Insulin autoantibodies in non-obese diabetic (NOD) mice and streptozotocin-induced diabetic mice.

Similar to Insulin-dependent diabetes mellitus (IDDM) in man, diabetes in the non-obese diabetic (NOD) mouse and that induced by low-dose of multiple injections of streptozotocin (low-dose SZ) develop in conjunction with the presence of insulitis. We measured insulin autoantibodies (IAA) in NOD and low-dose SZ mice and compared the levels with mice given a single diabetogenic dose of streptozotocin (high-dose SZ) as well as control CD-1 mice. The mean insulin binding in female NOD mice was 3.08 +/- 1.49 (mean + SD)% and that in male NOD mice was 2.86 +/- 3.70%, as compared with 1.10 +/- 0.35% in the control CD-1 mice (p less than 0.01, p less than 0.05). Sera from low-dose SZ and high-dose SZ mice showed 1.07 +/- 0.23% and 0.93 +/- 0.45% of IAA which did not differ from controls. The number of mice with IAA above the mean + 2SD value of CD-1 mice were 8/9 female NOD mice and 9/20 male NOD mice. Insulitis was found in all NOD and low-dose SZ mice but not in any high-dose SZ mice and control CD-1 mice. These results suggest that (a) IAA are markers for islet autoimmunity in the NOD mouse, (b) presence of IAA does not reflect insulitis, and (c) the appearance of IAA may reflect a difference of the immune response genotype.