Biomedical subjects

G F Erf

Publications and source records attributed to G F Erf.

At least 37 records · Page 2Linked to original sources

PubMed2002

Effect of cage vs. floor litter environments on the pulmonary hypertensive response to intravenous endotoxin and on blood-gas values in broilers.

Intravenous endotoxin has been shown to trigger a delayed pulmonary hypertensive response that varies widely in magnitude and duration among individual broilers. It was proposed that this individual variability may reflect immunological differences acquired during previous respiratory challenges that might have subsequently altered the endotoxin-initiated biochemical cascade. In Experiment 1, we tested the hypothesis that, when compared with broilers reared in clean stainless steel cages (Cage group), broilers reared on floor litter (Floor group) should experience a greater respiratory challenge and therefore may consistently exhibit a more enhanced pulmonary hypertensive response to intravenous endotoxin. Birds in the Cage group were grown in stainless steel cages at a low density (72 birds/8 m2 chamber), and fecal and dander materials were removed daily. Birds in the Floor group were reared on wood-shavings litter at a higher density (110 birds/8 m2 chamber). Pulmonary and systemic mean arterial pressures and blood-gas values were evaluated prior to and following the intravenous administration of 1 mg Salmonella typhimurium endotoxin. Broilers in the Floor and Cage groups exhibited pulmonary hypertensive responses to endotoxin that were very similar in terms of time of onset, duration, and magnitude, as well as variability in the response among individuals. Systemic hypotension also developed similarly in both groups following endotoxin injection. Blood-gas values indicated that the partial pressure of CO2 and the HCO3- concentration in arterial blood were higher (P < 0.05) in the Floor group than in the Cage group prior to and subsequent to the endotoxin injection. In Experiment 2, we reevaluated the effect of a dirty vs. a clean environment on blood-gas values using a different strain of broilers, and confirmed the negative impact of floor rearing on blood-gas values. We conclude that broilers reared on the floor inhaled litter dust and noxious fumes, which impaired pulmonary gas exchange and increased the arterial partial pressure of CO2 when compared with broilers reared in clean stainless steel cages. Nevertheless, the pulmonary hypertensive response to endotoxin did not differ between broilers reared on the floor and those in cages.

Animal Husbandry↗

PubMed2002

Intravenous micro-particle injection and pulmonary hypertension in broiler chickens: cardio-pulmonary hemodynamic responses.

Experiments were conducted to determine whether intravenous injections of micro-particles, having a size suitable to be trapped by the pulmonary precapillary arterioles, could be used to increase the pulmonary vascular resistance and thereby trigger an acute increase in the pulmonary arterial pressure (pulmonary hypertension). Anesthetized male broilers injected intravenously with inorganic (silica gel, polystyrene) or organic (cellulose, Sephadex) micro-particles developed an immediate pulmonary hypertension in proportion to the cumulative quantities of micro-particles injected. Micro-particle occlusion of a portion of the pulmonary arterioles forced the cardiac output to flow at a higher rate through the remaining vascular channels, thereby exposing a diffusion limitation characterized by undersaturation of the systemic arterial blood with oxygen (hypoxemia). The concurrent onset of systemic hypotension (reduced systemic arterial blood pressure) was not due to a reduction in cardiac output but rather was attributed to hypoxemic vasodilation of the systemic vasculature (reduced total peripheral resistance). Preliminary histological evaluations revealed micro-particles lodged in inter- and intraparabronchial arterioles, surrounded by aggregates of thrombocytes and mononuclear leukocytes within 30 min post-injection. These observations infer that intravenously injected micro-particles are carried to the lungs by the returning venous blood, where trapping of the micro-particles by the pulmonary vasculature triggers acute responses (increased pulmonary vascular resistance, pulmonary hypertension, systemic hypoxemia, systemic hypotension) that mirror those previously observed following acute occlusion of one pulmonary artery. Additional studies will be required to determine the extent to which the focal immune response to trapped micro-particles promotes local vasoconstriction that amplifies the pulmonary hypertension attributable to direct physical obstruction of precapillary arterioles.

Animals↗

PubMed2002

Intravenous micro-particle injections and pulmonary hypertension in broiler chickens: acute post-injection mortality and ascites susceptibility.

Intravenously injected micro-particles become trapped within the pulmonary vasculature where they increase the resistance to blood flow and trigger pulmonary hypertension. We tested the hypothesis that i.v. micro-particle injections can be used to trigger acute (24 to 48 h) post-injection mortality in broilers having the most limited pulmonary vascular capacity, or ascites in broilers whose marginal cardiopulmonary capacity renders them susceptible to pulmonary hypertension syndrome (PHS). Progressive inflammation-associated responses were initiated within the lung parenchyma by 10 to 80 microm diameter dextran polymer (Sephadex) and 30 microm diameter cellulose micro-particles, leading to the scavenging of Sephadex micro-particles from the pulmonary vasculature by <5 d post-injection, whereas the cellulose micro-particles persisted for >7 d post-injection. The persistency and size of the cellulose apparently facilitated chronic occlusion of blood flow through precapillary arterioles, thereby triggering appreciable post-injection mortality and PHS at relatively low injection volumes (0.3 to 0.6 mL at 0.02 g/mL). In contrast, the small size of the polystyrene microspheres (15 microm), and the lack of persistency of the Sephadex micro-particles, apparently precluded the reliable occurrence of post-injection mortality or PHS until higher volumes (>0.8 mL at 0.02 g/mL) were injected. Values for the total susceptibility index (TSI: 24 to 48 h post-injection mortality + PHS mortality) following cellulose injections were higher for broilers reared at cool temperatures than at thermoneutral temperatures. The incidences of PHS induced by exposing broilers from different genetic lines to constant cool temperatures qualitatively paralleled the respective post-injection mortalities elicited by injecting the cellulose micro-particle suspension into the same lines. These observations indicate the micro-particle injection methodology potentially can replace unilateral pulmonary artery occlusion as the technique of choice for genetically selecting broilers that have a sufficiently robust pulmonary vascular capacity to resist the onset of pulmonary hypertension and PHS. The functional importance of the relative antigenicity of different micro-particle types, and the extent to which key immune-mediated responses, either beneficial or detrimental, might be co-selected by the micro-particle injection technology, remain to be clarified.

Animals↗

PubMed2002

Pulmonary hypertensive response to endotoxin in cellulose-primed and unprimed broiler chickens.

Previous studies indicate that individual broilers vary widely in their pulmonary vascular responsiveness to i.v. injections of endotoxin. This individual variability may reflect differences acquired during previous respiratory challenges or genetic variability that may be associated with susceptibility to pulmonary hypertension syndrome (ascites). In the present study, we compared the endotoxin responses of 4- to 5- wk-old control broilers (unprimed) and broilers in which the pulmonary vasculature had been immunologically challenged 48 h previously by an i.v. injection of cellulose micro-particles (primed). The injected cellulose micro-particles are carried in the venous blood to the lungs, where they become trapped in the pulmonary vasculature and initiate acute focal inflammatory responses within the surrounding lung parenchyma. Physiological variables (respiratory rate, heart rate, pulmonary and systemic arterial pressures) were evaluated prior to and following the i.v. administration of 1 mg of Salmonella typhimurium endotoxin. Prior to endotoxin injection, the respiratory rate was higher in primed than in unprimed broilers; however, the heart rate, pulmonary arterial pressure, and systemic arterial pressure did not differ between groups. Broilers in both groups exhibited similar ranges of individual variability in their endotoxin responses. The overall time of onset, magnitude, and duration of the pulmonary hypertensive responses were similar for both groups. Accordingly, the initiation of a preexisting inflammatory response within the lung parenchyma did not alter the timing, amplitude, or variability of the subsequent pulmonary hypertensive response to endotoxin in broilers.

Animals↗

PubMed2002

Immunohistochemical evidence of cytochrome C oxidase subunit II involvement in pulmonary hypertension syndrome (PHS) in broilers.

Defects and variation in the relative amount of protein subunits in the mitochondrial electron transport chain (ETC) have been hypothesized to be involved, in part, in the pathogenesis of pulmonary hypertension syndrome (PHS), a costly metabolic disease. Thus, the major objective of this study was to determine whether differences in relative amounts of cytochrome c oxidase subunit I and II (COX I and II) can be detected by immunohistochemistry and digital image analysis in muscle tissue of broilers with PHS compared to control broilers. Cross sections of the breast muscle (pectoralis major) were stained with monoclonal antibodies for COX I and II. Relative areas of multiple microscope viewing fields (400x) per tissue section of COX I and II were quantified by counting immunopositive pixels on the digital images. Whereas the number of immunopositive pixels for COX II was higher in PHS birds compared to controls, there were no difference for COX I. The amount of COX II was positively correlated with the right to total ventricular weight ratio (RV:TV), suggesting that there may be increased expression of COX II associated with severity of pulmonary arterial hypertension. Thus, it is possible that COX II expression in PHS broiler may be involved in the pathogenesis of PHS.

Animals↗

PubMed2001

Herpesvirus connection in the expression of autoimmune vitiligo in Smyth line chickens.

The Smyth line (SL) chicken is an animal model for human vitiligo, a common acquired depigmentary disorder affecting about 1-2% of people worldwide. The vitiligo-like depigmentation in SL chickens typically develops when the birds are between 6 and 14 weeks of age and may affect 70-95% of hatch mates. The development of SL vitiligo is considered to depend on two interacting components, namely an inherent melanocyte defect and an autoimmune reaction to melanocytes. Recently, a role for an environmental factor in the expression of vitiligo was suggested by the observation that only 10% of SL chicks imported from the University of Massachusetts (UM) and reared in isolation at biosecurity level 2 (BSL 2) at the University of Arkansas (UA) exhibited vitiligo. Following further assessment of environmental differences between UA and UM SL chickens, three environmental factors that may have influenced the expression of SL vitiligo were identified. Included were housing condition, status of Mycoplasma synoviae infection, and turkey herpesvirus (HVT) vaccination status. Studies were subsequently conducted at UA and UM to assess the role of these environmental factors in the expression of SL vitiligo. M. synoviae infection was not found necessary for vitiligo expression in SL chickens. However, HVT emerged as a strong candidate for an important environmental factor in SL vitiligo. The connection between HVT and SL vitiligo was confirmed for both BSL 2 and conventional housing. Therefore, the observations reported here suggest a strong causative link between HVT infection and SL vitiligo.

Age Factors↗

PubMed2001

Avian T helper one/two immune response balance can be shifted toward inflammation by antigen delivery to scavenger receptors.

Whether immune responses are dominated by inflammation or antibody production is often key to surviving infections. Therefore, differential control of these immune pathways determined by CD4 T cells is of fundamental interest for vaccine design. Little is known about how inflammatory [T helper cell (Th) type 1 (Th1)] versus antibody-inducing (Th2) choices are controlled in domestic fowl. To address this, MHC-matched chickens were immunized to test whether antibody-dominated Th2 or inflammatory Th1 responses could be preferentially activated, and our findings subsequently extended to outbred broiler breeders. Strategies used were known to shift the response in mice from Th2 to Th1 by delivering the injected antigen preferentially to macrophages. The model antigen, BSA, was maleylated to allow binding to scavenger receptors (SR) present on mammalian macrophages. Maleyl-BSA bound well in receptor-specific fashion to a chicken macrophage cell line. Compared with native BSA, immunization with SR-binding, maleyl-BSA modulated the immune response toward the Th1 pathway, as evident by increases in the magnitude of in vivo inflammatory reactions and declines in antibody-making responses. Initiation of a maleyl-BSA Th1 pathway is further supported by the enhanced ability of splenocytes to express mRNA for interferon-gamma in response to antigens. Together, these data establish the presence and functional relevance of SR in domestic fowl as well as provide a system for investigating the mechanisms controlling Th1/Th2 pathways in chickens. Moreover, the ability to direct immune responses toward either pathway by antigen maleylation will contribute significantly to the development of better vaccines for poultry diseases.

Animals↗

PubMed2001

Intravenous endotoxin triggers pulmonary vasoconstriction and pulmonary hypertension in broiler chickens.

Bacterial endotoxins stimulate endothelin-mediated, thromboxane-dependent increases in pulmonary vascular resistance in mammals, and thromboxane has been shown to cause an immediate but transient pulmonary vasoconstriction in broiler chickens. In the present study, i.v. injections of 1 mg endotoxin into anesthetized male broilers caused a pulmonary vasoconstrictive response that was delayed in onset by 15 min and that elevated the pulmonary arterial pressure by 10 mm Hg within 25 min postinjection. Thereafter, pulmonary hemodynamic variables gradually (> or = 15 min) returned toward pre-injection levels, and supplemental injections of 4 mg endotoxin during this recovery period failed to reinitiate pulmonary hypertension. In contrast, injecting the thromboxane A2 mimetic U44069 during the endotoxin recovery period triggered pulmonary vasoconstriction and pulmonary hypertension similar in magnitude to the responses triggered by U44069 before endotoxin had been administered. The time course and magnitude of the pulmonary hemodynamic responses to endotoxin were highly variable among individual broilers, whereas the individual responses to U44069 were more consistent. Unanesthetized broilers resembled anesthetized broilers in the time course, magnitude, and variability of their pulmonary hemodynamic responses to endotoxin. Overall, these observations are consistent with the hypothesis that endotoxin initiates a biochemical cascade, culminating in the delayed onset of pulmonary vasoconstriction and pulmonary hypertension within 20 min postinjection. Subsequently, the pulmonary vasculature remains responsive to large bolus injections of exogenous thromboxane mimetic; however depletion of endogenous vasoconstrictive components of the endotoxin-mediated cascade, a compensatory increase in endogenous vasodilators, or the induction of a transient cellular tolerance to endotoxin prevented fourfold higher doses of endotoxin from reversing the return toward a normal pulmonary vascular tone. Individual differences among broilers in their susceptibility to pulmonary hypertension syndrome (ascites) may be related to innate or acquired variability in their pulmonary vascular responsiveness to vasoactive mediators.

Animals↗

PubMed1999

Research on the probable cause of an outbreak of field rickets in turkeys.

An outbreak of field rickets in turkeys prompted studies on the cause. In Experiment 1, there were four treatments with two replicate pens of 10 poults per pen. The treatments consisted of poults fed newly manufactured feed (control), poults fed a diet containing control feed and 5% clean litter, poults fed control feed and 5% litter from the pens of affected poults, and poults challenged with an intestinal homogenate by gavage. Field rickets did not develop with these treatments. The feed was suspect, and, in Experiment 2, poults were either fed the suspect feed or newly manufactured feed. There were four replicate pens of 25 poults per pen. Poults fed the suspect feed had a decrease (P < or = 0.05) in BW at 1, 2, 3, and 4 wk of age; an increase in the relative weight of the liver, pancreas, kidney, and bursa of Fabricius; and a decrease in bone ash. There were changes in clinical chemistries. In the third study, there were five dietary treatments with two replicate pens of 25 poults per treatment. The treatments consisted of poults fed newly manufactured feed; new feed mixed with 25, 50, or 75% suspect feed; or 100% suspect feed. Body weights of poults fed 100% suspect feed were decreased at 2, 3, and 4 wk as was the relative weight of the liver, pancreas, and bursa of Fabricius. The relative weight of the kidney increased. Lameness, a decrease in bone ash, and changes in hematology and blood chemistry were observed in the poults consuming 100% suspect feed. These data demonstrate that feed from the original outbreak could induce field rickets and was toxic. Because the feed contained adequate vitamin D, calcium, and phosphorus, the cause of this outbreak of field rickets is thought to be a toxic feed contaminant affecting bone development.

Alkaline Phosphatase↗

PubMed1998

CD4, CD8 and TCR defined T-cell subsets in thymus and spleen of 2- and 7-week old commercial broiler chickens.

To better understand immune development and function in meat-type chickens (broilers), the proportions of T-cells expressing CD4, CD8, and T-cell receptors (TCR) in the thymus and spleen were determined by three-color fluorescence and flow cytometry in 2- and 7-week old broilers raised in commercial growing conditions. Broiler thymocytes consisted of single-(CD4+CD8- and CD4-CD8+) and double-(CD4+CD8+) positive subpopulations. Within these CD4+ and/or CD8+ thymocyte populations, all types of TCR (y delta, V beta 1 alpha beta, and V beta 2 alpha beta) could be identified. In the thymus, percentages of CD4+CD8- cells increased, CD4-CD8+ cells remained unchanged, and CD4+CD8+ cells decreased between 2 and 7 weeks of age. In the spleen, in addition to single-positive lymphocytes, double-positive populations were identified, expressing either y delta or alpha beta TCR. The percentage of CD4+CD8- splenocytes decreased, and the percentages of both CD4-CD8+ and CD4+CD8+ splenocytes increased between 2 and 7 weeks of age. Age-associated shifts in TCR usage (the proportion of cells expressing a certain type of TCR) were observed in the single-positive, but not in the double-positive, T-cell populations of both thymus and spleen. This multiparameter cell population analysis in broilers demonstrates thymic and splenic T-cell subsets similar to those previously described in layers. Differences in the proportions among T-cell subsets between 2- and 7-week old broilers likely reflect a more competent immune system in the older birds.

Aging↗

PubMed1998

Effects of dietary vitamin E on the immune system in broilers: altered proportions of CD4 T cells in the thymus and spleen.

To gain insight into the immunomodulatory effects of vitamin E (VE), immune cell population analyses were conducted using thymus and spleen from male broilers fed diets with various levels of VE supplementation (0, 17, 46, and 87 mg dl-alpha-tocopherol acetate/kg of feed). At 2 and 7 wk of age, the percentages of B cells, macrophages, and T cell subsets, delineated by the expression of CD4, CD8, and T cell receptor (TCR) isotype, in thymus and spleen were determined by flow cytometry. The percentages of thymic and splenic B cells and macrophages from 2- and 7-wk-old chickens, as well as the percentage of thymic T cells in 2-wk-old chickens, were unaffected by VE treatment. However, 7-wk-old broilers maintained on 87 mg VE/kg feed had a higher percentage of CD4+CD8- thymocytes, a higher CD4+CD8- to CD4-CD8+ thymocyte ratio, and a lower percentage of CD4+CD8+ thymocytes than chickens receiving no dietary VE supplementation. The VE-induced increase in the percentage of CD4+CD8- thymocytes was due to an increase in the TCR2+CD4+CD8- thymocyte subset, whereas the decrease in the percentage of CD4+CD8+ thymocytes involved all TCR defined T cell subsets. In the spleen, the percentage of CD4+CD8- T cells was lower in 2-wk-old chickens and higher in 7-wk-old chickens maintained on 87 mg/kg feed than in chickens receiving no dietary VE supplementation. The decrease in CD4+CD8- splenocytes at 2 wk of age was due to a decline in the percentage of TCR2+CD4+CD8- splenocytes, whereas the increase in CD4+CD8- splenocytes in 7-wk-old chicks was due to an increase in the percentages of all TCR defined CD4+CD8- T cell subsets. These data support an immunomodulatory effect of VE on CD4+CD8- T cells.

Administration, Oral↗

PubMed1997

Lymphocyte populations in dermal lymphoid aggregates of vitiliginous Smyth line and normally pigmented light brown Leghorn chickens.

Smyth line (SL) chickens develop a spontaneous, autoimmune loss of melanocytes (vitiligo) from the feather. To determine whether lymphocyte infiltration into two-week-old regenerating feathers of vitiliginous chickens was accompanied by lymphocyte infiltration into the skin, skin biopsies were conducted in SL chickens at two-week intervals throughout the development of vitiligo (SLV) when the chicks were 6 to 14 weeks of age. Control skin samples were obtained from age-matched, normally-pigmented Light Brown Leghorn (LBL) chickens. Frozen skin sections were labelled with a panel of mouse mAb to identify various lymphocyte populations. There was no lymphocyte infiltration into the skin of SL or control chickens. However, in both lines of chickens, dermal lymphoid aggregates (DLA), consisting primarily of T cells, were observed. In the DLA of SL chickens, the ratio between CD4+ and CD8+ T cells was lower (P = 0.005) and the percentage of gamma delta T cells higher (P = 0.027) than in the controls. Additionally, in SL chickens the lymphocyte populations in the DLA varied depending on the developmental stage of vitiligo. These data suggest a relationship between the DLA and autoimmune vitiligo in the SL model.

Animals↗

PubMed1997

Effect of dietary dl-alpha-tocopherol on tissue alpha- and gamma-tocopherol and pulmonary hypertension syndrome (ascites) in broilers.

The objectives of this experiment were to determine the effects of high dietary levels of vitamin E on growth performance and pulmonary hypertension syndrome (PHS) mortality. Male broiler chicks (Cobb 500) were randomly assigned to one of four dietary treatments consisting of standard starter and grower diets supplemented with 0, 17, 46, and 87 mg dl-alpha-tocopherol acetate/kg. To encourage the development of PHS, air temperature in the house was 32 and 28 C for Weeks 1 and 2, dropped to 18 C during Week 3, and kept between 10 and 15 C during Weeks 4 through 7. Also, chicks were placed in floor pens on litter used for five previous flocks and ventilation reduced to increase dust and ammonia in the house. Ammonia levels increased from an initial 18 to 36 ppm on Day 42 with the increase in ammonia corresponding to an obvious increase in dust in the air. Lung and liver tissue obtained at 2, 5, and 7 wk of age were analyzed for tissue alpha- and gamma-tocopherol by liquid chromatography. Dietary vitamin E had no effect on body weight, feed intake, or feed efficiency. Cumulative PHS mortality through 7 wk of age was 21% and was also unaffected by dietary treatment. Liver and lung alpha-tocopherol concentrations exhibited a dose-response increase to dietary tocopherol and there was a high correlation between lung and liver tissue alpha-tocopherol (r = 0.72, P < 0.05). Whereas gamma-tocopherol concentrations in lung and liver were unaffected by dietary treatment, liver and lung exhibited age-dependent increases in both alpha- and gamma-tocopherol. Despite dose-dependent increases in tissue alpha-tocopherol, supplementation of diets with up to 87 mg dl-alpha-tocopherol acetate had no effect on growth performance or PHS mortality in broilers under the conditions used in this study.

Ammonia↗

PubMed1997

Profiles of pulp infiltrating lymphocytes at various times throughout feather regeneration in Smyth line chickens with vitiligo.

Smyth line (SL) chickens develop a spontaneous, autoimmune, posthatch loss of pigment cells (vitiligo) in regenerating feather tissue. Smyth line vitiligo (SLV) is associated with lymphocyte infiltrations prior to and throughout the development of the disorder. It was the purpose of this study to determine the type, relative amounts, and proportions of pulp-infiltrating lymphocytes at various times throughout the growth of regenerating feathers. Feathers were plucked from 8-week-old chickens with and without SLV. Feather pulp cell suspensions were prepared when the regenerating feathers were 2, 3, 4, and 6 weeks of age. Cells were fluorescently labeled using a panel of mouse monoclonal antibodies specific for chicken lymphocytes. Both T and B cells infiltrated the feather pulp of chickens with SLV. T cell levels remained elevated throughout the 6 weeks of feather growth, while B cell levels steadily declined to control levels over the same time. The pulp-infiltrating cells were primarily T cells with an alphabeta T cell receptor expressing the Vbeta1 gene (TCR2+). The ratio between CD4+ and CD8+ cells was 1.42 and 0.75 in 2- and 6-week-old regenerating feathers from chickens with autoimmune SLV, respectively. In non-vitiliginous chickens this ratio was always near 1. These data suggest that TCR2+ T cells play an important role in SLV. CD4+ cells may play a recruiting/activating role, whereas CD8+ cells may have cytotoxic activity specifically directed against melanocytes. Additionally, this is the first report demonstrating the infiltration of B cells into the feather pulp of vitiliginous chickens. These B cells may directly/indirectly contribute to melanocyte destruction in SLV.

Animals↗

PubMed1996

5-azacytidine treatment induces autoimmune vitiligo in parental control strains of the Smyth line chicken model for autoimmune vitiligo.

The effect of 5-Azacytidine (5-AzaC) on melanization was examined in two sublines of the Smyth line (SL) chicken model for autoimmune vitiligo, in two MHC-matched vitiligo-susceptible but normally pigmented controls (BL), and in nonsusceptible controls (LBL). 5-AzaC was administered ip every 3 days from day of hatch to 18 weeks at levels of 1 or 3 mg/kg body wt. Both treatments increased (P < 0.01) the incidence of autoimmune vitiligo in BL controls. In contrast, treatment significantly depressed (P < 0.01) the expected high incidence of vitiligo in one SL subline, but not in the other. There were no apparent pigmentation changes in 5-AzaC-treated LBL controls. 5-AzaC had dose-dependent depressing effects (P < 0.01) on body and lymphoid organ weights. Histological and mitogen assay data suggest negative effects on lymphocyte number and function. The data show that 5-AzaC can initiate autoimmune disease in genetically susceptible but phenotypically normal individuals.

Animals↗

PubMed1996

Alterations in blood leukocyte populations in Smyth line chickens with autoimmune vitiligo.

Smyth line (SL) chickens spontaneously develop a posthatch autoimmune loss of pigment cells (vitiligo) in the feather. Concurrent with the development of Smyth line vitiligo (SLV), mononuclear cell infiltration and altered T cell profiles can be observed in the pulp of developing feathers. To determine whether the development of SLV is preceded by or associated with alterations in blood lymphocyte and leukocyte populations, blood leukocyte profiles were established at various times prior to and throughout the spontaneous development of SLV. The proportions among various blood leukocyte populations (percentage of lymphocytes, monocytes, heterophils, eosinophils, and basophils) were determined by immunofluorescence and flow cytometric analyses. Lymphocyte markers included fluorescence-conjugated monoclonal antibodies to identify T cells (CD3), T helper cells (CD4), cytotoxic T cells (CD8), and B cells (IgM). The proportions among blood lymphocyte populations examined did not differ between SL and MCH-matched parental Brown line (BL) control chickens prior to and throughout the development of SLV. Compared to BL controls, SL chickens had, however, increased proportions of inflammatory leukocytes in the blood, particularly at the time when most hatchmates developed SLV. Examination of leukocyte alterations with respect to first observation of SLV revealed that inflammatory leukocyte levels were elevated early in SLV. Although altered leukocyte profiles in the blood were observed during the development of SLV, blood from SL chickens did not reflect alterations in lymphocyte populations known to occur at the site of melanocyte destruction. The role of inflammatory blood leukocytes in the development of SLV needs to be further investigated.

Animals↗

PubMed1995

T cells in regenerating feathers of Smyth line chickens with vitiligo.

Smyth line (SL) chickens exhibit a spontaneous, autoimmune, depigmentation (SL vitiligo, SLV) in regenerating feather tissue due to the death of pigment cells (melanocytes). It was the purpose of this study to characterize mononuclear leukocytes which infiltrate the feather as SLV develops. Frozen sections of regenerating features from SL and control chickens were labeled with a panel of mAbs specific for chicken mononuclear leukocytes. SL chickens were found to have significantly greater numbers of T cells in the feather pulp prior to, and throughout, the development of SLV. Initially, both SL and control chickens had a CD4/CD8 ratio near 1.0 in their feather pulp. Following the onset of SLV, the CD4/CD8 ratio in SL chickens dropped below 0.4. Throughout the development of SLV, SL chickens had greater proportions of T cells with alpha/beta T cell receptors than controls. Histological evidence strongly supports an important role for T cells in the pathology of SLV.

Animals↗

PubMed1995

Immune response to sheep red blood cells in two Smyth line populations homozygous for different major histocompatibility complex haplotypes.

The Smyth line (SL) chicken is characterized by a high incidence of spontaneous, posthatch, selective destruction of melanocytes, caused by an autoimmune phenomenon. It has been shown that the MHC is associated with the development and severity of the disease. To clarify further the role of MHC haplotypes and other factors leading to an autoimmune response, mean antibody titers to SRBC were determined for 37-wk-old females from 2 SL sublines (SL101 and SL102), each homozygous for a different MHC haplotype, their MHC-matched parental control sublines (BL101 and BL102), and a normally pigmented control, LBL. Although total incidence of amelanosis is approximately the same for both SL sublines, amelanosis occurs earlier and is more severe in SL101 birds. Within sublines, chickens were further classified as to the extent of the feather amelanosis. Neither SL MHC subline had a mean SRBC titer that differed significantly from unrelated LBL controls. Although the secondary response of the two sublines differed from each other (P < .05), neither differed from its MHC-matched parental control; therefore, the differences in immune response appear to be largely MHC-related and not closely related to melanocyte destruction. When SRBC titers were related to amelanotic severity, no differences were found within the SL101 subline, although, SL102 birds that became amelanotic at a later age had a lower primary response to SRBC (P < .05) than the more severely affected group. Birds simultaneously producing both pigmented and amelanotic feather tissue had higher (P < .05) primary and secondary anti-SRBC titers than did the complete amelanotics.

Animals↗