Medycyna Wet. 62 (9), 1045-1047, 2006
| Urban-Chmiel R., Puchalski A., Wernicki A. |
| Influence of transport stress on susceptibility of bovine leukocytes on cytotoxic effect of M. haemolytica leukotoxin |
| The purpose of the study was estimating the viability and susceptibility effect of leukocytes isolated from cattle before and after the transportation in vitro on M. haemolytica leukotoxin (Lkt) cytotoxicity. 40 Simentaler heifers that were transported by truck a distance of 1700 km for 72 hours were used in the experiment. The material for the study was the blood (40 samples) collected on heparin directly before and after transportation. In relation to leukocytes the examination of susceptibility on cytotoxic effect of Lkt has been carried out with the use of MTT (microtitration assay) and the viability of leukocytes after 1, 2, 3 and 6 hour of incubation. The results obtained in the cell viability test did not show statistically significant differences (P³0.05) in 1st and 2nd hour of incubation in leukocytes obtained from heifers before and after transportation. After the 1st hour of incubation the percentage of leukocyte viability was on a very high level and showed 87% in both groups of animals. The significantly lower cell viability values in comparison to leukocytes isolated from animals before the transportation was observed in the transported heifers from 3rd to 6th hour of incubation. The analysis of the results obtained by MTT test indicated statistically significant differences in the susceptibility of leukocytes for cytotoxic activity of Lkt. The average values of toxic activity of Lkt in relation to leukocytes isolated before and after transportation was 79% and 92% respectively. The lytic activity of Lkt for 50% of the cell population referred as 1 unit (1U) was observed in Lkt concentration 15 mg/ml (leukocytes before transportation) and 7.5 mg/ml (after the transportation). The increase of susceptibility of leukocytes isolated after transportation on the cytotoxic effect of leukotoxin suggest the significant influence of transporting stress on the increase of respiratory diseases caused by M. haemolytica strains. |
| Keywords: M. haemolytica, transporting stress, leuktoxin (Lkt) |