LDL receptor determination in mononuclear blood cells

: The determination of the LDL-receptor-activity with 125I-LDL according to Goldstein and Brown is regarded as reference method, because it permits the quantitative measuring of the partial receptor functions binding, internalization and degradation of LDL. The authors inform of their experiences with the assaying of the LDL-degradation in mononuclear blood cells (lymphocytes and monocytes). The most critical step of the method is the radioactive labelling of the LDL. The quality criteria of the labelling are discussed. The results of the receptor activity assays from patients with heterozygous familial hypercholesterolemia demonstrate that it is necessary to assay patients and normal persons for each 125I-LDL-lot and to calculate the data of the patients in relation to the normal persons because of the limited standardization of the method. In the clinical medicine, today the receptor assay is only indicated for the genetic counseling of patients which are suffering possibly from familial hypercholesterolemia.