Special Precautions/Comments:

Method: Indirect Immunofluorescence (IIF). Calibration: WHO 97/550. EQA Scheme: UK NEQAS scheme for Diabetic Markers. IQC: Commercial preparation

Interpretation: Results are reported as being either: Negative, BORDELINE POSITIVE or POSITIVE

Additional Information:

Indication: Insulin dependent diabetes mellitus (IDDM).

Background Information: Islet cell antibodies are antibodies which bind to pancreatic islets in IIF assays and are markers of beta-cell damage and usually aid in the diagnosis of type 1 diabetes (IDDM). Various antibody targets will result in similar staining. In first-degree relatives of patients with insulin-dependent diabetes mellitus (IDDM), the presence of high titre islet cell antibodies (ICA) confers a risk for development of IDDM. Islet cell antibodies are transient and disappear soon after diagnosis (within 6 months often) once the islets have been destroyed. The presence of multiple antibodies associated with diabetes such as glutamic acid decarboxylase 65 antibodies (GAD65) and protein tyrosine phosphatase-like protein (IA2) antibodies, results in a higher positive predictive value for the development of type 1 diabetes [2]. The presence of ICA does not always correspond to GAD65 and/or IA2 antibodies [3]. Individuals with two or more of the autoantibodies have a 68% 5 year risk of developing type 1 diabetes. Those with 3 autoantibodies had a 100% 5 year risk of the disease [2]. Islet cell antibodies along with GAD65, insulin antibodies and IA2 antibodies may be of use when investigating latent autoimmune diabetes of adulthood (LADA). Approximately 10% of patients diagnosed with type 2 diabetes have LADA which requires insulin therapy. LADA may be distinguished from type 2 diabetes by the presence of the autoantibodies [1]. Experience is required to determine the true presence of islet-specific staining from other patterns and heterophile staining. In cases of suspected heterophile antibodies (inter-species reactive IgG antibodies) or those with high background staining an absorbed conjugate is used in order to reduce the interference

References: Brophy S, et al. Interventions for latent autoimmune diabetes (LADA) in adults. The Cochrane Collaboration. 2009. [Ref 1]. Pihoker C, Gilliam LK, Hampe CS et al. Autoantibodies in diabetes. Diabetes. 2005. 54 (supplement 2): S52-S61. [Ref 2] Nice guideline 15. 2004. Type 1 diabetes: diagnosis of type 1 diabetes in adults. Torn C. C peptide and autoimmune markers in diabetes. Clinical Laboratory. 2003. 49(1-2): 1-10. Borg H, Gottsater A, Lanin-Olsson M. High levels of antigen-specific islet antibodies predict future B-cell failure in patients with onset of diabetes in adult age. J. Clin. Endocrin & Metab. 2001. 86(7): 3032-3038. Borg H, Marcu C, Sjoblad S et al. Islet cell antibody frequency differs from that of glutamic acid decarboxylase antibodies/IA2 antibodies after diagnosis of diabetes. Acta Paediatrica. 2000. 89(1): 46-51. [Ref 3]

See Also: GAD65;IA2

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