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A case of antibody formation against octreotide visualized with 111 In‐octreotide scintigraphy
Author(s) -
Kwekkeboom D. J.,
Assies J.,
Holland L. J.,
Reubi J. C.,
Lamberts S. W. J.,
Krenning E. P.
Publication year - 1993
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1993.tb01780.x
Subject(s) - octreotide , medicine , endocrinology , scintigraphy , antibody , in vivo , somatostatin , immunology , biology , microbiology and biotechnology
Summary A case of antibody formation in a patient with carcinoid syndrome is described. The patient was treated with octreotide in dosages up to 1 5 mg/day. Serum samples were analysed for the presence of octreotide antibodies before and after 20 months of octreotide treatment. In‐vivo 111 ln‐octreotide scintigraphy was performed before and during therapy, and after antibodies had developed. Before treatment, no serum antibodies against octreotide were detected. After 20 months of treatment, they were detectable up to a 1:115 serum dilution. The serum binding of 125 I‐Tyr 3 ‐octreotide was blocked by adding excess unlabelled Tyr 3 ‐octreotide, indicating the presence of specific octreotide antibodies. Before treatment, a normal distribution of radioactivity in the spleen and kidneys, irregular uptake in the liver due to metastases, and a hot spot in the lower abdomen were found during 111 ln‐octreotide scintigraphy. After antibodies had developed, increased radioactivity over the heart and high background radioactivity in the abdomen with only faint visualization of the spleen, liver, and kidneys were found, indicating a prolonged presence of 111 ln‐octreotide in the blood resulting from its being bound to antibodies. Increased radioactivity was also seen at the injection sites of the drug in the upper legs. In‐vitro incubation of biopsy tissue from this site with 125 l‐Tyr 3 ‐octreotide revealed diffuse guanosine triphosphate (GTP) independent specific binding, indicating non‐G‐protein linked binding of labelled octreotide. This report describes the characteristic abnormalities during in‐vivo 111 ln‐octreotide scintigraphy in a patient with octreotide antibodies. These consisted of high back ground radioactivity due to prolonged circulation of antibody coupled 111 ln‐octreotide together with visualization of the injection sites, which most probably results from local accumulation of antibodies.