Biochemical and morphological alterations in xylazine-induced pulmonary edema.

Sprague-Dawley rats were given 42 mg/kg xylazine intramuscularly, and lungs were lavaged with phosphate-buffered saline 3, 6, and 12 hr later. Total protein, lactate dehydrogenase (LDH), xanthine oxidase (XO), tumor necrosis factor (TNF), and interleukin 1 (IL-1) were measured in bronchoalveolar lavage fluid (BALF). Protein concentration, LDH, XO, and TNF levels were increased (p < 0.05) in the BALF from xylazine-treated rats as compared to controls. IL-1 level was unchanged at 3 and 6 hr and was reduced (p < 0.05) at 12 hr. Another group of rats was given 42 mg/kg xylazine intramuscularly, and lungs were fixed 0.5 and 12 hr later. Histologically, severe pulmonary edema (PE) involving the alveoli and perivascular stroma was observed. Fibrin, increased numbers of eosinophils, and macrophages with foamy cytoplasm were present in the alveoli of all treated animals. Ultrastructurally, endothelial damage, characterized by thinning, detachment from basement membranes, or bleb formation, was observed. The lesions were similar in both xylazine groups, differing mainly in severity with the 12-hr group having more severe lesions than the 0.5-hr group. To determine whether endothelial injury is caused by direct toxicity of xylazine, bovine pulmonary artery endothelial cells (BPAECs) were incubated with xylazine (0.3, 3, and 30 micrograms) for 0.5 or 3 hr. Xylazine did not have any effects on BPAECs, as indicated by phase-contrast microscopy and dye-exclusion viability assay. These results indicate that xylazine-induced PE is due to increased permeability resulting from endothelial injury, which is not caused by direct effect of xylazine on pulmonary endothelium. While oxygen radicals and TNF are possibly involved, IL-1 does not appear to play a role in xylazine-induced PE.

The effects of adjuvants on immune responses in cattle injected with a Brucella abortus soluble antigen.

Five different adjuvants were examined for potentiation of humoral and cell-mediated immune (CMI) responses in cattle to a Brucella abortus soluble antigen (BASA). Two separate experiments were performed involving a total of 64 steers, divided among six groups (Experiment 1) and 9 groups (Experiment 2). The adjuvants used were: muramyl dipeptide, Freund's incomplete adjuvant, dimethyl-dioctadecyl ammonium bromide (DDA), Bordetella pertussis and Propionibacterium acnes. In each experiment, three groups received BASA (2 mg protein) subcutaneously with adjuvant, one group received a reduced dose of B. abortus Strain 19 (S19), one group served as unvaccinated controls, and another group received BASA alone. Primary responses were studied following a single immunization in comparison to the single inoculation with S19. For each experiment serum antibody responses and CMI responses were sequentially determined over a period of 56 days. Antibody responses to B. abortus were measured using the brucellosis card, rivanol precipitation-plate agglutination, complement fixation, and fluorometric immunoassay tests, and as well as with an enzyme-linked immunosorbent assay. The CMI response was measured using antigen-specific lymphoproliferation (LP) and skin testing for delayed-type hypersensitivity (DTH) to BASA (Experiment 2). Specific aspects of induced CMI responses investigated were macrophage activation (IL-1 production), helper T cell activation (IL-2 production), and release of soluble suppressor factor(s). In general, mean antibody responses were significantly higher (P less than 0.05) in immunized steers than in control steers and those receiving BASA alone. The LP responses to heat-killed B. abortus were generally higher in immunized groups than in the controls. The LP and DTH responses were greatest in the groups receiving S19 and BASA + DDA. Increased induction of IL-1 was largest in the group receiving BASA + DDA whereas IL-2 release was greatest in S19 vaccinated steers. Suppressor T cell responses were most obvious in the groups receiving S19, BASA + B. pertussis, and P. acnes. These studies demonstrated that DDA potentiates CMI responses to a soluble B. abortus antigen and may be useful as an adjuvant for future vaccines, particularly subunit vaccines.

Immunopotentiation of cattle vaccinated with a soluble Brucella abortus antigen with low LPS content: an analysis of cellular and humoral immune responses.

The adjuvant effects of dimethyl dioctadecyl ammonium bromide (DDA) alone or in combination with trehalose dimycolate (TDM) or muramyl dipeptide (MDP) on bovine humoral and cellular responses to a soluble protein extract of gamma irradiated Brucella abortus strain 19 (SPEBA) were investigated. Thirty-five beef steers were randomly allotted to nine groups. Three of these groups received SPEBA (2 mg protein per dose) subcutaneously in combination with adjuvants, one group received the reduced dose of B. abortus strain 19 (S19), and one group received SPEBA alone. Controls included groups receiving adjuvant preparations only or no vaccine. Immune responses to the various immunizations were assessed sequentially for 56 days using various in vitro and in vivo assays. The humoral response to B. abortus was measured using standard serologic tests, an enzyme-linked immunosorbent assay, and a quantitative fluorometric immunoassay. The cell-mediated immune (CMI) response was measured by antigen-specific lymphoproliferation (LP), interleukin 2 (IL 2) production, and soluble suppressor factor release. Skin testing at day 35 for delayed-type hypersensitivity (DTH) to SPEBA was also performed. Minimal humoral responses were induced with SPEBA alone. The highest and most sustained serum antibody responses to B. abortus antigens were elicited by the S19 vaccine. A combination of SPEBA with DDA + TDM induced higher antibody levels than SPEBA with DDA or SPEBA with DDA + MDP. Responses to DTH among the groups receiving SPEBA were most notable in the SPEBA with DDA + TDM groups. Increased IL 2 production was greatest in the S19 and SPEBA with DDA + TDM vaccinates. The results indicated that a combination of DDA + TDM best potentiated immune responses to a soluble B. abortus antigen preparation and may be useful as adjuvants for future vaccines.

Multisystemic granulomatous inflammation in a horse.

A one-year-old Thoroughbred filly was examined because of poor body condition and reluctance to move its neck. Complete blood count revealed leukocytosis (15,700 WBC/microliters) and hyperproteinemia (8 g/dl). Radiography of the cervical vertebrae revealed multifocal lesions of bone lysis surrounded by zones of sclerosis. The horse was euthanatized and necropsied. Granulomatous lesions were identified in the heart, spleen, lungs, bones, and lymph nodes. The multifocal granulomatous inflammatory lesions in this horse were suggestive of mycobacteriosis.