Islet cell transplantation in type I diabetes mellitus: evaluation of humoral immune response.

Four males and three females ranging in age from 20 to 35 years and afflicted with complicated Type 1-diabetes for more than 8 years underwent islet cell allotransplantation (ATx, 6 cases) and xenotransplantation (XTx, 1 case). Precultured islet cells derived from human or bovine fetal pancreata were injected into the m. rectus abdominis. Immunosuppression was not applied. Plasma C-peptide and islet cell surface antibodies (ICSA) were continually measured both before and until the twentienth week following islet cell transplantation. All recipients were subdivided as "responsive" (RR, 3 males) or "non-responsive" (NRR, 1 male and 3 females), according to the dynamics of their ICSA levels. All 3 RR (1XTx and 2 ATx) showed a peak of ICSA two weeks after cell injection. Subsequent ICSA levels had the tendency to either diminish or increase. Heterogeneity of preoperative antibody level, especially in NRR, was also observed. No associations between ICSA and ATx or XTx, age at diabetes onset, or duration of the disease was found. Only one RR with XTx had a reduced daily insulin requirement and a significant C-peptide response similar to the dynamics of ICSA levels. A greater mass of available bovine islet cells might be responsible for this effect.