Twenty-six adult patients with preformed IgG donor lymphocytotoxic antibodies received primary liver allografts under FK 506 immunosuppression. The effect of the crossmatch-positive state on early graft function and on the immunopathological and histo-pathological findings was compared with that of 52 crossmatch-negative control recipients. The presensitized (Crossmatch-positive) patients had prolongation of early graft dysfunction, underwent more clinically indicated biopsies and had a higher incidence of cellular rejection, both overall (p < 0.05) and within 10 days of transplantation (p < 0.01). They also had a higher incidence of graft failure in the first 180 days (p < 0.01). Hyperacute rejection with necrotizing or neutrophilic arteritis was not seen in the crossmatchpositive grafts. However, histological findings associated with presensitization included platelet margination in central veins and sinusoids in biopsy specimens 60 to 90 min after graft revascularization. Later biopsy specimens had neutrophilic portal venulitis followed by cholangiolar proliferation, acute cholangiolitis and centrilobular hepatocyte swelling that mimicked preservation injury, endothelial activation of arteries with medial changes and relapsing episodes of acute cellular rejection. These clinicopathological observations suggest that lymphocytotoxic antibodies can have a deleterious effect on liver allograft function and survival, even if they do not precipitate immediate or hyperacute rejection. (Hepatology 1992;16:671-681.) Although the liver is known to be more resistant than other solid organs to injury from preformed graft antibodies in the recipient (1-3), this privileged state is not absolute (4,5). Identification of the consequences of humoral antibody states on the liver has been hampered by the lack of distinctive pathological findings in many cases in which humoral rejection was suspected but was not proved. Consequently, in this study of liver recipients with preformed donor lymphocytotoxic antibodies, we have attempted to determine whether a unique, pathologically identifiable form of graft injury could be recognized and whether pathophysiological mechanisms of liver allograft injury could be deduced. A similar study on the pathological nature of ABO-mismatched livers in which the graft antibodies were isoagglutinins was published recently (6). MATERIALS AND METHODS Patient SelectionDuring the 11-mo period between November 31, 1989, and September 9, 1990, 243 adult patients ( > 16 yr) were given primary liver allografts under FK 506 and low-dose steroid therapy. The sera of 26 (11%) contained donor lymphocytotoxic antibodies. The crossmatchnegative control patients (n = 52) were those treated just before and after the crossmatchpositive cases. Most of these same cases were part of a recent clinical report (5). There were no statistically significant differences between the two cohorts with respect to age, United Network of Organ Sharing urgency of need status, original disease, donor demographic data or...

The new immunosuppressive drug FK 506 was used from the outset with low doses of prednisone to treat 120 recipients of primary liver grafts and 20 more patients undergoing liver retransplantation. The patient survival rate after 2 to 8 months in the primary liver transplantation series is 93,3%, with original graft survival of 87.5%. Of the 20 patients in the hepatic retransplant series, 17 (85%) are living. Almost all of the surviving patients have good liver function. In addition 11 hearts, 2 double lungs, and a heart-lung have been transplanted under .FK 506, with survival of all 14 patients. With all of the organ systems so far tested, including the kidney (which has been reported elsewhere), rejection usually has been controlled without additional drugs and with lower average steroid doses than in the past. Nephrotoxicity has been observed, but not to an alarming degree, and there has been a notable absence of hypertension. There is a suggestion that serum cholesterol may be lowered by FK 506, but this is unproved. Although the adverse reactions of FK 506 and the immunosuppressive mechanisms resemble those of cycIosporine, our preliminary observations suggest that FK 506 may have a more advantageous therapeutic index.

Because of the liver graft's ability to resist cytotoxic antibody-mediated rejection, it has become dogma that the conventional transplant crossmatch used to avoid hyperacute rejection of other organs is irrelevant to the liver. We examined this hypothesis in a consecutive series of adult primary liver recipients treated with FK506 and low-dose steroids. Twenty-five of 231 (10.8%) patients received a liver from a cytotoxic-positive crossmatch donor (more than 50% of donor T lymphocytes were killed by dithiothreitol-pretreated recipient serum). The outcome was compared with that of 50 negative crossmatch patients who had their transplantations just before and after the crossmatch positive cases. The one-year graft and patient survivals were 56% and 68%, for positive and 82% and 86% for negative crossmatch patients (P = 0.004, P = 0.03, respectively). The difference between patient and first graft survival was accounted for by retransplantation, which was 4 times more frequent in the positive-crossmatch cases. Histologically, failed allografts obtained at the time of retransplantation revealed a spectrum of pathologic findings related to vascular injury. This study showed a higher difficulty of intraoperative blood product management, a degraded prognosis, and a poorer average quality of ultimate graft function when liver transplantation was performed against positive cytotoxic crossmatches. In such patients for whom crossmatch-negative donors may never be found because of the broad extent and intensity of sensitization, special therapeutic strategies perioperatively must be evolved if results are to improve.

We have come a long way in our understanding of antibodies as effectors of liver graft damage, but we still have much to learn. Animal heterografts provided the first evidence that livers are susceptible to antibody-mediated damage. The pathophysiologic events are similar to those of extrahepatic organ grafts, but the liver is relatively resistant and rapidity of graft destruction is slower, if it occurs at all. Nevertheless, the ABO isoagglutinins can predictably cause human liver allograft failure, often in a quickened, but rarely a hyperacute fashion. The liver is more resistant to lymphocytotoxins, and in many cases will suffer no apparent damage. However, when present, a spectrum of graft pathologic changes can be seen. Early manifestations include hemorrhagic necrosis and lesions mimicking "preservation" injury. Later on, ischemic biliary necrosis and small bile duct loss may be seen. The variability is likely related to a balance between destructive antibody class, specificity, and titers and the ability of the liver to withstand the assault. More precise characterization of lymphocytotoxic antibodies is needed in clinical practice. In addition, antigen distribution in the graft, release of soluble MHC antigens, the role of Kupffer cells and other mechanisms of liver resistance are likely areas of fruitful investigation.