Renal allograft infiltrate in the absence of rejection

The presence of a mononuclear infiltrate in a renal allograft biopsy does not per se prove that clinically important rejection, or drug toxicity, is present. The inhomogeneity of the infiltrate, in terms of number of cells and of proportion of different cell types, underscores the problem of sampling error if biopsies are too small. An intense infiltrate accompanied by vasculitis correlates well with clinical rejection. These preliminary data do not indicate that the percentage of T cells or the helper/suppressor ratio in the infiltrate are useful in distinguishing rejection. A more valid interpretation of biopsies may be achieved if they are performed as a routine at two or three intervals during the first six weeks postoperatively, as well as at the time of suspected rejection.