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Biomedical subjects

J B Hay

Publications and source records attributed to J B Hay.

At least 19 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

Intracerebroventricular infusions of TNF-alpha preferentially recruit blood lymphocytes and induce a perivascular leukocyte infiltrate.

Tumour necrosis factor (TNF)-alpha is important in several central nervous system (CNS) inflammatory diseases, however, its role in the recruitment of leukocytes into the cerebral spinal fluid (CSF) and CNS is incompletely understood. Therefore, we examined the effect of intracerebroventricular (icv) and parenchymal infusions of TNF-alpha on the type of leukocyte, the pool and subset of lymphocytes recruited into CSF and brain parenchyma. Parenchymal injections of 500 ng of recombinant human TNF-alpha did not induce inflammation, whereas an icv infusion of TNF-alpha caused CSF leuckocytosis and a perivascular infiltrate. Twenty-four hours after the icv infusion neutrophils predominated, with CD4+ T cells being the major lymphocyte subset in CSF. By 48 h lymphocytes were the dominant cell type with CD8+ cells surpassing CD4+ cells in both the CSF and the perivascular infiltrate. The labeled recirculating lymphocyte pool prevailed in normal CSF, but after the infusion of TNF-alpha, the blood pool of lymphocytes was preferentially recruited. These results have implications for the immune surveillance of the CNS.

Animals↗
PubMed2001

Stochastic regulation of cell migration from the efferent lymph to oxazolone-stimulated skin.

The systemic immune response is a dynamic process involving the trafficking of lymphocytes from the Ag-stimulated lymph node to the peripheral tissue. Studies in sheep have demonstrated several phases of cell output in the efferent lymph after Ag stimulation. When skin contact sensitizers are used as Ag, the efferent lymph cell output peaks approximately 96 h after Ag stimulation and is temporally associated with the recruitment of cells into the skin. To investigate the relative contribution of this high-output phase of efferent lymphocytes to lymphocytic inflammation in the skin, we used a common contact sensitizer 2-phenyl-4-ethoxymethylene-5-oxazolone (oxazolone) to stimulate the skin and draining prescapular lymph node of adult sheep. The efferent lymph ducts draining the Ag-stimulated and contralateral control lymph nodes were cannulated throughout the experimental period. The lymphocytes leaving the lymph nodes during the 72-h period before maximum infiltration were differentially labeled with fluorescent tracers, reinjected into the arterial circulation, and tracked to the site of Ag stimulation. Quantitative tissue cytometry of the skin at the conclusion of the injection period (96 h after Ag stimulation) demonstrated more migratory cells derived from the Ag-stimulated lymph node than the contralateral control (median 18.5 vs 15.5 per field; p < 0.05). However, when corrected for total cell output of the lymph node, the Ag-stimulated migratory cells were 3.8-fold more prevalent in the skin than the contralateral control cells. These results suggest that the in situ immune response generally mirrors the frequency of recruitable lymphocytes in the peripheral blood.

Adjuvants, Immunologic↗
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↗
PubMed2001

Cervical lymph cannulation to investigate the efflux and effects of intracerebroventricular cytokine infusions.

It is well documented that there is communication between the cerebral spinal fluid (CSF) and cervical lymphatics. Recently, it has been demonstrated that tumor necrosis factor alpha (TNF-alpha) introduced into the CSF appears in the cervical lymph. However, the functional significance of this is less clear. Here we describe a protocol to quantitate the efflux of TNF-alpha from the CSF into cervical lymph. In addition, we describe a methodology to examine the effects of an intracerebroventricular (i.c.v.) infusion of TNF-alpha on lymph volume, cellularity and cell phenotype. While TNF-alpha was recovered in the cervical lymph following infusion of 125-I labeled TNF-alpha, the dosage of TNF-alpha used in this study had no effect on cervical lymph flow, cellularity or cell subsets. This protocol can be used to study the efflux of i.c.v. injected macromolecules and their effects on lymphocytes in cervical lymph and the regional lymph nodes.

Animals↗
PubMed2001

Epinephrine causes a reduction in lymph node cell output in sheep.

The lymphatic system has a critical role in the return of fluids, proteins, and cells to the circulatory system. However, the effects of stress, including exercise, on this system have not been adequately studied. We investigated the effect of a physiological dose (1 mg) of epinephrine (Epi) on lymph flow, cell concentration, and lymphocyte subsets in efferent subcutaneous lymph in sheep. Blood leukocyte numbers, differential, lymphocyte subsets, and blood and lymph pools of lymphocytes were determined simultaneously. A significant acute increase in lymph flow was followed by a post-injection decrease in flow and cellular output. No changes in lymphocyte subsets or pools of lymphocytes were seen in either blood or lymph. The timing of elevated plasma and lymph concentrations of Epi and norepinephrine (NE) corresponded with the increased lymph flow. In conclusion, Epi injection caused no change in lymphocyte subset distribution, leukocyte concentration, or pools of lymphocytes. A decrease in lymph flow and cellularity was documented post-injection, indicating that lymphatic tissue has no role in the leukocytosis seen after Epi injection. Lymphocyte retention by lymph nodes, however, may contribute to post-injection lymphopenia.

Adrenergic alpha-Agonists↗
PubMed2000

The relationship of lymphocytes in blood and in lymph to sleep/wake states in sheep.

Based on evidence of a role for immune-associated cytokines in sleep induction, we investigated the possibility that lymphocyte distribution between blood and lymphatics could be altered as a function of sleep/wakefulness. Blood and lymph sample were obtained from 5 sheep during periods of slow-wave sleep and wake. Blood and lymph lymphocytes were phenotyped using monoclonal antibodies against CD4, CD8, gd T-cell receptors and a surface marker on ovine B cells. Lymph flow rates and efferent lymph cell output were measured. Lymph flow and prescapular efferent lymphocyte output were reduced during sleep compared to wakefulness (p<0.0005). There were no differences in lymphocyte subsets in the blood and in the lymph during sleep/wake brain states. These data indicate that migration of cells in the peripheral lymphatic system is altered during sleep compared to wakefulness.

Animals↗
PubMed2000

A role for lymphatic endothelium in the sequestration of recirculating gamma delta T cells in TNF-alpha-stimulated lymph nodes.

TNF-alpha is one of the most potent immunoregulatory molecules in vivo. In addition to important regulatory effects, it is also a potent inducer of extravascular lymphocyte infiltration. To examine the dynamic changes that are induced in local lymphocyte migration through regional lymph nodes following TNF-alpha injection, we used a protocol of direct lymphatic cannulation to quantitatively and qualitatively examine the traffic of lymphocytes through regional lymph nodes. We observed that local TNF-alpha injection reduced the output of lymphocytes from lymph nodes up to 90% within 6-10 h following stimulation. TNF-alpha also altered the specificity of migration of lymphocyte traffic through subcutaneous lymph nodes. In addition to the decreased output, phenotypic analysis demonstrated decreases in the concentration of gamma delta T cells by up to 30% following TNF-alpha injection. Histological examination showed that the gamma delta T cells were found in close association with VCAM-1-expressing cells in TNF-stimulated lymph nodes, at least some of which appeared to be lymphatic endothelium. These data indicate that TNF-alpha is capable of altering the number and specificity of lymphocytes recirculating through stimulated lymph nodes by selectively altering the entry of lymphocytes into the efferent lymphatics of inflamed lymph nodes in vivo.

Animals↗
PubMed2000

Brain-blood permeability: TNF-alpha promotes escape of protein tracer from CSF to blood.

The objective of this study was to determine the effect of tumor necrosis factor (TNF)-alpha on the efflux of protein from the central nervous system to blood based on assessing the clearance of radiolabeled albumin from the cerebrospinal fluid (CSF) to blood in rats. (125)I-labeled human serum albumin ((125)I-HSA) was injected into a lateral ventricle, and venous blood was sampled hourly to determine the basal CSF protein clearance into the blood. After this, rats were intraventricularly infused with 10 microliter TNF-alpha and 10 microliter (131)I-HSA (n = 6) or 10 microliter saline and 10 microliter (131)I-HSA (n = 6). Venous blood was sampled hourly for 3 h. (131)I-HSA tracer recovery increased threefold in the venous blood and was significantly higher in the spleen, muscles, and skin in animals treated with TNF-alpha. No significant changes were observed in control animals treated with saline. The data suggest that TNF-alpha promotes the clearance of protein macromolecules from the CSF to the venous blood.

Animals↗
PubMed2000

Adhesion molecule expression in acute and chronic exercise.

Adhesion molecules expressed on leukocytes and the vascular endothelial lining include the selectins, integrins, members of the immunoglobulin superfamily, and mucins. The changes in their expression that develop with acute and chronic exercise are briefly reviewed. Adhesion molecules are thought to modulate leukocyte trafficking, accounting for changes in the counts and possibly also the functional activity of various leukocyte subsets during and following an acute bout of physical activity. Some of the changes in the surface density of adhesion molecules can be explained through the action of epinephrine and other humoral factors on their expression, but an influence of sympathetic nerve terminals on cells sequestered in the spleen and liver, and an influx into the general circulation of leukocytes of differing phenotype also appear to be involved.

Cell Adhesion↗
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↗
PubMed1999

Intracerebroventricular injection of TNF-alpha promotes sleep and is recovered in cervical lymph.

Recent studies have shown that the central nervous system (CNS) communicates with the periphery by the drainage of cerebrospinal fluid and brain interstitial fluid into blood and lymph. We hypothesized that tumor necrosis factor (TNF)-alpha would not only influence the CNS by promoting sleep but also would be directly transmitted into the peripheral immune system. Five hundred nanograms of 125I-labeled TNF-alpha were injected into the lateral ventricles of the brain of six sheep and sampled in venous blood and cervical and prescapular lymph every 30 min for 6 h. 125I-TNF-alpha was measured in lymph nodes and control fat, skin, and muscle tissues 6 h postinjection. 125I-TNF-alpha was detected in the cervical lymphatics within the first 30 min and peaked within 2-3 h. 125I-TNF-alpha counts were elevated in the nodes of the head and neck region. Polysomnographic recordings of four animals showed that TNF-alpha induced a significant increase in slow-wave sleep at postinjection hours 4 and 5. CNS TNF-alpha and its direct drainage into the lymphatic system may influence both the sleeping/waking brain and peripheral immune functions.

Animals↗
PubMed1998

Cerebral spinal fluid lymphocytes are part of the normal recirculating lymphocyte pool.

We have investigated the migration of lymphocytes from blood into the central nervous system (CNS) under normal physiological conditions. Using sheep as our model, we simultaneously sampled blood, lymph and cerebral spinal fluid (CSF). Normal, nonactivated, recirculating lymphocytes can migrate into the CSF in similar concentrations as found in subcutaneous lymph and there is no difference in the temporal appearance between them. Lymphocytes infused into the CNS could be found in cervical lymph nodes. These data suggest that lymphocytes found in the CNS are part of the recirculating lymphocyte pool and do not require activation to enter the CSF.

Animals↗
PubMed1998

The relationship of blood lymphocytes to the recirculating lymphocyte pool.

Lymphocyte recirculation facilitates the detection and elimination of pathogens and the dissemination of immunologic memory. It is generally assumed that all small lymphocytes in the blood are actively recirculating, yet there is little quantitative data directly comparing the migration of this population with actively recirculating, lymph-derived lymphocytes. In this study blood lymphocytes were labeled with fluorescein isothiocyanate (FITC), and lymph lymphocytes were labeled with CM-DiI, reinfused intravenously, and monitored in blood and lymph. After equilibration the concentration of blood lymphocytes was several times higher in blood than in lymph, whereas lymph lymphocytes displayed the opposite behavior. This suggested that blood lymphocytes did not recirculate as efficiently as lymph lymphocytes, so we examined the following blood lymphocyte subsets in greater detail: B cells, CD4+, CD8+, and gammadelta T cells. Within 4 hours postinjection the percentage of FITC+ CD8+ and CD4+ lymphocytes fell in the blood and remained significantly lower than the injected sample. In contrast, the concentration of FITC+ gammadelta T cells did not change, and the percentage of FITC+ B cells increased. These data suggest that subpopulations of B and perhaps gammadelta T lymphocytes in the blood do not recirculate efficiently through lymph nodes.

Animals↗
PubMed1998

Lymphocyte recirculation, exercise, and immune responses.

Alterations in leukocyte concentrations in the blood are associated with exercise, stress, and other pathophysiological perturbations. The continuous migration and redistribution of cells of the recirculating lymphocyte pool between the blood and lymphatic systems can be influenced by a variety of physiological, immunological, and pathological processes. The phenotypic distribution of lymphocyte subsets is not the same in blood, afferent lymph, and efferent lymph, and cell-tracking experiments have shown that lymphocytes vary in their migratory properties. The most comprehensive physiological studies tracking these cells in vivo have been done in sheep. It has been shown that lymph-derived cells have different migratory capacities than blood-derived lymphocytes, that antigenic challenge of a single lymph node can first reduce the output of lymphocytes from the node and then markedly increase the recruitment from the blood and subsequently the output into efferent lymph. In most mammals, the blood pool of lymphocytes represents only about 1% of the total lymphocytes and only a small fraction of the recirculating lymphocyte pool. Therefore, testing the effects of exercise on lymphocyte recirculation by examining blood samples only requires considerable deduction and inference to interpret multicompartmental effects.

Brain↗
PubMed1996

The use of the lipophilic fluorochrome CM-DiI for tracking the migration of lymphocytes.

In this study we examined the new cell dye CM-DiI for tracking the migration of lymphocytes from blood to lymph. This lipophilic marker intercalates in the plasma membrane like the PKH dyes and older DiI derivatives. The stability and intensity of staining achieved with these dyes is better than most other fluorochromes or radioisotopes, yet they are poorly soluble in aqueous solutions, which can make staining difficult, and they are not fixable in tissue sections. CM-DiI is reported to have increased water solubility and it can be fixed using traditional aldehyde fixatives, making it feasible to detect labeled cells in histological sections. To determine the suitability of CM-DiI as a lymphocyte marker, a labeling protocol was developed. We tested the ability of stained cells to recirculate in vivo. Following the intravenous injection of CM-DiI positive cells, their recovery in lymph over 40 h was comparable to that of cells labeled with other fluorochromes or radioisotopes. The kinetics of recirculation were also very similar, as labeled cells were detectable in lymph within 4 h of injection, and the peak percentage of labeled cells in lymph was generally observed between 20-30 h. We also confirmed that CM-DiI is retained in the lymphocyte membrane following routine paraffin processing. Thus CM-DiI does not appear to alter the process of lymphocyte recirculation, and it should be a useful marker for tracking these cells.

Animals↗
PubMed1996

Cyclosporine A inhibits lymphocyte migration into ovine peripheral nerve allografts.

Lymphocyte migration into nerve allografts was measured to estimate the cyclosporine A (CsA) dose required to suppress rejection. Twelve outbred sheep received daily subcutaneous CsA at 0, 5, 10, or 15 mg/kg/day for 2 weeks prior to implantation of multiple heterotopic subcutaneous nerve grafts. Lymphocyte migration was determined after 7 days by an intravenous pulse of autologous 111indium-labeled lymphocytes and subsequent quantitation of gamma radioactivity in nerve tissue (CPM/g, mean +/- SEM). Measurement by radioimmunoassay revealed a dose-dependent increase in blood cyclosporine levels. Lymphocyte migration into autografts (404+/-44) was significantly less than migration into allografts (16,554+/-2,049), in control animals (P < 0.01). A dose-dependent inhibition of lymphocyte migration into nerve allografts was observed with counts of 7,662+/-1,692, 4,083+/-1,112, and 1,561+/-232 in sheep receiving 5, 10, or 15 mg/kg/day of CsA, respectively. Daily CsA administration produced effective blood levels and immunosuppression sufficient to inhibit lymphocyte migration into nerve allografts.

Animals↗