Biomedical subjects

D L Watson

Publications and source records attributed to D L Watson.

At least 73 records · Page 4Linked to original sources

PubMed1988

Modulation of IgG subclass expression during antibody responses in sheep.

Experiments were undertaken to investigate IgG subclass expression during epitope-specific antibody responses in sheep. Animals were immunised with conjugates of bovine serum albumin-DNP (BSA-DNP), or killed Staphylococcus aureus-DNP (Sa-DNP) alone or with muramyl dipeptide (MDP), dextran sulphate (DXS), or staphylococcal exotoxins (toxin). Sheep received two injections of the same preparation intracutaneously at six weeks interval. Total and IgG subclass-specific anti-DNP, and anti-carrier (BSA or S aureus) antibody levels were measured by ELISA in blood taken at weekly intervals before and after immunisation. Anti-DNP antibody levels in animals given Sa-DNP alone were considerably greater than in those immunised with BSA-DNP alone. Toxin suppressed antibody responses to DNP and both carriers; MDP suppressed anti-hapten antibody responses below the levels obtained with antigen alone. Neither toxin nor MDP significantly altered the IgG subclass profile of antibody to DNP bound to either carrier. DXS did not significantly change total levels of anti-DNP antibody measured in sheep given BSA-DNP or S aureus-DNP. However, DXS promoted IgG1 and suppressed IgG2 anti-DNP antibody responses during the secondary response to Sa-DNP but not to BSA-DNP.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1988

Origin of antibody-containing cells in the ovine mammary gland following intraperitoneal and intramammary immunisation.

Previous studies in sheep indicate that a combination of intraperitoneal and intramammary immunisation with ovalbumin results in a population of anti-ovalbumin-containing plasma cells of the IgG1 isotype in the immunised mammary gland. These cells are not present in the unimmunised contralateral gland. The studies reported here were undertaken to determine the source of these cells. The failure of chronic intestinal lymphatic drainage or either mesenteric or supramammary lymphadenectomy to abrogate this response was interpreted as evidence against their origin from gut-associated or mammary-associated lymphoid tissue. It is concluded that the success of prior intraperitoneal immunisation in stimulating an enhanced IgG1-specific response to local antigen in the mammary gland probably results from recruitment of cells from systemic lymphoid tissue primed by intraperitoneal immunisation.

Animals↗

PubMed1988

Vaccination against experimental staphylococcal mastitis in ewes.

Experiments were carried out in ewes using a new vaccine developed for the prevention of mastitis caused by Staphylococcus aureus. The vaccine comprised three major components: (i) killed S aureus cells which had been cultured to induce synthesis of pseudocapsule; (ii) toxoided staphylococcal beta haemolysin and (iii) the adjuvant dextran sulphate. Ewes systemically vaccinated twice during pregnancy developed significantly elevated circulating levels of IgG1 and IgG2 anti-pseudocapsule antibody, as well as increased serum titres of anti-beta haemolysin. Five different strains of S aureus were used to challenge both vaccinated and control ewes by the intramammary route during the ensuing lactation. The incidence of acute gangrenous mastitis and nonacute, clinical mastitis was significantly lower in vaccinated than in control groups after challenge with each strain. Vaccinated ewes produced significantly more milk than control ewes after challenge with four of the five strains of S aureus.

Animals↗

PubMed1987

Inflammatory and immunological responses in skin and peripheral lymph of sheep following intracutaneous injection of Staphylococcus aureus.

The cellular response within lesions and in draining lymph was examined in sheep following a primary intracutaneous injection of live or killed S. aureus. Microscopic examination of sections from live S. aureus lesions (12, 24, 48, and 96 h following vaccination) revealed a high ratio of neutrophils to macrophages at all times. This ratio was initially high following inoculation of killed S. aureus but decreased steadily at successive sampling times. Representative sections from lesions were subjected to indirect immunofluorescent staining to identify IgM-, IgG1-, and IgG2-containing cells. The ratio of IgG2- to IgG1-containing cells in lesions produced following live S. aureus vaccination was significantly greater than the ratio in lesions produced by killed staphylococci. Lesions induced by live S. aureus recruited significantly greater numbers of 51Cr-labeled allogeneic neutrophils from blood than did lesions induced by killed S. aureus. During the first 6 h this difference was approx. 20-fold. The volume of lymph and the number of leukocytes draining live S. aureus lesions was considerably greater than from lesions produced by killed staphylococci. The proportion of neutrophils in lymph draining both types of lesions increased markedly during the first two days of the response but was observed to be greater and remained higher for a longer period of time in lymph draining vaccine lesions produced following injection of live staphylococci. The increase in proportion of neutrophils in lymph was accompanied by a concomitant decrease in proportion of lymphocytes and macrophages. No immunoglobulin-containing cells or anti-staphylococcal antibody production was detected in lymph draining either type of lesion. These differences in inflammatory responses may contribute to the documented differences in immune responses to live and killed staphylococcal vaccines.

Animals↗

PubMed1987

Synergism between antibody and neutrophils in the ruminant mammary gland.

Immunological activities of the mammary gland are important both as a means of transferring immunity from mother to young and for defending the mammary gland itself against infection. The presence of immunoglobulins G1, G2 and A, and of neutrophils, macrophages and complement in the ruminant mammary gland is described, in particular the synergistic role of antibody and neutrophils is discussed and studies of immunization against staphylococcal mastitis are outlined.

Animals↗

PubMed1987

Serological response of sheep to live and killed Staphylococcus aureus vaccines.

Adult sheep were immunized intramuscularly with a killed, in vivo-grown Staphylococcus aureus vaccine combined either with dextran sulphate (group DD) or with Freund's incomplete adjuvant (group FF). Another group (LL) received an attenuated live S. aureus vaccine intracutaneously. The animals were given a primary vaccination followed two weeks later by a booster vaccination. A fourth group of sheep (group LD) was primed with the live vaccine and given a booster vaccination with the killed vaccine combined with dextran sulphate. ELISA was used to quantify blood serum levels of IgM, IgG1 and IgG2 antibody directed against the pseudocapsular antigens of S. aureus grown under in vivo conditions. Groups LD, DD, and FF had sharp increases in mean levels of IgM antibody in the first few weeks after vaccination with another large increase in mean values for group FF at 12 weeks after primary vaccination. Group LL showed virtually no increase in levels of IgG1 antibody; the other three groups had maximum mean values for IgG1 antibody at 5 weeks (FF) and 8 weeks (LD and DD) after primary vaccination. All groups had large IgG2 antibody responses (the largest for group LD), but the response for this isotype had waned by 14 weeks after primary vaccination. Examination of the ratios of IgG2 antibody to IgG1 antibody suggested that dextran sulphate may be a useful adjuvant for preferentially stimulating synthesis of IgG2 antibody against staphylococcal pseudocapsular antigens.

Animals↗

PubMed1987

Effect of dextran sulphate on IgG subclass of antibody in efferent popliteal lymph of sheep.

IgG1 and IgG2 participation in anti-hapten, anti-carrier and immunoglobulin-containing cell (Ig-cc) responses was studied in sheep immunised with killed Staphylococcus aureus-Dinitrophenyl (DNP) conjugates. The antigen was given with or without the polyanionic adjuvant dextran sulphate (DXS). Animals were immunised intracutaneously on the lateral hock of one hind leg with 1 X 10(9) S. aureus-DNP with or without 20 mg DXS. Six weeks later, primed sheep underwent surgery to cannulate an efferent popliteal lymphatic vessel in the immunised leg. Forty-eight hours after surgery, each sheep was given a further intracutaneous injection of 1 X 10(9) S. aureus-DNP with or without 20 mg DXS adjacent to the primary injection site. IgG1-cc and IgG2-cc in lymph were counted using indirect immunofluorescence. Total IgG1 and IgG2 anti-staphylococcal and anti-DNP antibody output in lymph was determined using enzyme-linked immunosorbent assays (ELISA's). DXS markedly increased antibody responses to S. aureus-DNP in the popliteal lymph node of sheep and was shown to strongly enhance immunological memory. The ratios of IgG2-cc:IgG1-cc and IgG2:IgG1 anti-staphylococcal antibody in lymph-draining popliteal lymph nodes of sheep stimulated with DXS and S. aureus-DNP was significantly greater than the same ratios in animals given antigen alone. The IgG subclass-specific immunomodulatory effects of DXS were exerted whether the adjuvant was given with primary and/or secondary inoculations. There was no difference in the ratio of IgG2:IgG1 anti-DNP antibody in lymph from animals given S. aureus-DNP with and without DXS.

Adjuvants, Immunologic↗

PubMed1987

The secondary immune response to Staphylococcus aureus vaccines in efferent popliteal lymph of sheep.

The secondary immune response to live and killed Staphylococcus aureus vaccines was studied in efferent popliteal lymph of sheep. Animals were immunized with either live or killed S. aureus intracutaneously on the lateral hock, in an area draining into the popliteal lymph node. Six weeks later, an efferent popliteal lymphatic vessel in the vaccinated leg was cannulated, and 48 hr after surgery a second inoculation (identical to the primary) was placed in the skin adjacent to the primary vaccination lesion. A dramatic decrease in lymphocyte output ('cell shutdown') was observed in lymph collected from sheep given the secondary inoculation of live S. aureus during the first 8 hr after inoculation. However, only a moderate decrease in lymphocyte output occurred in lymph from animals receiving killed S. aureus or from control animals. The proportion of eosinophils in lymph collected from animals given live S. aureus increased to a peak (14% of total leucocytes in lymph) between 6 hr and 8 hr, and returned to prechallenge levels by 24 hr post-inoculation. The percentage of neutrophils in lymph peaked between 8 hr and 1 day after injection of live bacteria. This granulocyte response was not observed in animals given killed S. aureus or control animals. IgM-, IgG1- and IgG2- containing cells (-cc) in lymph were quantified by indirect immunofluorescence. Animals given live S. aureus produced lymph with greater numbers of Ig-cc of these isotypes than those given killed organisms. The ratio of IgG2-cc:IgG1-cc was significantly greater in lymph from animals given live S. aureus from Day 2 to Day 6 post-challenge. IgM and IgG1 anti-staphylococcal antibody levels increased in lymph collected from all vaccinated animals, but only sheep given live S. aureus showed any increase in levels of IgG2 antibody.

Animals↗

PubMed1986

Variations in immunoglobulin isotype produced during the antibody response to Brucella abortus and Staphylococcus aureus vaccines in sheep.

Experiments in sheep were carried out to examine factors modifying the immunoglobulin (Ig) isotype of the antibody response to Brucella abortus. Live B abortus (S19) stimulated higher titres of agglutinating antibody and IgG1 and IgG2 antibody than did killed B abortus. Live B abortus stimulated a more protracted synthesis of IgG2 antibody during the primary and secondary responses than did the killed S19 vaccine. In a second experiment, the capacity of live and killed Staphylococcus aureus to modify the antibody response to killed B abortus was examined. Both live and killed S aureus enhanced production of anti-brucella antibodies; this response was attributed to the adjuvant properties of S aureus. Killed S aureus enhanced production of anti-brucella antibody to a greater extent than live S aureus. Live S aureus did not preferentially enhance production of IgG2 anti-brucella antibody. The results suggested that the enhanced production of IgG2 antibody induced by live vaccines does not depend solely on a pyogenic lesion at the vaccination site.

Adjuvants, Immunologic↗

PubMed1985

Purification and characterization of goblet-cell mucin of high Mr from the small intestine of sheep.

Crude soluble mucus from sheep small intestine was freed of nearly all the nucleic acid contaminants by precipitation with protamine sulphate and treatment with nucleases. After removal of non-covalently bound proteins by equilibrium density-gradient centrifugation in CsCl, a high-Mr glycoprotein was isolated by repeated h.p.l.c. from the partially purified mucin. The high degree of purity of the high-Mr mucin was borne out by (a) the observation of a single boundary on analytical ultracentrifugation in the presence of 5M-guanidinium chloride and (b) the observation of apparent monodispersity on sedimentation-equilibrium analysis. The Mr of the highly purified mucin, determined by sedimentation equilibrium, was 5.0 (+/- 0.1) X 10(6) and was concentration-independent. Finally, only goblet cells and the mucus blanket lining the intestinal epithelial cells were immunofluorescent when guinea-pig anti-(highly purified mucin) serum was used in an indirect immunofluorescence assay. The above antiserum reacted with apparently equal strength with goblet cells and with free mucin in abomasum, caecum and colon. The chemical composition of the glycoprotein was 66% carbohydrate and 34% protein, 45% of the latter being composed of valine and threonine. The glycoprotein migrated anodally on immunoelectrophoresis and contained 7.1% (w/w) sulphate. Neutral hexoses accounted for nearly half of the total carbohydrate content, followed by galactosamine and glucosamine. Whereas fucose and sialic acid were present in only small amounts, uronic acid was not detectable in the highly purified mucus glycoprotein.

Amino Acids↗

PubMed1985

Eclampsia. IV. Neurological findings and future outcome.

Sixty-five patients with eclampsia were longitudinally evaluated regarding neurological abnormalities and maternal outcome (6 to 42 months) after eclampsia. Electroencephalograms were obtained on all patients during the subsequent 6 months. Computerized axial tomographic scans (n = 20) and cerebral arteriograms (n = 3) were obtained on patients with neurological deficits and/or those with an atypical clinical course. The electroencephalogram was abnormal in 49 patients (75%) at initial assessment but gradually returned to normal in all observed patients within 6 months. Cerebral arteriograms and computerized axial tomographic scans were normal in each patient studied. None of the patients had neurological deficits or subsequent convulsions on follow-up examination. Thirty-eight patients had one or more subsequent pregnancies without recurrent eclampsia, but 14 (37%) had pregnancy-induced hypertension. The findings suggest that neurological events of eclampsia are acute and transient and that long-term neurological deficit is rare in the properly managed patient. Computerized axial tomography and electroencephalography are rarely indicated in the management of such patients.

Adolescent↗

PubMed1985

Humoral and cellular factors affecting the neutrophil response of the locally immunised mammary gland to staphylococcal infection.

Locally immunising the non-lactating ovine mammary gland by infusing killed Staphylococcus aureus enhances neutrophil accumulation in mammary secretion during subsequent staphylococcal infection. Immunological factors influencing this increased neutrophil response were studied in the present experiments. Glands locally immunised with killed Brucella abortus supported a greater neutrophil response to staphylococcal infection than did glands immunised with killed S. aureus. An enhanced neutrophil response to staphylococcal infection was recorded in 3 of 7 ewes locally immunised with zymosan. Passive immunisation by intramammary infusion of secretions from immunised glands conferred an enhanced neutrophil response during staphylococcal infection. Absence of haemolytic complement in secretions of immunised glands suggested complement was not implicated in the response. Secretions of immunised glands contained elevated concentrations of mononuclear cells. When exudates rich in mononuclear cells were established by infusion of endotoxin into non-immunised glands there was no increase in the neutrophil response to subsequent staphylococcal infection. However, when the mononuclear cell concentration was elevated by intramammary infusion of staphylococcal antigens in systemically immunised ewes there was an increase in the neutrophil response to subsequent infection. Thus humoral and cellular characteristics of the locally immunised mammary gland influence the kinetics of the neutrophil influx during staphylococcal infection.

Animals↗

PubMed1985

The immunophysiological basis for vaccinating ruminants against mastitis.

The roles of humoral and cellular defence mechanisms in protection of the mammary gland against bacterial infection are reviewed. Effective protection depends on opsonisation of pathogens and subsequent phagocytosis by neutrophils. A concomitant requirement for protection is the rapid infiltration of neutrophils into the infected gland. Immunological studies have shown the need to prime animals against antigens expressed by bacteria when they grow in vivo. Vaccination procedures which promote these mammary defence mechanisms are discussed.

Animals↗

PubMed1985

Specific antibody-containing cells in the mammary gland of non-lactating sheep after intraperitoneal and intramammary immunisation.

Ewes were immunised intraperitoneally with ovalbumin and Brucella abortus in Freund's complete adjuvant, followed seven days later by intramammary immunisation in which ovalbumin was presented to one mammary gland and Brucella abortus to the other. Mammary tissue taken after a further seven days contained more antigen-specific plasma cells than ewes given intraperitoneal or intramammary immunisation alone. These cells were found predominantly in the specifically immunised gland and only a few were found in the contralateral gland. Most of these cells were of the IgG1 isotype. There was also an increase in the total number of IgG1- and IgG2-containing cells in mammary gland tissues of these ewes, indicating a non-specific response to immunisation. Following either intraperitoneal or intramammary immunisation there was also a significant increase in the number of antigen-specific IgA cells in the lamina propria of the jejunum. The gut response following intramammary immunisation alone was abrogated by chronic drainage of intestinal lymph but not mammary lymph. This suggests that antigen may relocate from the mammary gland to the intestine where an IgA response is generated from gut associated lymphoid tissue. These data provide evidence for interaction between the gut and mammary gland of sheep in response to antigen.

Animals↗

PubMed1985

Immunophysiological activity of supramammary lymph nodes of the ewe during the very early phase of staphylococcal mastitis.

Efferent mammary lymph was collected from lactating ewes which were unimmunised (controls) or immunised during pregnancy with two doses of an attenuated live Staphylococcus aureus vaccine either in the hindlimb ("directly primed' supramammary nodes) or in the brisket ("indirectly primed' supramammary nodes). Mammary lymph was also collected from unimmunised animals in which the supramammary nodes had been extirpated several months before. Ewes in which the supramammary nodes had been directly primed by staphylococcal vaccination before challenge had a significantly greater output of IgM- and IgG2-containing cells in lymph and higher concentrations of IgG1 and IgG2 antibody against S aureus surface antigens than did other groups. Lymphadenectomised ewes had fewer leucocytes in mammary lymph but a much higher proportion of neutrophils than other ewes, indicating that afferent mammary lymph has an unusually high number of neutrophils and most of these cells are filtered out in the supramammary lymph nodes under normal circumstances. The results indicated that most of the leucocytes in efferent lymph were derived from the supramammary nodes. After induction of experimental staphylococcal mastitis there was a rapid drop in leucocyte output in lymph within one to four hours after infection; the data indicated that events within the supramammary nodes were responsible for this phenomenon. The output of immunoglobulin-containing cells was reduced during this phase. No significant increases in output of lymphoblasts, immunoglobulin-containing cells or specific antibody occurred during the six hours immediately following infection.

Agglutination Tests↗

PubMed1985

The effect of intraperitoneal and intramammary immunization of sheep on the numbers of antibody-containing cells in the mammary gland, and antibody titres in blood serum and mammary secretions.

The contribution of gut-associated lymphoid tissue (GALT) to the local response in the mammary gland is well documented in laboratory animals and has been evaluated in this study in ruminants. Ewes were immunized intraperitoneally (IP) with antigen in Freund's complete adjuvant (FCA), a procedure which stimulates the production of antibodies of the IgA class in the intestine, and challenged intramammarily (IMam) either during colostrum formation or mammary gland involution. Despite a substantial IgA antibody-containing cell (ACC) response in the intestine in IP immunized sheep, there was no evidence to suggest a relocation of IgA-specific ACC to the mammary gland. There was, however, an IgA antibody response in mammary secretion of IP immunized animals, regardless of whether the mammary gland was locally immunized, but the origin of this antibody is unclear. IP/IMam immunized sheep did have an enhanced antigen-specific ACC response of the IgG1 isotype in locally immunized glands, but whether these cells were of GALT or systemic origin is also unclear.

Animals↗

PubMed1984

Synthesis and transudation of antibody during acute inflammation in the mammary gland.

Nonlactating ewes were immunized with a mixture of ovalbumin and tetanus toxoid either in the hind limb, resulting in "priming" of the supramammary lymph node (group L), or in the brisket, resulting in "priming" of the precapsular lymph node (group B). Substantial systemic antibody responses were mounted in both groups. The animals were challenged by intramammary infusion of either tetanus toxoid and lipopolysaccharide (LPS) or ovalbumin and LPS, and changes in the ratios of the two antibody specificities in mammary secretions were monitored for the first 8 h of the resulting acute inflammatory episode. Following challenge with tetanus toxoid and LPS, the ratio of antitetanus toxoid-antiovalbumin in mammary secretion remained close to 1 for the first 6 h postchallenge in both group L and group B. Similarly in animals challenged with ovalbumin and LPS, the ratio of antiovalbumin-antitetanus toxoid in mammary secretion approximated 1 for the first 6 h postchallenge but increased sharply in both groups between 6 and 8 h postchallenge. Measurement of antibody in efferent supramammary lymph suggested that cells in the supramammary lymph node synthesized significant quantities of specific antibody to the infused antigen during the 8-h inflammatory episode.

Animals↗

PubMed1984

Evaluation of attenuated, live staphylococcal mastitis vaccine in lactating heifers.

Four heifers were immunized in late pregnancy with two doses of attenuated, live Staphylococcus aureus and challenged during early lactation by intramammary infusion into one quarter of approximately 100 organisms of the same attenuated strain. Three unvaccinated control heifers were challenged similarly. At challenge immunoglobulins G1 and G2 antibodies against Staphylococcus aureus surface antigens were significantly greater in blood serum of vaccinated heifers than in controls. Also at challenge, serum from vaccinated heifers had a significantly greater opsonizing capacity for Staphylococcus aureus than did that of controls. The challenge dose of Staphylococcus aureus did not produce prolonged clinical signs of acute mastitis in any of the heifers; however, once of the control animals remained chronically infected. There was a decrease of milk production following challenge for controls but no such decrease for the immunized heifers. Taken together, results of clinical assessments, bacteriology, and measurements of milk production suggested that vaccinated heifers had higher resistance to the challenge dose than did controls.

Animals↗