P. B. Carroll

The thymus in adults infected with the HIV-1 is generally thought to be inactive, both because of age-related involution and viral destruction. We have revisited the question of thymic function in adults, using chest-computed tomography (CT) to measure thymic tissue in HIV-1-seropositive (n = 99) or HIV-1-seronegative (n = 32) subjects, and correlating these results with the level of circulating CD4(+) and CD8(+) T cells that are phenotypically described as naive thymic emigrants. Abundant thymic tissue was detectable in many (47/99) HIV-1-seropositive adults, aged 20-59. Independent of age, radiographic demonstration of thymic tissue was significantly associated with both a higher CD4(+) T cell count (P = 0.02) and a higher percentage and absolute number of circulating naive (CD45RA+CD62L+) CD4(+) T cells (P < 0.04). The prevalence of an abundant thymus was especially high in younger HIV-1-seropositive adults (</= 39 yr) with CD4 counts in the range 300-500 cells/microl and in older subjects (> 40 yr) regardless of CD4 count (P = 0.03). These studies suggest that the thymus is functional in some but not all adults with HIV-1 disease.

Autoimmune chronic active hepatitis (CAH-A) is a chronic liver disease of unknown etiology that is believed to have an autoimmune pathogenesis. The disease is slowly progressive until hepatic failure and portal hypertension develop and either death or liver transplantation occur. Currently, the only widely recognized therapy is the administration of glucocorticoids, which have both anti-inflammatory and immunosuppressive actions. Many patients cannot tolerate such therapy because of the psychiatric, osteoporotic, and weight-enhancing actions of steroids. Tacrolimus (FK 506) is a new macrolide antibiotic that has an immunosuppressive activity that is estimated to be 10-200 times greater than that of cyclosporine. Because of its greater immunosuppressive activity, we have used it in the treatment of 21 patients with autoimmune chronic active hepatitis. Before each subject was treated, a liver biopsy and a panel of hematological, serological, and biochemical parameters were assessed. The Tacrolimus was administered orally at 12-h intervals, and the dose was controlled by monitoring plasma FK trough levels. After 3 months of therapy at an oral dose of 3 mg twice a day, having achieved a median blood level of 0.5 ng/ml, the serum ALT level was reduced by 80%, and the AST level was reduced by 70%. Modest change in the white blood cell count and platelet count were noted. The median BUN level increased from a level of 12 to 18 mg/dl, and the serum creatinine increased from 0.9 to 1.3 mg/dl. These preliminary data demonstrate that: 1) Tacrolimus can be used to successfully treat CAH-A; 2) the response of CAH-A to Tacrolimus treatment is rapid and sustained; and 3) a minor increase in the serum BUN and creatinine levels occurs as a consequence of Tacrolimus treatment. It is anticipated that with continued treatment for periods of 1-2 yr, the natural history of CAH-A will be changed such that hepatic failure and the requirement for liver transplantation may be averted.

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disease of the liver that is characterized by progressive cholestasis and the development of secondary biliary cirrhosis. There is no widely recognized therapy for this disease, although anti-inflammatory agents (steroids), immunosuppressive agents (methotrexate), anti-fibrotics (colchicine), and choleretic agents (ursodeoxycholic acid) have been used in various small series. In the present study, Tacrolimus (FK 506), a new and powerful immunosuppressive macrolide antibiotic, has been used to treat 10 patients with PSC. Each subject had a liver biopsy, ERCP with visualization of the intra- and extrahepatic biliary tree, and a panel of hematological, serological, and biochemical laboratory tests before the initiation of the FK 506 therapy. The FK 506 was administered orally at 12-h intervals and was monitored by serial plasma FK 506 trough levels. After 360 days of treatment, the median serum bilirubin level was reduced by 75%, and the serum alkaline phosphatase was reduced by 70%. Moreover, the serum ALT and AST levels were reduced by 80 and 86%, respectively. No change in the serum level of BUN and creatinine levels occurred as a consequence of the FK 506 treatment. These data demonstrate that: 1) FK 506 can be used to treat PSC; 2) the response to FK 506 by patients with PSC is rapid; and, 3) no adverse effect on the serum BUN and creatinine levels was observed. It is anticipated that FK 506 will become an important agent for the treatment of patients with PSC because of its powerful immunosuppressive activity.

Early reports on the use of FK 506 after kidney transplantation emphasized the ability to stop prednisone in a significant percentage of successfully transplanted patients.1,2 In addition, there was a relative freedom from antihypertensive agents and a tendency toward low serum cholesterol levels. This report will summarize our experience to date with FK 506 in renal transplantation and will compare the results with a nearly concurrent group of patients treated with cyclosporine (CyA)-based immunosuppression.