Contributions of donor CD4 and CD8 cells to liver injury during murine graft-versus-host disease.

We have determined the capacity of donor CD4 and CD8 T cells to mediate liver injury in the B10.D2 (donor) into BALB/c (host) chronic graft-versus-host disease (GVHD) model. First, we compared the effects of treating GVHD mice with anti-CD4 or anti-CD8 versus no treatment on the liver histology scores and elevated serum IgE levels in this model. We also examined the abilities of purified donor total T, CD4, and CD8 cells to mediate hepatic GVHD lesions. Anti-CD4 and anti-CD8 treatments caused profound depletion of peripheral CD4+ and CD8+ cells, respectively, and produced a relative enrichment of the CD8+ and CD4+ cells in the liver. Hepatic GVHD lesions and elevated serum IgE concentrations were both suppressed by anti-CD4 treatment. Anti-CD8 treatment had no effect on the severity of hepatic lesions and caused a significant increase in serum IgE levels. Attempts to induce hepatic GVHD with purified donor CD4 and CD8 cells were inconclusive because the onset of liver lesions was delayed and the lesions in both groups were contaminated by the opposite subset. Altogether, our results indicate that both hepatic lesions and elevated serum IgE concentrations in this GVHD model are dependent on donor CD4 cells. Donor CD4 cells mediated hepatic GVHD in the absence of CD8 cells. Donor CD8 cells did not produce hepatic GVHD in the absence of CD4 cells and appeared to be dependent on CD4 cells.