Plasma protein which has been known as one of nonspecific immunostimulators was added to feedstuff to examine its effect on the enhancement of cellular immune response in porcine immune system. A total of 40 piglets, 20 male and 20 female each, were fed for 30 days with or without plasma protein. The peripheral blood were collected and analyzed for the investigation of leukocyte subpopulations and their activities by using a panel of monoclonal antibodies specific to porcine leukocyte differentiation antigens and flow cytometry.
The results obtained as follows.
1. Subpopulations expressing major histocompatibility complex(MHC) class I antigen were 96.2±3.1% and 86.6±3.8% in piglets fed with plasma protein and in piglets fed without plasma protein, respectively.
2. Proportion of leukocyte subpopulation expressing MHC class II antigens were significantly higher in the piglets fed with plasma protein than ones without plasma protein. The proportion was 27.6±3.6% and 16.6±2.2% in MHC class II DQ antigen, and 28.1±2.0% and 20.0±0.3% in MHC class II DR antigen, respectively.
3. A significant increase in the proportion of cells expressing poCD2 was not found in piglets fed plasma protein. 4. Proportion of subpopulation expressed porcine(Po) CD4 antigens which specific to helper T lymphocytes were not increased (18.3-19.1% vs. 25.6-28.8%), rather slightly decreased, in plasma protein-treated group.
5. The most important increase of proportion in plasma protein-treated group was the leukocyte subpopulation specific to poCD8^+ T cytotoxic/suppressor lymphocytes. The expression level was significantly higher up to 45.9-47.1% in plasma protein-treated group in comparing with 29.7-33.0% in non-plasma protein-treated group.
6. Lymphoblastogenetic responses using different concentrations of Con A mitogen and plasma protein has found that the responses of lymphocyte from piglets fed plasma protein was significantly activated (p<0.01). The activities measured by 3[H]-thymidine incorporation showed 3-ti times stronger in plasma protein-treated group than those in non-plasma protein-treated group.
The study has concluded that plasma protein, which has known as a nonspecific immunostimulator, may have an immunoenhancing activities in porcine lymphoid system by increase the activated cell proportions and their blastogenetic properties which is critical to host immune responses.
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