Background: Percutaneous biopsy is the method of choice for differential diagnosis of renal allograft dysfunction, although it is not risk-free. The use of less aggressive methods for diagnosis should limit the need for percutaneous biopsy to some specific situations.
Methods: We analysed 42 fine-needle aspiration biopsies from 36 kidney allograft recipients immunosuppressed with quadruple sequential therapy who suffered renal allograft dysfunction. Seven cases with stable renal function were used as controls and included as non-rejection cases in the analysis. In all aspirates the Corrected Increment was calculated and an immunocytochemical analysis of renal tubular cells with the monoclonal antibodies HLA-DR and ICAM-1 was performed.
Results: The Corrected Increment was increased in 13 out of 18 acute rejection cases and in one out of 31 non-rejection cases. HLA-DR expression was found in more than 30% of tubular cells from the aspirates in 16 out of 18 acute rejection cases and in eight out of 31 cases without rejection (P < 0.001). ICAM-1 expression was detected in more than 30% of tubular cells in 14 out of 18 cases with acute rejection, and in four out of 31 cases without acute rejection (P < 0.001). Interestingly, all acute vascular rejection cases (n = 6), and six out of 12 acute cellular rejection cases expressed both, HLA-DR and ICAM-1, in more than 30% of tubular cells. On the other hand, none of the non-rejection allograft dysfunctions or control samples showed more than 30% of tubular cells immunostained with both HLA-DR and ICAM-1 antibodies.
Conclusions: The immunocytochemical analysis of HLA-DR and ICAM-1 on renal tubular cells taken by fine-needle aspiration biopsy, allows the diagnosis of acute cellular rejection and acute vascular rejection even when the Corrected Increment is not increased. Moreover, the risk of a core renal biopsy can be avoided when both tests are negative since an acute rejection is a remote possibility.