Penka Moneva, Ivan Yanchev, Nikola Metodiev
Agricultural Academy, Institute of Animal Science, 2232 Kostinbrod, Bulgaria
Moneva, P., Yanchev, I. & Metodiev, N. (2023). Dynamics of leukocytes and cytokines after moderate altitude exposure in pregnant ewes with low and high hematocrit levels. Bulg. J. Agric. Sci., 29(4),723–732
The object of the present study was to investigate leukocyte subsets distribution and the dynamics of some pro-inflammatory and anti-inflammatory cytokines in response to moderate altitude exposure in sheep having different hematocrit values. Thirty Ile De France ewes were selected from an experimental herd according to their hematocrit levels and were allocated into 3 groups as follows: low hematocrit (LHct) group (hematocrit range 19.7-27.9 %), high hematocrit (HHct) group (hematocrit range 32.0-36.9 %) and mean hematocrit (MHct) group (hematocrit range 28.3-29.8 %). Immediately after shearing, ewes were transported from the Institute farm (altitude 500 m) to a mountain pasture (altitude 1440 m). Blood samples were taken by jugular venepuncture at the following time points: before transportation (baseline level), on day 7, 20 and 42 after the transport. The traits investigated were leukocyte subsets (basophils, eosinophils, neutrophils, lymphocytes, monocytes, large immature cells) and cytokines (IL-2, Il-4, IL-6, IL-10, IL-17A, IFN-γ, TNF-α). Moderate altitude exposure elicited significant decrease in lymphocyte numbers in all the 3 groups at d 7 after transport to moderate altitude followed by a return to normal levels at d 20 after transport. Neutrophil numbers were not influenced by moderate altitude hypoxia. There was hematocrit associated changes in basophil, eosinophil and monocyte numbers suggesting different trafficking patterns of these leukocyte subsets. There was a tendency of slight increase in large immature cells in HHct ewes at d 7. There was a relation between N/L ratio and large immature cells as follow: baseline levels (r = 0.627995, P < 0.01); at 7 d (r = 0.771221, P < 0.001); at 20 d (r = 0.606801, P < 0.01); at 42 d (r = 0.566646, P < 0.01). IL-10 levels in HHct and MHct ewes tended to decrease at 7 d compared to basal levels. There was relation between IL-2 and IL-6 at 20 d (r = 0.531371, P < 0.01) and 42 d (r = 0.586212, P < 0.01). Investigated pro-inflammatory Th17 (IL-17A) and Th1 cytokines (IL-2, IL-6, IFN-γ, TNF-α), as well as anti-inflammatory Th2 cytokines (IL-4 and IL-10) were not influenced by moderate altitude exposure. The results are interpreted to suggest that exposure of pregnant ewes at ambient temperature below the lower critical temperature at moderate altitude prevents cytokines increase.