Immunoassay of Plasma Low-Density Lipoproteins

This 1970 paper described an immunoassay method for measuring the protein component of plasma low-density lipoprotein — one of the earliest efforts to quantify LDL by its protein content rather than by cholesterol concentration.

The assay revealed that LDL protein was elevated in familial hyperbetalipoproteinemia and endogenous hyperlipemia, and lower in fat-induced and mixed hyperlipidemia. This differentiation among hyperlipidemic syndromes by protein measurement anticipated what would eventually become the apolipoprotein B field: the recognition that the protein component of LDL varies meaningfully across disease states and conveys distinct risk information.

The historical significance is substantial. This work foreshadowed — by decades — the recognition that LDL particle number (measured by apoB) is clinically superior to LDL cholesterol concentration for identifying atherogenic risk. What Lees was measuring in 1970 was, in essence, apoB — though the concept and clinical application would require decades more to develop.

We rate the evidence limited by contemporary standards. A foundational historical paper that anticipated the apoB field; its clinical relevance today is primarily as a marker of intellectual lineage rather than a source of actionable data.