Immunoperoxidase demonstration of human serum globulin binding to islet tissue.

Sera from juvenile diabetic and nondiabetic controls were tested, using the immunoperoxidase 
method, for the presence of islet-binding immunoglobulins. All diabetic sera tested 
contained an islet-binding protein and on the average the sera were 
more positive than age- matched controls. Normal adult sera are undifferentiated 
from juvenile diabetic sera. Most sera from children less than two 
years of age did not bind to islet tissue and sera 
from cystic fibrosis patients had a markedly diminished ability to bind 
to islet tissue. The binding protein appears to be an immunoglobulin 
which selectively reacts with elements of the islet beta cell. 