Expression of interleukin-12 and its signaling molecules in peripheral blood mononuclear cells in systemic lupus erythematosus patients.
OBJECTIVE
To determine the in vitro expression of interleukin-12 (IL-12) and its effect on signal transducers and activators of transcription (STAT) signaling molecules in peripheral blood mononuclear cells (PBMCs) in patients with systemic lupus erythematosus (SLE).


METHODS
Peripheral blood mononuclear cells in 39 patients with definite systemic lupus erythematosus and 11 healthy volunteers were collected. Expression of IL-12 P40mRNA in PBMCs was determined with reverse transcription-polymerase chain reaction (RT-PCR). Quantity of IL-12 protein supernatant was measured by enzyme-linked immunosorbent assay (ELISA). The levels of phosphorylated STAT3 and STAT4 signaling molecules in PBMCs were detected by immunoblot.


RESULTS
Levels of IL-12 protein and mRNA expression in patients with active or inactive SLE were significantly higher than those in controls. Phytohemagglutinin (PHA ) may promote the expression of IL-12. IL-12 alone induced the phosphorylation of STAT3 and STAT4 in PBMCs from patients with SLE, especially in active SLE. However it had no obvious effect on normal PBMCs. Phosphorylated STAT3 and STAT4 might be observed in normal PBMCs treated with IL-12 plus PHA.


CONCLUSIONS
IL-12 is produced aberrantly in patients with SLE. IL-12 might exert its biological role in SLE via the aberrantly phosphorylated STAT3 and STAT4 signaling molecules.
Li
Zhijian
Z
Department of Nephrology, Institute of Nephrology, the First Affiliated Hospital, Sun Yat-Sen University of Medical Sciences, Guangzhou 510080, China. lizhijianlzj@sina.com
Li
Youji
Y
Huang
Linghong
L
Xu
Hanshi
H
Yu
Xueqing
X
Ye
Rengao
R
D000293:Adolescent; D000328:Adult; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D018664:Interleukin-12 / Q000097:blood / Q000235:genetics*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008180:Lupus Erythematosus, Systemic / Q000378:metabolism*; D008875:Middle Aged; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D050796:STAT3 Transcription Factor; D050797:STAT4 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism*
D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050797:STAT4 Transcription Factor; C494090:STAT4 protein, human; D015534:Trans-Activators; D018664:Interleukin-12