Characterization of IgG Fc receptors on CD34 antigen‐expressing cell lines (KG‐1 and KG‐la)

Publisher Website
Google Scholar
Abstract
Although Fc receptors (FcR) on mature blood cells have been extensively studied, there are only limited data on FcR expression in the early haematopoietic progenitor cells. In this study, we used the stem cell antigen (CD34)-expressing cell line (KG-1) and its less differentiated subline (KG-1a) as a model for the study of FcR in the early haematopoietic progenitors. Flow cytometry and immunoprecipitation studies on KG-1 and KG-1 a cells with anti-FcR mAb showed that FcRII is the only FcR expressed on the cell surface. Analysis of the steady-state levels of FcR mRNA in KG-1 and KG-la cells using a quantitative in situ hybridization assay revealed the presence of only FcRII mRNA. On further analysis FcRIIA mRNA but no FcRIIB or FcRIIC transcripts were found in these cells: FcRIIA transcripts with and without the transmem-brane exon were present in approximately equal amounts. These findings are surprisingly similar to those observed previously with FcR in platelets and megakaryocytic cells but different from those found with FcR in cells of other lineages. These data suggest that the FcR transcript distribution pattern observed in the early haematopoietic progenitors (KG-l cells) is retained in later stages of haematopoietic differentiation only in cells of megakaryocytic lineage.