Molecular cloning of a soluble form of the granulocyte-macrophage colony-stimulating factor receptor alpha chain from a myelomonocytic cell line. Expression, biologic activity, and preliminary analysis of transcript distribution.
OBJECTIVE
To analyze the molecular and functional characteristics of a soluble form of the granulocyte-macrophage colony-stimulating factor receptor alpha chain (sGM-CSFR alpha), and analyze transcript expression in immune cells and the cellular constituents of rheumatoid arthritis synovial tissue.


METHODS
We amplified, cloned, and expressed the sGM-CSFR alpha and transmembrane form of the receptor (tmGM-CSFR alpha) from complementary DNA derived from a human myelomonocytic cell line. Competitive polymerase chain reaction assays were developed to determine the absolute and relative amounts of tmGM-CSFR alpha versus sGM-CSFR alpha message synthesized by various cell lines and tissues.


RESULTS
sGM-CSFR alpha transcripts were detected in bone marrow, monocyte/macrophages (cultured in GM-CSF), rheumatoid synovial tissue, and rheumatoid synovial tissue T cell lines, and represented the predominant transcript in synovial fibroblasts and osteoarthritis synovial tissue. Levels of expression in monocyte/macrophages and some synovial fibroblast and T cell lines approached those seen in transfected cell lines producing functional sGM-CSFR alpha.


CONCLUSIONS
sGM-CSFR alpha represents a functional antagonist of GM-CSF activity in vitro. Expression of sGM-CSFR alpha in bone marrow, rheumatoid synovial tissue T cells, and synovial fibroblasts suggests an important role in vivo, both in regulating myelopoiesis and in modulating the immune response.
Williams
W V
WV
Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104.
VonFeldt
J M
JM
Rosenbaum
H
H
Ugen
K E
KE
Weiner
D B
DB
D001172:Arthritis, Rheumatoid / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007951:Leukemia, Myeloid; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D013583:Synovial Membrane / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor