Plasma from rheumatoid arthritis patients does not contain abnormally high levels of alpha 2-macroglobulin-proteinase complexes.
We measured the levels of alpha 2-macroglobulin (alpha 2M)-proteinase complexes in the plasma of 18 patients with classic rheumatoid arthritis, 11 age-matched patients with noninflammatory back pain and osteoarthritis, and 8 healthy volunteers. In contrast with previous reports, we found no evidence of alpha 2 M-proteinase complexes in the plasma samples from individuals in any of the groups. In our assays, all activity that might have been the result of the presence of such complexes in the plasma samples proved instead to be an artifact attributable to contamination of the anti-alpha 2M antibody immobilized on the AffiGel solid phase with a trypsin-like proteinase. When the contaminating activity was eliminated by pretreatment of the antibody with 1 mM diisopropyl fluorophosphate, no degradation of substrate was detected with any of the plasma samples. However, the ability of the solid-phase assay to detect and quantitate alpha 2M-proteinase complexes when they are present was confirmed in control experiments with plasma samples to which performed alpha 2M-trypsin complexes had been added, or in which alpha 2M-kallikrein complexes had been generated by activation of Hageman factor (coagulation factor XII). We therefore conclude that neither normal plasma nor that from rheumatoid arthritis patients contains measurable amounts of alpha 2M-proteinase complexes.
D001172:Arthritis, Rheumatoid / Q000097:blood*; D001793:Blood Preservation; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007610:Kallikreins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism; D000511:alpha-Macroglobulins / Q000378:metabolism
D007074:Immunoglobulin G; C053069:alpha 2-macroglobulin-kallikrein complex; C028939:alpha-2-macroglobulin-trypsin complex; D000511:alpha-Macroglobulins; D007610:Kallikreins; D014357:Trypsin