Anti-Insulin
Anti-Insulin is an indirect solid phase enzyme immunoassay (ELISA) for the quantitative measurement of IgG class autoantibodies against bovine, porcine and recombinant human insulin in human serum or plasma.
Type I Diabetes is mainly characterized by limited or fully missing secretion of the hormone insulin. Morphological studies demonstrated a destruction of the beta cells of the so-called Langerhanns’sche Cells (Islet Cells) in Type I diabetics. Numerous researchers described the appearance of antibodies directed against the islet cells and insulin as the causal reason for the onset of the disease.
Anti-Insulin antibodies are found in 37 percent of patients with newly detected Type I Diabetes, in 4 percent of their relatives of the first degree and in up to 1,5 percent of healthy controls. A positive correlation between the appearance of anti-Insulin and anti-Islet Cell anti-bodies has been reported.
Anti-Insulin autoantibodies may be detected several months and in some cases years before the onset of the fully clinical manifestation of the diseases. Occasionally also autoantibodies to Pro-Insulin may appear.
These ”true” anti-Insulin autoantibodies directed against endogenous insulin have to be distinguished from those autoantibodies which are developed in insulin dependent diabetics undergoing therapy with insulin preparations of animal origin. In fact the latter have to be referred to side effects. These side effects may occur as local reactions of the skin by development of insulin-specific autoantibodies. These autoantibodies are causing the formation of an insulin depot and they may simulate a resistance against the hormonal treatment with animal insulin.
Additionally other immunological phenomenon have been reported for Type I diabetics. A lot of other autoantibody specificities have been detected in those patients too, but these antibodies must not cause additional autoimmune phenomenon.
A mixture of highly purified preparations of bovine, porcine and recombinant human insulin is bound to microwells. Antibodies against these antigens, if present in diluted serum or plasma, bind to the respective antigen. Washing of the microwells removes unbound serum and plasma components. Horseradish peroxidase (HRP) conjugated anti-human IgG immunologically detects the bound patient antibodies forming a conjugate/antibody/antigen complex. Washing of the microwells removes unbound conjugate. An enzyme substrate in the presence of bound conjugate hydrolyzes to form a blue color. The addition of an acid stops the reaction forming a yellow end-product. The intensity of this yellow color is measured photometrically at 450 nm. The amount of colour is directly proportional to the concentration of IgG anti-bodies present in the original sample.
- Reeves,W.G. Insulin Antibody Determination: Theoretical and Practical Considerations. Diabetologia 24, 399 (1983).
- Atkinson, M.A., Fisk, D.D., Spillar, R.P. and MacLaren, N.K. Insulin antibodies as markers for Insulin dependent diabetes mellitus (IDD). Diabetes 34, 926 – 930 (1985).
- Willein, T., Nicholson, S. and Casey, C. A Micro Enzyme-Linked Immunosorbent Assay for Insulin Antibodies in Serum. J. Imm. Methods 76, 185 (1985).
- Kobayashi, N. et al. A Solid-Phase Enzyme Immunoassay for Anti-Insulin Antibody in Diabetes Mellitus Patients. J. Imm. Methods 84, 245 (1985).
- Wissllein, T. et al. Value of Insulin Antibodies as Serum marker for Insulin-Dependent Diabetes Mellitus. Lancet 1, 480 (1985).
- Soeldner, J.S. et al. Insulin-Dependent Diabetes Mellitus and Autoimmunity: islet-cell Autoantibodies and betacell failure. New Engl. J. Med. 313, 893 (1985).
- Torfs, C.P. et al. Long Term Frozen Sera for Epidemiological Studies of Antibodies. Lancet 1, 503 (1986).
- Seino, S. et al. Characterisation of Circulating Insulin in Insulin autoimmune Syndrome.Clin. Endo. & Metab. 62, 64 (1986).
- Boitard, C.H. and McDewitt, H.O. Immunology of insulin-dependent diabetes mellitus. In. Cohen, J.R., (ed.) Perspectives on autoimmunity, 39-58 (1987). CRC Press, Boca Raton, FL
- Nouvo, J.A., Baker, Jr., J.R.,Wartowsky, l. et al. Autoantibodies to insulin are present in sera of patients with autoimmune thyroid diseases. Diabetes, 37, 317-320 (1988).