Expression of FC epsilon II/CD23 on human neutrophils isolated from rheumatoid arthritis patients

CD23, the low affinity receptor for IgE, is a 45 kiladalton molecule belong ing to the C-type lectin family some members of which have been identified as adhesion molecules. Since it has been described upregulated in different cells in chronic inflammatory diseases and in rheumatoid arthritis in part icular, where neutrophils are directly involved in tissue damage, our inter est, in this work, has been focused on the expression and regulation of thi s antigen on neutrophil membrane. We studied 22 patients suffering from rhe umatoid arthritis and 22 healthy control subjects. CD23 expression on neutr ophil membrane was analyzed by immunofluorescence. Neutrophils of 9 out of 22 patients expressed CD23 molecules, neutrophils of 11 out of 22 patients expressed CD23 only after 24 h of incubation in RPMI; only 2 out of 22 pati ents did not express the CD23 antigen on neutrophil membrane either after i solation or after a 24 h incubation. On the contrary neutrophils isolated f rom healthy subjects did not express CD23 molecules upon isolation. Only in 7/22 control subjects neutrophils resulted positive after 24 h of incubati on in RPMI. Moreover, we found that in our experimental conditions the pres ence of IFN-g or GM-CSF alone or in combination with IL-4 inhibited CD23 ex pression during the 24 h incubation. Our results show that there is a stron g association between neutrophil ability to express CD23 and rheumatoid art hritis, and that such expression may be regulated by GM-CSF, IFN-gamma and IL-4.