PHENOTYPIC AND FUNCTIONAL-CHARACTERIZATION OF A NEW HUMAN MACROPHAGE CELL-LINE K1M DEMONSTRATING IMMUNOPHAGOCYTIC ACTIVITY AND SIGNALING THROUGH HLA CLASS-II

A human macrophage line, designated Klm, has been established from per ipheral blood. Klm expresses a number of lineage-specific markers as w ell as a broad array of intercellular adhesion molecules. In particula r, Klm expresses high levels of human leucocyte antigen (HLA) class I and class II. In response to ligation of HLA class II (HLA-DR), but no t in response to ligation of HLA class I, Klm forms tighter homotypic aggregates and develops a striking 'stellate' culture phenotype. Klm a lso expresses Fc receptors for immunoglobulin G (IgG) (CD64, CD32, and CD16) and can be shown to phagocytose polystyrene latex beads, as wel l as neuroblastoma cells in the presence of tumour-specific monoclonal antibody (mAb). The Klm cell line should therefore prove useful for s tudying both signalling through macrophage HLA class II and immunophag ocytosis.