[Expression of interleukin-6 and its receptors in peripheral blood of patients with systemic lupus erythematosus].
OBJECTIVE
To investigate the level of interleukin-6 (IL-6) and soluble-IL-6 receptor (sIL-6R) in serum of patients with systemic lupus erythematosus (SLE) and its correlation with disease activity and to explore IL-6 signal transduction pathways in SLE patients.


METHODS
By using MTT colorimetry and ELISA, the levels of IL-6 and sIL-6R in serum from 16 patients with SLE (9 active, 7 inactive), 17 with active rheumatoid arthritis (RA) and 29 controls were measured. The expressions of acute phase reaction factor (APRF) in peripheral blood mononuclear cells (PBMCs) were also detected by using electrophoresis mobility shift assays (EMSA) after the PBMCs were isolated and then stimulated by IL-6.


RESULTS
Serum IL-6 and sIL-6R levels in active SLE patients were significantly higher than those in normal controls (P < 0.01), but were significantly lower than those in active RA patients (P < 0.01). Serum IL-6 rather than sIL-6R level in active SLE patients was significantly higher than that in inactive ones (P < 0.01). Serum IL-6 was correlated positively with the anti-dsDNA antibody (r = 0.658, P < 0.01), but not with CRP (r = 0.041, P > 0.05). There were no expression of APRF in PMNC from SLE patients and 8 normal controls, whereas PMNC from 11 RA patients expressed APRF activity (11/17).


CONCLUSIONS
The level of IL-6 is a useful parameter for monitoring disease activity of SLE. In active SLE, no significant elevation of serum sIL-6R and no expression of APRF in PMBCs may be responsible for mild CRP elevation.
Liu
X
X
Department of Rheumatology, General Hospital of PLA, Beijing 100853.
Lin
H
H
Yuan
G
G
Huang
F
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D003124:Colorimetry; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000097:blood / Q000502:physiology; D008180:Lupus Erythematosus, Systemic / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D019947:Receptors, Interleukin-6 / Q000096:biosynthesis* / Q000097:blood; D015398:Signal Transduction
D015850:Interleukin-6; D019947:Receptors, Interleukin-6