Fourth component of complement (C4) polymorphism in human orthotopic liver transplantation.

C4 polymorphism was investigated in 13 orthotopic liver transplantations. It could be shown that recipient C4 phenotype disappears after transplantation and is replaced by donor phenotype on days 10-19 posttransplantation. This indicates that C4 is mainly produced in the liver. The delayed appearance of donor C4 phenotype compared with other complement components produced in the liver cannot be explained by different rates of synthesis or serum protein levels. The limited number of patients investigated in this study does not permit assessment of the role of C4, C3, Bf, and HLA-A, B, and DR in orthotopic liver transplantation.