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Biomedical subjects

D L Watson

Publications and source records attributed to D L Watson.

At least 109 records · Page 6Linked to original sources
PubMed1980

Immunological functions of the mammary gland and its secretion--comparative review.

The mammary gland performs vitally important immunological roles, both in providing passive immune protection to the suckling infant and in immunological defence of its own tissues against infection with microorganisms. These immunological functions differ greatly between species of mammals in both nature and magnitude. In ungulates the mammary gland is singularly responsible for transfer of immunoglobulin (IgG) from mother to young. This process is dependent on a highly selective mechanism which results in the transport of blood-borne IgG molecules across secretory epithelial cells of the colostrum-forming mammary gland and into secretion. Upon ingestion of colostrum by the young ungulate this immunoglobulin is absorbed across the wall of the small intestine and thence into the bloodstream. In other species, including rodents and primates, there is a well-developed local IgA system operating in the mammary gland. In this situation, plasma cells located near the basal membranes of secretory epithelial cells secrete IgA which passes through the epithelial cells and into colostrum of milk. In the species the IgA in mammary secretions is not absorbed into the circulation of the suckling infant; because of its unique property of resisting proteolytic degradation, it may mediate a local protective role in the lumen of the intestine of the suckling infant. Specific immunological protection of mammary tissue may be mediated through blood-derived antibody (particularly IgG), locally synthesized antibody (particularly IgA) or phagocytic cells. Neutrophils arrive in mammary tissue and secretions in very large numbers following bacterial invasion of the gland. It has been established recently that these cells carry cytophilic antibody on their cell membrane. This cytophilic antibody can play an important functional role in enhancing the phagocytic capacity of neutrophils in the mammary gland.

Animals↗
PubMed1980

The interactions of porcine and ovine, serum and colostral immunoglobulins with staphylococcal Protein A.

The purpose of these studies was to determine the proportion of each immunoglobulin class/subclass in blood and colostrum of the pig and sheep, which would bind to staphylococcal Protein A. The concentrations of porcine IgG, IgM, and IgA were determined for serum and colostral whey from five sows. Similar measurements were made on two fractions produce by elution of the sample through a Protein A-Sepharose column: fraction 1, immunoglobulins which did not bind to Protein A, and fraction 2, immunoglobulins which bound to Protein A. The concentrations of ovine IgG1, IgG2, IgM, and IgA were measured for serum and colostral whey from six ewes, and again similar measurements were made after elution of each ovine sample through Protein A-Sepharose. All classes/subclasses of porcine and ovine serum and colostral immunoglobulins bound to Protein A to some extent. More than 90% of IgG from both porcine colostral whey and serum bound to Protein A. Ovine IgG1 from most ewes possessed a low affinity for Protein A whereas ovine IgG2 generally possessed a high affinity; 100% of the IgG2 in ovine colostral whey samples bound to Protein A. There was remarkable variation between individuals in the binding capacity of porcine IgM and each of the ovine immunoglobulins. For the ovine samples, in particular there were distinct differences between Protein A binding capacity of serum and colostral immunoglobulins of the same class/subclass.

Animals↗
PubMed1979

The local immune response in the mammary gland of the sow following infusion of a protein antigen.

A study was made of the local immune response in the udder of the sow following infusion of a soluble antigen. Four mammary glands of each of four pregnant sows were infused with ferritin prepartum. Samples of blood, colostrum, and milk were collected during the following lactation; animals were slaughtered and mammary tissue removed for immunohistology. Blood, colostrum, milk, and mammary tissues were similarly collected from nonimmunized (control) sows. Colostral and milk whey from immunized sows contained higher levels of immunoglobulins than whey from control sows. There was an increase in numbers of IgA-containing plasma cells and total lymphoid cells in mammary tissue of immunized sows compared with controls. The results suggested that the local immune response was at least as great in non-infused glands as infused glands of immunized sows.

Animals↗
PubMed1979

Vaccination against experimental staphylococcosis in sheep -- observations on bacteriology and pathology following challenge.

Sheep were vaccinated with a killed Staphylococcus aureus vaccine (2 doses) which had been cultured in vitro (Group 1), a killed S. aureus vaccine (2 doses) cultured in vivo (Group 2) or a single dose of a live vaccine (Group 3). Other sheep were used as non-vaccinated controls. All sheep were challenged by intravenous injection of 2.6 x 10(11) washed, viable S. aureus organisms, the vaccinated animals being given the challenge inoculum at various intervals after vaccination. The control sheep survived for 29h (mean) after challenge. Animals given killed vaccines survived longer, (particularly Group 2) if challenged less than 40 days post-vaccination, compared with those challenged more than 40 days post-vaccination. Animals in Group 3 survived longer if challenged after 40 days post-vaccination than those in Groups 1 or 2. There were no significant differences between the treatment groups for numbers of S. aureus recovered from blood in the 3h period following challenge. Histological and bacteriological evidence showed that the kidneys were more severely affected by the challenge inoculum than heart, spleen, liver or lungs. The kidneys showed both toxigenic and lymphoreticular reactions and large numbers of staphylococci were recovered more reliably from kidneys than other organs.

Animals↗
PubMed1979

Immunofluorescent studies of the local immune response in the mammary glands of rats.

Two irritants, phosphate-buffered saline and alcohol, and antigens including killed Brucella abortus, live B. abortus, Staphylococcus aureus, and rat parvovirus were separately infused into rat mammary glands during pregnancy, and by using immunofluorescent techniques, the numbers of immunoglobulin-containing cells in glands during lactation and involution were determined. The study provided basic information on the local immune response of the mammary gland to antigens of various types. In all experiments, the number of immunoglobulin M (IgM) cells present was small and no trends were apparent. IgA cells were always more prevalent than IgG cells. Fewer IgA cells were in the glands of rats infused with phosphate-buffered saline and alcohol than in normal rats. IgA cell prevalence was greatest in response to infusion of live B. abortus. Responses to live S. aureus and parvovirus were less pronounced, and infusion of killed B. abortus did not induce an elevation in IgA cell prevalence. IgG cell prevalence was greatest in response to infusion of live B. abortus or S. aureus and was decreasingly less pronounced in response to killed B. abortus and rat parvovirus. With the exception of parvovirus infusion, in regard to IgA cells, all glands locally infused with antigen had elevated IgA and IgG cell numbers when compared with noninfused glands in the same animal.

Animals↗
PubMed1979

Immunological parameters in the intestinal lymph of pigs including changes during experimentally induced diarrhoea.

Experiments were undertaken to provide basic immunological data on the intestinal lymph of young pigs. For this purpose indwelling cannulae were established in the main efferent intestinal lymphatic ducts of 12 animals and measurements were made of lymph flow rate, and concentrations of IgG, IgA and IgM. Measurements were also made of cell numbers, differential counts and immunoglobulin specificity of lymphoid cells in lymph. Similar measurements were also made on six pigs in which experimental diarrhoea was induced. The mean number of leucocytes in intestinal lymph was extremely low (0.66 X 10(5)/ml). However a high proportion of lymphocytes contained cytoplasmic IgA (19.65 per cent) and IgM (12.53 per cent), with few containing IgG (1.35 per cent). The concentrations of IgM and IgA in intestinal lymph were 0.51 mg/ml and 1.64 mg/ml respectively, values which suggest that the intestine is an important organ for synthesis of these two classes of immunoglobulin in young pigs. Following induction of diarrhoea and consequent dehydration of the intestine, the lymph: serum concentration ratios for immunoglobulins increased but subsequently declined when the water balance in the intestine returned to normal.

Animals↗
PubMed1978

Immunoglobulins in blood serum of foetal pigs.

A total of 1,147 samples of blood serum, collected from porcine foetuses, were examined for the presence of immunoglobulin. The foetuses, from 182 sows, were sampled at abattoirs in Queensland during 1975. For detection and measurement of immunoglobulins, rabbit anti-pig serum and monospecific anti-pig IgG, anti-pig IgM and anti-pig IgA were employed in immunoelectrophoresis, double diffusion and single radial immuno-diffusion assays. Twenty-four foetuses (from 7 litters) had detectable IgG or IgM. None of the samples were positive for IgA. Two of the serums (from siblings) had high antibody titres to porcine parvovirus but in the remainder of the immunoglobulin-positive serums no antibody activity was detected.

Animals↗
PubMed1978

Immunity to experimental staphylococcal mastitis--comparison of live and killed vaccines.

Eleven pregnant Merino ewes were immunised with either a killed Staphylococcus aureus cell-toxoid vaccine (intramuscularly) or a living culture of the same organism (subcutaneously). A further 3 animals were used as non-immunised controls. There were no significant differences between the vaccinated groups for agglutinating antibody to staphylococci or for anti-alpha-haemolysin in either serum or whey. Three weeks after lambing the ewes were challenged by intramammary infusion of virulent staphylococci. All animals developed an acute mastitis with significant decreases in milk yields being recorded 48 hours post-challenge. Seven days after challenge the mean milk production of ewes given the live vaccine had recovered to within 5% of the pre-challenge mean yield. However, milk productions of controls and ewes given the killed vaccine had further decreased and were significantly lower than for animals vaccinated with live staphylococci. There were no significant differences between the two vaccinated groups for numbers of bacteria or leucocytes in milk samples collected after challenge. The ewes were killed 7 days post-challenge and mammary tissues were examined for immunoglobulin-containing cells. Large numbers of IgA-containing cells, and few IgM-containing cells were found, but there were no significant differences between the treatment groups for these parameters.

Animals↗
PubMed1978

Serological procedures to determine time of infection of pigs with porcine parvovirus.

It was found possible to correlate serological responses to porcine parvovirus (PPV) with the time after infection. Two procedures were used for PPV antibody measurement: an immunodiffusion technique to measure precipitating antibody and a haemagglutination inhibition (HI) procedure to measure concentration of 2-mercaptoethanol (2-ME) sensitive antibody. Both procedures successfully related antibody titres to time post-infection, but it was considered that a 2 M 2-ME HI procedure showed the greater promise for field investigations.

Animals↗
PubMed1977

Immunological events in the popliteal lymph node of sheep following injection of liver or killed Corynebacterium ovis into an afferent popliteal lymphatic duct.

Efferent popliteal lymph and blood were collected daily for three weeks from sheep following injection of live or killed Corynebacterium ovis organisms into an afferent lymphatic duct. The total lymphocyte output, proportion of blast cells and class specificity of immunoglobulin-containing groups of animals and antibody titres and concentrations of IgG1, IgG2, IMg and IgA were measured in both lymph and blood...

Animals↗
PubMed1976

Antibody to porcine, feline and rat parvoviruses in various animal species.

Porcine, feline and rat parvoviruses were shown to be antigenically distinct. Specific antibody to feline and rat parvoviruses was shown in a high proportion of porcine sera, and to the porcine parvovirus in sera from cattle, sheep, cats, guinea-pigs, mice and rats, but not from horse, dog, rabbit, chicken or human.

Animals↗
PubMed1976

The effect of cytophilic IgG2 on phagocytosis by ovine polymorphonuclear leucocytes.

Non-lactating, multiparous ewes were immunized either by subcutaneous infection with live Staphylococcus aureus (seventeen ewes) or by intramuscular injections of a killed S. aureus-oil adjuvant vaccine (seventeen ewes). Polymorphs which were subsequently collected from the mammary glands of the animals were used in in vitro phagocytosis assays against Pseudomonas sp. or S. aureus. There was no difference between polymorphs from the two groups of ewes in their ability to phagocytose Pseudomonas organisms. Polymorphs from the infected ewes showed significant phagocytic superiority over cells from ewes given the killed vaccine when S. aureus was the target organism. This phagocytic superiority could be abrogated by removal of cytophilic immunoglobulin from polymorphs and restored by replacement of cytophilic immunoglobulin. It was shown by staining polymorphs with FITC-conjugated anti-immunoglobulin sera that cytophilic immunoglobulin on the surface of polymorphs belonged to the IgG2 class of immunoglobulins. When 'neutral' polymorphs (from non-immunized ewes) were coated with IgG2 purified from the sera of infected ewes, they exhibited enhanced phagocytosis of staphylococci compared with 'neutral' polymorphs carying IgG2 from the sera of ewes given the killed vaccine.

Animals↗
PubMed1975

Antibody response in sows following intramammary or intramuscular immunization with a killed Escherichia coli vaccine.

Pregnant sows were immunized either intramuscularly or intramammarily with a killed E. Coli vaccine. Samples of blood and mammary secretion were assayed for antibody to E. Coli cells and E. coli enterotoxin. The association of each class of immunoglobulin with antibody to the bacterial cells was also estimated. It was found that immunization by either method increased direct agglutination titres and antiglobulin enhancement titres in serum and mammary secretion. There were no major differences in these parameters between the two groups of sows. In serum and mammary secretion from both groups of sows IgG was quantitatively the most important class of immunoglobulin associated with antibody to E. coli cells. Immmunization had the effect of increasing the percentage of IgG and IgM associated with antibody in blood serum from about 5% to about 20%. In contrast, the percentage of IgA in serum with antibody activity against E. coli was around 20% prior to immunization and did not alter significantly after immunization. Samples of blood and mammary secretion from sows immunized intramammarily were more effective in neutralizing E. coli enterotoxin than corresponding samples from sows immunized intramuscularly; the biological significance of this finding is at present uncertain.

Agglutinins↗