Biomedical subjects

T Seabrook

Publications and source records attributed to T Seabrook.

3 recordsLinked to original sources

PubMed2006

Lymph, lymphocytes, and lymphatics.

This is a summary of recent developments regarding the role of the lymphatic system in immune responses. Emphasis is on physiological considerations from experiments in sheep. Cell- and tissue-specific lymphocyte traffic patterns measured over several days are considered. Particular attention is given to recent data on the relationship between the central nervous system and the lymphatic system, to cell labeling in situ, and to the entry of immune cells into afferent lymph from the interstitial tissues.

Animals↗

PubMed2001

Tissue specificity of lymphocyte migration into sheep gingival tissue.

T cells show a bias in their migration pathways: some migrate preferentially to peripheral lymph nodes, some to mucosal tissues and some to peripheral tissues such as skin. The aim here was to determine the types of T cells that migrate preferentially into inflamed gingival tissue and compare this migration to that found in inflamed subcutaneous and mucosal tissues. The experiments were designed so that the simultaneous 3 h localization of two, differentially radiolabelled, lymphocyte populations (subcutaneously and mucosally derived) into sites of purified protein derivative/bacillus Calmette-Guerin-induced, delayed-type hypersensitivity, inflammatory lesions in skin, bowel and gingiva in the sheep model could be compared. The relative migration of two populations in each of the tissues was expressed as a ratio of the radioactivity of intestinal/subcutaneous lymphocytes recovered from that tissue. From nine experiments, the ratios [mean+/-S.E.M. (n)] for skin, bowel and gingiva were 0.53+/-0.02 (84), 1.98+/-0.11 (85), and 0.73+/-0.05 (29), respectively. These findings suggest that inflammation in skin and gingiva favoured the localization of subcutaneously derived lymphocytes (ratio significantly <1, P<0.025), while in bowel, the localization of intestinally derived lymphocytes was favoured (ratio significantly >1, P<0.025). Statistical analysis demonstrated that the relative localization of the two lymphocyte populations to the gingival lesions differed significantly from that for inflamed skin and bowel lesions (P<0.05). When tumour necrosis factor-alpha was used as a non-antigenic inflammatory agent to induce lymphocyte migration into skin and gingiva, a similarly greater increase in the localization of subcutaneously derived lymphocytes was detected, but the relative localization of lymphocytes was not significantly different between the two tissues. Therefore, it appears that there is tissue specificity in the migration of lymphocytes into the inflamed gingival tissues and that antigen is required for distinct tissue-specific lymphocyte traffic to occur.

Analysis of Variance↗

PubMed1999

The traffic of resting lymphocytes through delayed hypersensitivity and chronic inflammatory lesions: a dynamic equilibrium.

This essay is designed as a partial summary of the work of several students and colleagues from our laboratory. For the most part the experimental data have been published and this seminar represents an attempt to summarize, integrate and speculate on this work. In some situations the speculation is rather unrestrained and it is hoped that it will provoke discussion, controversy and better future experiments. Reference is made to the original articles and to recent reviews. In addition, since we have had the advantage of reading the other contributions to this volume, there is considerable reference to other chapters. We and others have argued in other publications that it is imperative to understand the normal physiological traffic of lymphocytes before one can adequately interpret data describing lymphocyte migration through pathological tissues. It has been useful to compare data derived from traffic through lymph nodes because there is considerable information on the individual lymph node with respect to blood-lymphocyte delivery and blood flow, prenodal input via peripheral lymphatics and, particularly in sheep, in the numbers and phenotypic analysis of the lymphocytes exiting lymph nodes in postnodal or efferent lymph (see Young, this volume). We consider the terms prenodal for afferent and post-nodal for efferent to be synonomous. In this volume, a significant contribution has been made by Cahill et al which describes the astonishing degree of lymphocyte traffic which occurs in fetal life prior to antigenic challenge. At the other extreme, in disease states, there is often profound activation of lymphocytes. This is most apparent in viral infections like HIV and SIV (Rosenberg et al, this volume) and also in the various models of diseases such as EAE (Hickey and Kulidjian et al, this volume). It is a central tenet of our paper that resting and activated lymphocyte migration need to be considered separately and that they are very different.

Animals↗