Regulation of Fc epsilonRI expression on human monocytic cells by ligand and IL-4.
BACKGROUND
The Fc epsilonRI subunit composition and kinetic of expression differ between antigen-presenting cells and mast cells. Up to now, there has been no human in vitro model available that mimics the characteristics on monocytes.


OBJECTIVE
The characterization of a natural human monocytic cell line (THP1), which expresses Fc epsilonRI, and the comparison to primary human monocytes and other monocytic cell lines, which only express Fc epsilonRI after transfection with the human Fc epsilonRI alpha-chain gene.


METHODS
Surface receptor expression was characterized by flow cytometry, the human Fc epsilonRI alpha-chain gene was introduced by electroporation, and induction of Fc epsilonRI alpha-chain message was detected by semiquantitative RT PCR.


RESULTS
Here we show that the parental human cell line THP1, but none of the other cell lines tested, displays surface Fc epsilonRI in response to IL-4 or incubation with receptor ligand (IgE, antibody). Transfection of Fc epsilonRI alpha-chain resulted in receptor expression on all cell lines, all of which increased surface Fc epsilonRI in the presence of IgE. Only the THP1-alpha transfectant, however, further increased receptor levels in response to IL-4, resulting from mRNA induction for the Fc epsilonRI-alpha, but not the beta- or gamma-subunit.


CONCLUSIONS
Based on THP1, U937 and HL60 and their alpha-chain transfectants we present a model system for the study of Fc epsilonRI regulation and signalling on human cells. THP1 in particular, due to its responsiveness to both ligand and IL-4, even without prior manipulation, is ideally suited to address questions on Fc epsilonRI modulation in an 'allergic environment'.
Reischl
I G
IG
Novartis Research Institute, Department of Immunology, Brunner Street 59, A-1235 Vienna, Austria.
Dubois
G R
GR
Peiritsch
S
S
Brown
K S
KS
Wheat
L
L
Woisetschläger
M
M
Mudde
G C
GC
D018274:Electroporation; D005434:Flow Cytometry; D018922:HL-60 Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007073:Immunoglobulin E / Q000494:pharmacology*; D015847:Interleukin-4 / Q000494:pharmacology*; D008024:Ligands; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D017455:Receptors, IgE / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D020298:U937 Cells / Q000187:drug effects / Q000378:metabolism
D008024:Ligands; D012333:RNA, Messenger; D017455:Receptors, IgE; D015847:Interleukin-4; D007073:Immunoglobulin E