Six horses with chronic obstructive pulmonary disease (COPD) and 8 horses with recurrent urticaria were skin tested with 67 extracts from 58 allergens, including pollens, epidermals, cultivated farm plants, dusts, molds, and insects. Reactions were evaluated 3 times over a 24-hour period immediately after the injections. Results were compared with those obtained from 11 clinically normal horses. All horses had positive skin test reactions. Significant difference was evident between horses with COPD and clinically normal horses for only 3.0% of the possible extract reactions, and between horses with urticaria and clinically normal horses for only 4.5% of the possible extract reactions. Horses with COPD or urticaria had greater total percentage of allergen extract reactions than did clinically normal horses. Positive reactions were observed at all 3 evaluation periods, and late-onset reactions were not always preceded by positive reaction at earlier periods. All horses with COPD or urticaria had at least 1 skin test reaction that exceeded the mean +/- 2 SD, as calculated for each of the 67 extracts for the group of clinically normal horses.

Sarcocystis cruzi sarcocysts were isolated from eosinophilic myositis (Em)-affected and nonaffected bovine hearts. Isolates were ruptured and used to prepare a bradyzoite antigen extract from each heart. The nonaffected heart from one newborn calf contained no apparent sarcocysts when examined histologically and was used to prepare Sarcocystis-negative control antigen. Blood samples were taken from the heart approximately 20 minutes after slaughter. Serum was obtained and evaluated, using a radioimmunoassay to measure Sarcocystis-specific IgG and IgE titers. Sarcocystis cruzi extract from a heart without EM lesions was used for antigen in the radioimmunoassay. Sarcocystis-specific IgG titer ranged between 1:1,280 and 1:2,560 in EM-affected cattle and was 1:640 in nonaffected cattle. Sarcocystis-specific IgE titer ranged between 1:640 and 1:1,280 in Em-affected and nonaffected cattle. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and protein (western) immunoblot analysis were used to compare antigen extracts and serum samples from EM-affected vs nonaffected cattle. Twenty protein bands, ranging from approximately 22 to 215 kD, were detected consistently on bradyzoite blots probed with anti-bovine IgG after incubation with serum samples. Seven of these bands, 37, 44, 53, 57, 94, 113, and 215 kD, were also detected consistently on bradyzoite blots probed with monoclonal anti-bovine IgE. One additional band, 61 kD, was detected consistently on bradyzoite blots probed for IgE, but was seldom recognized when probed for IgG. Sixteen protein bands were evident in silver-stained gels of S cruzi-negative, newborn calf antigen, but none were recognized by antisera on western blots. Consistent differences were not found among antigen extracts or among serum from EM-affected vs nonaffected cattle on silver-stained gels or western blots.

The possible development of type-1 hypersensitivity reactions in the abomasal mucosa caused by soluble L3 products of Ostertagia ostertagi was studied in 4-month-old calves sensitized by repeated exposure to L3 over a 50-day period followed by anthelmintic treatment. Four groups each of 4 calves were used. Group 1 served as nonsensitized controls and group 2 as sensitized controls, group 3 was challenge exposed at 2-week intervals beginning at week 10 with a soluble L3 product (OAG), and group 4 was challenge exposed at 2-week intervals with an oral dose of L3, followed by anthelmintic treatment 3 days later. All calves infected with L3 became sensitized, as indicated by a positive reaction to an intradermal skin test. However, a passive cutaneous anaphylaxis was only partly effective in indicating the presence of homocytotropic antibody in the infected calves. Sensitized calves had significantly (P < 0.05) higher eosinophil counts and plasma pepsinogen values for the entire 14 weeks than uninfected controls. Globule leukocyte and mast cell counts from the abomasal mucosa were also significantly (P < 0.05) higher. Studies for possible immunomodulation revealed that lymphocyte counts decreased between every 2-week challenge-exposure period for groups-3 and -4 calves. A transient depression of blood lymphocyte (BL) responses to phytohemagglutinin (PHA), a T-cell mitogen, was observed over the first 8 weeks in the infected calves. Increases in BL responses to OAG were also observed. Differences were not observed in BL responses to pokeweed mitogen, a T- and B-cell mitogen. Blood lymphocyte responses to PHA in group-3 calves were low following the initial challenge exposure with OAG. The sensitized calf lymphocytes did not have suppressive activity on the response of control calf lymphocytes to PHA. Differences were not observed in lymphocyte responses to PHA in a suppressive assay done on abomasal lymph node lymphocytes. Increases in abomasal lymph node mass and lymphocyte responses to PHA, pokeweed mitogen, and OAG were observed in all sensitized calves. Histologic examination of abomasal lymph node sections from challenge-exposed calves revealed increased mitotic activity in germinal centers. Plasma pepsinogen values in groups 3 and 4 increased between each challenge exposure, which further suggested that type-1 hypersensitivity reactions had occurred in the abomasal mucosa, resulting in increased permeability and leakage of macromolecules.

Experiments were conducted to evaluate the effect of restricted feeding of a starter diet to suckling pigs (creep feeding) in a model of postweaning colibacillosis. The hypothesis that restricted creep feeding primes an intestinal allergic reaction to starter diet ingested after weaning was tested. Twenty-eight suckling pigs were fed a starter diet for 3 h/d on days 7, 8, and 9 after birth (creep-fed). Twenty-six suckling pigs were not fed the diet until 3 weeks of age (not creep-fed), when all pigs were weaned and given the starter diet. One day after weaning, 24 creep-fed and 22 not creep-fed pigs were inoculated with K88+ enterotoxigenic Escherichia coli, and 4 pigs in each group were kept as noninoculated controls. Among inoculated pigs (principals), 10 creep-fed and 12 not creep-fed pigs were found to be genetically resistant to K88+ E coli and remained healthy during the 6-day postinoculation period, as did the noninoculated controls. Eighteen (10 creep-fed and 8 not creep-fed) of the 24 genetically susceptible principals developed diarrhea after inoculation. There were no significant differences in the incidence and severity of diarrhea, amount of body weight loss, and mortality between creep-fed and not creep-fed susceptible principal pigs. Histologic examination of intestine from control pigs and principals that survived for 6 days after infection did not reveal any substantial morphologic difference between creep-fed and not creep-fed groups. In conclusion, creep feeding was not required for the production of diarrhea in this model. Creep feeding did not induce morphologic changes characteristic of an allergic reaction in the small intestine.

A micro-ELISA, using horseradish peroxidase-conjugated anti-canine IgE and polystyrene microtitration wells for detection of allergen-specific IgE in canine serum, was developed. Specificity of anti-canine IgE was confirmed by reversed cutaneous anaphylaxis evaluations, gel-precipitation reactions, immunoelectrophoresis, immunoaffinity chromatography, and heat inactivation. Individual allergen blanks were used to account for variable nonspecific binding among various allergens, and results were normalized using 4 reference sera. Coefficients of variation for intra-assay and interassay variability ranged from 0.77 to 5.66% and 3.15 to 9.83%, respectively. Results observed with wells coated with mixtures of various allergen extracts yielded results approximately equal to results (average) of wells containing individual components. Agreement between ELISA and skin test results ranged from 43 to 64%, depending on allergen used.

Eight bovine hearts with lesions of eosinophilic myositis (EM) and 2 bovine hearts without EM lesions were collected at slaughter. Blood samples from these 10 hearts, and the heart of a newborn calf also were collected. Histologically, Sarcocystis cruzi was identified in the 8 hearts with EM lesions and the 2 hearts without EM lesions, but not in the heart of the newborn calf. Serum was harvested from the 10 blood samples and was used in homologous, modified, passive cutaneous anaphylaxis test. Antigen was prepared from S cruzi bradyzoites isolated from the 2 hearts without EM lesions. Serum samples from the 8 cattle with EM lesions reacted positively to S cruzi antigen. When heat-inactivated IgE in serum (56 C for 4 hours) was used, all passive cutaneous anaphylaxis responses were considered negative. Using ELISA, serum IgE concentrations from the 10 cattle with and without EM lesions were 2.2 to 9 U/ml. As determined by radial immunodiffusion, IgM concentrations were 80 to 215 mg/dl. Immunoglobulin G concentrations were 420 to 2,050 mg/dl, but most were less than or equal to 1,700 mg/dl. Immunoglobin A concentrations were 0 to 62 mg/dl; 1 steer with EM lesions had 0 mg/dl. Double-gel immunodiffusion confirmed the presence of Sarcocystis-specific precipitating antibodies. Sera from the 10 cattle with and without EM lesions formed at least 1 precipitin band.

Using polyclonal rabbit and monoclonal mouse anti-dog IgE antibodies, we developed ELISA for measurement of ragweed-specific IgE in canine serum. In the ELISA, microtitration plates were coated with ragweed extract and sequentially incubated with canine serum, purified monoclonal or polyclonal anti-dog IgE, and conjugated goat antibody to mouse IgG or rabbit IgG. Serum ragweed-specific IgE values were measured by the 2 ELISA in serum samples from 60 ragweed-allergic dogs and in serum from 10 control dogs. Passive cutaneous anaphylaxis (PCA) tests were performed on these sera to compare results with those of the ELISA, Mean coefficient of variation between assays was 0.20 +/- 0.10 for the assay using the polyclonal antibody and was 0.17 +/- 0.10 for that using monoclonal antibody. Sensitivity was 0.6 U/ml for the ELISA, using polyclonal antibody, and 2.5 U/ml for the ELISA, using monoclonal antibody. Serum ragweed-specific IgE values measured by the 2 ELISA strongly correlated with PCA titers (P < 0.0000), but the ELISA using polyclonal antibody had higher correlation with PCA titer (r = 0.84) than the ELISA using monoclonal antibody (r = 0.59). The geometric mean ragweed-specific IgE value measured by the 2 ELISA and by PCA testing, was significantly higher (P < 0.0000) in allergic dogs than in control dogs. The 2 ELISA were specific, sensitive, and reproducible for measurement of ragweed-specific IgE in canine serum.

The lungs of sensitized horses were exposed to aerosolized ovalbumin. Some horses (n = 4) were given ovalbumin in 1 lung only, whereas in others (n = 7), ovalbumin or vehicle were inoculated in the cranial, ventral, and caudal regions of the caudal lung lobe. Horses were exercised 5 hours after ovalbumin exposure. Immediately before exercise, endoscopy failed to reveal any abnormality. After exercise, endoscopic examination of horses subjected to unilateral ovalbumin exposure revealed extensive blood in airways leading to the exposed lung in all horses. Blood was not observed in the airways leading to the control lung. Mean (+/- SEM) minimum volume of the exposed and control lungs was 9.5 +/- 1.5 and 5.5 +/- 1.6 L, respectively; this difference was statistically significant (P < 0.05). Bronchoscopy of horses subjected to regional ovalbumin or vehicle exposure and exercise revealed a small amount of blood-tinged fluid in the bronchi serving the regions of the lung inoculated with ovalbumin. Minimum volumes of such regions were not significantly different from one another. However, their minimum volume was significantly (P < 0.05) larger than that of vehicle-inoculated regions. Gross and histologic examination confirmed inflammation and hemorrhage in the ovalbumin-exposed, but not the control lungs or lung regions. Thus, exercise can cause blood from an injured region of lung to appear in the larger airways. Regional differences in lung structure and function do not influence the appearance of blood in the airways.