Characterization and epitope mapping of human monoclonal antibodies to PDC-E2, the immunodominant autoantigen of primary biliary cirrhosis

Further to define the epitopes of PDC-E2, the major autoantigen in primary biliary cirrhosis (PBC), we have developed and characterized five human monoclonal antibodies. These antibodies were derived by fusing a regional hepatic lymph node from a patient with PBC with the mouse human heterohybrid cell line F3B6. Previous studies of epitope mapping of PDC-E2 have relied on whole sera and have suggested that the immunodominant epitope lies within the inner lipoyl domain of the molecule. However, selective absorption studies using whole sera and a series of overlapping recombinant peptides of PDC-E2 have suggested that the epitope may also include a large conformational component. Moreover, several laboratories have suggested that autoantibodies against the 2-oxo acids dehydrogenase autoantigens are cross-reactive. The five monoclonal antibodies generated included three IgG2a and two IgM antibodies and were studied for antigen specificity using recombinant PDC-E2, recombinant BCKD-E2, histone, dsDNA, IgG (Fc), collagen and a recombinant irrelevant liver specific control, the F alloantigen. The antibodies were also used to probe blots of human, bovine, mouse and rat mitochondria. Finally, fine specificity was studied by selective ELISA and absorption against overlapping expressing fragments of PDC-E2. All five monoclonals, but none of the other mitochondrial autoantigens were specific for PDC-E2. In fact, although affinity purified antibodies to PDC-E2 from patients with PBC cross-reacted with protein X, the human monoclonals did not, suggesting that protein X contains an epitope distinct from that found on PDC-E2. Additionally, all three IgG2 monoclonals recognized distinct epitopes within the inner lipoyl domain of PDC-E2.

Surgical management of severe liver trauma: a role for liver transplantation

Severe devascularizing liver injuries continue to carry a high mortality. Rapid operative intervention to achieve hemostasis and debride devitalized tissue remains essential to salvaging these patients. For those with unsalvageable liver injuries liver transplantation can be employed. Careful support of the patient in the anhepatic state, reversal of coagulopathy, and use of venous bypass intraoperatively permit successful transplantation.

False positive ELISA tests for anticardiolipin antibodies in sera from patients with repeated abortion, rheumatologic disorders and primary biliary cirrhosis: correlation with elevated polyclonal IgM and implications for patients with repeated abortion

Non-specific binding in an ELISA test for antibodies to cardiolipin (ACA) was investigated in sera from patients with primary biliary cirrhosis, rheumatological disorders, and repeated abortion. Binding to wells without phospholipid was most frequent in ELISA assay for IgM class ACA and correlated with levels of serum polyclonal IgM in patients with repeated abortion and rheumatologic disorders (r = 0.79, 0.76). Using added polyclonal IgM we demonstrated that the increase in non-specific binding was most significant when levels of ACA were low; subtraction of binding to the unoccupied well over-corrected specific antibody estimates when a high affinity antibody was present. Absorption studies on three sera suggest that this 'non-specific' binding includes low affinity antibody binding. Elevated levels of polyclonal IgM in sera from patients with repeated abortion may account for some reports of elevated IgM class antibodies in other ELISA assays. The prevalence of a positive test for ACA in a sequential series of 412 such patients was reduced to 6.1% (95% confidence limits 4-9%) after subtraction of non-specific binding.

Lung uptake of technetium-99m phosphate compounds after liver transplantation

Pulmonary calcification can be detected easily using Tc-99m phosphate compounds. Lung uptake of Tc-99m bone imaging agents was observed in two patients after liver transplantation. Transient hypercalcemia due to calcium infusion during hepatic transplantation may be responsible for the pulmonary calcification.

Using ABO-incompatible blood in massive transfusion in orthotopic liver transplantation

With massive plasma exchange, transfusion with major ABO-incompatible blood was possible. Herein we reported the experience of two cases of liver transplantation without serious adverse effects. However, further refinement of the procedure is warranted before it can be used as routine treatment.