RECEPTOR-SPECIFIC UPTAKE AND DEGRADATION OF ACETYLATED, OXIDIZED AND NATIVE LDL IN THE HUMAN MONOCYTIC MONO MAC-6SR CELL-LINE

We have identified a subline of the human monocytic cell line Mono Mac 6, termed Mono Mac 6sr. Untreated Mono Mac 6sr took up and degraded [ I-125]acetylated (acetyl-) and [I-125]-oxidized (ox-) low-density-lipo protein (LDL) via receptor-specific pathways. Degradation of [I-125]-a cetyl-LDL was saturable at a ligand concentration of approximately 10 mu g/ml. Fucoidan and polyinosinic acid efficiently blocked [I-125]-ac etyl-LDL cell association, while polycytidylic acid and an excess conc entration of native LDL were ineffective, suggesting the presence of s cavenger receptors similar to those found in human monocyte-derived ma crophages. In contrast to the Mono Mac 6sr cell line, the original Mon o Mac 6 cells were scavenger receptor negative. Both cell lines specif ically degraded native LDL. We conclude that Mono Mac 6sr cells consti tutively take up and process modified as well as native lipoproteins a nd therefore could be used as a cell model in studies of human monocyt e lipoprotein metabolism. (C) 1994 Academic Press, Inc.