Reduction of in vivo deiodination of radioiodinated antibodies using N-Succinimidyl-4-[125i]iodobenzoate

Human nonspecific polyclonal IgG was labeled with 125I through direct and indirect labeling methods using chloramin-T and a non-phenolic radioiodinated intermediate N-Succinimidyl-4-[125I]iodobenzoate (125I-SIB), respectively. Tissue distribution of radioiodinated IgG was assessed in normal and induced inflammation mice. Although, radioiodinated IgG accumulated in inflammatory area, results showed decreased thyroid and stomach activity and improved inflammatory thigh-to-normal tissue ratios with indirect labeling method (125I-IB-IgG) compared with direct labeling method (125I-IgG), indicating reduced in vivo deiodination. Results demonstrate that the 125I-SIB is probably the preferable approach for labeling antibodies with iodine radioisotopes