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Regulation of FcεRI expression on human monocytic cells by ligand and IL-4

Authors


Reischl NIH, 9000 Rockville Pike, Building 10, Room 9N256, Bethesda, MD 20892–1820, USA

Abstract

Background

The FcεRI 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 FcεRI, and the comparison to primary human monocytes and other monocytic cell lines, which only express FcεRI after transfection with the human FcεRI α-chain gene.

Methods

Surface receptor expression was characterized by flow cytometry, the human FcεRI α-chain gene was introduced by electroporation, and induction of FcεRI α-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 FcεRI in response to IL-4 or incubation with receptor ligand (IgE, antibody). Transfection of FcεRI α-chain resulted in receptor expression on all cell lines, all of which increased surface FcεRI in the presence of IgE. Only the THP1-α transfectant, however, further increased receptor levels in response to IL-4, resulting from mRNA induction for the FcεRI-α, but not the β- or γ-subunit.

Conclusion

Based on THP1, U937 and HL60 and their α-chain transfectants we present a model system for the study of FcεRI 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 FcεRI modulation in an ‘allergic environment’.

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