[Specific protein in the plasma of rheumatoid arthritis patients]

A unique protein was detected in the plasma of rheumatoid arthritis patients by two-dimensional electrophoresis. We named it rheumatoid arthritis specific protein (RASP). According to the pattern and concentration of its spot, RA patients were classified into three groups as RASP+, RASP +/- and RASP-. RASP+ was detected only in RA and its occurrence was 45/120 (38%). The occurrence of RASP including RASP +/- was 84/120 (70%) in RA, 6/13 (46%) in SLE, 2/8 (25%) in PSS, 11/51 (22%) in liver disease and 4/44 (9%) in normal. RA patients with RASP+ indicated significantly high level of ESR, CRP and platelet counts comparing with RA patients with RASP-. These results suggested that RASP might be a good indicator for the diagnosis and evaluation of the activity of RA. RASP was purified with gel chromatography repeated three times. RASP was very similar with immunoglobulin G in its biochemical and immunological properties.