High variation of individual soluble serum CD30 levels of pre-transplantation patients: sCD30 a feasible marker for prediction of kidney allograft rejection?

BACKGROUND Previous studies have suggested that the pre-transplant levels of the soluble CD30 molecule (sCD30) represent a non-invasive tool which can be used as a biomarker for the prediction of kidney allograft rejections. METHODS In order to evaluate the feasibility of sCD30 for pre-transplantation monitoring the sera of potential kidney recipients (n = 652) were collected four times in a 3 months interval. Serum from healthy blood donors (n = 203) served as controls. The sCD30 concentrations of all samples were determined using a commercially available ELISA. This strategy allowed the detection of possible variations of individual sCD30 levels over time. RESULTS Heterogeneous sCD30 concentrations were found in the samples obtained from individual putative kidney transplant recipients when quarterly measured over 1 year. Total 95% of serum samples obtained from healthy controls exhibited sCD30 values <30 U/ml, whereas most recipients displayed higher serum levels (>30 U/ml). Total 524 patients (80.4%) constantly exhibited serum concentrations of <100 U/ml during the period investigated, whereas 109 patients (16.7%) showed variations by exceeding the proposed 'cut off' of 100 U/ml for one to three times. The frequency of samples exhibiting sCD30 values >100 U/ml was significantly lower than that previously reported. CONCLUSIONS The high degree of variation does not allow the stratification of patients into high and low immunological risk groups based on a single sCD30 value > 100 U/ml. Due to the heterogeneity of sCD30 levels during time course and the high values of SD, its implementation as a pre-transplant marker cannot be justified to generate special provisions for the organ allocation to patients with single sCD30 values > 100 U/ml.