Immunological implications of bovine leukemia virus infection.

Abstract

This study examined neutrophil and monocyte functions and the blood lymphocyte profile of naturally BLV-infected cows with or without persistent lymphocytosis (PL). The percentage of neutrophils and monocytes that phagocytosed Staphylococcus aureus was lower in BLV-infected dairy cows, particularly those with PL. The relative percentage of CD44monocytes and neutrophils and CD11b expression by neutrophils was also lower in BLV-infected dairy cows with PL. A correlation between the percentage of CD11bneutrophils and that produced reactive oxygen species (ROS) was found. Furthermore, the percentage of CD44monocytes was positively correlated with the percentage of monocytes that phagocytosed S. aureus and the same phenomenon was observed for neutrophils. In BLV-infected dairy cows, particularly those with PL, inhibition of monocyte and neutrophil apoptosis was observed. Additionally, the percentage of neutrophils producing ROS was lower in BLV-infected cows with PL, in contrast to higher intensity of intracellular production of ROS by monocytes. The result from the lymphocyte immunophenotyping of BLV-infected cows with PL was an increase in B cells, mainly B CD5CD11b, due to the apoptosis inhibition. In conclusion, this study provides novel insight into the implications of BLV infection for cattle, which can include the dysfunction of blood monocytes and neutrophils.