Antibody responses to BSA in dogs: a source of error in diagnostic immunoassays.
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Biomedical subjects
Publications and source records attributed to S D Carter.
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The pathogenesis of canine coronavirus (CCV) infection in 10-week-old puppies was studied up to 14 days after oronasal inoculation. Mild diarrhoea was seen from three to 11 days after inoculation, approximately coincident with faecal virus shedding. Virus was initially isolated from the tonsils on day 3, and then from both small and large intestinal tissues up to 14 days after inoculation. Virus was also isolated from liver and lung. Histological changes were not seen in any tissues, but CCV antigen was detected, using a peroxidase antiperoxidase staining technique, mainly in epithelium overlying gut-associated lymphoid tissue. Virus neutralising antibody was first detected on day 10. Specific anti-CCV IgM was first detected in plasma three days after inoculation and IgG on days 4 to 7. Small amounts of anti-CCV IgG, IgM and IgA were detected in duodenal secretion, but none in bile.
Synovial fluid samples of horses with osteoarthritis were investigated to detect interleukin-1 (IL-1) activity which could contribute to the disease pathogenesis. Of the 32 samples tested, 12 (37.5 per cent) showed an augmented phytohaemagglutinin induced proliferation of C3H/HeJ mouse thymocytes. Positive results were also seen in horses with infected arthritis, osteochondritis, traumatic arthritis and undefined synovial effusions. Normal synovial fluid and sera from all groups failed to show any detectable IL-1 activity. Fractionation of synovial fluid showed that the IL-1 activity was in the 15 to 20 Kd fractions. In the absence of mitogen, synovial fluid failed to stimulate thymocytes and did not stimulate the growth of an interleukin-2 (IL-2) dependent CTLL cell line, but synovial fluid stimulated IL-2 release by mouse spleen cells incubated with suboptimal doses of lectin. Evidence of an IL-1 inhibitor in synovial fluid from osteoarthritic horses was provided by ultrafiltration experiments and by the inhibitory activity of synovial fluid at particular dilutions in the thymocyte assay. The presence of IL-1-like activity could be relevant in the pathogenesis of arthritis in horses.
Dogs with canine rheumatoid arthritis had significantly elevated levels of antibodies to canine distemper virus. This increase was particularly seen in the synovial fluids, compared with paired sera, and was not found in dogs with infective arthropathies, osteoarthritis or in osteoarthritis secondary to rupture of the cranial cruciate ligament. Analysis of the immune complexes precipitated from synovial fluids showed immunoglobulins in all types of arthropathy. Western blotting analyses showed reactivity with anti-distemper antisera in immune complexes from dogs with rheumatoid arthritis, but not in immune complexes from dogs with other joint diseases. These results suggest that there are increased immune responses to distemper in canine arthritis and that these may be due to the presence of this paramyxovirus in affected joints. The implications for the role of a possible infectious agent in rheumatoid arthritis in the dog are considerable.
Serum immunoglobulin concentrations and densities of IgA-producing immunocytes in intestinal mucosa were compared in a group of clinically healthy dogs of various breeds, a group of clinically healthy German shepherd dogs, and a group of German shepherds with bacterial overgrowth in the proximal small intestine. Serum concentrations of IgA, but not IgM or IgG, were significantly lower in the clinically healthy German shepherd dogs than in other purebreed and mixbreed dogs, indicating that production of IgA by gut-associated lymphoid tissue might be relatively low in this breed. However, densities of IgA-producing cells were not significantly different comparing these two groups, suggesting that any impairment of mucosal IgA production is more likely to be related to defective synthesis or secretion of IgA than to reduced numbers of IgA-producing immunocytes. Comparable findings in German shepherd dogs with small intestinal bacterial overgrowth provided further indirect evidence that local immunity might be defective in this breed, since these luminal bacteria would be expected to stimulate mucosal IgA production. However, it is not clear whether such a defect is directly responsible for the overgrowth, or whether there is an indirect relationship between defective local immunity and bacterial overgrowth in German shepherd dogs.
The efficacy of keyhole limpet haemocyanin (KLH) as a test antigen was determined in calves. Humoral and cellular (in vivo and in vitro) responses were compared. Calves were immunized with KLH at either 3 weeks or up to 5 months of age and immune responses were subsequently tested. Class and subclass antibody responses were detected by ELISA, lymphocyte blastogenesis was measured using a whole blood culture technique (LTT) and skin sensitivity responses were measured as an increase in skin thickness following intradermal injection. In young calves, skin test responses were maximal at 24 h and were found to correlate with IgG1 and IgG2 responses (P less than 0.01), with IgA (P less than 0.05) but not with IgM or LTT. Histological examination of skin swellings found a sequence of cellular events, with polymorphonuclear cells dominating until 48 h after intradermal injection, when mononuclear cells became involved. However, in older calves, skin test responses correlated not only with IgG1 and IgA responses but also with lymphocyte transformation (P less than 0.05). These findings suggest that, while immune responses to KLH may be a useful indicator of immune competence in calves, interpretation should be made with caution particularly in young calves.
IgG1 antibody responses to Ostertagia ostertagi third stage larvae (L3) and the third party antigen, keyhole limpet haemocyanin (KLH), and faecal egg counts were determined in calves infected with a single dose of O. ostertagi and in uninfected, pair-fed calves. The infected and uninfected calves were given diets either high (H) or low (L) in protein and energy. The diets were within the normal range of husbandry practice in the UK. IgG1 antibody responses to L3 antigen were significantly greater from 6 weeks post-infection in infected calves given the L diet than in infected calves given the H diet (P less than 0.05). The effects of diet and infection on anti-KLH IgG1 responses were independent of each other. IgG1 responses to KLH were decreased by infection and by the L diet compared with the H diet.
Two groups of cats were inoculated oro-nasally with one of two isolates of feline calicivirus (FCV) from clinical cases of chronic stomatitis. All cats developed signs typical of acute FCV infection; namely, ocular and nasal discharge, conjunctivitis, and marked oral ulceration. None of the cats shed virus beyond 28 days. Seronegative control cats were then infected with a lower dose of one isolate, but again only acute signs were seen and no carriers produced. The original cats were then re-infected with the heterologous isolate. As before, only signs of acute disease were seen, but the range of clinical signs and severity was reduced. Virus shedding patterns in one group were similar to those seen originally, but in the other the duration was reduced. No chronic stomatitis developed over the 10 months of the study. Serum virus neutralising and serum and salivary class specific immunoglobulin responses were investigated. Although long-term carriers were not induced, no relationship between cessation of virus shedding in an individual animal and systemic and local antibody responses was seen.
Cytoecetes phagocytophila, the causative agent of tick-borne fever, was successfully separated by Percoll and Renografin density gradient centrifugation and by cellular affinity chromatography, from the peripheral blood leucocytes of experimentally infected sheep. After centrifugation on Renografin or Percoll density gradients, infectious particles of C. phagocytophila banded at buoyant densities which ranged between 1.063 to 1.140. Rickettsiae separated by wheat germ lectin cellular affinity chromatography retained their morphology but often lost their infectivity. Cell-free C. phagocytophila remained infective to susceptible sheep for 6 months when kept at -114 degrees C in sucrose phosphate buffer with 10 per cent dimethylsulphoxide as a cryopreservative.
Taenia multiceps coenurus fluid was analysed by fast protein liquid chromatography in order to separate the factors responsible for previously reported modification of immunological activity in macrophages and T-cells. One factor, F7, was found to be mitogenic for murine L3T4+ T-cells, to be macrophage dependent, to require macrophage compatibility at the I region of the H2 complex, to increase the sensitivity of T-cells to regulatory signals from macrophages and to increase the rate of generation of splenic rosette-forming cells (RFC) against sheep red cells. A second factor, F24, was found to alter macrophages so as to render them suppressive, rather than stimulatory, for parasite-activated and Con A-activated lymphocyte transformation, to depress the rate of generation of RFC and to antagonize the mitogenic effect of F7. The combined actions of these two factors are, therefore, sufficient to explain the known immunomodulatory effects of the metacestode.
Many liver-invasive parasites cause extensive liver damage which may result in an impaired ability to catabolize endotoxin. The influence of endogenous endotoxin on the progress of liver-invasive parasitic diseases has been investigated in murine Mesocestoides corti infection. Invasion of liver tissue by tetrathyridia resulted in extensive parenchymal destruction with fibrosis. In association with this, undetoxified endotoxin, in potentially biologically active concentration, was found on peritoneal macrophages, 5 months post-M, corti infection. Host susceptibility was influenced by the Lps gene for responsiveness to lipopolysaccharide (LPS). The parasite burden of LPS-responsive (C3H/HeN) mice was significantly increased in the livers of these mice when compared to LPS-resistant (C3H/HeJ) mice. LPS reduced the ability of normal peritoneal macrophages to kill tetrathyridia, when co-cultured in vitro. LPS also abrogated the ability of recombinant interferon-gamma (r.IFN-gamma) to enhance macrophage larvicidal activity. These in vitro findings were confirmed in vivo. Daily intraperitoneal administration of LPS, at low concentration, caused a 4-fold increase in parasite burden in the liver, while r.IFN-gamma at optimal concentration reduced parasite burden by 57%. Post-infection macrophages have previously been shown to be refractory to cytokine-activation for larval killing. In this report, we conclude that (1) this refractoriness may be due to the presence of undetoxified endotoxin on post-infection macrophages and (2) endotoxin may reduce host resistance by abrogating effector macrophage response to IFN-gamma.
This study was designed to test the accessory function of macrophages after activation with products of Taenia multiceps coenuri. Activation was carried out by intraperitoneal injection of mice with coenurus fluid or protoscolex culture supernatant, and function was assessed by adding these macrophages in progressively increasing numbers to macrophage-depleted lymphocyte cultures transforming under the influence of plant mitogens or coenurus-fluid mitogen. In contrast to normal macrophages, which have a progressively enhancing action on the above reactions, parasite-activated macrophages at similar concentrations were progressively inhibitory. However, low concentrations of the activated macrophages enhanced mitosis as well as, or better than, normal. Lymph node cells from injected mice showed abnormal response to macrophage-derived signals. In particular there was subnormal reaction to macrophages in the presence of coenurus mitogen. These results suggest that T. multiceps coenuri may survive in the host because of their ability to reduce effective interaction between lymphocytes and accessory cells.
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Horse articular cartilage glycosaminoglycans (GAGs) were measured in synovial fluids from 48 joints affected with osteoarthritis (OA), 22 normal joints, four joints with osteochondritis, three joints with traumatic arthritis and seven joints infected with bacteria. Serum and urine from individual horses were also examined for the presence of GAGs. High levels of GAGs were found in synovial fluids (SF) from horses with OA. In each case, the level was higher in the synovial fluid than in the serum or urine from the same horse. Horses with OA showed high GAG levels in SF, serum and urine compared to horses with normal and infected joints. High levels were also found in horses with osteochondritis and traumatic arthritis. Levels of synovial fluid GAG reflect cartilage destruction in arthritis and may be useful for monitoring disease progression in the equine species.
Peritoneal macrophages and splenic lymphocytes were collected from BALB/c mice, normal or previously infected with Echinococcus multilocularis. In an accessory cell function assay, peritoneal macrophages, in increasing numbers, were added to cultures of splenic lymphocytes. Cultures were stimulated by concanavalin A (Con A) or E. multilocularis culture supernatant (EMSN). Post-infection macrophages, unlike normal macrophages, suppressed Con A- and EMSN-driven lymphocyte transformation. Modification of accessory cells could also be repeatedly induced in vivo by EMSN or a single FPLC fraction of EMSN. Lymphocytes were made more sensitive to accessory cell signals following incubation with EMSN.
Analysis of a detergent-solubilized somatic antigen of Ostertagia ostertagi 3rd stage larvae by SDS-PAGE and Western blotting has revealed two specific antigens with apparent molecular weights of 17 and 43 kD under reducing conditions. Probing of the Ostertagia ostertagi preparation with preinfection control sera has shown two cross-reacting antigens with apparent molecular weights of 67 and 81 kD. Both the 17 and the 43 kD antigens were recognised by IgG1 which was the predominant reactive subclass. FPLC fractionation of the crude extract with gel filtration and ion-exchange columns demonstrated immune reactivity in discrete peaks. Comparisons of ELISA and lymphocyte transformation showed antigenic components reactive with both antibodies and primed lymphocytes.