BACKGROUND: Liver transplantation for type IV glycogen storage disease 
(branching-enzyme deficiency) results in the resorption of extrahepatic deposits 
of amylopectin, but the mechanism of resorption is not known.
METHODS: We studied two patients with type IV glycogen storage disease 37 and 91 
months after liver transplantation and a third patient with lysosomal 
glucocerebrosidase deficiency (type 1 Gaucher's disease), in whom tissue 
glucocerebroside deposition had decreased 26 months after liver replacement, to 
determine whether the migration of cells from the allograft (microchimerism) 
could explain the improved metabolism of enzyme-deficient tissues in the 
recipient. Samples of blood and biopsy specimens of the skin, lymph nodes, 
heart, bone marrow, or intestine were examined immunocytochemically with the use 
of donor-specific monoclonal anti-HLA antibodies and the polymerase chain 
reaction, with preliminary amplification specific to donor alleles of the gene 
for the beta chain of HLA-DR molecules, followed by hybridization with 
allele-specific oligonucleotide probes.
RESULTS: Histopathological examination revealed that the cardiac deposits of 
amylopectin in the patients with glycogen storage disease and the lymph-node 
deposits of glucocerebroside in the patient with Gaucher's disease were 
dramatically reduced after transplantation. Immunocytochemical analysis showed 
cells containing the HLA phenotypes of the donor in the heart and skin of the 
patients with glycogen storage disease and in the lymph nodes, but not the skin, 
of the patient with Gaucher's disease. Polymerase-chain-reaction analysis 
demonstrated donor HLA-DR DNA in the heart of both patients with glycogen 
storage disease, in the skin of one of them, and in the skin, intestine, blood, 
and bone marrow of the patient with Gaucher's disease.
CONCLUSIONS: Systemic microchimerism occurs after liver allotransplantation and 
can ameliorate pancellular enzyme deficiencies.