Radiotherapy and Immunity – A Mini Review

Beginning in November 1981, eight patients with end stage diabetic nephropathy underwent renal cadaveric transplantation after TLI. Transplantation was done between 2 to 11 days after the end of a fractionated TLI to a total dose of 20 to 30 Gy. During the same observation period, 60 nondiabetic patients with end stage renal disease of different origin also received a cadaveric kidney graft, with a conventional regimen of immunosuppression that consists of anti-lymphocyte-globulin, tapering high doses of prednisone, and azathioprine. In the TLI-treated group only a low maintenance dose of prednisone (15 mg) was given. Immunologic monitoring was performed after transplantation at regular intervals and was compared in both groups. Phytohemagglutinin (PHA)-, concanavalin A (con A)-, and pokeweed mitogen (PWM)-induced blastogenesis, as well as the mixed lymphocyte reaction (MLR) and the cell-mediated lympholysis (CML) decreased progressively during the first months after conventional immunosuppression to 50% of the pretransplantation level, and remained there for the first year after transplantation. These tests were much more impaired after TLI (less than 15% of pre TLI value) and again no recovery occurred during the first year. Natural killer (NK) cell activity progressively decreased from a mean value of 53% lysis before transplantation to 15% lysis at the end of the first year after transplantation in the conventionally treated patients. In TLI-treated patients, however, the NK activity, which declined during irradiation from 46% specific lysis to 12%, recovered rapidly after TLI to reach levels of 35 to 40% of specific lysis from the second month on after TLI. In both groups of patients the ratio of helper-inducer (TH) to suppressor-cytotoxic (TS) lymphocytes, as determined with monoclonal antibodies, progressively declined during the first 2 mo after transplantation to a low value of about 1.2. In TLI-treated patients however, this fall progressed further, so that very low levels (less than 0.6) were noticed from the third month on after TLI. The decline of the TH:TS ratio after TLI is due to an absolute increase in the number of suppressor cells. This is in contrast with the conventionally treated patients, where the low ratio is mainly provoked by a more important decrease of the helper cell population. These changes in the balance between TH and TS subpopulations are more frequently associated with positive functional suppressor cell assays in the TLI-treated patients.(ABSTRACT TRUNCATED AT 400 WORDS)

When BALB/c mice received 17 daily fractions of 2 Gy each of total lymphoid irradiation (TLI, total dose 34 Gy) and 30 X 10(6) C57 B1 bone marrow cells (BM) on the day after the last fraction, stable bone marrow chimerism without signs of graft-vs-host disease (GVHD) was obtained in 84% of the animals. On the contrary, in BALB/c mice receiving only seven fractions of TLI (total dose 14 Gy), all bone marrow grafts were rejected. When the last two fractions of a 14-Gy TLI course were given without shielding the extra lymphatic tissues (combined total lymphoid + total body irradiation, TLBI), chimerism could be induced in 53% of the animals. When this 14-Gy TLBI schedule was used, it was even possible to administer four fractions per day (multiple fractions per day schedule, MFD), thus reducing the overall treatment time to 2 consecutive days. After this concentrated form of TLBI, chimerism was detected in 35% of the animals. As in the 34-Gy TLI schedule, graft-vs-host reaction could not be prevented in the 14-Gy TLBI schedule when spleen lymphocytes (10 X 10(6) were added to the BM inoculum. Leucopenia or suppression of the phytohaemagglutinin (PHA)-induced blastogenesis could not predict which schedule would result in a successful allogeneic bone marrow take. Suppressor cells of the mixed lymphocyte reaction, on the other hand, were only found in the spleen of BALB/c mice treated with the TLI or TLBI schedules, which also resulted in stable bone marrow chimerism.

Total Lymphoid Irradiation

The survival of heterotopic heart allografts was determined in mongrel dogs treated with total lymphoid irradiation (TLI) alone or in combination with other immunosuppressive agents. TLI alone (total dose, 1800 rad) minimally prolonged graft survival as compared with untreated controls. However, marked synergy was observed when TLI was combined with a 10-day post-transplant course of rabbit anti-dog thymocyte globulin (ATG). Approximately 40% of recipients given TLI and ATG showed specific unresponsiveness, as judged by the lack of rejection on serial biopsies for more than 1 yr and the prompt rejection of third party hearts. The addition of post-transplant azathioprine (90 to 180 days) to the TLI and ATG regimen increased the mortality of recipients and reduced the fraction of dogs showing specific unresponsiveness. Infusion of donor bone marrow cells at the time of heart transplantation failed to induce specific unresponsiveness in recipients given TLI alone or TLI in combination with post-transplant methotrexate, cyclosporine A, or ATG. The results indicate that the combination of TLI and a brief course of ATG without marrow transplantation was the most effective regimen for the induction of specific unresponsiveness in mongrel dogs.

Phase I Trial of Total Marrow and Lymphoid Irradiation Transplantation Conditioning in Patients with Relapsed/Refractory Acute Leukemia

Irradiation in solid organ transplantation and the treatment of autoimmune disease

To evaluate the characteristics of cataracts following hematopoietic stem cell transplantation (HSCT), 561 patients without any ocular complications before HSCT were reviewed. Ocular complications occurred in 196 patients (34.9%). Cataract was diagnosed in 45 of 561 patients. The 10-year estimated cataract incidence was 14%. The median onset time was 498 days after transplant (range, 38-4,535 days). The onset of cataracts was later than that of other ocular complications. Phacoemulsification was performed in 13 patients (29%) at a median of 1,028 days after HSCT (range, 375-4,549 days). In 6 of 13 patients (46%) who underwent cataract surgery, visual acuities gradually deteriorated because of the development of posterior capsule opacification. YAG (yttrium-aluminum-garnet) laser posterior capsulotomy successfully recovered their sight without any sequelae. A multivariate analysis revealed that age, acute and chronic graft versus host disease (GVHD), and systemic infection were significant risk factors for cataract, whereas neither steroid nor total body irradiation (TBI)-containing regimens affected the development of cataract. Our results showed that the clinical outcomes of cataract after HSCT are favorable and comparable to those in the general population. Hyperfractionated TBI with eye shielding may be effective for the prevention of cataract.

Effect of total lymphoid irradiation (TLI) on the primary and secondary antibody response to sheep red blood cells

In three different murine models of bone marrow (BM) transplantation the capacity of asialo GM1+ cells to suppress graft-vs-host disease (GVHD) was investigated. In a first model, total lymphoid irradiation (TLI)-treated BALB/C mice were given 1 mg of anti-asialo GM1 antibody. This led to the disappearance of functional suppressor cells after TLI. Injections of anti-asialo GM1 into TLI-treated BALB/C mice before infusion of 30 x 10(6) fully allogeneic (C3H) BM cells, led to a significantly decreased survival rate as compared to TLI-treated mice injected with control serum before BM transplantation (survival 29 and 83%, respectively, at 120 days after transplantation, p = 0.0032 log rank). The mortality of the former group was due to GVHD as 1 degree all dying animals showed clinical and histologic signs of GVHD, 2 degrees all animals were chimeric and 3 degrees mice receiving no or syngeneic BALB/C BM had excellent survival rates excluding BM aplasia or increased susceptibility for infections as reason for the mortality of the allogeneic BM recipients. In a second model, asialo GM1+ cells were removed in vitro from the C3H BM inoculum before injection into lethally irradiated (9 Gy) BALB/C recipients. In mice kept in specific pathogen-free conditions, this procedure resulted into a significant mortality (12/12) as compared to mice receiving BM pretreated with control serum (1/12, p = 0.0001 log rank). When kept in conventional housing, GVHD occurred in both groups but much earlier in the group receiving anti-asialo GM1-treated BM (median survival time 6 vs 46 days for the control mice, p = 0.001 log rank). No animal receiving anti-asialo GM1 and treated with syngeneic BM died, thus excluding toxicity, increased susceptibility to infections, or decreased graft take as a cause of mortality. In a last model, asialo GM1 cells were removed from syngeneic BM in a BM transplantation model in which T cell-depleted syngeneic (BALB/C) and non-T cell-depleted allogeneic (C3H) BM was administered to lethally irradiated (9 Gy) BALB/C mice. Also in this model GVHD-related mortality only occurred in the group of mice receiving syngeneic BM from which asialo GM+ cells were depleted before infusion (3/12). Our experiments thus clearly show that asialo GM1+ cells from both recipient (the TLI model) as well as donor origin (the TBI experiments) can suppress the occurrence of GVHD.

The evolution of Vbeta6-expressing C3H (H2k, Thy 1.2, Mls a-) lymphocytes was investigated in C3H recipients mice pretreated with total body irradiation (TBI) or total lymphoid irradiation (TLI) and infusion of AKR (H2k, Thy 1.1, Mls a+) cells. After TBI (9.5 Gy) all Vbeta6+ Thy 1.2 (C3H) cells, which are capable of reacting against the Mls a antigen that like expressed by AKR mice, were deleted in the thymus and the periphery in stable bone marrow (BM) chimeras obtained by infusion of 5 x 10(6) T-cell-depleted (TCD) AKR BM cells. When, in the opposite combination, 30 x 10(6) C3H spleen cells were infused into TBI-treated AKR cells, all animals developed graft-versus-host disease (GVHD) with no clonal deletion and in contrast, showed an increase in Vbeta6+ C3H cells. After injection of 30 x 10(6) AKR BM cells into TLI-treated C3H mice no C3H cells were detected in the thymus and only a small percentage in the periphery. Within these C3H cells Vbeta6+ cells were only partially deleted and anergized as they did not respond in vitro after stimulation with Mls a+ AKR cells or anti-Vbeta6 mAb. Cells suppressing anti-Mls a-reacting C3H cells were not found. After injection of 15 x 10(6) AKR cells more C3H cells were found in the thymus, but only a minority of Vbeta6+ cells persisted in the periphery of these animals. In conclusion in TBI-prepared chimeras only clonal deletion occurred, whereas in TLI-prepared chimeras both clonal deletion and anergy occurred in maintaining tolerance.

Heart and kidney transplantation using total lymphoid irradiation and donor bone marrow in mongrel dogs

BALB/c mice were treated with total lymphoid irradiation (TLI; 3400 rads) or single-dose, whole-body irradiation (WBI; 550 rads), and the lymph nodes and spleen were assayed for the level of H-2, Ia, Thy-1.2, Lyt-1.2, Lyt-2.2,3.2, and TL-bearing cells by an in vitro cytotoxicity assay. The level of cells bearing all these markers, except for TL, was similar to that observed in normal unirradiated mice. The level of TL+ cells was increased 10- to 20-fold in the TLI-treated mice as compared to WBI-treated mice or normals. The increased number of TL+ cells persisted for at lest 200 days after radiotherapy, and was not dependent upon irradiation of the thymus. However, thymectomy before TLI prevented the subsequent development of peripheral TL+ cells. The findings suggest that this abnormal subpopulation of T cells develops as a result of changes in the peripheral lymphoid tissue microenvironment induced by TLI.

Cellular engineering using allogeneic bone marrow offers an attractive form of therapy for a variety of human immunologic and hematologic disorders. The full potential of allogeneic marrow transplantation is yet to be realized, in large part due to problems associated with graft rejection and graft versus host disease [1–5]. Graft rejection (GR) continues to provide formidable obstacles to allogeneic marrow grafting when cyclophosphamide (CY) alone or CY in combination with other agents is used for pretransplant immunosuppression [1–5]. Graft versus host disease (GVHD) has been reported to occur following all immunosuppression combinations including CY and total body irradiation, reported to date [1–5]. In the present studies, we have attempted to reduce the incidence of GR and GVHD in man using new combinations of CY irradiation, or more recently, CY combined with total lymphoid irradiation. Results to date are the subject of this report.KeywordsAplastic AnemiaGraft RejectionTotal Body IrradiationGraft Versus Host DiseaseFanconi AnemiaThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Total body irradiation and cigarette smoking interact to increase the risk of lung cancer in blood or marrow transplant (BMT) survivors – a BMTSS report

A conditioning regimen for allogeneic hematopoietic cell transplantation (HCT) combining total lymphoid irradiation (TLI) plus anti-thymocyte globulin (ATG) has been developed to induce graft-versus-tumor effects without graft-versus-host disease (GVHD). We compared immune recovery in 53 patients included in a phase II randomized study comparing nonmyeloablative HCT following either fludarabine plus 2 Gy total body irradiation (TBI arm, n = 28) or 8 Gy TLI plus ATG (TLI arm, n = 25). In comparison with TBI patients, TLI patients had a similarly low 6-month incidence of grade II-IV acute GVHD, a lower incidence of moderate/severe chronic GVHD (P = 0.02), a higher incidence of CMV reactivation (P < 0.001), and a higher incidence of relapse (P = 0.01). While recovery of total CD8(+) T cells was similar in the two groups, with median CD8(+) T-cell counts reaching the normal values 40 to 60 days after allo-HCT, TLI patients had lower percentages of naïve CD8 T cells. Median CD4(+) T-cell counts did not reach the lower limit of normal values the first year after allo-HCT in the two groups. Furthermore, CD4(+) T-cell counts were significantly lower in TLI than in TBI patients the first 6 months after transplantation. Interestingly, while median absolute regulatory T-cell (Treg) counts were comparable in TBI and TLI patients, Treg/naïve CD4(+) T-cell ratios were significantly higher in TLI than in TBI patients the 2 first years after transplantation. Immune recovery differs substantially between these two conditioning regimens, possibly explaining the different clinical outcomes observed (NCT00603954).