Objective: To test the difference of gene expression patterns in peripheral blood mononuclear cells (PBMCs) among patients with ankylosing spondylitis (AS) or rheumatoid arthritis (RA) and healthy volunteers and to find potential discriminating genes.
Methods: The PBMC gene expression spectra of 7 patients with active AS, 6 patients with active RA, and 7 healthy volunteers were tested by microarray assay with 588 target gene filters. Semi-quantitative RT-PCR was performed to test the expression rates of thirteen inflammation related genes which had been with high expression rates in at least 4 arthritis patients by microarray assay, among 22 AS patients, 8 RA patients, and 7 healthy volunteers.
Results: The expression rates of inflammation related genes by cDNA microarray assay in healthy volunteer group, AS group, and RA group were 8.4%, 32.5% and 44.8% respectively (P < 0.001). The positive rate in RA patients was much higher than that in AS patients (P < 0.012). A significant increase of positive rate of these genes was also noticed in 2 active pulmonary tuberculosis patients. The expression rates of the 13 genes which were positive in at least 4 arthritis patients tested by semiquantitative RT-PCR in 22 AS patients, 8 RA patients and 7 healthy volunteers were very similar to those expression rates tested by cDNA microarray.
Conclusion: The gene expression profiles of PBMC among AS patients are significantly abnormal and are significantly different from those among RA patients. The high expression of the 13 cytokines is not specific to AS.