The functional dynamics of neutrophils during different seasons in zebu cattle.

The present study was conducted inHarianaandSahiwalcows to study neutrophil functional dynamics during different seasons (summer, rainy and winter) in terms of expression of toll like receptor 2 & 4, neutrophils’ apoptosis in terms of caspase 3, 7 activities, and transmembrane mitochondrial potential. Blood samples were collected fromHariana(n = 10) andSahiwalcows (n = 10) throughout the year to evaluate the effects of season on neutrophil dynamics. In each season, eight blood samples were collected from each animal (twice in each month). Toll-like receptor 2 and 4 expressions were significantly (p < 0.05) decreased in neutrophils during summer season as compared to rainy and winter seasons. Significantly, (p < 0.05) higher caspase 3 & 7 activities and significantly higher per cent of neutrophils with low transmembrane mitochondrial potential indicating its enhanced apoptosis were found during extreme summer and lowest during winter. BothSahiwalandHarianabreeds exhibited similar trends in neutrophil apoptosis. The results of the study evidently indicate that neutrophil competence varies from season to season in zebu cattle and could determine the possible incidences of infections in these cows. Hot-humid season could be conducive for microbial infections owing to accelerated apoptosis of neutrophils and down regulation of TLR2 and TLR4 of immune cells of zebu cattle. [ABSTRACT FROM AUTHOR]