Figure 3

M-CSF reversibly stimulates SR-A expression and AcLDL association. (A) Incubation scheme: Cultured resident MPM were incubated (I) without M-CSF; (II) with M-CSF (25 ng/ml) for 24 hrs; (III) with M-CSF (25 ng/ml) for 24 hrs and then in absence of M-CSF for additional 72 hrs; or (IV) with M-CSF (25 ng/ml) for 24 hrs, then in absence of M-CSF for additional 72 hrs, and incubated again with M-CSF (25 ng/ml) for 24 hrs. SR-A expression and function were assessed at the end of incubation (arrows). (B) Following incubations, cell lysates were prepared and SR-A protein was quantified by immunoblotting. (C) Following incubations, surface SR-A (top) and SR-A-mediated uptake (bottom) were quantified by flow cytometry using Alexa⁶⁴⁷-conjugated 2F8 mAb and Alexa⁴⁸⁸-AcLDL as described in Materials and Methods. The results of representative experiments are shown. (D) The mean ± SEM of at least three separate flow cytometry experiments are shown.