Chimerism after organ transplantation

Recent evidence suggests that passenger leukocytes migrate after organ transplantation and produce persistent chimerism, which is essential for sustained survival of the allograft. Here, we describe how this hematolymphopoietic chimerism provides an important framework for interpretation of post-transplant phenomena and for initiation of therapeutically oriented transplantation research.

Autologous lymphokine-activated killer cell therapy of lymphoproliferative disorders arising in organ transplant recipients

Lymphoreticular malignancies, collectively called posttransplant lymphoproliferative disorders (PTLD), eventually develop in 2–5% of organ transplant recipients. They frequently undergo regression when immunosuppression is reduced or stopped. This feature has been associated with a previous or de novo Epstein-Barr virus (EBV) infection. We herein describe immunotherapy with autologous lymphokine-activated killer (LAK) cells in seven patients with PTLD (four EBV-positive patients and three EBV-negative patients). Autologous peripheral blood mononuclear cells were obtained by leukapheresis, depleted of monocytes, and cultured in the presence of interleukin 2 for 10 to 11 days. A single dose of 5.2 × 109 to 5.6 × 1010 LAK cells was given intravenously. Systemic interleukin 2 was not administered.

The four patients with EBV+ PTLD had complete tumor regression; two of them developed controllable rejection. Three patients are well 13–16 months after treatment; the fourth patient died of pneumonia 41 days after infusion. Three patients with EBV− lymphomas had no response despite prior evidence that their tumors also were subject to immune surveillance. Two of these three patients died after being given other treatment, and the third patient has persistent tumor.

In conclusion, autologous LAK cell infusion was effective for treatment of four EBV+ organ transplant recipients. LAK cell efficacy for three patients with EBV− PTLD was not evaluable under the management circumstances in which this treatment was utilized.

The future of transplantation: with particular reference to chimerism and xenotransplantation

The assumption for the last third of a century that stem cell-driven hematolymphopoietic chimerism was irrelevant to successful conventional whole organ transplantation has prompted alternative inadequate explanations of organ allograft acceptance. This assumption clouded the biologic meaning of successful organ as well as bone marrow transplantation, and precluded the development of a cardinal principle that accommodated all facets of transplantation. Recognition of this error and the incorporation of the chimerism factor into a two-way paradigm have allowed previous enigmas of organ as well as bone marrow engraftment to be explained. No credible evidence has emerged to interdict this interactive concept. If the two-way paradigm is correct, it will allow the remarkable advances that have been made in basic immunology to be more meaningfully exploited for transplantation, including that of xenografts.

Hydatid cyst in head of pancreas presenting with obstructive jaundice

We report a patient with hydatid cyst in the head of the pancreas who presented with obstructive jaundice. At operation, the cyst was compressing the common bile duct and pancreatic duct. Excision of the cyst with choledochoduodenostomy was performed.

The lost chord: microchimerism and allograft survival

Recent evidence suggests that passenger leukocytes migrate after organ transplantation and produce persistent chimerism, which is essential for sustained survival of the allografts. Here, Thomas Starzl and colleagues argure that this hematolymphopoietic chimerism provides an important framework for the interpretation of basic and therapeutically oriented transplantataion research.

The two-way paradigm of transplantation immunology

The events following organ transplantation require a reciprocal cell interaction which includes both the conventional host-versus-graft reaction and a graft-versus-host component. With all successful transplantation, both graft and recipient become genetic composites. Where donors were available, chimerism has been confirmed in 30-year kidney-recipient survivors, as well as in several liver and lung recipients. A majority of liver recipients have been able to acquire an immunosuppressant-free state after 10-year survival. Animal models suggest that donor-derived cells may exert a tolerogenic effect.

TGF-beta 1 pretreatment impairs the allostimulatory function of human bone marrow-derived antigen-presenting cells for both naive and primed T cells

Transforming growth factor-beta (TGF-beta) exhibits strong antiproliferative effects upon lymphocytes and inhibits many of the effector functions of activated immune cells. However, its influence on the inductive phase of immune responses, and in particular its effect on antigen-presenting cells (APC), has not been well studied. In this investigation, we examined the influence of human TGF-beta 1 on the antigen-presenting function of human bone marrow (BM)-derived APC propagated in liquid culture for 11-17 days in response to granulocyte/macrophage colony-stimulating factor (GM-CSF). These cells were predominantly macrophages, accompanied by a minor population of dendritic cells. TGF-beta 1 had no effect upon the allostimulatory function of vertebral body whole BM cells cultured for 3-5 days in GM-CSF. However, it markedly reduced the allostimulatory capacity of BM-derived APC exposed to the cytokine for the last 3 days of culture. This inhibitory action could not be ascribed to cytokine 'carry-over', or to any consistent changes in the expression of cell surface molecules implicated in antigen presentation (HLA-DR), intercellular adhesion (ICAM-1; CD54), or costimulatory activity (B7-1; CD80). Mechanisms that may underlie the inhibitory action of TGF-beta on APC function and the immunologic and possible clinical implications of the findings are discussed.

Effect of AS101 on bryostatin 1-mediated differentiation induction, cell cycle arrest, and modulation of drug-induced apoptosis in human myeloid leukemia cells

Based upon earlier reports of synergism in cells of lymphoid origin, we have examined interactions between the organotellurium compound AS101 and the protein kinase C (PKC) activator bryostatin 1 with respect to differentiation and Ara-C-induced apoptosis in human myeloid leukemia cells (HL-60). Although preincubation with bryostatin 1 (10 nM) for 24 h significantly increased DNA fragmentation and apoptosis in cells subsequently treated with 10 microM Ara-C for 6 h, this effect was not enhanced by co-administration of AS101 (1.5 microM). However, while exposure of cells to AS101 or bryostatin 1 alone for 72 h was ineffective in inducing cellular maturation, combined treatment resulted in the induction of differentiated features in a subset of cells, manifested by an increase in cell adherence, CD11b expression, cytoplasmic granularity and cell spreading. In addition, cells exposed to the combination of AS101 and bryostatin 1, in contrast to cells incubated with these agents individually, displayed a significant decline in the S-phase and a corresponding increase in the G0/G1 cell populations. These events were accompanied by an increase in protein expression of the cyclin-dependent kinase inhibitor, p21 (WAF1/CIP1/MDA6), and a decline in expression of the c-myc protein. AS101 failed to increase intracellular free Ca2+ ([Ca2+]i) in HL-60 cells, or reverse the profound PKC down-regulation induced by bryostatin 1. Whereas treatment of cells with 1.5 microM AS101 or 10 nM bryostatin 1 for 24 h exerted minimal growth inhibitory effects, combined exposure to these agents reduced colony formation by over 70%. Finally, although addition of AS101 did not potentiate apoptosis induced by the bryostatin 1/Ara-C combination, it did lead to a further reduction in clonogenicity. Together, these findings demonstrate that AS101 partially restores the ability of bryostatin 1 to trigger a differentiation program in an otherwise unresponsive HL-60 cell line, possibly by facilitating bryostatin 1-mediated G1 arrest. They also indicate that AS101 potentiates the antiproliferative effects of bryostatin 1 administered alone or in combination with Ara-C through a mechanism other than, or in addition to, induction of apoptosis.

Tacrolimus pretreatment attenuates preexisting xenospecific immunity and abrogates hyperacute rejection in a presensitized hamster to rat liver transplant model

In the hamster to rat liver transplant model, we determined the efficacy of tacrolimus in attenuating natural xenospecific humoral immunity and in abrogating the hyperacute liver rejection that is produced by presensitizing the Lewis rat recipient. Hamster livers, transplanted orthotopically into naive rats (controls), were rejected with animal death after 6.4.+/- 0.5 (SD) days. The infusion on (day -6) of 1.5 x 10(7) hamster hepatocytes, or of 1.5 x 10(8) nonparenchymal cells (NPC), resulted in hyperacute rejection and death in < or = 1.9 days. However, when the rats were pretreated with 1 mg/kg/day tacrolimus from days -6 to -1, survival of non-presensitized animals was prolonged to 25 +/- 20 days and that of recipients presensitized with hamster hepatocytes to 36 +/- l6 days or with NPC to 32 +/- 1.7 days. The tacrolimus pretreatment significantly reduced the hamster-specific complement-dependent cytotoxic antibodies response directed to liver NPC but not to lymph node cell targets. These observations suggest that the prolongation of survival by appropriately timed treatment with this T cell directed drug model is caused by the inhibition of humoral as well as cellular xenograft rejection.

Impact of donor MHC class I or class II antigen deficiency on first- and second-set rejection of mouse heart or liver allografts

The influence of donor major histocompatibility complex (MHC) class I- or class II-deficiency on the initiation of first- and second-set rejection of mouse heart and liver allografts was examined. C3H (H-2k) mice received heterotopic cardiac or orthotopic liver grafts from unmodified B10 (H-2b), B6 (H-2b), b2m (H-2b; class I deficient) or AB0 (H-2b; class II deficient) donors. Organ survival was also investigated in C3H recipients that had been presensitized by a normal B10 skin graft 2-3 weeks before heart or liver transplantation. The absence of cell surface MHC class I or class II resulted in significant prolongation of primary cardiac allograft survival. Three of seven (43%) MHC class I-deficient, and two of five (40%) class II-deficient heart grafts were accepted indefinitely (survival time > 100 days). Thus both MHC class I and class II molecules appear to be important for the elicitation of first-set rejection in the heart allograft model. All liver allografts survived > 100 days in normal recipients. In C3H recipients that had been presensitized by a B10 skin graft, however, both heart and liver grafts from AB0 (class II deficient) donors underwent accelerated rejection (median survival time [MST] 3 and 4 days, respectively). In contrast, liver grafts from class I-deficient mice (b2m) were still accepted indefinitely by B10 skin-presensitized C3H recipients, whereas class I-deficient hearts survived significantly longer than those from class II-deficient or normal donors. These data demonstrate that the expression of donor MHC class I, and not class II is crucial in initiating second-set organ allograft rejection. In vitro monitoring revealed that at the time of organ transplant, both splenocytes and serum of the skin-presensitized animals displayed high cytotoxicity against AB0 (class II-deficient) but not against b2m (class I-deficient) targets.