Serum levels of soluble interleukin-2 receptor, C-reactive protein, neopterin, myoglobin and light chains of cardiac myosin fail to correlate with the occurrence of rejection in long-term renal and heart transplant patients

Even in the late phase following heart and kidney transplantation (> 1 year post-Tx) there are still acute interstitial rejections which are generally verified by invasive diagnosis (biopsy). We raised the question whether serum parameters pointing to immunologic activation (neopterin, C-reactive protein [CRP], soluble interleukin-2 receptor [sIL-2R]), which have been described to be diagnostically relevant for an "early" rejection (during the first months post Tx), are also suitable for noninvasive diagnosis of "late" rejections of heart and kidney transplants. In addition, myoglobin and light chains of cardiac myosin (myosin L-chains), being markers pointing to an ischemically injured myocardium, have been quantified in the serum of heart transplant recipients. 161 heart allograft recipients (13 with moderate to severe rejection, 34 with mild rejection) and 20 kidney allograft recipients (10 with acute rejection) were investigated in this study. In all cases, the diagnosis has been confirmed by the histology of transplant biopsy. More than 300 sera have been investigated. Although about one third of the patients had an increased sIL-2R level and more than 80% of the heart transplant patients increased myoglobin and myosin L-chain levels (10% even strongly increased), we were not able to detect a significant relation between the increase in serum parameters and the occurrence and degree of rejection in long-term transplant patients. We therefore concluded that the serum parameters tested are not suitable for non-invasive rejection diagnosis in the late phase after transplantation. Long-term follow-up studies will show whether increased myoglobin and myosin L-chain levels in heart transplant recipients might be considered as an early diagnostic marker for coronary artery disease.