High affinity IgE-Fc receptor α and γ subunit interactions

To explore the relationships between the subunits (α, β and γ) of the high affinity IgE receptor (Fc&RI) and its ability to mediate transmembrane signaling.

Experimental study.

Department of Molecular Biology and Biotechnology, University of Sheffield, UK, from 2008 to 2009.

The approach employed was to create a chimera (human αγγ) using the extracellular (EC) domain of the human high affinity IgE receptor. The alpha subunit (huFc&RIα) of IgE receptor was spliced onto the rodent gamma TM and cytoplasmic domain (CD). This was transfected into the Rat Basophilic Leukemia cell line in order to assess the possibility of selectively activating cells transfected with this single pass construct for antigen induced mediator release.

The RBLs cell lines transfected with the huFc&RIα/γ/γ cDNA constructs were assessed for the cell surface expression of the huFc&RIα subunit and the response to the antigenic stimulus by looking for degranulation and intracellular Ca2+ mobilisation. The results obtained showed the absence of huFc&RIα subunit expression on the surface of transfected cells as seen by flowcytometric studies, β-hexosaminidase assays and intracellular calcium mobilisation studies.

In the present study the grounds for non-expression of huFc&RIα/γ/γ cDNA remains elusive but may be due to the fact that the human-rodent chimeric receptors are assembled differently than the endogenous rodent receptors as seen in study in which COS 7 cells were transfected with human/rat chimeric complexes.