Expression of CD44 variant isoforms in leukocytes of the joint fluid of rheumatoid arthritis patients and the effect of steroids

Several CD44 variant isoforms have been reported in the synovium of patients with rheumatoid arthritis (RA), but the physiological and pathological roles of these isoforms have not been identified In this study, we investigated the expression of CD44 variant isoform mRNA using the reverse transcription-polymerase drain reaction (RT-PCR) and TaqMan(TM) PCR methods in leukocytes of blood and joint fluid obtained from the knee joints of 20 RA patients. We also examined the effects of steroids (prednisolone and/or dexamethasone palmitate) and some disease-modifying antirheumatic drugs (DMARDs) on the expressions of CD44 variants. The expressions of CD44H mRNA and CD44V10 mRNA of leukocytes were significantly higher in both the blood and joint fluid samples of the RA patients compared with the samples of healthy healthy volunteers. The level of CD44V10 mRNA in the leukocytes of the joint fluid was higher than that in the blood of the Rrl patients. These results suggest that the increase of CD44V10 mRNA expression in the leukocytes of RA patients can induce a focusing of leukocytes oil synovial tissue and an infiltration of leukocytes into the joint fluid. In the steroid-treated RA patients, the expression of CD44H mRNA in the leukocytes was significantly decreased in the joint fluid samples, whereas the expression of CD44V10 mRNA of leukocytes was a higher level. None of the DMARDs used here showed any influence on the expressions of CD44 variants. These results suggest that steroid treatment affects CD44H mRNA expression. whereas steroids and DMARDs have no influence on CD44V10 mRNA expression. Therefore, only the suppression of CD44H mRNA expression will not be enough to control RA. It is possible that the expression of CD44V10 is associated with a pathway of RA immunological processes. (C) 1998 Prous Science. All rights reserved.