Nitric oxide synthase is expressed in the lymphomononuclear cells of synovial fluid in patients with rheumatoid arthritis.
OBJECTIVE
To investigate the expression of inducible nitric oxide synthase (iNOS) in subpopulations of peripheral blood and synovial fluid (SF) leukocytes in patients with rheumatoid arthritis (RA).


METHODS
iNOS was detected in peripheral blood and SF samples after cell permeabilization, by 2 color immunofluorescence flow cytometry. Samples from 14 patients with RA and 8 with osteoarthritis (OA) were studied. Nitrite concentration was determined by Griess reaction, interleukin 1beta and tumor necrosis factor alpha by an immunoenzymatic assay, and C-reactive protein (CRP) by an immunonephelometric method.


RESULTS
In SF, iNOS was detected in 11 of 14 patients with RA and 2 of 8 with OA. In blood cells, iNOS was detected in 8 of 14 patients with RA and none of the OA group. iNOS was consistently detected in monocytes and was not detected in granular cells. In RA, there was no correlation between the number of iNOS positive mononuclear cells and cytokine concentrations. CRP concentration was correlated with the number of iNOS positive mononuclear cells in RA SF samples.


CONCLUSIONS
SF mononuclear cells from patients with RA express iNOS and are involved in NO production in the joint. The number of positive cells is correlated with CRP concentration, suggesting the implication of NO production in the inflammatory process.
Borderie
D
D
Laboratoire de Biochimie A, Hôpital Cochin, Paris, France.
Hilliquin
P
P
Hernvann
A
A
Kahan
A
A
Menkes
C J
CJ
Ekindjian
O G
OG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000201:enzymology*; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D013582:Synovial Fluid / Q000201:enzymology*
D016207:Cytokines; D009573:Nitrites; D002097:C-Reactive Protein; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II