Nonvaccinated pregnant cows were segregated retrospectively into 2 groups following inoculation with Brucella abortus stain 2308. One group resisted infection (resistant cows) and the other group developed active infections (susceptible cows) and subsequently aborted. Mammary gland macrophages collected from the 2 groups of cows were compared, using in vitro functional assays. In a chemiluminescence assay, mammary gland macrophages from resistant cows produced significantly (P = 0.014) higher oxidative burst activity than did macrophages from susceptible cows. Macrophages from resistant cows had significantly (P = 0.038) greater bacteriostatic activity against B abortus than did macrophages from susceptible cows. Differences in lysosomal enzymatic activity or Fc receptor expression were not observed for macrophages from the 2 groups of cows. Differences in macrophage function may be one factor responsible for natural resistance to Brucella infection in cattle.

Electron microscopy revealed several unique features in canine bone marrow, compared with that of other species. The marrow was fatty and extensively trabeculated and was enclosed by a complete layer of endosteal bone-lining cells. Branched reticular cells were closely associated with each other and, occasionally covered part of the sinus wall as an adventitial layer. The extent of adventitial coverage varied markedly and was less extensive, compared with that of other species. On average, only 23% of the sinus wall was covered by adventitial layer, in contrast to 65% reported in laboratory animals. Unilaminar sinuses, with no adventitial coverage, accounted for greater than 38% of all sinuses. Quantitative analysis indicated that 60% of the latter sinuses contained apertures, as opposed to 35% of sinuses with adventitial coverage (P less than 0.05). Moreover, the number of apertures in unilaminar sinuses was significantly (P less than 0.009) greater than that in multilaminar sinuses. Apertures were observed every 59 micromoles in unilaminar sinuses, in contrast to every 109 micromoles in multilaminar sinuses. Approximately 75% of the apertures were occupied by cells in transit, and only 25% were free of cells. Macrophages were distributed throughout the marrow and were closely associated with all blood cell lines. Occasionally, cells that entered the lumen were not fully mature. Erythroblasts were seen migrating across the wall and within the lumen of sinuses. The less-extensive adventitial coverage in canine bone marrow might indicate that the rate of cell delivery from the marrow into the circulation was relatively high in this species. The prevalence of unilaminar sinuses, along with the larger number of apertures, suggested that these sinuses were more accessible to the migrating cells and that the cellular traffic across them was intense.

Bronchoalveolar lavage fluid was collected from 12 anesthetized cats by use of an endotracheal tube and syringe adapter. The safety of the technique was evaluated by monitoring mucous membrane color, capillary refill time, pulse rate, respiratory rate, ECG, and arterial blood gas tensions and by necropsy findings. Group A consisted of 3 cats that were administered (by lavage) 4 aliquots of 20 ml of saline solution during anesthesia for placement of femoral artery catheters. Group B consisted of 4 cats that were administered a smaller total volume of saline solution (3 aliquots of 5 ml/kg of body weight) during a separate anesthetic period, other than the one for placement of catheters. Group C consisted of 5 cats administered 3 aliquots (5 ml/kg) of saline solution during a separate anesthetic period and administered supplemental oxygen for 5 to 10 minutes before and for 20 minutes after the lavage procedure. Group-A cats had a prolonged recovery period that was attributed to the lengthy anesthetic period required for placement of femoral catheters. The effect was eliminated in the cats of the other groups in which the lavage procedure itself accounted for only 5 to 10 minutes of anesthetic time. Evaluation of mucous membrane color, capillary refill time, ECG, pulse, and respiratory rate revealed no persistent abnormalities. Transient increase in pulse and respiratory rate was seen in some cats. Blood gas analysis revealed noticeable decrease in arterial oxygen pressures (PaO2) after the lavage procedure. In group-C cats, oxygen supplementation allowed the maintenance of normal or above normal PaO2. When oxygen was discontinued at 20 minutes, PaO2 was maintained at greater than or equal to 60 mm of Hg. The variability in oxygen pressures did not appear to correlate with the volume of fluid remaining in the lungs. Histologic evaluation of the lungs revealed no changes attributable to the lavage procedure. Most cats had minimal to mild inflammatory changes, and 4 cats had moderate to moderately severe bronchopneumonia. These changes were reflected in the bronchoalveolar lavage fluid, indicating that they were present at the time of lavage.

Liposomes with entrapped gentamicin were used to treat mice with infection attributable to Brucella melitensis. Liposomes bearing positive charge and formed by egg yolk lecithin, cholesterol, and stearylamine were effective in the elimination of B melitensis residing in liver and spleen. Negatively charged liposomes, formed by egg yolk lecithin, cholesterol, and dicetyl phosphate were also effective in suppression of the infection in liver, but were less so in suppression of the infection in the spleen. Free gentamicin was less effective than the encapsulated antibiotic. At 20 hours after administration of gentamicin encapsulated in liposomes, the gentamicin concentrations in liver and spleen were similar, regardless of the charge of the liposomes--neutral, positive, or negative. However, positively charged liposomes were more efficient than were other liposome types for the treatment of brucellosis caused by B melitensis.

Animals recovered from viral diseases represent an important model to study the host cellular and humoral immune responses to the etiologic agents. This is particularly important for African swine fever virus (ASFV) infections in which antibodies have little or no virus-neutralizing effect. Pigs surviving experimental infection with the naturally occurring low-virulent, nonhemadsorbing ASFV/NH/P68 (NHV) isolate did, however, exhibit virus-specific T-cell activities, as measured by a variety of assays. A strong virus-induced, antigen-specific blastogenic response was observed only with blood mononuclear cells (BMC) from ASF-recovered swine, whereas cells from recovered and naive swine responded similarly to the mitogens concanavalin A and phytohemagglutinin. The ASFV-induced blastogenesis was dependent on virus dose and on the presence of adherent cells. Blood mononuclear cells cultured with antigenically related hemadsorbing ASFV isolates of different virulence characteristics, the highly virulent L60 isolate and moderately virulent DRII isolate, exhibited a similar magnitude of blastogenesis to cells infected with the low-virulent NHV isolate. Virus-infected cells proved to be an efficient inducer of interleukin-2 (IL-2) activity to cells from recovered swine, but not from naive swine, whereas T-cell-specific lectins induced production of similar amounts of IL-2 activity from cells of naive and recovered swine. Correlated with the appearance of virus-induced IL-2 activity in the culture supernatant was the induction of promiscuous killing in cells exposed to prolonged (7 days) virus stimulation. This lymphokine-activated killing could be induced experimentally early in the virus stimulatory process (3 days) by the addition of exogenous lymphokines to the cultures. It was concluded that swine inoculated with low-virulent ASFV isolates are a useful model for identifying and characterizing ASFV immune mechanisms in vitro. Furthermore, this ASFV model implicates lymphokines as inducers of nonspecific cell-mediated immunity; in fact, lymphokine-activated killer type responses may contribute to recovery from this viral infection. More important, ASFV-specific blastogenic and cytotoxic T-cells are prime candidates for the cells inducing and/or conferring protective immunity against challenge ASFV infection.

Live Pasteurella haemolytica biotype A, serotype 1 isolates (n = 3) and Escherichia coli K-12, strain W3110, were reacted with bovine pulmonary lavage cell (PLC) suspensions. The comparative effects of the different bacteria on the functional and metabolic activity of alveolar macrophages (AMO) in the PLC suspensions were assessed simultaneously by use of 51Cr release, luminol-dependent chemiluminescence (LDCL), and AMO bactericidal assays. The bovine PLC reponsed differently to E coli, than to the 3 P haemolytica isolates in each of the 3 experimental test systems; however, responses to each of the P haemolytica isolates were not found to be significantly different. Unopsonized live P haemolytica cells adversely affected the functional and metabolic response of PLC, whereas there was no evidence of a cytotoxic (cytocidal) influence of E coli. A difference in 51Cr release for reaction mixtures containing E coli and P haemolytica was not detected at zero time; however, at each subsequent time, reaction mixtures phagocytically stimulated with P haemolytica had significantly increased amount of 51Cr release (P less than 0.05), compared with those mixtures containing E coli. Bovine AMO in the PLC suspensions were able to effectively kill E coli in vitro, but were unable to prevent survival and subsequent growth of P haemolytica. The luminol-dependent chemiluminescence profiles for reaction mixtures phagocytically stimulated with E coli provided evidence of sustained production of oxygen radicals with antimicrobial capabilities by bovine AMO in the PLC. Production of these highly reactive antimicrobial oxidants appeared initially in cultures containing P haemolytica but, subsequently, their production declined precipitously and ceased altogether.

A study was performed to determine the effect of proadifen hydrochloride on prostacyclin (prostaglandin I2 [PGI2]) and thromboxane A2 (TxA2) synthesis by equine peritoneal macrophages and the effect of proadifen on endotoxin-induced synthesis of PGI2 and TxA2 by equine macrophages. Peritoneal macrophages (2.5 X 10(6)/ml) were incubated for 6 hours in tissue culture media containing 1) nothing (nontreated control), 2) proadifen hydrochloride (20, 100, 250, and 500 micromol/L, 3) endotoxin (5 ng/ml), or 4) the calcium ionophore A23187 (0.95 micromol/L). In a second series of experiments, peritoneal macrophages were incubated with endotoxin (5 ng/ml) and proadifen (250 micromol/L), for 6 hours. Concentrations of 6-keto-prostaglandin F 1alpha (6-keto-PGF 1alpha) and thromboxane B2, the stable metabolites of PGI2 and TxA2, were determined in the incubation media by radioimmunoassay. Proadifen caused increased synthesis of PGI2 by equine macrophages, without affecting TxA2 production. The increased PGI2 production was similar to that induced by endotoxin and calcium ionophore; however, the latter 2 agents significantly stimulated TxA2 production as well (P less than 0.05). There were no significant differences among mean concentrations of 6-keto-PGF 1alpha in media from macrophages treated with 100, 250, or 500 micromol/L proadifen, but there was a significant curvilinear regression between their concentrations. The ratio of thromboxane B2 to 6-keto-PGF 1alpha was significantly lower than baseline in incubation media from macrophages exposed to proadifen, endotoxin, and calcium ionophore. Proadifen hydrochloride did not significantly change equine peritoneal macrophage production of PGI2 or TxA2 in response to endotoxin.

Oxidative respiratory burst activity was examined in lavage-procured bovine pulmonary alveolar macrophages. Nonstimulated alveolar macrophages released a minimal quantity of superoxide anion and had small amounts of glucose flux through the pathways of energy metabolism. Nonstimulated cells metabolized substantial amounts of glucose through the hexose monophosphate shunt. Stimulation with opsonized zymosan particles induced a tonfold increase in the release of superoxide anion and a twofold increase in the flux of glucose through the hexose monophosphate shunt and the pathways of energy metabolism. Preliminary observations also indicated that the magnitude of the burst varied between sets of bronchoalveolar cells obtained from the same calf over time.