Histological distribution of the interleukin-4 receptor (IL4R) within the normal and pathological synovium

The authors sought the synovial distribution of the interleukin-4 receptor in the synovium of 3 normal subjects, 5 cases of osteoarthritis (OA) and 10 cases of rheumatoid arthritis (RA) and various other inflammatory arthritic conditions. The specific receptor for interleukin-4 was mainly found on cells around subintimal blood vessels and within lymphocytic aggregates where dendritic-like cells were strongly stained. Conversely, synovial lining cells did not express the interleukin-4 receptor. In conclusion, it is believed that the expression of interleukin-4 receptor is restricted to the early activation stage of the mononuclear cells in the pathological joint.