Evidence that intrathymic islet transplantation does not prevent diabetes or subsequent islet graft destruction in RT6-depleted, diabetes-resistant BioBreeding/Worcester rats.
Pancreatic islet allografts transplanted intrathymically are accepted and restore normoglycemia in streptozotocin-diabetic rats given one injection of antilymphocyte serum. Intrathymic allografts similarly restore normoglycemia in diabetes-prone (DP) Bio-Breeding (BB) rats that have developed spontaneous autoimmune diabetes. Intrathymic islets also reduce the frequency of subsequent diabetes when transplanted prophylactically into young DP rats. These findings suggest that intrathymic transplantation can prevent not only allograft rejection, but also the appearance and recurrence of autoimmune tissue destruction. To explore these hypotheses further, we attempted both to confirm previous studies and to extend them to another model of autoimmune diabetes, the RT6-depleted diabetes-resistant (DR) BB rat. Fewer than 1% of DR-BB rats develop spontaneous diabetes, but most become hyperglycemic after in vivo immune elimination of RT6+ T cells. Using the protocols described in the literature, we observed the following: (1) Consistent with previous reports, intrathymic islet allografts survived indefinitely in streptozotocin-diabetic, antilymphocyte serum-treated, non-BB recipient rats. (2) Consistent with previous reports, intrathymic islet grafts produced long-term normoglycemia in diabetic DP-BB rats and also reduced the frequency of spontaneous diabetes in young animals transplanted prophylactically. (3) In contrast, intrathymic islets (iso- and allografts) neither prevented nor reversed diabetes in RT6-depleted DR rats. We hypothesize that intrathymic islet grafts survive in DP-BB rats because they are lymphopenic and immunocompromised, whereas immunocompetent diabetic DR rats successfully recapitulate the autoimmune disease process. Although intrathymic allograft transplantation is postulated to induce a state of tissue-specific tolerance, our results indicate that this tolerant state may not extend to autoimmune destruction of either isografts or allografts.
Battan
R
R
Department of Medicine, University of Massachusetts Medical Center, Worcester 01605.
Mordes
J P
JP
Abreau
S
S
Greiner
D L
DL
Handler
E S
ES
Rossini
A A
AA
D036002:ADP Ribose Transferases; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D003921:Diabetes Mellitus, Experimental / Q000517:prevention & control* / Q000601:surgery; D003922:Diabetes Mellitus, Type 1 / Q000517:prevention & control* / Q000601:surgery; D005260:Female; D006084:Graft Rejection / Q000517:prevention & control; D006649:Histocompatibility Antigens / Q000494:pharmacology; D016381:Islets of Langerhans Transplantation / Q000276:immunology; D008212:Lymphocyte Depletion; D008297:Male; D008562:Membrane Glycoproteins; D051381:Rats; D011913:Rats, Inbred BB; D011916:Rats, Inbred F344; D011920:Rats, Inbred WF; D013950:Thymus Gland; D016042:Transplantation, Heterotopic
D000945:Antigens, Differentiation, T-Lymphocyte; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D036002:ADP Ribose Transferases; C090163:Art2b protein, rat