Abstract

VALDEZ, Silvina Noemí; VILLALBA, Anabel; IACONO, Ruben Francisco  and  POSKUS, Edgardo. Preparation of rembinant human ³⁵S-proinsulin and its application in a combined radioligand-binding assay: Usefulness of the novel method as first-line screening for predicting insulin requirement in adult onset diabetic patients. Acta bioquím. clín. latinoam. [online]. 2004, vol.38, n.1, pp.3-15. ISSN 0325-2957.

The presence of the glutamate decarboxylase and insulin/proinsulin autoantibodies (GADA and IAA/PAA) can have predictive value about the insulin requirement in adult-onset diabetic patients. In this work, we developed a new tracer ³⁵S-Proinsulin and it was employed in a combined radioligand binding assay with ³⁵S-GAD for the simultaneous determination of GADA and PAA (RBA-combi). This novel assay was applied to sera from 85 young type 1 and 98 adult-onset diabetic patients, and to 53 normal control. Among type 1 diabetes sera, 100% of those with at least one positive marker by single methods, and 17.7% of those with double negative markers, were positive by RBA-combi (RBA-combi+). Among sera from adult-onset diabetes, 100% of those PAA+ (GADA+ or GADA-), 92.3% of GADA+/PAA-, and 1.3% of GADA-/PAA-, were RBA-combi+. Moreover, 88.9% of adult patients RBA-combi+ evolved to insulin requirement, suggesting a good predictive value for this method. In conclusion, the new tracer ³⁵S-Proinsulin was able to be used in the RBA-combi allowing the simultaneous detection of GADA and PAA markers. Such marker combination is a valuable tool for assessing autoimmune processes associated to future insulin requirement in adult-onset diabetes.

Keywords : Autoantibodies; Adult-onset diabetes mellitus.; Insulin; Proinsulin.; Glutamate decarboxylase.; Radioligand-binding assay.

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