Binding Affinity of Human Autoantibodies: Studies of Cryoglobulin IgM Rheumatoid Factors and IgG Autoantibodies to Albumin

Abstract

The binding affinity of cryoglobulin Ig[immunoglobulin]M rheumatoid factors (RF) for human IgG and of human IgG anti-albumin autoantibodies for HSA [human serum albumin] was measured by the molecular sieving technique. The binding affinities of the 2 autoantibodies were consistently low (104-105 l/M) as compared to the affinities of corresponding hyperimmune animal antibodies (106-108 l/M). The findings were discussed in relation to theories on human autoimmunity. The existence of strict autotolerance at the T [thymus-derived] cell level and of autoreactivity at the low affinity B [bone marrow-derived] cell level was considered to be best compatible with the findings of this study and with the major known facts of autoimmunity.