Binding of antihuman globulin by exfoliated renal tubular cells following kidney transplantation.

Exfoliated renal tubular epithelial cells (RTCs) from kidney allograft recipients may bind antibody against human globular proteins. Urine from sixty consecutive transplant recipients was studied in the first month following transplantation to relate this binding to the clinical course and rejection. The spun, washed sediment was incubated with fluoresceinated goat antihuman globulin and examined under light and fluorescent microscopy for fluoresceinated RTCs. Of 28 patients who were never positive, 27 manifested no clinical rejection episodes. Of 22 total rejection episodes, 21 were preceded by the appearance of fluorescent RTCs. Five patients in this group did not revert to negative in this test, and all went on to loss of graft from acute rejection. Of 46 patients who were discharged from the hospital with negative RTCs, only four were readmitted within one month for treatment of rejection. In contrast, of the 11 patients who were positive at the time of discharge, 10 were readmitted in the first month. Graft survival was only 55% (6/11) in this latter group as compared with 91% (42/46) in the former. There were 11 patients with transiently positive tests who did not warrant a clinical diagnosis of rejection. In no case of acute tubular necrosis (ATN) alone or in obstructive uropathy was the assay positive. However, in some cases, in which the ATN merged imperceptibly into rejection, the RTCs started to fluoresce well in advance of the clinical suspicion of rejection. Information obtained from this examination may be used to assess the cause of renal failure in the early posttransplant period and to differentiate rejection from ATN and obstruction. This phenomenon of fluorescent RTCs may be an early manifestation of an immunological change occurring in a cell that is targeted by the host for rejection.