Differences in the relative counts of peripheral blood lymphocyte subsets in various age groups of pigs.

The aim of the study was to determine age-related changes in peripheral blood lymphocytes in pigs. Previous studies looking at age-related differences in lymphocyte subsets in porcine blood have not established reference ranges for these parameters. Moreover, most studies have concentrated on the dynamic changes in the first months of life, failing to continue observations in older animals. Therefore, in the present study, relative counts of various lymphocyte subpopulations (cytotoxic and helper T-cells, B-cells, and γδ T-cells) were evaluated to characterize the development of the cellular immune system at 28, 35, 135, and 200 days of age in growing pigs and adult sows (i.e., first and subsequent parity). In all examined groups, CD3 cells constituted the largest percentage of cells. A statistically significant higher percentage of TCRγδCD3 was noted in fatteners and gilts in comparison to other age groups. These results may be a reflection of antigenic pressure and show an immune response to viral or bacterial agents/environmental microbism.