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N MacIntyre

Publications and source records attributed to N MacIntyre.

23 records · Page 2Linked to original sources
PubMed1992

Phenotypic analysis of lymphocyte populations in the lungs and regional lymphoid tissue of sheep naturally infected with maedi visna virus.

We have analysed the phenotype of lymphocytes in lung and regional lymph node of symptomatic and asymptomatic sheep infected with the ovine lentivirus, maedi visna virus (MVV). Compared to equivalent tissues from age-matched, non-infected controls, MVV-infected sheep show increased numbers of lymphocytes in the lung, both in the bronchus-associated lymphoid tissue (BALT) and in the alveolar septae. Both CD8+ and CD4+ T lymphocyte numbers in alveolar septae were increased, particularly in animals with clinical respiratory disease. The ratio of CD8+ to CD4+ lymphocytes was similar to that in normal lung. In both MVV-infected and uninfected animals a high proportion of pulmonary lymphocytes, particularly in the alveolar septae, did not express the CD5 antigen, suggesting that they were activated. The number of activated cells was higher in infected sheep. Variable numbers of alveolar macrophages containing MVV-core protein were present in alveolar lumina, the majority of positive cells showing morphological evidence of activation. In regional lymphoid tissue there were increased numbers of CD8+ and gamma delta expressing T cells in lymphoid follicles and germinal centres of infected animals. The specificity of these cells is unknown and we could find no evidence for the presence of cells productively infected with the virus in these structures. This study shows that activated T lymphocytes, particularly of the CD8 subset, play a major part in the pathogenesis of MVV-induced pulmonary and regional lymph node lesions.

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PubMed1992

Immunocytological responses in porcine proliferative enteropathies.

The ileum, colon, and mesenteric lymph nodes of pigs naturally affected by either of the two major forms of proliferative enteropathy, namely, intestinal adenomatosis or hemorrhagic enteropathy, were examined for immunocytological responses to infection by immunocytochemistry, using antibodies directed against elements of the porcine immune system. In both forms, there was mucosal proliferation of immature enterocytes which lacked substantial major histocompatibility complex class II expression and a marked accumulation of immunoglobulin A (IgA) at the apical cytoplasm of affected enterocytes in association with intracellular Campylobacter-like organisms. In intestinal adenomatosis, there was only a mild infiltration of CD8+ and CD25+ T cells in the intestinal lamina propria. In hemorrhagic enteropathy, there was a moderate infiltration of CD8+ and CD25+ T cells and IgM+ B cells in the lamina propria. In rats and humans, villous enterocytes are thought to act as antigen-presenting cells, with major histocompatibility complex class II molecules present on their surface, capable of initiating a T-cell response (particularly of CD8+ T cells) in response to bacterial antigens. Therefore, the selection of immature crypt cells by the intracellular Campylobacter-like organisms for entry and multiplication may represent a remarkable microbial adaptation associated with local immunomodulation and enhanced bacterial survival. The accumulation of IgA within affected enterocytes may represent a reduced capability of the cells to process nonspecific IgA or an accumulation of specific IgA.

Animals↗
PubMed1989

Early lesions of proliferative enteritis in pigs and hamsters.

Gnotobiotic pigs and conventional hamsters were given suspensions of intestinal mucosa from a pig with proliferative hemorrhagic enteropathy and killed 10 or 21 days later. Affected animals had evidence of marked proliferation of immature enterocytes in the intestinal crypts. Numerous Campylobacter-like organisms were in the cytoplasm of enterocytes, and in some instances, bacteria were closely associated with enterocytes. Some intracellular bacteria lying below the microvillous border were within membrane-bound structures. Immunofluorescence and electron immunogold staining with specific antibodies indicated that these organisms were antigenically different from curved bacteria in the crypt lumen of early lesions. This study indicates that the life cycle of the intracellular organisms may involve entry into crypt enterocytes from the intestinal lumen with subsequent intracellular multiplication.

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PubMed1985

Demonstration of a new intracellular antigen in porcine intestinal adenomatosis and hamster proliferative ileitis.

In the proliferate enteropathies of the pig, intracellular Campylobacter-like organisms can be demonstrated in the apical cytoplasm of affected cells. A new antigen (omega) can be visualised at the site of bacterial parasitism using certain rabbit sera in a sandwich immunofluorescence test; the rabbit sera tested were largely derived from rabbits immunised with bacterial antigens including Campylobacter spp., but it appeared that the reaction was not related to the immunisation procedure and was also present in at least one "normal" rabbit serum. Rabbits immunised with bacteria extracted from the tissues sero-converted to omega-antigen yet did not react with Campylobacter spp., cultured from pig intestine. The omega-antigen was also present in the lesions of hamster proliferative ileitis.

Animals↗