Claudine Helg

Reconstitution of the immune system after hematopoietic stem cell transplantation in humans

Hematopoietic stem cell transplantation is associated with a severe immune deficiency. As a result, the patient is at high risk of infections. Innate immunity, including epithelial barriers, monocytes, granulocytes, and NK cells recovers within weeks after transplantation. By contrast, adaptive immunity recovers much slower. B- and T-cell counts normalize during the first months after transplantation, but in particular, T-cell immunity may remain impaired for years. During the last decade, much of the underlying mechanisms have been identified. These insights may provide new therapies to accelerate recovery.

Quality of life and social integration after allogeneic hematopoietic SCT

In total, 124 adult patients in remission after allogeneic hematopoietic SCT (HSCT) participated in a cross-sectional study to assess health-related quality of life (HRQL). Assessment of HRQL was carried out using two questionnaires: the (EORTC QLQ-C30) and the Functional Assessment of Cancer Therapy (FACT) with specific modules for BMT (FACT-BMT). Transplanted patients differed from healthy controls in many HRQL-related dimensions in the EORTC QLQ-C30: social functioning 73.4 versus 85.8, P<0.0001; role functioning 74.6 versus 83.3, P<0.004; physical functioning 83.9 versus 89.9, P<0.001; emotional functioning 72.2 versus 82.8, P<0.0001 but were not significant for global HRQL 71.2 versus 75.3, P<0.03. In total, 60% of the patients returned to work after HSCT; 31% part time and 29% full time. Age at HSCT and employment status were significantly associated with HRQL. Other factors such as disease and disease stage and especially the occurrence of late complications did not impact the perception of HRQL. This study suggests that the perception of HRQL after HSCT differs from the general population. Issues to increase work-related capabilities and improve social support need to be addressed.

CD45 isoform phenotypes of human T cells: CD4(+)CD45RA(-)RO(+) memory T cells re-acquire CD45RA without losing CD45RO.

We have studied the alterations in CD45R phenotypes of CD4+CD45RA–RO+ T cells in recipients of T cell‐depleted bone marrow grafts. These patients are convenient models because early after transplantation, their T cell compartment is repopulated through expansion of mature T cells and contains only cells with a memory phenotype. In addition, re‐expression of CD45RA by former CD4+CD45RA– T cells can be accurately monitored in the pool of recipient T cells that, in the absence of recipient stem cells, can not be replenished with CD45RA+ T cells through the thymic pathway. We found that CD4+CD45RA–RO+ recipient T cells could re‐express CD45RA but never reverted to a genuine CD4+CD45RA+RO– naive phenotype. Even 5 years after transplantation, they still co‐expressed CD45RO. In addition, the level of CD45RA and CD45RC expression was lower (∼ 35 %) than that of naive cells. In contrast, the level of CD45RB expression was comparable to that of naive cells. We conclude that CD4+CD45RA–RO+ T cells may re‐express CD45high isoforms but remain distinguishable from naive cells by their lower expression of CD45RA / RC and co‐expression of CD45RO. Therefore, it is likely that the long‐lived memory T cell will be found in the population expressing both low and high molecular CD45 isoforms.

The frequency of pretransplant donor cytotoxic T cell precursors with anti-host specificity predicts survival of patients transplanted with bone marrow from donors other than HLA-identical siblings

Transplantation with bone marrow from other than genotypically HLA-identical donors is associated with an increased incidence and severity of graft-versus-host disease (GvHD). The precise influence of HLA incompatibilities is not easy to analyze as even perfectly matched, HLA-identical unrelated donors might still express HLA differences that remain undetected by conventional typing. To measure T cell activity against serologically detectable and nondetectable HLA antigens, we analyzed the frequencies of CTL precursors (CTLp) between 11 unrelated HLA-matched and five related haploidentical donor/recipient pairs in graft-versus-host direction. Our results show that whenever HLA class I disparities could be identified by serology, high precursor frequencies (1/28,000–1/94,000) were measured. In contrast, in donor/ recipient pairs that differed for class II only, no precursors were detected. CTLp were elevated in two out of eight fully matched donor/recipient combinations. These combinations displayed activities as high (1/21,000; 1/ 52,000) as the combinations that were serologically HLA class I disparate. The incompatibilities detected by the cellular assay were highly significant for the clinical results after transplantation. High CTLp frequencies before transplantation correlated with unfavorable clinical results independent of the incidence of detected HLA differences. Five out of the six patients with high (>1/ 100,000) CTLp frequencies died within 120 days after transplantation. GvHD IV was the cause of death for all (3/5) patients who had received an unmanipulated bone marrow. In the group with intermediate or undetectable CTLp frequencies, eight out of 10 patients are alive, seven (CTLp frequency undetectable) without GvHD more severe than grade II, while one patient (CTLp frequency = 1/180,000) suffered from GvHD grade III. One patient rejected the graft and was rescued by an autologous BMT.

Total body irradiation before allogeneic bone marrow transplantation: is more dose better?

PURPOSE This study was performed to retrospectively assess the potential influence of total-body irradiation (TBI) dose on overall survival in patients undergoing allogeneic bone-marrow transplants (BMT) for hematologic malignancies. METHODS AND MATERIALS Between October 1984 and December 1996, 116 patients were conditioned with high-dose chemotherapy and fractionated TBI before allogeneic BMT. The median age was 34 years (range 3-60). The TBI dose was given in 6 fractions, twice-a-day, over 3 days before BMT. The total dose was 10 Gy in 24 patients, 12 Gy in 66 patients, and 13.5 Gy in 26 patients. RESULTS TBI dose was inversely correlated with overall survival. Five-year survival was 62% for patients conditioned with 10 Gy, 55% for patients conditioned with 12 Gy, and 46% for patients conditioned with 13.5 Gy. Age at BMT was also independently correlated with survival, with the best outcome for patients < 40 years old. CONCLUSION A TBI dose (fractionated) > 10 Gy may not necessarily be associated with a better outcome in patients undergoing allogeneic bone-marrow transplant for hematologic malignancies.

HA-1 and the SMCY-derived peptide fidsyicqv (H-Y) are immunodominant minor Histocompatibility antigens after bone marrow transplantation.

BACKGROUND Allogeneic bone marrow donors can be incompatible at different levels. Even HLA-identical pairs will be still incompatible for numerous minor histocompatibility antigens (mHag). Nevertheless, some incompatibilities are found to be associated with an increased risk of graft-versus-host disease (GVHD), which could be related to the way the immune system recognizes these antigens. METHODS We determined the specificity of cytotoxic T-cell clones isolated during acute GVHD or during bone marrow graft rejection in patients (n=14) transplanted with marrow from donors who were histoincompatible for different minor and/or major histocompatibility antigens. RESULTS We found a clear hierarchy among the different types of histoincompatibilities. In three combinations mismatched for a class I allele, all 27 clones isolated during GVHD were specific for the incompatible HLA molecule. In the 11 class I-identical combinations, 14 different mHags were recognized. The mHag HA-1, known to have a significant impact on the development of GVHD, was recognized in the two HA-1-incompatible combinations. In one of these combinations, which was sex mismatched, all 56 clones analyzed were directed against HA-1, demonstrating the dominance of this mHag. In the four HA-1-compatible, sex-mismatched combinations, the anti-H-Y response was directed against one immunodominant epitope rather than against multiple Y-chromosome-encoded epitopes. All male specific cytotoxic T lymphocytes (n=15) recognized the same high-performance liquid chromatography-purified peptide fraction presented by T2 cells. Moreover, all cytotoxic T lymphocytes tested (n=6) were specific for the SMCY-derived peptide FIDSYICQV, originally described as being the H-Y epitope recognized in the context of HLA-A*0201. CONCLUSIONS Some histocompatibility antigens are recognized in an immunodominant fashion and will therefore be recognized in the majority of mismatched combinations. Only for such antigens, correlations between mismatches and the occurrence of GVHD or graft rejections will be found.

Donor Lymphocyte Infusion for the Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

The results of donor lymphocyte infusion (DLI) for treatment of relapse after bone marrow transplantation (BMT) are reviewed. Durable complete remission can be achieved at the molecular level for a majority (more than 70%) of patients with CML, when treated at early relapse. Results are less favourable for acute leukemias, although useful responses have been reported. Data are scarce though promising for myelodysplastic syndromes and multiple myeloma. Major treatment-associated toxicities are GVHD and bone marrow aplasia. The latter complication can be predicted by evaluating the level of residual donor-derived hematopoiesis. Modification of infused cells (CD8 negative selection or transduction with a suicide gene), addition of peripheral blood stem cells, and early implementation of escalating doses may counteract the complications and increase the response rate. Response rate is variably influenced by the presence of chronic GVHD after initial BMT, T-cell depleted BMT, underlying disease and stage at relapse, and the level of mixed chimerism. DLI is a direct demonstration of the graft-versus-leukemia effect (GVL). Because GVL after BMT is sometimes the predominant cause of cure, it may be advisable in such situations to redirect the conditioning regimens for BMT towards engraftment and less immediate cytotoxicity.

T-cell repertoire complexity after allogeneic bone marrow transplantation

We analyzed the T-cell repertoire in patients transplanted with bone marrow from an HLA identical sibling by determining the TCR diversity through Vbeta-CDR3-size spectratyping with Vbeta/Cbeta- and Vbeta/Jbeta-specific primers. Using the Vbeta/Cbeta primers, we observed limited TCR diversity only in recipients of a T-cell-depleted graft, whereas the TCR diversity of patients transplanted with an unmanipulated graft seemed to be indistinguishable from the one of a normal individual. However, with Vbeta/Jbeta-specific primers, increase of the resolution by approximately 10-fold also allowed the detection of imbalances in the TCR repertoire of recipients of an unmanipulated graft. This demonstrates that when high numbers of T cells are cotransfused with marrow, the TCR repertoire is more complete but still not as complete as in normal individuals, thereby emphasizing the important role of coinfused mature T cells in the restoration of the T-cell compartment after bone marrow transplantation.

Resistant pure red cell aplasia after allogeneic stem cell transplantation with major ABO mismatch treated by escalating dose donor leukocyte infusion

Abstract:  We report a case of pure red cell aplasia (PRCA) following allogeneic stem cell transplantation (SCT) with major ABO mismatch which proved resistant to all standard treatment options such as change in immunosuppressive treatment, high‐dose erythropoietin (EPO) or plasma exchange. We therefore proceeded to administer five cycles of Rituximab therapy, without success. Finally, escalating doses of donor‐derived leukocyte infusion (DLI) resolved the PRCA of our patient 415 d after bone‐marrow transplantation (BMT) and 140 d after the first infusion of donor leukocytes. A review of the literature shows the efficacy of various treatments; the role of DLI and other treatment options are discussed. Furthermore, the underlying pathophysiological mechanisms especially with regard to the role of NK cells in alloreactivity after allogeneic SCT are explained.

Long-term complete responses after 131I-tositumomab therapy for relapsed or refractory indolent non-Hodgkin's lymphoma

We present the long-term results of 18 chemotherapy relapsed indolent (N=12) or transformed (N=6) NHL patients of a phase II anti-CD20 131I-tositumomab (Bexxar®) therapy study. The biphasic therapy included two injections of 450 mg unlabelled antibody combined with 131I-tositumomab once as dosimetric and once as therapeutic activity delivering 75 or 65 cGy whole-body radiation dose to patients with normal or reduced platelet counts, respectively. Two patients were not treated due to disease progression during dosimetry. The overall response rate was 81% in the 16 patients treated, including 50% CR/CRu and 31% PR. Median progression free survival of the 16 patients was 22.5 months. Median overall survival has not been reached after a median observation of 48 months. Median PFS of complete responders (CR/CRu) has not been reached and will be greater than 51 months. Short-term side effects were mainly haematological and transient. Among the relevant long-term side effects, one patient previously treated with CHOP chemotherapy died from secondary myelodysplasia. Four patients developed HAMA. In conclusion, 131I-tositumomab RIT demonstrated durable responses especially in those patients who achieved a complete response. Six of eight CR/CRu are ongoing after 46–70 months.