Binding of Fluorescent Insulin to Intracellular Antibodies in Guinea Pigs Immunized with Insulin. ∗

Summary

Fluorescein isothiocyanate-insulin (bovine and porcine) conjugates, containing 2 to 3 chromatographic and electrophoretic fractions, showed a 70–80% retention of capacity to bind insulin antibodies, produced in guinea pigs, as compared to unmodified crystalline insulin. The conjugates and unconjugated insulin-I¹³¹ behaved similarly, electrophoretically and chromatographically, in the presence of antibody. Direct staining, with fluorescent insulin, of frozen sections of lymphoid tissues from guinea pigs immunized with insulin produced specific cytoplasmic fluorescence in plasma cells which were present in increased numbers. Non-lymphoid tissues from the same animals contained no specifically staining elements beyond occasional scattered plasma cells. No differences in staining were observed when lymphoid tissues from animals immunized with bovine insulin were stained with porcine fluorescent insulin and vice versa.