The value of the Luminex magnetic bead immunoassay in detecting serum MBL in kidney transplantation patients

Objective To evaluate the performance of serum mannose-binding lectin(MBL) using Luminex magnetic bead immunoassay, and further clarify the value of serum MBL in the patients of renal transplantation. Methods A retrospective study based on 110 patients who had underwent renal transplantation in Peking University First Hospital from February 2012 to May 2016 was carried out, and 50 healthy persons were selected as controls. The precision, linearity and correlation of serum MBL were evaluated using Luminex magnetic bead immunoassay, and compared with the traditional ELISA method. The frequency of infection and clinical rejection after transplantation was evaluated according to serum pre-transplant MBL level before transplantation, based on the Luminex method. Statistics analysis was implemented with SPSS 19.0 and MedCalc 12.7.0 software. Results The repeatability precision and inter-day precision were less than 7.15% and 8.44% respectively, and linear range was 0.05-11 233.00 μg/L detected by Luminex immunoassay.The linear range of MBL detected by ELISA was 3.20-4 202.70 μg/L. The Luminex method had a wider range compared with ELISA. Correlation analysis showed that the regression equation was Y=1.248 6X+231.81, and the correlation coefficient was r=0.978 (P<0.01). Bland-Altman analysis showed that the average deviation percentage was 37.4% (95%CI 33.7%-41.1%).The median (quartile) of pre-transplant serum MBL was 4 164.00 (2 124.00, 7 064.50) μg/L. Patients with a serum MBL<4 164.00 μg/L and MBL≥4 164.00 μg/L were defined as low-and high-level group, respectively. The incidence of infection among the low-level group and high-level group was 47.4% (27/57) and 28.3% (15/53)respectively, which showed a statistical difference(χ2=4.230, P<0.05). The incidence of rejection among the low-level group and high-level group was 43.9% (25/57) and 20.8% (11/53)respectively, which also showed a statistical difference(χ2=6.659, P<0.05). Conclusions The Luminex magnetic bead immunoassay has a wider linearity compared with ELISA in detecting serum MBL. Additionally, serum pre-transplant MBL level has a good predictive value for the infection and rejection reaction after transplantation. Key words: Kidney transplantation; Mannose-binding lectin; Immunoassay; Enzyme-linked immunosorbent assay