Measurement of human plasma phospholipid transfer protein by sandwich ELISA

Background: Plasma phospholipid transfer protein (PLTP) plays a central rol e in the remodeling of HDLs. Reliable and accurate methods for assaying PLT P concentration are required. Methods: A sandwich ELISA for PLTP has been developed, using two monoclonal antibodies against recombinant human PLTP (rhPLTP) expressed in Chinese ha mster ovary cells. The ELISA allows for the quantification of PLTP in the r ange 0.625-15.0 ng/assay (1.2-30.0 mg/L). Intra- and interassay CVs were <3 .0% and <4.2% respectively. The assay was used to quantify plasma PLTP conc entrations in 132 Japanese subjects (75 males and 57 females). Results: PLTP concentrations were 12.0 +/- 3.0 mg/L (mean +/- SD; range, 4. 9-20.5 mg/L). No sex difference was observed. Plasma PLTP concentration was positively correlated with HDL-cholesterol (v = 0.72; P <0.001), apolipopr otein (apo) A-I (r = 0.62; P <0.001) and HDL2-cholesterol (r = 0.72; P <0.0 01), and was negatively correlated with triacylglycerol (r = -0.45; P <0.00 1). There was no correlation with plasma apo A-II. These results agree with other evidence that plasma PLTP is associated with large apo A-I-containin g lipoproteins. There was no correlation (r = -0.01) between plasma PLTP an d plasma phosphatidylcholine transfer activity (range, 3.5-10.5 mu mol.mL(- 1).h(-1)), suggesting that PLTP may exist in active and inactive forms. Conclusion: This new ELISA will be of value for further studies of PLTP in health and disease. (C) 2000 American Association for Clinical Chemistry.