Observations on the Passage of Apoproteins from Plasma Lipoproteins into Peripheral Lymph in Two Men

1. The passage of radioactive apolipoproteins into lymph draining the foot was investigated in two men, each given a single intravenous injection of low-density lipoprotein containing ¹³¹I-labelled apoprotein B and of very-low-density lipoprotein containing ¹²⁵I-labelled apoprotein A and apoprotein C.

2. Protein-bound ¹²⁵I and ¹³¹I appeared in the lymph of both subjects. Immunoelectrophoresis of lymph lipoproteins against anti-(high-density lipoprotein) and anti-(low-density lipoprotein) showed the presence of apo-high-density lipoprotein and apo-low-density lipoprotein with faster mobilities than plasma high-density and low-density lipoprotein respectively. Most of the protein-bound ¹³¹I in lymph was recovered in the precipitin line formed by the apoprotein B-containing lipoprotein after immunoelectrophoresis. Polyacrylamide gel electrophoresis of the lymph lipoprotein fraction showed the presence of ¹²⁵I-containing bands with mobilities similar to those of the apoprotein A of high-density lipoprotein and of three of the fast-moving C apoproteins.

3. These results suggest that most, if not all, of the apoproteins of plasma lipoproteins reach the interstitial fluids and that some lipoproteins undergo modification during their passage into peripheral lymph.