Diabetes, Vol 39, Issue 6 653-656, Copyright © 1990 by American Diabetes Association
Persistence of serum antibodies to 64,000-Mr islet cell protein after onset of type I diabetes
MR Christie, D Daneman, P Champagne and TL Delovitch
Banting and Best Department of Medical Research, University of Toronto, Canada.
Antibodies to an islet protein of 64,000 Mr (64K antibodies) were measured
in 15 diabetic children who were followed prospectively for up to 3 yr
after onset of type I (insulin-dependent) diabetes. Of the 15 children, 12
were positive for 64K antibodies at diagnosis. Those patients who were
negative for these antibodies at onset remained negative throughout the
study. Modest increases in 64K antibodies were observed in 7 patients
within 1 mo of diabetes onset, concomitant with an increase in C-peptide
concentrations. All antibody-positive patients were still positive at the
end of the study, with no significant decrease in antibody levels relative
to those at diagnosis, whereas C-peptide concentrations decreased between 3
and 24 mo after onset. Islet cell antibodies, measured by immunochemical
staining on sections of rat pancreas, were detected in 9 of 15 patients at
onset, whereas only 3 of 11 patients were still positive after 3 yr. In an
additional group of 11 patients with diabetes for 6-7 yr, when basal and
stimulated C-peptide concentrations were undetectable, 4 patients were
still positive for 64K antibodies. These results demonstrate that levels of
64K antibodies persist during the first 3 yr of diabetes, despite declining
beta-cell function and decreased immune responses to other islet antigens,
but decrease during the next 3-4 yr as the remaining functional beta-cells
disappear.