 In rheumatoid arthritis, it has been observed that the level of sulfate incorporation as well as the 'plumpness' (or 'tallness') of the endothelium in areas of lymphocytic infiltration in the synovial membrane are closely related to the concentration of the lymphocytes in the perivascular infiltrates.Similarly, expression of MECA-79 and HECA-452 on these vessels is most pronounced in association with extensive lymphoid infiltrates.Therefore, the development of bona fide HEVs in the synovial membrane of patients with rheumatoid arthritis is likely to facilitate large-scale influx of lymphocytes, leading to amplification and maintenance of chronic inflammation.