Biomedical subjects

I G Colditz

Publications and source records attributed to I G Colditz.

At least 37 records · Page 2Linked to original sources

PubMed1997

Leukocyte and cytokine accumulation in the ovine teat and udder during endotoxin-induced inflammation.

The accumulation of leukocytes, ovine serum albumin and the cytokines interleukin-1 beta(IL-1 beta), tumour necrosis factor-alpha(TNF-alpha), interleukin-8 (IL-8), granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon-gamma(IFN-gamma) was studied during endotoxin-induced inflammation in lactating and dry ovine udders, and in the teat cisterns of dry ewes after surgical closure of the passage between the teat and udder cisterns. Samples were taken before infusion and hourly up to 10 h after infusion of 0.1, 1 or 10 micrograms of endotoxin, or infusion of pyrogen-free saline (PFS) as a control. Rectal temperatures were measured. A significant dose- and time-dependent accumulation of leukocytes, mainly neutrophils, was observed in the lactating udders and in the teat cisterns. In the dry udders, the leukocyte accumulation was significant for time but not for dose. Peak numbers of cells were reached at 3-4 h in the dry udders and in the teat cisterns, but not until 10 h after infusion in the lactating udders. The changes in the ovine serum albumin concentrations mostly paralleled changes in leukocyte numbers. A role was indicated for TNF-alpha, IL-8 and GM-CSF, but not for IL-1 beta and IFN-gamma, during endotoxin-induced inflammation in the ovine udder. Release of TNF-alpha, IL-8 and GM-CSF was most prominent in lactating udders, peaking at 2 or 3 h after infusion, but was also detected in dry udders and teat cisterns. Detectable levels of IL-1 beta and IFN-gamma were occasionally found in all three groups.

Animals↗

PubMed1996

Growth of Lucilia cuprina larvae following treatment of sheep divergently selected for fleece rot and fly strike with monoclonal antibodies to T lymphocyte subsets and interferon gamma.

Intensive lymphocytic infiltration of the underlying dermis occurs during cutaneous myiasis caused by larvae of the blow fly, Lucilia cuprina. To determine the effect of this infiltrate on larval growth, monoclonal antibodies (mAb) to CD4, CD8 or WC1 lymphocyte subset determinants were injected intravenously before and during experimental infection of sheep with larvae. The effect of intravenous injection of mAb to ovine interferon (IFN) gamma was also examined. The experiments were performed in 18-month-old maiden ewes with genetic resistance or susceptibility to the disease complex, bacterial dermatitis/cutaneous myiasis. mAbs induced profound depletion of CD8+ and WC1+ subpopulations from blood and skin at sites of larval growth. mAb to CD4+ gave only a moderate reduction in lymphocytes from blood or skin. mAb treatments did not modify larval growth or survival at 20 or 50 h after infection. Larval growth rates did not differ between resistant and susceptible genotypes. No evidence was found for a role of T lymphocyte subpopulations or the cytokine IFN, in modifying larval growth during the first 50 h of infection. It seems unlikely that T lymphocyte-dependent immunological effector mechanisms contribute to the lower prevalence of fly strike seen in the resistant genotype in the field.

Animals↗

PubMed1996

Cytokine-induced inflammation in the ovine teat and udder.

The inflammatory response, as measured by the accumulation of leukocytes and ovine serum albumin, induced by interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha), interleukin-beta (IL-8), and granulocyte-macrophage colony stimulating factor (GM-CSF) was studied in lactating ovine udders, and in test cisterns of dry ewes after surgical closure of the passage between the teat and udder cisterns. In the lactating udders, IL-1 beta and TNF-alpha, but not IL-8 and GM-CSF, induced significant accumulation of cells. In the teat cisterns, all four cytokines IL-1 beta, TNF-alpha, IL-8, and GM-CSF induced significant cell accumulation. IL-1 beta was the most potent cytokine. A slight increase in serum albumin, paralleling the changes in leukocyte numbers, was observed after infusion of IL-1 beta and, to some extent, TNF-alpha. The cell accumulation induced by IL-1 beta or TNF-alpha was dose and time dependent in lactating udders, and time-dependent in teat cisterns. The cell numbers were considerably higher in lactating udders than in teat cisterns after infusion with IL-1 beta. The first influx of cells was observed earlier, and the cell numbers peaked earlier in the teat cisterns than in the lactating udders. IL-8 and GM-CSF induced dose and time dependent cell accumulation in teat cisterns only. The differences between lactating udders and teat cisterns may be attributable to the differences in tissue area involved and the number of receptors available, or to dilution of cytokines in milk, or to presence of inhibitory factors. Differences between cytokines in their inflammatory effects may be explained by their modes of action. IL-1 beta and TNF-alpha have a wide range of cellular functions enabling them to induce a more prominent response than IL-8 and GM-CSF. Furthermore, receptors for IL-1 beta and TNF-alpha are present on a larger number of cell types. Finally, the results indicated that the teat cisterns, being the port of entry for udder infections, as well as the lactating udders are capable of a diversified inflammatory response which is important in the defence against udder infections.

Animals↗

PubMed1996

In vivo depletion of T-cells and cytokines during primary exposure of sheep to parasites.

This study examined the role of CD8+ and WC1+ T-cells and of interferon (IFN)-gamma in the development of protective immunity against infection with the enteric nematode parasite Trichostrongylus colubriformis in sheep. Monoclonal antibodies (mAb) were administered during induction of the immune response to deplete or neutralise these components. Protection against the primary and challenge infections was assessed by faecal egg count and total worm count. Prolonged administration of mAb recognising IFN-gamma and CD8 resulted in significantly increased protection during the 6 week primary infection and following challenge. CD8+ cells were depleted from blood but not from intestinal mucosa. After injection of mAb (CC15) recognising the surface antigen WC1, WC1+ and Tcr gamma delta + cells were depleted from blood but not markedly from enteric mucosa, and protection against challenge, although variable, was increased by up to 88%. It appears that CD8+ and WC1+/gamma delta+ cells and IFN-gamma all retard the potential development of naturally acquired immunity against the parasite.

Animals↗

PubMed1994

The effect of immune and inflammatory mediators on growth of Lucilia cuprina larvae in vitro.

Immune and inflammatory responses occurring during dermal infestation by larvae of Lucilia cuprina can retard larval growth and development. This study examined the effect of 4 classes of humoral inflammatory mediators on larval growth in an in vitro assay. Mediators of plasma leakage (histamine, bradykinin, platelet-activating factor and serotonin), leucocyte chemotactic agonists (activated complement, leukotriene B4 and interleukin-8), effector molecules of immune responses (interleukin-1 beta, tumour necrosis factor-alpha and interferon-gamma) and endotoxin all failed to inhibit larval growth. In contrast, immunoglobulins isolated from immune serum caused marked retardation of larval growth. The results suggest that humoral mediators of inflammatory and immune responses do not play a role in immune defence against Lucilia cuprina.

Animals↗

PubMed1994

Age-dependent immune response in Merino sheep.

The numerical and functional attributes of populations of lymphocytes were compared in the blood, lymph and skin of young and mature sheep. Young sheep, four to eight months old, had a lower proportion of CD4+ cells in blood, lymph and skin than mature sheep three to six years old. In contrast, B cells and T19+ cells were as prevalent or more prevalent in young sheep as in mature sheep. Blood lymphocytes from young sheep, cultured in vitro produced less interferon-gamma, both spontaneously and in the presence of concanavalin A than did lymphocytes from older sheep. The serum antibody responses of adult sheep to the T cell-independent antigen Brucella abortus lipopolysaccharide (LPS) were greater over a range of antigen doses, suggesting that an apparent excess of antigen could not overcome the relative immune deficiency of young sheep. The adjuvant Quil A corrected the depressed antibody response of young sheep to B abortus LPS, but dextran sulphate did not. The skin contact hypersensitivity of mature sheep to dinitrochlorobenzene was greater. However, the T cell phenotypes present in infiltrates of lymphocytes elicited by the intradermal injection of tetanus and diphtheria, but not tuberculin antigens, were comparable for the two age groups. The capacity of Quil A to raise the antibody responses of both young and mature sheep to a similar titre suggests that it may be possible to overcome the immunological hyporesponsiveness that may contribute to the disease susceptibility of young sheep.

Aging↗

PubMed1994

Cloning, sequencing, expression and inflammatory activity in skin of ovine interleukin-8.

Ovine IL-8 (oIL-8) cDNA was obtained by probing a spleen cell cDNA library with human IL-8 (hIL-8) cDNA. The oIL-8 cDNA was 1434 base pairs long with a single open reading frame encoding a 101 amino acid precursor protein of relative molecular mass 11,268. The inferred amino acid sequence has 78, 82, 84 and 67% similarity with human, rabbit, porcine and guinea-pig IL-8, respectively. By analogy with the most prevalent form of hIL-8, a 72 amino acid form of oIL-8 was expressed as a fusion protein containing glutathione-S-transferase and purified by affinity chromatography on a glutathione-Sepharose column yielding 8 mg IL-8/L broth culture. The fusion protein lacked chemotactic activity for ovine neutrophils, whereas the 72 amino acid form of oIL-8 was equipotent with rhIL-8. At 6 and 24 h after intradermal injection of 10(-9) mol oIL-8, there was intense accumulation of neutrophils, and very mild accumulation of eosinophils, CD5, CD4 and T19 (a gamma delta TCR subset) cells but not CD8 cells. The availability of roIL-8 and its cDNA probes will permit the role of this important member of the IL-8 family of chemotactic cytokines to be determined in inflammatory diseases of sheep.

Amino Acid Sequence↗

PubMed1994

Cellular inflammatory responses in skin of sheep selected for resistance or susceptibility to fleece rot and fly strike.

Leucocyte populations were examined in normal and inflamed skin of sheep bred for resistance (R) or susceptibility (S) to bacterial fleece rot and the common sequela, body strike caused by the dipteran parasite Lucilia cuprina. No differences between R and S lines were found in numbers of neutrophils accumulating in acute inflammatory lesions induced by activated complement, leukotriene B4, interleukin (IL)-1 beta, tumour necrosis factor-alpha, IL-8 or endotoxin from Pseudomonas aeruginosa. T19+ (alpha gamma delta T cell subset) lymphocytes and eosinophils were more prevalent in skin of sheep from the S line whereas IgE+ cells were more prevalent in skin of sheep from the R line. In an unrelated population of sheep, animals with low fleece rot scores had more intense neutrophil migration into inflammatory lesions induced by all the mediators examined than did animals with high fleece rot scores. IgE+ cells were more prevalent in animals with low fleece rot scores, although in contrast to R and S lines, T19+ cells tended to be elevated in this group of animals. The results suggest that defence mechanisms associated with IgE+ cells in skin may play an important role in resistance to fleece rot and fly strike.

Animals↗

PubMed1993

Migratory responses of ovine neutrophils to inflammatory mediators in vitro and in vivo.

The migration of 111In-labeled ovine neutrophils towards a range of inflammatory mediators was examined in vitro using a 48-well chemotaxis chamber. Typical curves were obtained for the chemotactic response to zymosan-activated plasma (ZAP, a source of C5a) and interleukin-8 (IL-8). In contrast, leukotriene B4 (LTB4), platelet-activating factor (PAF), interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF-alpha), N-formyl-methionine-leucyl-phenylalanine (fMLP), and endotoxins from Escherichia coli and Pseudomonas aeruginosa failed to induce neutrophil migration in vitro. Of these mediators LTB4, ZAP, IL-1 alpha, TNF-alpha, IFN-gamma, and IL-8 have been reported to induce neutrophil accumulation in skin of sheep, and in the current study E. coli endotoxin was a potent inducer of 111In-labeled neutrophil accumulation and plasma leakage in skin. In contrast, PAF induced intense plasma leakage but failed to induce accumulation of 111In-labeled neutrophils in skin. Histologic examination of skin sites receiving PAF confirmed the failure of PAF to stimulate neutrophil extravasation. FMLP lacked inflammatory activity in skin. Coinjection of actinomycin D did not abrogate recruitment of neutrophils to skin sites receiving LTB4; thus neither induction of endothelial adhesion molecules nor synthesis of IL-8 was necessary for LTB4 to exhibit inflammatory activity in vivo.

Animals↗

PubMed1993

Immune responsiveness of lambs selected for resistance to haemonchosis.

Several parameters of immune competence were measured in lambs with genetic resistance to Haemonchus contortus and in lambs with average susceptibility to H contortus (random-bred). Increase in skinfold thickness following intradermal injection was greater in resistant lambs for concanavalin A and to a lesser extent for phytohaemagglutinin. Both mitogens induced infiltration of superficial and deep dermis by eosinophils, CD4+, CD8+ and T19+ lymphocytes, though the responses did not differ between groups. Primary but not secondary antibody responses to the T cell-dependent antigen, ovalbumin was greater in resistant lambs. In contrast, antibody responses to the T cell-independent antigen, Brucella abortus lipopolysaccharide, did not differ between groups. Taken together the data suggest that enhanced T lymphocyte function may contribute to the greater resistance to H contortus of genetically resistant lambs.

Animals↗

PubMed1992

Induction of tissue eosinophilia by platelet-activating factor in Merino sheep.

A study was undertaken on the capacity of platelet-activating factor (PAF) to induce eosinophil accumulation in the mammary glands of non-lactating sheep. Platelet-activating factor induced dose-dependent accumulation of eosinophils in mammary exudates 24 h after infusion. Infection, by intraruminal injection of 20,000 infective Trichostrongylus colubriformis larvae, did not modify the responsiveness of outbred sheep to intramammary infusion of PAF. Mature ewes from high and low responder lines of a flock of sheep, selected on the basis of their responses to vaccination and experimental challenge with T. colubriformis as lambs, did not differ in the magnitude of the eosinophil responses to doses of PAF from 5 x 10(-13) to 5 x 10(-7) mol per gland. Intramammary infusion of an extract from third stage larvae of Haemonchus contortus elicited inflammatory exudates containing five- to ten-fold more eosinophils than that elicited by the highest dose of PAF tested. The experiments indicate that the eosinophil chemotactic agonist PAF can induce tissue eosinophilia in sheep and thus may play a role in directing the accumulation of eosinophils in tissues during disease states such as gastrointestinal parasitism.

Animals↗

PubMed1992

Intradermal and percutaneous transudation of IgG1 and transferrin in sheep.

The leakage of [125I]-IgG1 into skin sites following injection of mediators of enhanced vascular permeability and during induction of transudates on the skin surface under negative pressure was examined to determine whether IgG is selectively transported into cutaneous transudates. 111In-transferrin was employed as a marker of plasma leakage unaided by selective transport. The leakage of IgG1 into interstitial spaces of untreated skin, into inflammatory transudates and into transudate fluid drawn to the skin surface under vacuum occurred at a lower rate than did leakage of transferrin. No evidence was found in favour of a selective transport mechanism to aid transport of IgG1 into extravascular skin compartments.

Animals↗

PubMed1992

Plasma leakage in skin of sheep selected for resistance or susceptibility to fleece rot and fly strike.

The leakage of plasma into skin following injection of histamine, bradykinin, activated complement, platelet-activating factor and serotonin was measured in sheep bred for resistance or susceptibility to fleece rot and fly strike. Genetically susceptible sheep had significantly greater plasma leakage to activated complement than genetically resistant sheep, and for all mediators there was a trend for plasma leakage to be greater in susceptible sheep. Within each genotype there was also a tendency for plasma leakage to be positively correlated with fleece rot score. In a flock of sheep of different genetic background not selected for resistance or susceptibility to fleece rot and fly strike, positive phenotypic correlations were also noted between fleece rot and plasma leakage. Plasma leakage provides nutrition for the first instar larvae of Lucilia cuprina, the major cause of primary blowfly strike in Australia. Diminished leakage of plasma following release of endogenous permeability mediators may be one component of the mechanism that confers resistance in animals bred for resistance to fleece rot and fly strike.

Animals↗

PubMed1992

The effect of cytokines and chemotactic agonists on the migration of T lymphocytes into skin.

The migration of lymphocytes and neutrophils into skin sites stimulated with chemotactic agonists or with cytokines known to induce leucocyte-endothelial adhesion molecules was examined in sheep. Lymphocytes, collected from efferent prefemoral lymph, labelled in vitro with [111In]oxine and reinjected intravenously, migrated in large numbers into delayed-type hypersensitivity (DTH) reactions elicited by purified protein derivative (PPD) and into sites stimulated with tumour necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma). In contrast, interleukin (IL)-1 alpha, a potent inducer of endothelial leucocyte adhesion molecule-1 (ELAM-1), caused moderate accumulation of [111In]lymphocytes at concentrations that induced intense accumulation of 111In-labelled neutrophils. The chemotactic agonists IL-8 and zymosan-activated plasma (ZAP) caused accumulation of very large numbers of neutrophils but only small numbers of lymphocytes, whereas platelet-activating factor (PAF) and leukotriene B4 (LTB4) failed to recruit lymphocytes into skin. IFN-gamma was the only mediator to recruit lymphocytes in preference to neutrophils into skin. The results suggest that those lymphocyte chemotactic agonists which lack the ability to induce adhesion molecules on endothelium play only a minor role in directing migration of lymphocytes into skin. Immunohistological examination of skin lesions confirmed the findings of studies with 111In-labelled lymphocytes and indicated that there was a tendency for CD4+ cells to outnumber CD8+ cells in infiltrates induced by all mediators. In contrast to the elevated numbers of T19+ subset of T-cell receptor (TcR+) gamma delta cells present in DTH reactions, none of the mediators induced migration of T19+ cells into skin.

Animals↗

PubMed1991

Immunity to Haemonchus contortus and the cellular response to helminth antigens in the mammary gland of non-lactating sheep.

Cellular exudates induced by infusion with helminth antigens were examined in non-lactating mammary glands of ewes immune to infection with the abomasal nematode, Haemonchus contortus. Secondary immunological responsiveness was expressed in two ways. Firstly, antigens from adult H. contortus elicited larger eosinophil-rich cellular exudates in immune compared to non-immune ewes. In this situation, secondary responsiveness in the mammary gland must have been generated through abomasal infection with the parasite. Secondly, repeated infusion with the antigens from adult H. contortus increased the size of cellular exudates in both immune and non-immune ewes. Eosinophils predominated but numbers of macrophages and lymphocytes were also increased. In this second situation, secondary responsiveness must have been either supplemented in immune ewes or derived completely in non-immune ewes by contact with helminth antigens through the mammary gland. The helminth antigens which induce eosinophil exudates in the mammary gland may not be potently protective against H. contortus. Furthermore, eosinophil exudation may not be an in vivo correlate of immunity which is directly useful for discriminating protective antigens and applicable to vaccine development. Infusion with antigens from adult forms of either H. contortus or Trichostrongylus colubriformis elicited cellular exudates equally well in immune ewes primed by infusion with H. contortus adult antigens 7 days beforehand. In addition, antigens from infective larvae of H. contortus elicited cellular exudates more potently than antigens from adult worms. However, vaccination with irradiated larvae has shown that species-specific protective immunity for H. contortus is stronger than cross-protective immunity conferred by T. colubriformis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

The induction of plasma leakage in skin by histamine, bradykinin, activated complement, platelet-activating factor and serotonin.

Vascular leakage of [125I]-human serum albumin into the skin of sheep was measured in response to intradermal injection of histamine, bradykinin, zymosan-activated plasma (ZAP), platelet-activating factor (PAF) and serotonin. Potency of the mediators was PAF greater than ZAP greater than bradykinin approximately histamine greater than serotonin. Maximal leakage occurred in the first 10 min following injection of bradykinin, histamine and PAF, and for histamine and bradykinin had effectively ceased by 40 min. In contrast, ZAP and serotonin induced relatively constant plasma leakage over the first 40 min following their intradermal injection. Prostaglandins E1 and E2 enhanced plasma leakage induced by histamine and bradykinin thus confirming the applicability of the two-mediator hypothesis of vascular leakage to permeability responses in skin of sheep.

Animals↗

PubMed1991

The effect of systemic treatment with platelet-activating factor on the migration of eosinophils to lung, pleural and peritoneal cavities in the guinea pig.

Subcutaneous treatment of guinea pigs with platelet-activating factor (PAF) caused an increase in the prevalence of eosinophils in lavage fluid recovered from pulmonary airways, and pleural and peritoneal cavities. In PAF-treated animals, total numbers of eosinophils and macrophages in washings were positively correlated, thus there was no apparent competition between the two cell types for migration at traffic sites into body cavities. The results indicate that PAF acts centrally to enhance the migration of eosinophils and monocytes into body cavities, perhaps by inducing bone marrow release of both classes of leucocytes which may then migrate constitutively into lung, pleural and peritoneal cavities.

Animals↗

PubMed1990

Neutrophil accumulation and plasma leakage induced in vivo by neutrophil-activating peptide-1.

Neutrophil accumulation and plasma leakage induced in rabbit skin by neutrophil-activating peptide-1 (NAP-1, a 72 amino acid peptide produced by monocytes and a variety of tissue cells), E. coli endotoxin, and interleukin-1 (IL-1) were compared. Neutrophil accumulation at sites injected with NAP-1 was intense, rapid, and long-lasting; it reached a maximum rate during the first 30 min, continued at constant rate for 4-6 h, and remained detectable up to at least 8 h. In contrast, the neutrophil-attracting effect of endotoxin and IL-1 was slower in onset and more transient; it peaked in the first 2 h and declined to a very low level after 4 h. Plasma leakage induced by NAP-1 had a shorter time course than neutrophil accumulation and ceased after 6 h. Depletion of blood neutrophils by treatment with hydroxyurea prevented the plasma leakage induced by NAP-1 or endotoxin but not by histamine. Desensitization to NAP-1 was studied by restimulation of lesions. Following restimulation with NAP-1 after intervals from 6-10 h, there was diminished infiltration of neutrophils, while nearly normal responses were obtained after an interval of 24 h. Desensitization was dose dependent and affected both plasma leakage and neutrophil accumulation. In lesions initiated with NAP-1 there were normal responses following restimulation with endotoxin but marked desensitization to IL-1, suggesting that NAP-1 may contribute to inflammation induced by IL-1 but not by endotoxin. This study indicates that NAP-1 is a potent mediator of neutrophil accumulation in vivo, with characteristics similar to those reported for C5 fragments, but with a more protracted action.

Animals↗