Impact of transfusions and acute rejection on posttransplantation donor antigen-specific responses in two study populations. Cooperative Clinical Trial in Transplantation Research Group

Depletion of alveolar macrophages abrogates prolongation of cardiac allograft survival induced by intratracheal delivery of alloantigen

BACKGROUND

We previously showed that pretreatment with intratracheal delivery (ITD) of alloantigen induced prolonged cardiac allograft survival and generated regulatory cells in mice. In this study, we examined the role of alveolar macrophages (AM) in our ITD model.

METHODS

Some CBA mice were given ITD of C57BL/6 splenocytes and underwent transplantation of C57BL/6 hearts 7 days later. In others, AM were depleted with clodronate-loaded liposomes 3 days before ITD. In adoptive transfer studies, whole splenocytes were obtained from ITD-treated CBA mice and administered to naïve CBA secondary recipients, which were given C57BL/6 hearts immediately afterward. Interleukin-10 concentrations in bronchoalveolar lavage fluid were assessed by enzyme-linked immunosorbent assays. Immunohistologic and flow cytometric studies were performed after ITD.

RESULTS

C57BL/6 splenocytes given by ITD were ingested by AM in 2 days and undetectable in paratracheal lymph nodes or spleen tissue. CBA mice given ITD of C57BL/6 splenocytes had markedly prolonged allograft survival (median survival time [MST], 86 days), whereas naïve CBA mice rejected allografts acutely (MST, 8 days). AM-depleted, ITD-treated mice also rejected allografts (MST, 5.5 days). Naïve secondary recipients given adoptive transfer of splenocytes from ITD-treated mice had prolonged allograft survival (MST, >100 days), whereas secondary recipients given adoptive transfer of splenocytes from AM-depleted, ITD-treated mice rejected the grafts (MST, 15.5 days). Interleukin-10 expression in bronchoalveolar lavage fluid was down-regulated in AM-depleted mice compared with naïve mice.

CONCLUSIONS

AM have an important role in the induction of regulatory cells in our model of ITD of alloantigen.

[Effect of donor-specific blood transfusion on the outcome of kidney transplantation]

Donor specific transfusion (DST) is proclaimed to improve graft survival in living related kidney transplantation (LRTx). The aim of the present study was to estimate the influence of DST on LRTx graft function, acute rejection rate (AR) and survival in the early and late posttransplant period. Fifty-five LRTx patients (grafted in the same year, and matched for recipients' and donor's age, sex) were included into the study. Ninety pts received DST: 4 patients were excluded from further evaluation (3 developed positive cross match reaction and one patients received cadaver graft) and 15 patients subsequently underwent LRTx from their respective blood donors (group 1). Their outcome was compared with 15 patients who had never been transfused before (group 2) and 25 random transfused patients (group 3). Besides similar patients' and donors' sex and age, kidney transplantations were performed in the same period. Graft functions were followed-up 6-60 months after LRTx. DST protocol consists of 3 x 150 ml potentially related donor's fresh whole blood at 2-week intervals (DST1, DST2, DST3) with 3 days azathioprine administration (2 mg/kg bw, one, day before to one day after DST administration). Donor specific cytotoxic antibodies were determined before DST1, at the day of DST2, DST3 and 14 and 28 days after DST3. All patients were grafted at least one month after the DST3. Immunosuppressive protocol consisted of three drugs. There is no difference in HLA mismatches, MLC answer, and pretransplant panel reactive antibodies level between groups. One patient from group 2 lost their graft in the first postTx month (acute tubular necrosis). A better graft function was preserved in patients from groups 1 and 3 than group 2 in the observed periods. Number of patients with acute rejection was unsignificantly different: 5/15 from group 1, 12/25 from group 3 but 8/10 patients from group 2. However, the acute rejection rate was lower in patients from group 1. One and five-year graft survival was 100% for grafts from groups 1 and 3, while it is gradually decreased for group 2 grafts: 84.5% and 57%. Our results confirmed the beneficial effect of blood transfusion on LRTx renal graft function and survival and DST on the incidence of acute rejection.

B7/CTLA4 pathway is essential for generating regulatory cells after intratracheal delivery of alloantigen in mice

BACKGROUND

The mechanism of hyporesponsiveness induced by intratracheal (IT) delivery of alloantigen was examined and its effect on cardiac graft survival was assessed in studies in mice.

METHODS

In CBA (H2 ) mice, donor splenocytes were given by IT delivery 7 days before transplantation of a C57BL/10 (H2 ) heart. To determine whether regulatory cells were involved in hyporesponsiveness, splenocytes from mice given IT delivery of alloantigen and antibodies for B7-1, B7-2, or CTLA4 were adoptively transferred to naïve secondary recipients 7 days after delivery; those recipients underwent heart transplantation the same day. Effects on cell proliferation and cytokine production of splenocytes from mice given IT delivery of alloantigen were examined in mixed leukocyte cultures (MLC).

RESULTS

Cardiac graft survival was significantly prolonged in mice given IT delivery of alloantigen (median survival time [MST], 81 days); those given syngeneic splenocytes rejected grafts acutely (MST, 7 days; P<0.05). Adoptive transfer of splenocytes also significantly prolonged survival of cardiac grafts in secondary recipients (MST, 62 days). When B7-1, B7-2, or CTLA4 antibody was combined with IT delivery of alloantigen in the first recipient, all grafts were rejected within 14 days in second recipients after adoptive transfer. In mixed leukocyte cultures, splenocytes from these mice did not respond to alloantigen and production of interleukin-4 and interleukin-10 was increased.

CONCLUSIONS

Donor splenocytes delivered IT induced hyporesponsiveness and regulatory cells in our animal model, and such induction was dependent on B7-1, B7-2, and CTLA4 signals.

Long-term graft survival with or without donor-specific transfusion in cyclosporine era in one haplo-identical living-related renal transplant recipients beyond the first year: a 19-year experience

With improvement in immunosuppressive drugs, the beneficial role of donor-specific blood transfusion (DST) in the preconditioning of renal allograft recipients has been diminished. This retrospective study was conducted to investigate the influence of DST on long-term graft survival in successful one haplotype-mismatched kidney transplantation in the cyclosporine (CsA) era at Iwate Medical University. Between August 1983 and October 1996, 52 one haplotype-mismatched living related first renal transplants were performed. Fifty grafts survived beyond the first year after transplantation. These 50 patients were divided into two groups according to maintenance immunosuppression, 12 kidney graft recipients received azathioprine (AZA), prednisolone (PSL), CsA, and DST, and 38 recipients received AZA, PSL and CsA. Our DST protocol consisted of three transfusions of 30 ml of donor-specific buffy-coat at 4-week intervals, without immunosuppressive coverage. In recipients receiving DST and CsA, the 5-, 10-, and 13-year graft survival rates were 100%, 83%, and 67%, respectively. In recipients without DST, the 5-, 10-, and 13-year graft survival rates were 95%, 74%, and 69%, respectively. There was no significant difference between the two groups in long-term graft survival. In conclusion, DST and CsA combination treatment in our protocol may not induce long standing donor-specific immunologic hyporesponsiveness. Other strategies are expected to induce immunotolerance.

Cellular methods used to evaluate the immune response in transplantation

Cellular assays have been developed to test for various effector, cytotoxic, and regulatory functions of T cells and have been used throughout the history of clinical transplantation to assess the immune profile of solid organ and marrow recipients. One goal of these cellular studies has been to determine if posttransplant changes in the donor antigen-specific cellular response could predict good and poor graft outcome, thereby allowing for individualization of immunosuppression. This review outlines the use of established and newly developed cellular assays to assess the dynamic processes of the posttransplant immune response and to provide insights into the mechanisms involved and potential points for intervention.