Definition: Glycoproteins with a molecular weight of approximately 620,000 to 680,000. Precipitation by electrophoresis is in the alpha region. They include alpha 1-macroglobulins and alpha 2-macroglobulins. These proteins exhibit trypsin-, chymotrypsin-, thrombin-, and plasmin-binding activity and function as hormonal transporters.
polyclonal B cell activator factor found in alpha(2)-macroglobulin fraction of serum of patients with rheumatoid arthritis which produces polyclonal B cell activation; combination of rheumatoid factor & polyclonal B cell activat