OBJECTIVETo study the effects of gene transfer cytotoxic T lymphocyte associated antigen 4 immunoglobulin (CTLA4-Ig) and anti-cluster of differentiation 154 (CD154) mAb on the rejection of rat islet xenografts.

METHODSHuman islets were infected with the recombinant adenoviruses containing CTLA4-Ig gene. Transduced islets were transplanted under the left kidney capsule of diabetic rats. And then the animal model were treated with anti-CD154 monoclonal antibody. The changes of blood sugar were measured and the survival rates of grafts and transplantation rats were observed after transplantation. The morphological changes of grafts were observed. Expression of CTLA4-Ig and insulin were detected by immunohistochemical staining and cytokines were quantified by ELISA.

RESULTS(1) The blood glucose of transplantation rats decreased to normal level on 2nd day post-transplantation. The average level blood glucose of control group A, anti-CD154mAb treatment group B, transfected group C and associated treatment group D increased on day 8, 18, 25, 36, post-transplantation respectively. (2) The grafts of group A, B, C and D survived for (10.0 +/- 2.1) d, (22.0 +/- 8.2) d, (28.0 +/- 6.5) d and (37.0 +/- 9.3) d respectively. The survival of grafts in group D was significant longer than that in group A, B and C, respectively; The survival of group B and C were significantly prolonged compared with group A and the survival of group B was significantly different with group C (P < 0.05). The survival of transplantation rats were (21.0 +/- 5.7) d, (35.0 +/- 6.5) d, (48.0 +/- 8.5) d and (65.0 +/- 12.5) d in group A, B, C and D, respectively. The survival of transplantation rats compared each other among four groups were same as the survival of grafts (P < 0.05). (3) In control animals (group A), serum IL-2 and TNF-alpha concentration were elevated to a high level within seven days post-transplantation and significantly increased compared with that before transplantation (P < 0.01). (4) Hematoxylin-eosin staining of grafts showed a lot of islets under the kidney capsule of transplantation rats, no inflammatory cell infiltrate and immunohistochemical staining of grafts demonstrated expression of insulin protein at islets in group B, C and D. These grafts positively stained for CTLA4-Ig in group C and D.

CONCLUSIONSGene transfer CTLA4-Ig and anti-CD154mAb treatment can inhibit the rejection of rat islet xenografts and treatment Ad-CTLA4-Ig and anti-CD154 mAb could induce immune tolerance of islet xenografts.