Histology of the islets of Langerhans following administration of human lymphocytes into athymic mice.

Lymphocytes from seven newly diagnosed insulin-dependent (Type 1) diabetics, five islet cell antibody positive unaffected children and five normal subjects were injected i.p. into athymic nude mice. A further six mice were injected with medium and six control mice received no injection. Blood was taken from the tail vein before injection for glucose determination. After 10 days blood was again obtained from the tail vein; the pancreas was removed under deep ether anaesthesia and the mice sacrificed by exsanguination. Routine histological sections of the pancreas were prepared. There was no difference between groups in respect of the initial blood glucose. However, final blood glucose levels were raised in all mice that had received an injection including medium only, the rise being statistically significant both after injection of lymphocytes from normal subjects (P less than 0.05) and from newly diagnosed diabetics (P less than 0.001). Histology did not reveal any evidence of 'insulitis' or islet cell damage although enlarged, hyperplastic islets could be found in each group of treated mice. We conclude that passive transfer of diabetes was not achieved in this animal model. Elevation of blood glucose levels and islet hyperplasia may simply reflect a non-specific 'stress' reaction.