Prospective analysis of eosinophilia in spontaneously diabetic BB rats: correlation with islet inflammation but not with diabetes development.

A prospective analysis of eosinophil counts in diabetes prone BB rats showed that eosinophilia (greater than 5%) occurred between 70-100 days of age. The presence of eosinophilia did not predict diabetes onset because persistently normoglycaemic animals developed eosinophilia as well. Nevertheless a correlation with the disease process in BB rats was found. Eosinophilia decreases a few weeks after diabetes onset but persists in non diabetic rats. Histological analyzes showed that eosinophilia correlates with eosinophil infiltration of islets (p less than 0.005) and the latter correlates with severe insulitis (p less than 0.005). These findings indicate that eosinophilia is associated with a late stage of islet inflammation in diabetes prone BB rats independent of whether the animals develop diabetes or not.