Figure 1. Scatchard Analyses of Equilibrium-binding Assay of Insulin Antibodies; Patient with Insulin Autoimmune Syndrome (A) Compared to a 64-year-old Man Studied Because of Episodes of Hypoglycemia as a Result of an Insulin-binding Monoclonal IgG (B)
(A) The patient with insulin autoimmune syndrome has curvilinear response compatible with polyclonal antibodies with a higher and lower affinity binding site. Also, IgG antibodies contained 52.3% kappa light chains and 35.1% lambda light chains. (B) The 64-year-old man with hypoglycemic attacks; his Scatchard plot showed straight-line relationship, suggesting homogeneity of antibody binding site, compatible with a monoclonal anti-insulin antibody. (k, affinity constant; k1, higher affinity binding site; k2, lower affinity binding site; b, maximum binding capacity; serum dilution 1:45.) (From Diabetes Care5 and reprinted with permission of the American Diabetes Association. Copyright 1989.)