Adoptive transfer of diabetes to and from old normoglycaemic BB rats

Approximately 4% of diabetes-prone BB/ Mol rats escape overt diabetes which occurs in other rats between 56 and 130 days of age. The ability of preactivated spleen cells from older non-diabetic and from acutely diabetic rats to adoptively transfer diabetes into young diabetes-prone rats was compared, and it was found that they transferred disease with similar incidence and with overlapping onset times in the recipients. Old non-diabetic rats were themselves susceptible to diabetes adoptively transferred from acutely diabetic or from old non-diabetic donors. Lymphocytic insulitis and pancreatic insulin content in unmanipulated old non-diabetic rats were both intermediate between those seen in acutely diabetic and in diabetes-resistant rats. In vivo treatment with polyinosinic-polycytidylic acid induced diabetes with faster onset in old non-diabetic rats than in young diabetes-prone rats. Adoptive transfer of fresh, whole spleen cells from old non-diabetic rats did not protect young BB rats against spontaneous diabetes, while cells from diabetes-resistant rats did. Spleens from old non-diabetic rats contained significantly lower percentages of T cells than spleens from acutely diabetic rats but not lower than spleens from age-matched diabetic rats, suggesting that this reduction was age-related. Finally, spleens from both old non-diabetic and from acutely diabetic rats were negative for the regulatory RT6+ T-cell subset. It is concluded that quiescent beta-cell autoimmunity seen in a fraction of BB/ Mol rats can be reactivated upon non-antigen-specific immune stimulation.