Objective: To induce the expression of human soluble Fc epsilon receptor I alpha (sFcepsilonR1α) in a prokaryotic expression vector, purify the recombinant human sFcepsilonR1α protein, detect its binding affinity for human serum IgE antibodies and detect the levels of sFcepsilonR1α, sFcepsilonR1α-IgE and FcepsilonR1α antibodies.
Methods: The FcepsilonR1α extracellular region gene was amplified using nested polymerase chain reaction (PCR) and was expressed in a prokaryotic expression vector pET-sFcepsilonR1α using recombinant DNA technology under optimal conditions. The human sFcepsilonR1α protein was purified using iminodiacetic acid (IDA) His binding resin and identified using Western blotting. The affinity between the recombinant human sFcepsilonR1α and serum IgE antibodies and the levels of total sFcepsilonR1α, sFcepsilonR1α-IgE and FcepsilonR1α antibodies were measured using ELISA.
Results: The amplified gene corresponding to the extracellular region FcepsilonR1α was approximately 600 bp. PCR, double enzyme digestion and sequencing confirmed the correct sequence of the expression vector pET-sFcepsilonR1α. After human sFcepsilonR1α protein was induced in the expression vector pET-FcepsilonR1α and purified, Western blotting showed that its relative molecular mass (Mr) was approximately 42,000. ELISA revealed that the human sFcepsilonR1α bound with a high affinity to serum IgE, and the lower levels of total sFcepsilonR1α and sFcepsilonR1α-IgE and higher levels of serum anti-FcepsilonR1α antibodies in the patients with allergic rhinitis than in the normal subjects.
Conclusion: We successfully synthesized human sFcepsilonR1α which had a strong binding affinity for human serum IgE. The higher levels of serum anti-FcepsilonR1α antibodies in the patients with allergic rhinitis than the normal subjects.