Recovery of the immune system in diabetic mice after transplantation of isolated islets of Langerhans.

Adult CBA/HZgb mice islets harvested by collagenase digestion were injected intraperitoneally in 52 singeneic diabetic recipients (CBA/Hgb leads to CBA/HZgb, 450-600 islets per mouse). Normal serum glucose levels, 24-h urine volume, insulin levels and body weight were completely restored to normal in all recipients during the next 2-5 months. Immunological function was assessed in control, diabetic and diabetic-transplanted mice by following their responses to sheep erythrocytes (expressed as the number plaque-forming cells in the spleen). In transplanted mice, the plaque-forming cell responses were as follows: 1 month after transplantation--43% of the plaque-forming cell counts in control (normal, non-diabetic) mice; 2 months after transplantation--56% of the control value; and 94% of the control value after 5 months. Ten months after the transplantation, the plaque-forming cell counts were slightly above the control value (148%). It appears, therefore that transplantated islet tissue positively affects the immunological as well as the diabetic state of the recipients.