Insulin autoimmune syndrome associated with benign monoclonal gammopathy. Evidence for monoclonal insulin autoantibodies.
A 64-yr-old man with benign monoclonal gammopathy developed recurrent episodes of severe hypoglycemia but lacked evidence of insulinoma or exogenous insulin administration. The patient's plasma was found to contain anti-insulin antibodies and large amounts of extractable insulin (1110 microU/ml), which was identified as human insulin by high-performance liquid chromatography (HPLC). The anti-insulin antibodies consisted solely of IgG and lambda-light chains. Scatchard analysis of these antibodies revealed an almost straight-line relationship, with markedly low affinity and high capacity. An immune complex made of 125I-labeled insulin and the patient's antibodies emerged in a molecular-sieve HPLC as almost a single peak, suggesting a homogeneous antibody population. In addition, the patient's M protein was separately shown to be the IgG and lambda-light-chain type. We suggest that the insulin autoantibodies responsible for the spontaneous hypoglycemia in this patient are monoclonal and of M protein origin.
Wasada
T
T
Diabetes Center, Tokyo Women's Medical College, Japan.
Eguchi
Y
Y
Takayama
S
S
Yao
K
K
Hirata
Y
Y
Ishii
S
S
D000911:Antibodies, Monoclonal / Q000032:analysis*; D000936:Antigen-Antibody Complex / Q000032:analysis; D001323:Autoantibodies / Q000032:analysis*; D001327:Autoimmune Diseases / Q000150:complications* / Q000276:immunology; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006942:Hypergammaglobulinemia / Q000150:complications*; D007122:Immunoelectrophoresis; D007330:Insulin Antibodies / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D008998:Monoclonal Gammopathy of Undetermined Significance / Q000150:complications* / Q000276:immunology
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001323:Autoantibodies; D007330:Insulin Antibodies