Assays and screens; imaging

An automated fluorescence microscopy method for detecting cell-cell interactions in human peripheral blood mononuclear cells (PBMCs) could be used to screen for immunomodulatory compounds. The method involved automated spinning disc confocal microscopy of PBMCs in a 384-well plate and labeled with cocktails of fluorophore-conjugated antibodies targeting two mononuclear cell types per well, followed by fluorescent imaging analysis to quantify cell-cell contacts between labeled cell types based on the distance between nuclei. Screening of a small molecule library in the assay identified Xalkori crizotinib as a hit that increased the number of major histocompatibility complex (MHC)-dependent interactions between CD11c-positive monocytes and lymphocytes compared with vehicle. In a human colorectal cancer cell line, and primary blasts from a chronic myelogenous leukemia (CML) patient, Xalkori increased levels of MHC class I (MHCI) levels, a marker of antitumor immune response. Next steps could include using the assay to screening libraries of cytokines, chemokines and antibodies...