Characterization of low density lipoprotein receptors in freshly isolated leukemic guinea pig lymphocytes (L2C).

The present study shows that L2C leukemic guinea pig lymphocytes have 10 times as many low density lipoprotein (LDL) receptors per cell as normal lymphocytes. The affinity of these receptors is higher for guinea pig LDL than for human LDL. In contrast to normal cells, in which the degradation of the receptor-bound LDL is quite efficient, the leukemic cells only degraded a small fraction of these same receptor-bound LDL. Thus, the internalization index was nearly 4 times higher in the normal cells than in the leukemic cells. In L2C cells, cholesterol homeostasis derived 38% of its cholesterol input from receptor-mediated degradation of LDL and 62% from cholesterol synthesis, whereas in normal cells, these fractions were 97% and 3% respectively.