Serial immunologic studies in recipients of hepatic allografts

Eosinophils in acute cellular rejection in liver allografts

Eosinophils have a role in various allergic and inflammatory disease processes and participate in the process of acute rejection in solid organ allografts. Initial studies described the diagnostic value of eosinophils in kidney allograft rejection. Graft eosinophilia is a sensitive and specific marker of acute rejection in liver allografts and has been incorporated as one of the diagnostic criteria of acute rejection by the Royal Free Hospital scoring system. Blood eosinophilia also has been investigated and is a useful diagnostic marker of acute rejection in liver and kidney allografts, although studies differ in defining the day of onset of eosinophilia in relation to rejection. Eosinophils probably act through the chemokines interleukin-5 and RANTES (regulated on activation, normal T cells expressed and secreted) in the pathogenesis of acute rejection. Basic cytotoxic proteins, such as eosinophil cationic protein and major basic protein, are released by the eosinophils, and their effector role in acute rejection has been studied through the use of specific monoclonal antibodies. Successful treatment of acute rejection with corticosteroids has been associated with a decrease in graft and blood eosinophil counts. Eosinophils also act as prognostic markers of acute rejection, as shown by studies reporting that patients with elevated eosinophil counts and steroid-resistant rejection showed a worse prognosis. Further research into the effector mechanisms of eosinophils in acute rejection needs to be performed. The ability of eosinophils to distinguish those diseases with different responses to standard immunosuppression and other diseases in the context of acute rejection also needs to be studied.

T lymphocyte subsets and activation status in patients following liver transplantation

Changes in T-lymphocyte subsets have previously been shown to relate to clinical events following liver transplantation and be of prognostic significance following renal transplantation. The aim of this study was to examine T lymphocyte subsets, their activation status and the mean fluorescence intensity of cell surface markers by flow cytometric analysis, in peripheral blood of patients following liver transplantation. Stable transplant patients (n=11) had a significantly higher level of activation (HLA-DR expression ) of all T cell subsets: CD3, CD4 and CD8 compared to healthy controls: 17.5% +/- 14.0 (mean +/- SD) vs 4.7 +/- 1.8 (p=0.04), 13.7% +/- 10.3 vs 4.3 +/- 1.7 (p=0.03) and 23.8% +/- 19.9 vs 3.6 +/- 2.4 (p=0.02) respectively. A further increase in activation status occurred in all T cell subsets in association with acute cellular rejection, reaching significance for the CD4+ population: 13.7% +/- 10.2 vs 23.3% +/- 20.6 (p=0.04). The mean fluorescence intensity of the CD3+DR- and CD3+ DR+ populations were increased to 1397 +/- 869 and 1282 +/- 810 following liver transplantation compared to values of 425 +/- 204 and 376 +/- 166 respectively for controls (p<0.05). T-lymphocytes maintain a high level of activation following liver transplantation and continue to express high levels of the surface marker CD3, which may account for the occurrence of acute cellular rejection despite immunosuppression in these patients.

Alpha-glutathione-S-transferase in acute rejection of liver transplant recipients

BACKGROUND

Alpha-glutathione-S-transferase (alphaGST) has been suggested as a sensitive marker of acute cellular rejection in liver transplantation. This study evaluated the usefulness of alphaGST as a marker of acute rejection in comparison with standard liver function tests.

METHODS

Daily measurements of liver function tests and alphaGST (enzyme immunometric assay, Biotrin) were prospectively recorded in 23 consecutive liver transplant recipients up to the time of discharge. Liver biopsies were performed as protocol biopsies or after clinical or biochemical deterioration in liver function, 38 of 56 showed acute rejection.

RESULTS

AlphaGST peaked on the second day (median, 125 microg/L; interquartile [IQ] range, 75-321 microg/L) and preceded the alanine transaminase (ALT) peak by 1 day. AlphaGST levels then steadily declined, reaching baseline by day 6, plateauing until day 8. After the initial peak, alphaGST still correlated well with the ALT (median correlation coefficient, 0.6; IQ range, 0.45-0.77) and with bilirubin concentration (median correlation coefficient, 0.47; IQ range, 0.14-0.6). There was no significant difference in alphaGST levels between those with rejection compared with other causes of hepatic dysfunction. The sensitivity and specificity of alphaGST for diagnosing acute rejection was 63.1% and 38.8%, respectively, compared with 97.4% and 16.7% for ALT. In 14 of the 16 patients treated for moderate or severe rejection, the improvement in the histological score of rejection was not associated with a consistent change in the alphaGST.

CONCLUSIONS

AlphaGST is not more useful than ALT in diagnosing rejection or determining response to treatment, but is a sensitive marker of liver injury.

Patterns of leukocyte chemotaxis to bile after liver transplantation

The role of chemotactic factors in the recruitment of leukocytes to human liver allografts was assessed by studying the effect of bile from transplant recipients on the chemotaxis of cells from normal subjects. Bile samples taken 2-3 days before clinical rejection were more chemotactic for lymphocytes than samples taken during rejection (p less than 0.01), during stable graft function (p less than 0.001), and from nontransplant patients (p less than 0.007). During clinical rejection there was an increase in bile chemotactic activity for both monocytes and neutrophils compared with samples from stable patients (monocytes: p less than 0.001; neutrophils: p less than 0.001) and nontransplant patients (monocytes: p less than 0.001; neutrophils: p less than 0.001). In serial studies chemotactic activity for lymphocytes reached a peak 1-3 days before the onset of clinical rejection, whereas maximum chemotactic activity for monocytes and neutrophils occurred at the time of rejection, when lymphocyte chemotaxis was decreasing. These results suggest that chemotaxis may be important in the recruitment of inflammatory cells to liver allografts and that chemotactic factors for lymphocytes, which appear in bile before clinical rejection, may be critical in the pathogenesis of rejection.

Evaluation of immune status in pediatric recipients of hepatic orthografts

Survival in children following hepatic transplantation is better than in adults. We evaluated the immunologic status of both pediatric and adult patients prior to and following transplantation, to determine if there were differences in immunologic status that might contribute to this phenomenon. Studies included determination of mononuclear cell subsets, including T cells, T helper cells, T suppressor cells, and monocytes. In addition, we evaluated immune function by studying in vitro immunoglobulin (Ig) synthesis. Following transplantation, the T8 (cytotoxic/suppressor) cells in pediatric patients did not decline, whereas in adults they did (P less than .05). In vitro Ig synthesis in both adult and pediatric patients declined following transplantation. By 4 weeks, the adult group had begun to recover, whereas in the pediatric group there was still significant suppression (P less than .05). These studies suggest that there is decreased immune function in children who are recipients of hepatic allografts. Such findings could contribute to better outcome of hepatic allografting in children.