Examination of serum amyloid A protein in kidney transplant patients--comparison of serum amyloid A and C-reactive protein for monitoring the occurrence of renal-allograft-related complications.

Serum amyloid A (SAA) is an inflammation-reactive protein, like C-reactive protein (CRP). In this study, we examined SAA levels in the sera of kidney transplant patients with acute rejection (N = 12), chronic rejection (N = 60) and cytomegalovirus (CMV) infection complications and compared them with serum CRP levels in terms of sensitivity and reactivity. The SAA and CRP showed almost similar kinetics in 10 patients within 2 months of kidney transplantation. However, in 2 patients SAA responded more sensitively to CMV infection and acute rejection. SAA increased significantly 10-fold relative to its baseline levels. The SAA levels also increased along with those of serum creatinine levels. Our experiments clearly showed that SAA and CRP responded sensitively to several stimuli with elevated serum levels including surgical trauma, acute allograft rejection and infection. However, the reactivity and sensitivity of SAA was clearly higher than those of CRP in patients with viral infections, on steroid therapy and undergoing chronic allograft rejection, suggesting that monitoring SAA levels provides more useful information than monitoring CRP.