Intestinal immunity : The role of intraepithelial lymphocytes

Ferguson, Anne (1973) Intestinal immunity : The role of intraepithelial lymphocytes. PhD thesis, University of Glasgow.

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Abstract

The mammalian small intestine is lined by a columnar epithelium, the orderly arrangement of which is interrupted by the presence within it of many intraepithelial lymphocytes, In this thesis the nature and possible functions of these intraepithelial (IF) lymphocytes have been investigated in two ways, by morphological examination and quantitation of human jejunal IF lymphocytes, and by a series of experiments in mice. Human small intestinal IF lymphocytes resemble their counterparts in other species, both in their light microscopic and ultrastructural features. They are basally situated in the epithelium, lie between and not within the epithelial cells, and are frequently seen crossing the epithelial basement membrane. IF lymphocytes were quantitated in 200 routinely processed jejunal biopsy specimens, and the normal range of values has been established as 6-40 IE lymphocytes per 100 villous epithelial cells. Only in biopsies from patients with coeliac disease were the IE lymphocyte counts consistently higher than normal. The design and interpretation of experiments in mice were facilitated by the use of "antigen-free" loops of small intestine. These were prepared by transplanting foetal small intestine under the kidney capsules of adult mice of the same strain. Such grafts healed in, grew and had normal morphological appearances as assessed by light and electron microscopy, although they had never been exposed to intraluminal antigens, Thymus-dependent and thymus-independent IF lymphocytes, and IF lymphocytes specifically related to antigens within the gut, were identified by examination of small intestine from normal mice, germ-free mice and antigen-free grafts. In all these situations, normal and thymus-deprived mice were compared. These experiments showed that in the absence of intraluminal stimulation by antigens normally present in the gut there were profound effects upon all the intestinal lymphoid tissues. Antigen deprivation had a profound effect on the IF lymphocytes, whose numbers were considerably reduced in germ-free and antigen-free gut when compared with normally sited gut of the same age. In addition, the consistent findings of low IF lymphocyte counts in thymus deprived animals demonstrated that there were both thymus-dependent and thymus-independent IF lymphocytes; thymus-dependent lymphocytes formed a relatively greater proportion of the total in young animals and in germ-free/germ-free mice. Antigen deprivation had similar effects on Peyer's patches, which contained both thymus-dependent and thymus-independent lymphocytes, were small in germ-free and antigen-free gut, and which lacked germinal centres in both of these situations. From these observations, it has been tentatively concluded that, in the normal small intestine, immune responses to commensal gut bacteria may be mediated by thymus-independent lymphoid tissue, whereas in young or germ-free mice, thymus-dependent lymphocytes are involved in the immune responses to non-living, dietary antigens. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: R G White
Keywords: Immunology
Date of Award: 1973
Depositing User: Enlighten Team
Unique ID: glathesis:1973-74174
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 23 Sep 2019 15:33
Last Modified: 23 Sep 2019 15:33
URI: http://theses.gla.ac.uk/id/eprint/74174

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