[LDL receptor determination in mononuclear blood cells]

Area of Science:

• Biochemistry
• Molecular Biology
• Clinical Chemistry

Context:

• The Goldstein and Brown method using 125I-LDL is the reference standard for quantifying LDL-receptor functions.
• Assessing LDL degradation in mononuclear blood cells (lymphocytes and monocytes) is crucial for understanding receptor activity.
• Radioactive labeling of LDL is a critical and sensitive step in the assay procedure.

Purpose:

• To report on the experiences and challenges of assaying LDL degradation in mononuclear blood cells.
• To discuss quality criteria for the radioactive labeling of LDL.
• To evaluate the utility of the LDL-receptor assay in diagnosing heterozygous familial hypercholesterolemia.

Summary:

• The study details the LDL-receptor activity assay, specifically LDL degradation in mononuclear blood cells, using the 125I-LDL method.
• Key challenges include the radioactive labeling of LDL and the limited standardization of the assay.
• Results from patients with heterozygous familial hypercholesterolemia indicate the necessity of comparing patient data against concurrently tested normal individuals due to lot-to-lot variability.

Impact:

• Highlights the importance of rigorous quality control in radioactive labeling for LDL-receptor assays.
• Underscores the need for comparative analysis between patients and normal subjects due to assay standardization limitations.
• Reinforces the clinical utility of the LDL-receptor assay primarily for genetic counseling in suspected familial hypercholesterolemia cases.