Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Receptor-specific uptake and degradation of acetylated oxidized and native LDL in the human monocytic Mono Mac 6sr cell line

Abstract

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 [125I]-acetylated (acetyl-) and [125I]-oxidized (ox-) low-density-lipoprotein (LDL) via receptor-specific pathways. Degradation of [125I]-acetyl-LDL was saturable at a ligand concentration of approximately 10 micrograms/ml. Fucoidan and polyinosinic acid efficiently blocked [125I]-acetyl-LDL cell association, while polycytidylic acid and an excess concentration of native LDL were ineffective, suggesting the presence of scavenger receptors similar to those found in human monocyte-derived macrophages. In contrast to the Mono Mac 6sr cell line, the original Mono Mac 6 cells were scavenger receptor negative. Both cell lines specifically degraded native LDL. We conclude that Mono Mac 6sr cells constitutively take up and process modified as well as native lipoproteins and therefore could be used as a cell model in studies of human monocyte lipoprotein metabolism.