Expression levels of chemokine receptors from the CC and CXC family, as well as CD27, were assessed by flow cytometry in CD20<sup>+</sup> mononuclear cells isolated from the peripheral blood (PB) and synovial fluid (SF) of RA and psoriatic arthritis patients.
The frequency of total CD19+ B cells in circulation was similar between controls and all RA groups, irrespective of treatment, but double negative (DN) IgD-CD27- memory B cells were significantly increased in ERA and established RA when compared to controls.
We found that CD19(+)CD27(-) naive B cells up-regulate the expression of the inhibitory CR1 during differentiation to CD19(+)CD27(+) memory B cells both in healthy donors and in RA patients, whereas the expression of the activatory CR2 is down-regulated.
These are the first data to demonstrate that expression of the IL-5 gene in RA SF CD27- lymphocytes is down-regulated and that IL-5 disregulation in RAcannot beruled out.