Objective

To identify and characterize estrogen receptor (ER) transcripts expressed in immune cells of patients with systemic lupus erythematosus (SLE) and healthy donors.

Methods

Peripheral blood monocytes and T cells were prepared from patients with SLE (n= 6) and healthy donors (n= 8). T cells were separated into CD4 and CD8. Some monocytes and T cells were stimulated with estradiol, PMA, and ionomycin. Epstein-Barr virus-transformed B cell lines (n= 7) and B cell hybridomas (n= 2) established from patients with SLE and a healthy individual were used as a B cell source. These cells were examined for ER mRNA by reverse transcription nested polymerase chain reaction. Amplified cDNA were sequenced by standard methods.

Results

In all cells tested, ER mRNA was expressed without prior in vitro stimulation. Partial sequences from exons 1-8 were nearly identical to the published sequence of the human ER mRNA. There were no notable differences in the ER transcripts between patients and healthy controls. Variant receptor transcripts lacking exon 5 or exon 7, which encodes the hormone binding domain, were identified in the majority of the cells. Precise deletion of the exons suggests that they are alternatively spliced transcripts. Whether the detected transcripts are translated into functional receptor proteins remains to be determined. In vitro stimulation did not affect ER mRNA expression. The presence of variants did not correlate with disease activity or medication.

Conclusion

Monocytes, T cells, and B cells in patients express transcripts of the normal wild type ER and the hormone binding domain variants in vivo.