Assuntos
Transfusão de Sangue , Citocinas/biossíntese , Transplante de Coração/imunologia , Terapia de Imunossupressão/métodos , Células Th1/imunologia , Células Th2/imunologia , Animais , Complexo CD3/análise , Antígenos CD4/análise , Antígenos CD8/análise , Ciclosporina/uso terapêutico , Interferon gama/biossíntese , Interleucina-4/biossíntese , Masculino , Mitomicina/farmacologia , Ratos , Ratos Endogâmicos ACI , Ratos Endogâmicos Lew , Células Th1/efeitos dos fármacos , Células Th2/efeitos dos fármacosRESUMO
The induction of transplantation tolerance is one of the primary goals following solid organ transplantation. The combination of a single dose of rapamycin (RAPA) with a short course of cyclosporine (CsA) has been shown to induce transplantation tolerance in the nonfunctional rat heterotopic cardiac transplant model. The purpose of this study was to assess this effective induction protocol in a functional renal transplant model. Male ACI (RTl(a)) and Lewis (RT1(1)) rats were used as donor and recipients respectively. Allografts received a single RAPA dose of (1.5 mg/kg) combined with CsA (10 mg/kg) 12-14 hr prior to transplantation. CsA (5 mg/kg) was given daily on days +1 - +7. Untreated Lewis to Lewis isografts served as histological controls. Chimerism, assessed in recipient skin, and intragraft interleukin (IL) 10 expression was determined utilizing PCR and RT-PCR techniques respectively. Treated animals and isografts were sacrificed 120-130 days posttransplant for functional and histological evaluation. Allografts (n=9) were functionally tolerant with serum creatinine (0.77+/-0.1 vs. 0.88+/-0.1; P=0.275), blood urea nitrogen (37.6+/-4.6 vs. 23.3+/-1.9; P=0.123), and 24 hr protein excretion (27.0+/-4.4 vs. 17.9+/-5.2; P=0.131) similar to single kidney ACI controls. Histologically, 45% (4/9) allografts were indistinguishable from isografts with no evidence of rejection, and were considered immunologically tolerant. Donor/recipient chimerism was not detected. All immunologically tolerant allografts had evidence of intragraft IL-10 expression. Rejecting allografts and isografts did not express intragraft IL-10. This study confirms the efficacy of pre-engraftment single-dose RAPA combined with CsA in inducing true immunologic tolerance in this stringent functional renal transplant model. The expression of intragraft IL-10 in tolerant recipients suggests a Th-2 shift as the mechanism of tolerance in this model.
Assuntos
Imunossupressores/uso terapêutico , Transplante de Rim/imunologia , Polienos/uso terapêutico , Actinas/biossíntese , Animais , Nitrogênio da Ureia Sanguínea , Creatinina/sangue , Ciclosporina/uso terapêutico , Primers do DNA , Quimioterapia Combinada , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/patologia , Tolerância Imunológica , Terapia de Imunossupressão/métodos , Interleucina-10/biossíntese , Transplante de Rim/patologia , Transplante de Rim/fisiologia , Masculino , Reação em Cadeia da Polimerase , Proteinúria , Ratos , Ratos Endogâmicos ACI , Ratos Endogâmicos Lew , Sirolimo , Quimeras de Transplante , Transplante Homólogo , Transplante IsogênicoRESUMO
While the existence of chimeric cells in host tissue following organ transplantation is well documented, its distribution, temporal evolution and relationship to allograft survival is less clear. To explore this phenomenon, Lewis recipients of ACI cardiac allografts representing a wide range of immunosuppressive protocols and graft survival times were examined for the presence of chimerism using a sensitive polymerase chain reaction assay. Four groups of animals were examined: untransplanted animals receiving donor specific transfusion (DST)/cyclosporine A (CsA); allograft recipients with no treatment; recipients treated with DST/CsA/supplementary immunosuppression with rejection at 21-183 days; and recipients sacrificed with functioning allografts, treated with DST/CsA/supplementary immunosuppression and surviving > 200 days. To elucidate variations in the tissue distribution of chimeric cells, bone marrow, skin, liver, spleen, and thymus were examined in each animal. Untransplanted animals receiving DST/CsA displayed no evidence of chimerism. In animals receiving a cardiac allograft but no treatment, there was extensive evidence of chimerism in four of five animals. Chimerism was also detected in seven of nine animals with intermediate graft survival at the time of rejection. In animals with long-term graft survival, only four of eight displayed chimerism. These results suggest that, without immunosuppression, early chimerism does not lead to prolonged graft survival and that, even when graft survival is moderately prolonged, these cells are not sufficient to prevent rejection. In conclusion, chimerism appears to be a common phenomenon following transplantation, is not a result of DST, and may not be necessary for maintenance of long-term graft survival.