Limited Loss of Tolerance to Islet Autoantigens in ICA+ First Degree Relatives of Patients With Type I Diabetes Expressing the HLA dqb1*0602 Allele

J Autoimmun. 1996 Jun;9(3):423-5. doi: 10.1006/jaut.1996.0058.

Abstract

The DQB1*0602 allele confers dominant protection from Type I diabetes even among islet cell antibody positive (ICA+) first degree relatives of affected individuals. Lack of progression to diabetes in these subjects, despite ICA positivity, could be explained by a loss of tolerance limited to fewer islet autoantigens than in ICA+ relatives progressing to the disease. To test this hypothesis we have determined autoantibodies by radioassay to three islet autoantigens, glutamic acid decarboxylase (GAD), insulin and the novel neuroendocrine antigen ICA512/IA-2 in 84 HLA-typed ICA+ first degree relatives of patients with Type I diabetes. Among the eleven relatives expressing the 0602 allele (0602+) only two were positive for more than one antibody as determined by radioassay. In contrast, 55/73 ICA+ relatives lacking this allele (non-0602) expressed more than one autoantibody (P < 0.01). The prevalence of antibodies to GAD (GAA) was not significantly different in ICA+ relatives with and without the 0602 allele (7/11 in 0602+ versus 60/73 in non-0602). In contrast, anti-insulin antibodies (IAA) were present in only 2/11 0602+ ICA+ relatives versus 47/70 in non-0602 ICA+ relatives (P < 0.01). Similarly, only one individual carrying the 0602 allele was positive for ICA512 autoantibodies versus 33/70 in the non-0602 group (P < 0.01). These data indicate that even among ICA+ relatives the 0602 allele is associated with a limited immune response to islet antigens and amongst 0602+ relatives this response is mostly directed against GAD.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Alleles
  • Autoantibodies / blood
  • Autoantigens / immunology
  • Child
  • Child, Preschool
  • Diabetes Mellitus, Type 1 / genetics*
  • Diabetes Mellitus, Type 1 / immunology*
  • Family Health
  • Glutamate Decarboxylase / immunology
  • HLA-DQ Antigens / genetics*
  • Humans
  • Immune Tolerance
  • Insulin / immunology
  • Islets of Langerhans / immunology*
  • Middle Aged
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1
  • Protein Tyrosine Phosphatases / immunology
  • Radioimmunoassay

Substances

  • Autoantibodies
  • Autoantigens
  • HLA-DQ Antigens
  • Insulin
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1
  • Protein Tyrosine Phosphatases
  • Glutamate Decarboxylase