DNA damage in peripheral blood mononuclear cells and neutrophils of dairy cows during the transition period

Abstract

This study was designed to investigate the apoptotic process in peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) in dairy cattle during the transition period. Blood samples  were collected from 4 dairy cattle at 3 weeks before the expected parturition (wk -3), parturition (wk 0) and 3  weeks after parturition (wk +3). The DNA damage of PBMC and PMN was evaluated based on the comet assay  using visual scoring (arbitrary units). Undamaged DNA remained within the core (score 0) and the broken DNA  migrated from the core towards the anode forming the tail of a comet (scores 1-4). Significantly higher scores  in PBMC at wk 0 and wk +3 were observed compared with those in PMN although there were no significant  changes of scores in either cell type during the experimental period. It is suggested that the apoptotic rate of  PBMC is accelerated compared with that of PMC during the transition period.

Keywords: Apoptosis, Comet assay, Cow, Leukocytes, Transition period.