrophages.

Role of M cells and macrophages in the entrance of Mycobacterium paratuberculosis into domes of ileal Peyer's patches in calves

Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti-M. paratuberculosis bovine serum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.

Immunohistochemical distribution of immunoglobulin and secretory component in the ileum of normal and paratuberculosis-infected cattle

The immunohistochemical distribution of IgA, IgG, IgM and secretory component in the ileum of 10 normal and 21 paratuberculosis-infected cattle was investigated. Semi-quantitative analysis of the number of each class of Ig-containing cells in the lamina propria mucosa of infected ileums showed that IgG and IgM-containing cells and total Ig-containing cells were significantly more numerous than those in the normal ileums. There was no significant difference in the numbers of IgA-containing cells between the two groups of cattle. The distribution of IgA, IgM and SC was basically similar in the two groups. However, IgG-containing cells characteristically accumulated around the granulomas. It was considered that excessive local production of Ig in the intestinal mucosa, along with subsequent formation of immune complex or release of histamine from mast cells, could account for the occurrence of diarrhoea and participate in the pathogenesis of bovine paratuberculosis. A comparison of the local immunological state in paratuberculosis and Crohn's disease was made.

Immunohistochemical distribution of ferritin, lactoferrin, and transferrin in granulomas of bovine paratuberculosis

Granulomatous lesions of bovine paratuberculosis contained ferritin, lactoferrin, and a small amount of transferrin, as demonstrated by the immunohistochemical method. Macrophages in the normal bovine ileum did not contain lactoferrin and transferrin; however, ferritin was found in individual macrophages of Peyer's patches. These results may help elucidate the relationship between intracellular growth of Mycobacterium paratuberculosis and the presence of iron-binding proteins in the granulomas.

Experimental subcutaneous granulomas in sheep with Dermatophilus-like microorganisms from porcine tonsil

The pathogenicity of the Dermatophilus-like microorganisms from porcine tonsil and the light and electron microscopic findings were studied with adult ewes. The early lesions were abscessess and advanced ones were granulomas after the subcutaneous inoculation. The granulomas were composed of the central bacterial colonies and the layers of the neutrophils, epithelioid cells and giant cells, and peripheral connective tissues. Epithelioid cells and giant cells were identified by the large euchromatic nuclei, abundant organelles and interdigitation of the blunt pseudopods in the ultrastructure. The lesions were very similar to subcutaneous granulomas in sheep and cattle due to Dermatophilus congolensis (atypical dermatophilosis), actinomycosis and nocardiosis.

Histopathological evaluation of disseminated intravascular coagulation in Haemophilus somnus infection in cattle

The frequency and distribution of fibrin thrombi (microthrombi) in the main organs of spontaneously infected cattle were investigated to evaluate disseminated intravascular coagulation (DIC) in Haemophilus somnus infection. This infection is well known as infectious thrombo-embolic meningo-encephalitis (ITEME) and is characterized histopathologically by formation of thrombi, necrosis of blood vessels and neutrophil infiltration. The precise pathogenic mechanism of this disease has not yet been fully elucidated. The liver, spleen, kidney, lung, heart and brain of 11 cattle showing thromboembolic meningo-encephalitis were examined histopathologically and special attention was paid to fibrin thrombi. PTAH staining showed a high frequency of fibrin thrombi in the small vessels and capillaries in more than 3 organs and all the cases were regarded as falling within the histopathological criterion of DIC. The results of the present study indicate that the pathogenesis of the infection is closely related to the DIC.

Granulomatous sub-dermal lesions in sheep inoculated with Dermatophilus congolensis

Dermatophilus congolensis was inoculated subcutaneously into 6 ewes and the resulting lesions were examined by light and electron microscopy. The organism was recovered from the subcutaneous lesions. The lesions were suppurative in the early stages and granulomatous in the advanced stage, but abscesses were the usual lesion observed. The granulomas were composed of several layers; central bacterial colony, neutrophil layer, layer of macrophages, epithelioid cells and Langhans and foreign body type giant cells with a periphery of connective tissue. Multiloculated granulomas were observed. Electron microscopic examination confirmed the cell types of the lesions. Epithelioid and giant cells were characterized by the shape and number of the nuclei and complex and abundant organelles. Interdigitations of the blunt pseudopodia of adjacent cells were also found. It is concluded that the organism can produce both granulomatous lesions and abscesses which differ from those of orthodox dermatophilosis but are similar to those described in "atypical dermatophilosis".

Morphology of experimental actinomycotic abscess in mice with Dermatophilus-like microorganisms from porcine tonsil

Experimental infection in mice with Dermatophilus (D.) congolensis-like microorganisms was carried out, intraperitoneally and subcutaneously. This strain had been isolated from porcine tonsil and reported to be different in some morphological and biological points from D. congolensis. Macroscopic examination revealed multiple abscesses in the peritoneal cavities, or subcutaneous abscesses after the intraperitoneal or subcutaneous injection respectively. Histopathologic examination revealed the characteristic arrangement of the neutrophils surrounding the bacterial colony and peripheral macrophages in the abscess lesions. The lesions contained many microorganisms which showed wide range of the characteristic morphologic variation such as: mycelial elements, coccoid elements and large coccoid elements with transverse or longitudinal septa. Chlamydospore-like elements were sometimes found in the microcolonies in early lesions. The morphology of the lesions and the microorganisms was compared with those of other bacteria including D. congolensis.

Morphologic evidence of the histogenesis of epithelial thymoma in a cow

Light and electron microscopic studies were performed on an epithelial thymoma obtained from a cow. Tumor masses were found in the cervical and dorsal mediastinal portions, in the hilus and parenchyma of the lung, on the surface of the kidney, and in a uterine horn. The masses were encapsulated and divided into distinct lobules or nodules by prominent trabeculae. Examination of the tumor cells by light microscopy showed squamous epithelial characteristics in both the eosinophilic granules and the periodic acid-Schiff-positive granules. Electron microscopic observations revealed that the tumor cells had intercellular microvilli, which appeared to be the interdigitations between the cells, tonofilaments, and desmosomes. A few of the tumor cells contained round vesicles which resembled the hypertrophic type of epithelial cells of a normal thymus. These findings indicated that the tumor originated in the thymus' epithelial cells.