According to many clinical experiences in liver transplantation, it is generally known that liver transplants are immunologically privileged. The regeneration of the liver seems to potentiate the ischemic tolerance and to suppress the rejection
of
transplants.
The liver immune regulatory factor, which exists only in the hepatocytes, might be released from the 70% resected liver as reported previously. This factor could inhibit in vitro mitogen and alloantigen stimulation unspecifically and achieve in
vivo
prolongation of renal graft survival in rat. And also, after 70% hepatectoy in rats the thymus atrophied and thymus cell differentiated to helper and suppressor/cytotoxic T-cell, completely on the 5th day.
Hypothetically, I assume that the mechanism of the immunosuppressive function of the liver component might be induce by alteration of T-cell mediated immune response, i.e., via the thymus route. The clarity this hyponthesis, I examined the
immunological
status by means of cell subpopulation analysis in thymus after whole(100%) or partial (30%) liver grafts (BDE→LEW) with mouse anti-rat monoclonal antibodies W3/13, OX-12, W3/25 and OX-8. With mouse anti-rat monoclonal antibodies W3/13, OX-12,
W3/25 and
OX-8 .
1. BDE hearts were grafted into LEW rats. After heart transplantation, the thymus weight and cell counts were slightly reduced. However, in thymus cell subpopulations could be shown no significant alteration. i.e., despite graft rejection due to
MHC
incompatibility, no differentiation in T-helper and T-suppressor/cytotoxic cell occured.
2. After liver transplantation in rats(BDE→LEW), in all animals thymus atrophy in weight and cell counts was found. In 100% liver transplantation thymus cells were slightly differentiated in T-helper and T-suppressor/cytotoxic cell on the 3 rd
day, on
day 5th and 7th, thymus cell differentiation was almost complete.
3. In 30% liver grafting(BDE→LEW), complete thymus cell differentiation was observed on the 3 rd day, even on the 7th day the thymus alteration we nearly the same. Moreover, in 30% liver grafting. I found that the thymus cells were
differentiated
more
suppressor/cytotoxic T-cells than helper T-cells. These results suggest that the regenerative potential after hepatic grafting pssess immunosuppressive ability. And in 305 liver transplantation thyums alterations indicating an immunosuppressive
status
are stronger than 100% liver grafting.
In my examination thymus cell differentiation is combined with thymus atrophy. Presumably, this phenomenon is partially based on thymus cell proliferation and cellular migration.
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