Expression of alpha 2-macroglobulin receptor low density lipoprotein receptor-related protein on surfaces of tumour cells: A study using flow cytometry

alpha 2-Macroglobulin receptor/low density lipoprotein receptor-related protein (alpha 2 MR/LRP) is a multifunctional cell surface receptor that binds and endocytoses several structurally and functionally distinct ligands. Very little is known about the expression and function of alpha 2 MR/LRP in tumour cells. The aim of this study was to quantify the number of alpha 2 MR/LRP on surfaces of human tumour cells by flow cytometry. Using human alpha 2 MR/LRP monoclonal antibody 8G1, human peripheral blood lymphocytes (negative control cells), monocytes (positive control cells), human neonatal foreskin fibroblast cells (NFF) (positive control cells), three human breast cancer cell lines (BT-20, T-47D, and MCF-7), two human ovarian tumour cell lines (JAM, and CI80-13S), and five human melanomas (MM418c1, MM253c1, A2058, MM138, MM370) were indirectly labelled with goat anti-mouse IgFITC. The fluorescent signals of stained cells were measured by flow cytometry. Using Quantum Simply Cellular bead standards, the number of alpha 2 MR/LRP binding sites per cell was assessed. The flow cytometric method to quantify of alpha 2 MR/LRP described here is simple and reliable. All the human tumour cell lines so far examined express alpha 2MR/LRP at different levels from similar to 300 to similar to 10000 sites per cell. (C) 1997 Elsevier Science Ireland Ltd.