Intra-and Extrahepatic Leukocytes and Cytokine mRNA Expression During Liver Regeneration After Partial Hepatectomy in Rats

We investigated intra- and extrahepaticleukocytes during liver regeneration after a 70% partialhepatectomy in the rats using flow cytometry and RT-PCRfor cytokine mRNA expression. Our study indicated that LFA-1⁺⁺⁺ CD3⁺ cell,NK3.2.3⁺⁺ T cells, and CD5⁺ Bcells, which are activated in autoimmune diseases andmalignancy in humans and mice, were activated in theearly phase of liver regeneration in the liver and the blood after partial hepatectomyin the rats. On measuring cytokine mRNA expression byRT-PCR, only IFN- mRNA was detected in the normalrat liver. IFN- mRNA expression clearly decreased in the liver on day 1 after partial hepatectomyand increased thereafter. IL-2 and IL-4 mRNA were notdetected in the liver regardless of hepatectomy. Everycytokine was detected in normal spleen and increased in the early phase after partial hepatectomy.These were also detected in normal thymus; however, IL-2and IFN- mRNA expressions decreased and IL-4 mRNAexpression increased slightly in the early phase after partial hepatectomy. Thus, the immunesystem dramatically changed both in the liver andelsewhere in the early phase of liver regeneration afterpartial hepatectomy.