A modulatory lipoprotein related to cancer cell inhibition

Three fractions of lipoprotein were isolated from sera and ascites of cancer-bearing mice by polyanion precipitation and density centrifugation. The cancer modulatory activity of isolated lipoproteins was estimated by means of trypan blue exclusion and cell potassium content. The activity of one of the isolated lipoprotein fractions was to kill cancer cells in vitro with little effect on normal bone marrow cells. This lipoprotein migrated as one band on agarose electrophoresis. After incubating cancer cells with the lipoprotein, the membrane fluidity of the cancer cells was markedly changed (p less than 0.01). The mechanism of modulation may be related to interaction of lipoprotein with plasma membrane of cancer cells.