Biomedical subjects

R L Boyd

Publications and source records attributed to R L Boyd.

At least 91 records · Page 5Linked to original sources

PubMed1991

Attenuation of Fos-like immunoreactivity induced by a single electroconvulsive shock in brains of aging mice.

c-fos is a proto-oncogene that encodes for a nuclear phosphoprotein with DNA binding properties and is presumed to have an important role in the long-term regulation of neuronal function. It is thought to act as a 'third messenger' molecule in signal transduction systems and its expression has been shown to be induced by a variety of exogenous and endogenous stimuli. This study examines the differential expression of the Fos protein in various brain regions after a single electroconvulsive shock (ECS) in 6-, 13-, and 28-month-old B6C3 mice. The animals received an acute electroconvulsive shock (90 V for 0.3 s), without prior anesthesia, through earclip electrodes and exhibited generalized tonic-clonic seizures lasting 20-36 s. Animals were anesthetized and perfused intracardially with 2.5% acrolein, 4% paraformaldehyde at 0.5, 1.0, 2.0 and 4.0 h postshock. The brains were Vibratome-sectioned (30 microns) and examined using a Fos antibody, directed against a conserved region of both mouse and human Fos by standard immunocytochemical methods. Systematic sampling of the total number of Fos immunostained neurons in amygdala, hippocampus and the cerebral cortex showed peak values at the 1-h time point followed by a steady decline thereafter in all age groups. In a second experiment, Fos-like immunoreactivity was compared 1 h after ECS in the hippocampus, amygdala and the cortex in all 3 age groups. There was increased expression of Fos-like immunoreactivity after ECS- compared to non-ECS-treated controls in all age groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1991

Characterization of immature CD4+CD8-CD3- thymocytes.

Previously we have described (Hugo, P. et al., Int. Immunol. 1990. 2: 209) an immature CD4+CD8-CD3- thymocyte subset which is thought to be the counterpart of the CD4-CD8+CD3- subset. In this study we show that the ontogeny of these two subsets is parallel in fetal thymic organ culture. Extensive phenotypic characterization of CD4+CD8-CD3- cells reveals that they closely resemble CD4-CD8+CD3- thymocytes being: HSAhigh, Thy-1high, interleukin 2 receptor alpha chain negative, CD44-, H-2K+/-, CD5low, MEL-14low/intermediate, CD2+, LFA-1+ and MTS 35+. Finally, we show that the proportion of CD4+CD8-CD3- thymocytes is highly variable between mouse strains.

Animals↗

PubMed1991

CD4+CD8+CD3high thymocytes appear transiently during ontogeny: evidence from phenotypic and functional studies.

During T cell development thymocyte subsets emerge in a defined order, reflective of their maturational stage. In this study we determined the timing of appearance of CD4+CD8+CD3high thymocytes during in vivo and in vitro embryonic development, and thymic reconstitution after cortisone treatment. In these models, CD4+CD8+CD3high cells followed CD4+CD8+CD3low and preceded mature CD4+CD8-CD3high/CD4-CD8+CD3high thymocytes, while cortisone resistance was first seen among CD4+CD8+CD3high cells. CD4+CD8+CD3high thymocytes were also shown to display a pattern of antigen receptor-mediated calcium influx intermediate between that induced in other CD4+CD8+ cells and mature thymocytes. These results are consistent with a precursor-progeny relationship between CD4+CD8+CD3low and CD4+CD8+CD3high thymocytes, the latter developing to mature thymocytes (Hugo, P. et al., Int. Immunol. 1991. 3: 265).

Animals↗

PubMed1991

Abnormalities associated with the bursal microenvironment in spontaneous dysgammaglobulinemia of UCD line 140 chickens.

UCD line 140 chickens have been previously reported to develop a syndrome of spontaneous 7s immunoglobulin deficiency and the presence of autoantibodies. Earlier studies demonstrated that these inbred birds have normal peripheral blood T and B cell numbers; they also respond normally to allogeneic stimulation. Although the 7s immunodeficiency does not manifest itself until several months of age, line 140 birds have a premature degeneration of bursa. Because of the recent development of monoclonal reagents specific for bursal elements, including surface epithelium, basement membrane associated epithelium, follicle associated epithelium, and lymphoid subpopulations, we have examined line 140 and control birds for the expression of bursal epithelial cell antigens. Line 140 birds, in contrast to control chickens, have a dramatic early alteration in the expression of an epithelial cell marker in the bursa, thymus, and intestine. Moreover, to further address this issue, we transplanted bursa from 10-day embryos onto the chorioallantoic membrane, a privileged site. Bursae from control birds became abnormal when transplanted onto line 140 CAM; they remained normal when transplanted among several control chicken lines. In contrast, line 140 bursa remained abnormal independent of the transplant procedure. Due to the marked bursal abnormality observed specific to the dysgammaglobulinemia chicken line, we propose that the microenvironmental features of line 140 bursa may predispose these birds to the development of humoral immunodeficiency and autoantibodies.

Animals↗

PubMed1991

The effect of infectious bursal disease virus on B lymphocytes and bursal stromal components in specific pathogen-free (SPF) White Leghorn chickens.

The effect of infectious bursal disease virus (IBDV) was studied on adult specific pathogen-free (SPF) white Leghorn chickens through analysis of peripheral blood cell suspensions and histological staining patterns on various tissue types, with specific mAbs. A rapid, progressive loss of B lymphocytes was observed in the bursal cortex and medulla, peripheral blood and thymic medulla. There was, however, a resistant population of MUI-36+ cells at the bursal cortico-medullary junction and scattered around splenic periellipsoidal sheaths. These resistant cells were suggested to be a subpopulation of macrophages which expressed the MUI-36 marker; alternatively these may have phagocytosed virally infected B cells or their remnants. Throughout the period of infection, T lymphocytes appeared nonsusceptible. Further, while the distribution of stromal cell antigens within the bursal cortex remained unaltered, particular epitopes on the surface epithelium and in the medulla were lost as a consequence of viral infection. The data presented therefore suggests that immunodepression of chickens post-IBDV infection, may arise as a direct consequence of infection of B lymphocytes; additionally, it is possible that the elimination of certain crucial elements within the bursal microenvironment may contribute to this state.

Animals↗

PubMed1991

Tachykinin-mediated modulation of the primary antibody response in rats: evidence for mediation by an NK-2 receptor.

Evidence for the involvement of primary afferent nerves and their associated neuropeptides in in vivo immunologic responses has been based on experiments in rats in which destruction of primary afferent nerves by the sensory neurotoxin capsaicin results in a diminished ability of the animal to mount a primary antibody response to sheep red blood cell (SRBC) antigen. This effect was shown to be reversed by substance P infusion immediately following antigenic stimulation. In this report we show that neurokinin A (NKA) is 12 times more potent than substance P in its capacity to reverse the effects of neonatal capsaicin pretreatment on the antibody response. Neurokinin A has a pD2 of 6.65 compared to 5.98 for substance P. In addition, NKA was more potent than substance P in reversing the effects of surgical lesions 2 days prior to antigenic stimulation. The effects of the D- and L-Pro9 analogues of [Glp6, Pro9]-SP6-11 on the plaque-forming cell response in capsaicin-treated rats provide further support for the hypothesis that the tachykinin receptor modulating the primary antibody response is an NK-2 receptor. These results demonstrate, for the first time, a role for NKA in in vivo immunomodulation.

Animals↗

PubMed1991

Towards an integrated view of thymopoiesis.

One prediction from the complex series of steps in intrathymic T-cell differentiation is that to regulate it the stroma controlling the process must be equally complex: the attraction of precursors, commitment to the T-cell lineage, induction of T-cell receptor (TCR) gene rearrangement, accessory molecule expression, repertoire expansion, major histocompatibility complex (MHC) molecule-based selection (positive and negative), acquisition of functional maturity and migratory capacity must all be controlled. In this review, Richard Boyd and Patrice Hugo combine knowledge of T-cell differentiation with thymic stromal cell heterogeneity to offer an integrated view of thymopoiesis within the thymic microenvironment.

Animals↗

PubMed1991

Selective abnormalities in the thymic microenvironment associated with avian scleroderma, an inherited fibrotic disease of L200 chickens.

As a prelude to deciphering the mechanisms of intrathymic T-cell maturation we produced a panel of 18 monoclonal antibodies (mAbs) against chicken thymic stromal elements. Eleven of these detected epithelial cells. They were: pan-epithelial; subcapsule and peri-vascular (pan type 1 epithelium); subcapsular, perivascular and medulla; medulla; or cortex. Of particular interest were the sub-specificities within these regions, especially the subcapsular region. Four mAbs stained both epithelial and non-epithelial cells in discrete regions. In addition, three mAbs recognized only non-epithelial cells. One identified macrophages scattered throughout the thymus, another the connective tissue and another the medullary vascular endothelium. These reagents have provided an extensive profile of the thymic stromal architecture and revealed that these cells are equally as complex as the T cells whose differentiation they induce and regulate. While the mAbs provide a valuable means for studying the mechanisms of normal thymopoiesis, their clinical significance is unknown. UCD line 200 chickens develop an autoimmune disease manifest by dermal and internal organ fibrosis, T cell infiltrates of skin and other affected organs and production of multiple autoantibodies. We have used our panel of mAbs to evaluate the thymic microenvironment in these autoimmunity-prone chickens. A comparative analysis with control chickens revealed striking deficiencies in the L200 subcapsular regions coupled with excessive expression of MHC class II antigens, particularly in the cortex. We hypothesize that these abnormalities induce altered T-cell differentiation, thereby predisposing the L200 chickens to autoimmune disease.

Animals↗

PubMed1991

Modulation of the immune response by tachykinins.

Neuro-immunology is becoming an increasingly important discipline of immunology. This review has examined the immunomodulatory function of one group of neuropeptides, the TK, particularly SP and NKA. These peptides are localized in primary afferent nerves which have been shown to innervate several immune organs. In addition, binding sites for the TK have been demonstrated in thymus, spleen and lymph node. Several immune cell types also express neurokinin receptors including human circulating lymphocytes with binding to the Th/i class predominating, murine T and B cells, a human T lymphoblastoid cell line, human monocytes, rabbit polymorphonuclear leucocytes and guinea-pig macrophages. The apposition of nerves with immune cells and receptors for neuropeptides thus produces an environment for interaction between the nervous and immune systems. Studies in vitro and, more recently, in vivo have examined how the TK regulate immune cell responses. The TK stimulate proliferation of T cells, enhance mitogen-induced release of cytokines including IFN-gamma, TNF-alpha, IL-1 and IL-6 from mononuclear cells and macrophages, enhance immunoglobulin secretion and affect cellular chemotaxis and phagocytosis. Studies in vivo have shown a role for TK in lymphocyte recirculation of sheep lymph nodes, reversal of stress-induced thymic involution and Ig production in both rat and mouse. Many of these effects appear to be mediated via NK-2 type receptors. To date, most of the work has involved studies in vitro, but the results from these are now being validated by studies in vivo where both the immune system and neuropeptides are able to interact at many anatomical sites. The complexities of the immune and the nervous systems mean that only a small number of potential interactions has been examined. Future studies can be expected to amplify these observations, especially with respect to the understanding of inflammatory and immune diseases in humans.

Amino Acid Sequence↗

PubMed1991

Effect of aging on GHRF-induced growth hormone release from anterior pituitary cells in primary culture.

Five criteria were developed to validate the primary cell culture model for comparison of GRF-induced release of growth hormone in pituitary tissue from aging animals. Pituitaries from young (5-mo), middle-aged (14-mo), and old (24-mo) male Fischer 344 rats were dispersed using either trypsin/trypsin inhibitor or dispase and compared with respect to the number of pituitary cells recovered, cell viability, 3H-leucine incorporation into total protein, time course for recovery of optimal response to GRF, and the dose-relationship for GRF-induced release of growth hormone 2, 4, and 6 days after dispersal. Results indicated that direct comparison of cellular responses between tissues from young, middle-aged, and old rats in primary cell culture is confounded by variations in time for recovery of optimal responses, the effects of the enzymes used for dispersal, and the methods used to express the data.

Aging↗

PubMed1991

Timing of deletion of autoreactive V beta 6+ cells and down-modulation of either CD4 or CD8 on phenotypically distinct CD4+8+ subsets of thymocytes expressing intermediate or high levels of T cell receptor.

In this paper we describe a differentiation sequence amongst adult murine thymocytes which goes from CD4+8+3lo(low) to CD4+8+3int(intermediate) to CD4+8+3hi(high) and then to mature single positive CD3hi thymocytes. Phenotypic characterization of CD4+8+3int/hi cells for a number of other surface markers is consistent with them being in transition from CD4+8+3lo phenotype to mature phenotype. The same observation was made for sensitivity towards ionomycin-mediated apoptosis. In the thymus of Mls-1a mice, where autoreactive TCR-V beta 6+ cells are negatively selected, deletion of TCR-V beta 6+ cells was first detected in the CD4+8+3int subset, and was complete by the CD4+8+3hi stage, suggesting that up-regulation of the TCR/CD3 complex is required for deletion of Mls-1a autoreactive thymocytes. No sign of apoptosis was detected among any fresh thymocyte subsets suggesting that apoptotic cells are rapidly cleared from the thymus. The CD4+8+3int/CD4+8+3hi cells are therefore populations in transit from the typical cortical thymocytes to the mature T-cells.

Animals↗

PubMed1990

Ontogeny of T cell development in avian scleroderma.

UCD line 200 chickens develop an inherited fibrotic disease associated with the production of antinuclear antibodies, antibodies to type II collagen, and early skin lesions characterized by intense T lymphocyte infiltrates. In the present study we have investigated the hypothesis that developmental abnormalities in T lymphocyte differentiation predispose the line 200 chickens to autoimmune disease. The status of the thymic microenvironment in these birds during ontogeny was studied with an extensive panel of monoclonal antibodies (mAbs) reactive with distinct stromal cell subsets including MHC determinants. In addition, their T-cell graft-versus-host reactivity and responses to mitogenic stimulation and interleukin (IL)-2 were also analyzed. Line 200 chickens have profound defects in thymic structure with a virtual complete absence of antigens specific for type I epithelium which lines the thymic subcapsular and perivascular regions. There are excessive levels of MHC class II positive cells, particularly in the cortex, and B cells/subset macrophages identified by mAb MUI 36. These defects are found from the late embryonic period, long before clinical disease is manifest. Furthermore, by FACS analysis, line 200 thymocytes have a major increase in IL-2 receptor density. In addition, line 200 chicken peripheral blood lymphocytes (PBL) respond poorly to mitogenic agents and have a reduced response to IL-2. Finally, it is important to note that line 200 PBL produce a normal graft-versus-host reaction. We propose that these abnormalities in T-cell differentiation are selective, not global, and may be reflective of a defect in thymic education resulting in an inappropriate response to self-antigens.

Animals↗

PubMed1990

Effects of capsaicin treatment on immunoglobulin secretion in the rat: further evidence for involvement of tachykinin-containing afferent nerves.

Neonatal capsaicin treatment has previously been shown to diminish the primary antibody response of adult rats to the subcutaneously administered T-dependent antigen, sheep red blood cells, as measured using a modification of the Cunningham plaque-forming cell assay technique. We have now studied the kinetics of this response in adult normal, neonatally capsaicin-pretreated and neonatally capsaicin-pretreated substance P-infused rats, and examined the effects of the tachykinin antagonist Spantide, on the plaque-forming cell response. Capsaicin pretreatment did not affect the antigen-specific plaque-forming cell response over the first 4 days following antigen injection. At days 5, 6 and 7 of the response, there was a statistically significant decrease in the number of plaque-forming cells secreting antigen-specific IgM, an effect not observed in capsaicin-pretreated rats which were given a subcutaneous infusion of substance P at the time of antigen injection. The tachykinin antagonist Spantide inhibited the plaque-forming cell response in normal rats after in vivo infusion at the time of antigen injection by more than 70%. This effect of Spantide was dose dependent, occurred with maximal effect at 10 microM, and appeared to be independent of any histamine-mediated action. The results of this study provide further evidence for a receptor-mediated immunomodulatory role of tachykinin-containing primary afferent nerves.

Animals↗

PubMed1990

The cytoarchitecture of the human thymus detected by monoclonal antibodies.

Seven monoclonal antibodies were produced against human thymic stromal cells. The monoclonal antibodies were put into two groups depending on whether the cells they detected were keratin-positive or -negative. Demonstrated in the keratin-negative group were a granular reticular meshwork, a stellate population predominantly in the medulla, and secretory cells associated with Hassall's corpuscles. In the keratin-positive group we showed two extensive epithelial networks, a trabecular and rare medullary epithelial population, and thymus-specific epithelium restricted to the subcapsule and the medulla. A novel finding was that some of the monoclonal antibodies and also OKM1 identified keratin-negative cells within Hassall's corpuscles, which implies that there are macrophages associated with these structures. The monoclonal antibodies should prove useful for separating and classifying subpopulations of stromal cells and also for monitoring changes in the thymic architecture in different thymic pathologies.

Animals↗

PubMed1990

Temporomandibular joint forces measured at the condyle of Macaca arctoides.

Forces were measured at the articular surface of the temporomandibular joint (TMJ) condyle in two stump-tail monkeys (Macaca arctoides) during chewing, incisal biting, and drinking and also during aggressive behaviors. Force was measured with a thin piezoelectric foil transducer, which was cemented over the anterior and superior surfaces of the condyle. Wires from the upper and lower surfaces of the foil were insulated between two layers of Teflon tape and run subcutaneously to a telemetry unit, which was implanted in the upper back. Force applied across the foil by the condyle was detected by the telemetry unit and transmitted to an FM radio receiver outside the animal. The FM signals were received and demodulated, and a signal proportional to the force applied between the condyle and the TMJ fossa was displayed on a chart recorder. Data were collected over an 8-day period. The animals were not constrained. The TMJ was found to be load bearing. The greatest force of 39.0 lb (17.7 kg) was measured during feisty vocal aggression. Forces ranged as high as 34.5 lb (15.7 kg) during chewing and 28.5 lb (13.0 kg) during incisal biting. Forces were greater on the working (food) side than on the nonworking (balancing) side by average ratios of 1.4 to 2.6. A large unilateral interference at the most distal molar greatly disturbed chewing. It reduced TMJ forces by 50% or more, and the monkey refused to chew on the side opposite the interference.

Aggression↗

PubMed1990

Ontogeny of a novel CD4+CD8-CD3- thymocyte subpopulation: a comparison with CD4- CD8+ CD3- thymocytes.

We have studied the ontogeny of a novel thymocyte subset, CD4+CD8-CD3-. Three-colour flow cytometric analysis demonstrated that these cells constituted approximately 1% of the total thymocyte content in adult CBA mice, and were not present in lymph nodes. They were mainly blastic, cortisone-sensitive, and localized in the outer thymic cortex. During foetal life they were first observed at day 15 and reached a maximum (6%) at day 17, beyond which they decreased to the adult level. This kinetic profile was similar to that of the CD4-CD8+CD3- subpopulation, except that the CD4+CD8-CD3- cells appeared slightly earlier and their percentage was lower. Both these populations appeared after the CD4-CD8-CD3- cells but before the CD4+CD8+CD3- cells. Similar observations were made during thymic reconstitution following dexamethasone treatment. In this case, both CD4+CD8-CD3- and CD4-CD8+CD3- thymocytes disappeared 48 h after the treatment. While their absolute number increased up to 14 days post-treatment, their percentage was maximal at day 7 post-treatment and returned to normal values by day 10 post-treatment. These results argue strongly that not only the CD4-CD8+CD3- population but also the CD4+CD8-CD3- population can be considered an intermediate precursor in CBA thymuses.

Animals↗

PubMed1990

The effects of interleukin 2 on early and late thymocyte differentiation in foetal thymus organ culture.

The effects of interleukin 2 (IL-2) on in vitro T cell development in organ cultures of day 14 foetal mouse thymus were investigated. Over a 12 day culture period IL-2 was found to inhibit the development of each of the major thymocyte subpopulations, defined by CD4 and CD8 expression. Since each subpopulation was reduced in number, a common precursor to these subsets was thought to be inhibited by IL-2. Indeed, subsequent analyses of subsets of CD4- CD8- cells, characterized by expression of HSA, Pgp-1, and IL-2R, demonstrated that CD4- CD8- cells expressing IL-2R and their postulated progeny were reduced in IL-2-treated cultures. The number of cells reputed to be the immediate precursor of CD4- CD8- IL-2R+ cells, i.e. CD4- CD8- Pgp-1+IL-3R- cells, was not change by treatment with IL-2. Interestingly, however, numbers of the most immature subset of CD4- CD8- cells, identified as having the HSA1oPgp-1+IL-2R- and CD3- phenotype, increased in IL-2-treated cultures and was the only population of cells to do so. We also document the failure to detect any LAK cell activity against syngeneic thymocytes in IL-2-treated cultures and therefore hypothesize that the inhibition of T cell differentiation in these cultures is due to an arrest in differentiation of CD4- CD8- cells bearing the IL-2R.

Animals↗

PubMed1990

Surface expression of CD4 and Thy-1 on mouse thymic stromal cells.

Subpopulations of thymic stromal cells (TSC) and T lymphocytes have been antigenically defined as a basis for understanding intrathymic cellular communications which result in the mature T-cell repertoire. In the current study we present data that the markers CD4 and Thy-1, standard T lymphocyte markers in mice, are also expressed by subpopulations of freshly isolated and cultured TSC. This was shown by flow cytometric analyses and fluorescence microscopy respectively. Use of F(ab')2 fragments of anti-CD4 mAb demonstrated specific antibody binding and not that due to FcR binding. Double-labelling experiments illustrated that the subpopulation of CD4+ stromal cells includes cells bearing the MAC-1 antigen. The majority of Thy-1+ stromal cells were epithelial cells (determined by double-labelling cultured TSC with anti-cytokeratin); however, there was also a novel subpopulation of non-epithelial stromal cells present. Whilst actual synthesis of these glycoproteins has not yet been demonstrated, their existence as surface antigens on TSC to any degree could have major relevance to the understanding of intrathymic intercellular events. It also cautions that experiments on T cell lineage relationships based on in vivo injection of anti-CD4 antibodies be interpreted with care.

Animals↗