Objective. To determine the levels of soluble CD154 (sCD154) in the plasma
of patients with rheumatoid arthritis (RA) and rheumatoid vasculitis (RV),
and to examine the relationship between the levels of sCD154 in plasma and
the clinical variables.
Methods. Levels of sCD154 were quantified in 39 plasma samples from patient
s with RA, including 9 patients who were also diagnosed with RV, and compar
ed with those of 20 healthy subjects. An ELISA was established and specific
ity of the ELISA was tested by control ELISA using isotype-matched IgG and
preabsorption assay. The titers of IgM and IgG rheumatoid factor (IgM-RF, I
gG-RF) for each patient were determined simultaneously, and values of other
laboratory variables were also determined.
Results. Levels of sCD154 in plasma were higher in patients with RA than in
the healthy subjects (p < 0.02). Compared with RA patients without vasculi
tis, patients with RV had significantly higher levels of sCD154 in their pl
asma (p < 0.001). Control ELISA and absorption assay of sCD154 indicated th
at our ELISA system was capable of measuring plasma sCD154 in RA patients.
Levels of sCD154 in RA plasma correlated significantly with both IgM-RF and
IgG-RF titers (r = 0.64 and 0.61, respectively, both p < 0.001). The level
s of sCD154 decreased after commencement of treatment for vasculitis in cas
es with RV.
Conclusion. We identified the presence of sCD154 in RA plasma, with especia
lly high levels in cases with vasculitis. Correlation between sCD154 and RF
liters indicates the CD154-CD40 pathway is likely related to pathogenic RF
production.