Preparation of the primary reference material preparations for Treponema pallidum IgM and IgG

Abstract

Objective To develop primary reference materials for TP immunoglobulin M and G detection in China and improve internal quality control,evaluation of qualitative test performance,proficiency testing and reference traceability of the clinical laboratories.Methods Two samples with TP antibodies positive were diluted into 1 IU/ml ( 200851 ) and 20 mIU/ml ( 200852 ) by negative human plasma.After dilution,subpackage and vacuum drying,the stability study at different temperatures and times ( -70,-20,4,37 ℃,and room temperature for3 day,1,2,3,and4 weeks) was carried out.Twenty subpackages were sampled randomly for uniformity study.The results were analyzed by analysis of variance (F test).ELISA,TPPA,TRUST and western blotting were used for quantification with international standard (NIBSC code:05/132 and 05/122 ) as calibrator respectively.Then uncertainties were analyzed.Results The results of statistical analysis showed that the preparations were completely stable at different temperature conditions for different periods (4 weeks at 37 ℃,8 weeks room temperature,16 weeks at 2 - 8 ℃ and 32 weeks at - 20 ℃ ).The analysis of variance demonstrated that the F values of 200851and 200852 were less than F0.01(1.38) =7.35.Therefore,the uniformity of preparation was good.The results of different methods (ELISA,WB,TRUST and TPPA) showed no significant difference.The titers of the preparations were( 1.27 ± 0.26 ) IU/ml and ( 19.4 ± 4.4 ) mIU/ml respectively.Conclusions The stability and uniformity of the preparations meet the requirements of national first reference standards.The preparations could be used as the reference material for Treponema pallidum IgG and IgM assay in China. Key words: Treponema pallidum; Immunoglobulin G; Immunoglobulin M; Reference standards