Phagocytic activity of macrophages of rainbow trout against Vibrio anguillarum and the opsonising effect of antibody and complement

The phagocytosis of Vibrio anguillarum by peritoneal macrophages from normal rainbow trout was enhanced by antibody and complement. Treatment of either macrophages or the bacteria by antibody also enhanced opsonisation. Five weeks after immunisation with V anguillarum, the phagocytic activity of macrophages from rainbow trout was increased significantly compared with the activity of those from unvaccinated fish. Although agglutinin titres did not increase until three weeks after immunisation, seven out of 10 fish challenged one week after immunisation survived, indicating that immunised fish had developed resistance to vibrio infection before significant levels of antibody or phagocytic activity became detectable.     

Existence of cytotoxic activity against BLV-transformed cells in lymphocytes from normal cattle and sheep

Peripheral blood lymphocytes (PBL) from normal cattle and sheep were tested for their cytotoxic activity against several target cells using a 20-hour 51Cr release assay. The following characteristics of the effector cells were observed; 1) PBL from animals showed cytotoxic activity against two sheep cell lines (FLK and SF-28) that were transformed with bovine leukemia virus. However, normal sheep and bovine cells and Molony leukemia virus-induced mouse lymphoma cell line (YAC-1) were not killed by these cells. 2) A time course study showed that the activity was first observed at 4 to 8 hours and reached a maximum at 20 to 30 hours after incubation. 3) Cytotoxic activity was observed in both adherent and nonadherent cell fractions when PBL were passed through a nylon-wool column. This indicated that the effector cells showed some degree of adherence. 4) Treatment of PBL with carrageenan did not change the cytotoxic activity against target cells, indicating that phagocytic capability is not perhaps necessary for cytotoxicity to take place. These results indicate that the effector cells participating in the cytotoxic reaction resembled natural killer cells or natural cytotoxic cells which are present in murine and human systems. However, analysis of the cell surface markers of the effector cells is yet to be done in future studies.     

Detection of fish antibody against protein antigen of Aeromonas salmonicida by enzyme-linked immunosorbent assay using biotin-avidin system

Antibody against Aeromonas salmonicida was detected in sera from immunised or experimentally infected rainbow trout by enzyme-linked immunosorbent assay (ELISA) using the biotin-avidin system. The ELISA titre correlated well with the agglutinin titres of the sera, but the ELISA was found to be more sensitive than the agglutination test. When the rainbow trout serum was separated by column chromatography, antibody activity (determined by ELISA and agglutination test) was detected in the IgM fractions. Minimum cross reaction was observed in the ELISA system between antigen prepared from A salmonicida and antibodies against Vibrio species and other species of Aeromonas. The specificity of the ELISA was also confirmed by inhibition test. Immunisation of rainbow trout with a virulent strain of A salmonicida provided good protection, though no correlation was observed between the protection and the ELISA titres of sera.     

Assessment of Alloxan-Induced Diabetic Rats as a Periodontal Disease Model Using a Selective Cyclooxygenase (COX)-2 Inhibitor

Several recent studies have reported that alloxan-treated rats with long-term hyperglycemia can develop naturally occurring periodontal disease (PD). Our previous studies detected dental caries in the same model. Therefore, these two lesions of different etiologies are expected to occur concurrently. In this study, we evaluated the use of diabetic rats as a PD model by employing a selective COX-2 inhibitor reported to be effective against PD. Six-week-old female F344 rats were divided into 3 groups: intact rats (control), alloxan-induced diabetic rats fed a standard diet (AL) and alloxan-induced diabetic rats fed a diet containing 0.01% etodolac (AL+Et). The animals were euthanized at 26 weeks of age, and their oral tissues were examined histopathologically. Gingivitis, marginal periodontitis and alveolar bone resorption were markedly enhanced along with dental caries in the AL group compared with the control group. However, the COX-2 inhibitor had no effect on periodontal inflammation in the AL+Et group. In addition, in the AL group, periodontitis was notably nonexistent around the normal molars, and gingivitis was scarcely worse than that in the control group. In the diabetic rats, the progression of periodontal inflammation was closely correlated with the severity of adjacent dental caries, and marginal periodontitis was frequently continuous with apical periodontitis. In conclusion, an alloxan-induced diabetic rat is not a model of PD but of dental caries. It is probable that in this model, hyperglycemia may enable crown caries to progress to apical periodontitis, while the associated inflammation may rostrally expand to surrounding periodontal tissue.