Detection of tumor-associated antigens in sera of canine cancer patients by monoclonal antibodies generated against canine mammary carcinoma cells.

Two murine monoclonal antibodies (MAbs), 1A10 and SB2, generated against a canine mammary carcinoma cell line, were used in a competitive enzyme-linked immunosorbent assay (ELISA) to measure tumor-associated antigens (TAAs) in canine serum samples. Sera were tested from disease-free dogs and from dogs diagnosed with mammary carcinoma, non-mammary carcinoma, sarcoma, benign mammary tumor, benign non-mammary tumor, or non-neoplastic disease. Serum antigen concentrations measured by ELISA were expressed as inhibitory units (IU). The upper limit of normal, defined as the mean plus 2 SD of the TAA concentration in disease-free dogs, was 20 IU with antibody 1A10 and 22 IU with antibody SB2. Compared with disease-free dogs, the frequency of TAA-positive sera was significantly greater (P < 0.05) among dogs with mammary or non-mammary carcinoma when tested with MAbs 1A10 or SB2, and also with sarcoma when tested with MAb SB2. Testing a serum sample with both antibodies rather than just one increased the sensitivity of the competitive ELISA for TAA detection. The presence of TAA in serum might serve as a useful marker for certain types of carcinomas or sarcomas in canine cancer patients.

Bovine neutrophil activation by culture fluid from Pasteurella haemolytica serotypes A1 and A11.

Neutrophil activation has been thought to contribute to the pathogenesis of fibrinous pneumonia caused by Pasteurella haemolytica serotype A1. The activation of bovine neutrophils by culture fluid from the pathogenic P. haemolytica serotype A1 and the non-pathogenic serotype A11 was compared. Logarithmic-phase bacteria of each serotype were incubated in RPMI 1640-medium for 3 h at 37 degrees C. The culture fluid was collected by centrifugation and concentrated by ultrafiltration. The concentrated culture fluids were then tested for their ability to induce chemotaxis and respiratory burst in bovine neutrophils. Chemotactic activity was of similar magnitude in response to both serotypes. An early chemiluminescence response occurred at 5 min at 1:100 dilution and a late peak at 11 min at 1:500 dilution for serotype A1. The early peak was absent at all dilutions tested for serotype A11. Maximal chemiluminescence response was observed at 1:25 dilution with serotype A11 while maximal response was seen at 1:500 dilution with the culture fluid from serotype A1. Superoxide anion release was greater in response to culture fluid from A1 than A11 at all dilutions tested. Leukotoxin activity was 50-fold higher in culture fluid from serotype A1 than in culture fluid from serotype A11. In this study, the ability of P. haemolytica to attract and activate bovine neutrophils was not restricted to the pathogenic serotype A1.

Effect of calf housing on plasma ascorbate and endocrine and immune function.

The effect of housing calves in indoor metal pens (1.2 m x 1.2 m) or commercial calf hutches was determined on plasma concentration of cortisol, antibodies, and ascorbate. Six calves per treatment were deprived of colostrum, assigned randomly to treatment, and fed a commercial milk replacer until 56 d of age. Calves housed in hutches had higher plasma IgG concentrations than calves in pens at 42 and 56 d of age. Housing had no effect on plasma IgM concentration. Antibody titers to keyhole limpet hemocyanin injected at 14 and 28 d of age were higher in hutch-housed calves from 21 to 56 d of age. Calves housed in hutches also had lower plasma cortisol concentrations, although cortisol decreased with age in both treatment groups. Plasma ascorbate and ascorbate plus dehydroascorbate were higher in hutch-housed calves. Regression analysis indicated a positive relationship between plasma ascorbate and IgG in metal penhoused calves and a negative relationship in hutch-housed calves. Housing in 1.2 m x 1.2 m metal pens decreases cortisol, plasma ascorbate, IgG, and specific antibody titers in dairy calves relative to calves housed in hutches.

Chemotactic response of bovine neutrophils to Pasteurella haemolytica culture fluid.

Bovine neutrophil chemotactic activity was detected in the supernatant fluid of logarithmic phase cultures of P. haemolytica serotype 1. The chemoattractant was produced under culture conditions suitable for P. haemolytica leukotoxin production. An inverse correlation existed between the leukotoxin LC50 and the chemotactic activity in the culture fluid. Elimination of leukotoxin activity by heating, dilution or ultrafiltration, exposed the chemotactic activity in the culture fluid. The chemoattractant was partially resistant to heating (60 degrees C, 30 min), and had an apparent molecular weight greater than 100,000. Detection of chemotactic activity in both the concentrate and filtrate after XM300 filtration suggested that there might be more than one component with chemotactic activity or else that polymerization was occurring. Production of a potent neutrophil chemoattractant by P. haemolytica may explain the rapid infiltration of neutrophils that occurs during the early stages of bovine pneumonic pasteurellosis.

Dietary ascorbic acid and immune response in dairy calves.

Colostrum-fed, colostrum-deprived, and colostrum-fed and colostrum-deprived calves fed ascorbic acid (1.75 g/d) in whole, raw milk to 6 wk of age were sampled from 0 to 8 wk of age in order to determine whether ascorbate supplementation would increase plasma Ig concentrations, antibody response to immunization, and disease resistance. Plasma IgG concentrations were lower at 14 and 28 d of age in calves fed ascorbate compared with plasma concentrations in calves not receiving ascorbate supplementation, irrespective of colostrum feeding. Colostrum feeding had no effect on antibody titer to keyhole limpet hemocyanin at any age, but ascorbate-supplemented calves had lower plasma antibody titers to keyhole limpet hemocyanin at 35 and 56 d of age. Calves fed ascorbate had lower clinical scores for diarrhea. Dietary ascorbate does not appear to be immunostimulatory in dairy calves to 56 d of age and appeared to inhibit antibody synthesis. However, at 14 d of age there was an interaction of ascorbate supplementation and colostrum feeding; plasma IgG concentrations were higher in colostrum-deprived calves fed ascorbate then in colostrum-deprived calves not fed ascorbate.

Comparison of serologic tests for detection of antigen in canine heartworm infections.

In 30 random-source dogs, we determined sensitivity and specificity of 5 serologic tests for detection of canine heartworm antigens. Seventeen of the dogs were infected naturally with adult Dirofilaria immitis, and 4 of the infected dogs were amicrofilaremic. The ability of the serologic tests to predict whether a dog was infected or uninfected (overall test accuracy) ranged from 73 to 97%. Sensitivity was not affected by circulating D immitis microfilariae, but was markedly influenced by the number of adult D immitis present. False-positive reactions were rare and were not associated with intestinal parasites or Dipetalonema reconditum microfilariae. Modifications of some of the test procedures were necessary to maximize test accuracy and reproducibility. These modifications and other technical details might limit the usefulness of some of the tests in a veterinary practice.

Natural transmission of Dirofilaria immitis by Aedes aegypti.

The Liverpool strain of the mosquito Aedes aegypti was infected with microfilariae of the canine heartworm, Dirofilaria immitis, and was used to transmit heartworm larvae to three dogs. Methods of confirming heartworm infection in these dogs included the modified Knott's test, a commercial enzyme-linked-immunosorbent assay (ELISA), an indirect fluorescent antibody (IFA) test, and post-mortem examination.

Terminal deoxynucleotidyl transferase activity in thymocytes of kittens.

Activity of terminal deoxynucleotidyl transferase (TdT) was measured in the thymus of 8- to 14-week-old kittens. Microscopic evidence of involution or other morphologic changes were not observed in formalin-fixed hematoxylin and eosin-stained thymic tissue sections. Thymic tissue from young kittens (8 weeks old) had low TdT activity, as determined by enzymatic catalysis or immunoassay procedures. Markedly higher TdT activity was measured in thymic tissue of older kittens (13 to 14 weeks old). Feline TdT catalyzed the polymerization of deoxynucleotides at a higher rate in Mn2+ than in Mg2+. Results of protein immunoblotting experiments indicated that the major form of feline thymic TdT is a single, high molecular weight polypeptide in 13- to 14-week-old kittens. Detection of TdT activity in the feline thymus indicated that TdT may have the same diagnostic and therapeutic value in feline oncology as in human oncology.

Immunomodulatory effects of levamisole.

The conditions under which the anthelmintic drug levamisole modulates immune function were reviewed. Treatment with the drug corrects defective leukocyte reactivity and can bring clinical improvement in chronic infections, inflammatory disease, and malignancy. Therapeutic effectiveness depends upon dose, timing, and the patient's immune status, and results are often inconsistent. Levamisole therapy can cause marked but reversible complications, many of which have immunopathologic features.

Induction of blastogenesis in bovine peripheral blood lymphocytes by oxidation with sodium periodate.

Suitable treatment and culture conditions are defined for the induction of blast transformation in bovine peripheral blood lymphocytes by oxidation with sodium metaperiodate (NaIO4). Stimulation with NaIO4 required slight modification of techniques used routinely for activation of lymphocytes in vitro with lectins and antigens. Gradient-separated mononuclear leukocytes responded with maximal [3H]TdR incorporation after oxidation with 0.50 to 1.0 mM NaIO4 for 30 minutes at 25 C. Oxidized cells cultured at 1 to 2 X 10(6)/ml responded better than cells cultured at any other concentration, when compared with untreated cells. Blastogenesis in response to oxidation reached its maximum rate within 48 hours of treatment, after which it declined rapidly. Partial removal of glass wool-adherent cells reduced periodate-triggered blastogenesis by 95%, but did not significantly affect activation with phytohemagglutinin, concanavalin A, pokeweed mitogen, or purified protein derivative. Reintroduction of macrophages restored responses to their precolumn level. Oxidation with NaIO4 provided a simple, rapid means of inducing blastogenesis in bovine lymphocytes. Manipulation of the well-defined triggering conditions may help to explain the mechanisms involved in lymphocyte activation.

Regulation of mitogen- and antigen-stimulated lymphocyte blastogenesis by prostaglandins.

Exogenously added prostaglandin E1 or E2 inhibited the blastogenic response of Mycobacterium bovis-sensitized bovine peripheral blood lymphocytes stimulated with concanavalin A, phytohemagglutinin, or M. bovis purified protein derivative as measured by [3H]thymidine uptake. The kinetics of the response showed that prostaglandins must be added to lymphocyte cultures within hours after mitogen or antigen addition to achieve maximum suppression of [3H]thymidine uptake. Addition of prostaglandins 24 h after the addition of mitogens or antigens resulted in considerably less suppression, supporting a hypothesis that prostaglandins initiate an early series of events which ultimately control lymphocyte blastogenesis rather than directly inhibit deoxyribonucleic acid synthesis.