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Natural killer (NK) cells recognize and may kill malignant cells via their cell surface receptors. Killer cell immunoglobulin-like receptor (KIR) genotypes of donors have been reported to adjust the risk of relapse after allogeneic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia. To test whether non-KIR NK cell receptors have a similar effect, we screened 1,638 genetic polymorphisms in 21 non-KIR NK cell receptor genes for their associations with relapse and graft-versus-host disease (GVHD) after HSCT in 1,491 HSCT donors (from Finland, the UK, Spain, and Poland), divided into a discovery and replication cohort. Eleven polymorphisms regulating or located in CD226, CD244, FCGR3A, KLRD1, NCR3, and PVRIG were associated with the risks for relapse and GVHD. These associations could not be confirmed in the replication cohort. Blood donor NK cells carrying alleles showing genetic protection for relapse had a higher in vitro NK cell killing activity than non-carriers whereas those with alleles genetically protective for GVHD had lower cytotoxicity, potentially indicating functional effects. Taken together, these results show no robust effects of genetic variation in the tested non-KIR NK cell receptors on the outcome of HSCT., (© 2024. The Author(s).)

Despite detailed human leukocyte antigen (HLA) matching and modern immunosuppressive therapy, severe graft-versus-host disease (GvHD) remains a major hurdle for successful allogeneic hematopoietic stem cell transplantation (HSCT). As the genetic diversity in GvHD complicates the systematic discovery of associated variants across populations, we studied 122 GvHD-associated single nucleotide polymorphisms (SNPs) in 492 HLA-matched sibling HSCT donor-recipient pairs from Finland and Spain. The association between these candidate SNPs and grade III-IV acute GvHD and extensive chronic GvHD was assessed. The functional effects of the variants were determined using expression and cytokine quantitative trait loci (QTL) database analyses. Clear heterogeneity was observed in the associated markers between the two populations. Interestingly, the majority of markers, such as those annotated to IL1, IL23R, TLR9, TNF, and NOD2 genes, are related to the immunological response by monocytes-macrophages to microbes, a step that precedes GvHD as a result of intestinal lesions. Furthermore, cytokine QTL analysis showed that the GvHD-associated markers regulate IL1β, IFNγ, and IL6 responses. These results support a crucial role for the anti-microbial response in GvHD risk. Furthermore, despite apparent heterogeneity in the genetic markers associated with GvHD, it was possible to identify a biological pathway shared by most markers in both populations.

Minor histocompatibility Ags (mHags) have been implicated in the pathogenesis of GVHD after allogeneic hematopoietic stem cell transplantation (HSCT). Uridine diphospho-glucuronosyltransferase 2B17 (UGT2B17) gene deletion may act as a mHag and its association with acute GVHD (aGVHD) has been described. We retrospectively studied the clinical impact of a UGT2B17 mismatch in a cohort of 1127 patients receiving a HSCT from an HLA-identical sibling donor. UGT2B17 mismatch was present in 69 cases (6.1%). Incidence of severe aGVHD was higher in the UGT2B17 mismatched pairs (22.7% vs 14.6%), but this difference was not statistically significant (P: 0.098). We did not detect differences in chronic GVHD, overall survival, relapse-free survival, transplant-related mortality or relapse. Nevertheless, when we analyzed only those patients receiving grafts from a male donor (616 cases), aGVHD was significantly higher in the UGT2B17 mismatched group (25.1% vs 12.8%; P: 0.005) and this association was confirmed by the multivariate analysis (P: 0.043; hazard ratio: 2.16, 95% confidence interval: 1.03-4.57). Overall survival was worse for patients mismatched for UGT2B17 (P: 0.005). We conclude that UGT2B17 mismatch has a negative clinical impact in allogeneic HSCT from HLA-identical sibling donors only when a male donor is used. These results should be confirmed by other studies.

Allo-SCT has a strong curative potential for AML patients mainly due to a GVL effect. Unfortunately, GvL and GVHD are intimately linked. IFN regulatory factor-3 (IRF3), by modulating innate immune reactions, could impact on the incidence and intensity of GVL and GVHD. We analyzed two gene variants in IRF3 (rs7251 and rs2304205) on the clinical outcome of 249 AML patients submitted to HLA-identical sibling allo-SCT. Patients with a donor carrying the dominant GG gene variant in rs7251 had, as compared with GC and CC variants, a lower acute GVHD (aGVHD) III-IV incidence (4% vs 11% vs 27%; P=0.0078), a higher relapse incidence (49% vs 35% vs 26%; P=0.018), and lower TRM (7% vs 24% vs 18%; P=0.0065). In functional studies, the GG variant was associated with lower production of IFN-γ, decreased lymphocyte proliferation after antigen presentation by DCs, and lower cytotoxic response of mature natural killer cells. Patients carrying the AA dominant variant in rs2304205 had higher relapse incidence (50% vs 39% vs 18%, P=0.0068). The presence of both variants (GG in rs7251 and AA in rs2304205) in donors and patients resulted in a stronger clinical impact.

Development of high-grade non-Hodgkin's lymphoma is a possible complication of chronic lymphocytic leukaemia/small lymphocytic lymphoma, known as Richter's syndrome (RS). Treatment for RS includes systemic chemotherapy and, recently, allogeneic stem cell transplantation (SCT). We describe a patient with B-chronic lymphocytic leukaemia who developed RS 4 months after allogeneic SCT from an HLA-identical sibling. The RS presented with systemic symptoms, lymphadenopathy, pancytopenia and serum lactate dehydrogenase elevation. The patient was treated with immunosuppressive drug withdrawal and a donor lymphocyte infusion (DLI) of 1 x 10(7) CD3/kg, leading to the disappearance of all symptoms and the attainment of complete donor chimerism. After 18 months of the therapeutic DLI, the patient continues in complete remission.

T cell depletion of the graft increases graft failure and relapse rate in allogeneic PBSC transplantation. Delayed lymphocyte add-back after T cell-depleted transplants might prevent these complications. We present 22 consecutive allogeneic PBSC transplants from related histocompatible donors with positive selection of CD34+ cells. Recipients received prophylactic donor lymphocyte infusions (DLI) depending on their risk of relapse and of developing GVHD. Patients were considered at high risk of relapse with AML > first CR, ALL > second CR, and CML in accelerated or blastic phase. Patients were considered at high risk of developing GVHD if older than 35 years, or with a donor sensitized through previous pregnancy or blood transfusion. Patients at high risk of relapse and low risk of GVHD were scheduled to receive three DLI. Patients at low risk of relapse and high risk of GVHD did not receive DLI. The remaining patients were scheduled to receive two DLI. The DLI were administered on days +28 (2 x 10(5)/kg), +60 (2 x 10(5)/kg) and +90 (2 x 10(6)/kg) after transplant. G-CSF mobilized peripheral stem cells from healthy donors were positively selected by an immunomagnetic method. The mean CD34+ cells and CD3+ cells infused were 4.4 x 10(6)(range 1.9-10.6) and 0.085 x 10(5) (range 0.01-0.67). Cyclosporin A was given to prevent GVHD. All the patients engrafted. Twenty-two prophylactic DLI were performed in 12 patients: seven developed acute GVHD (one case grade III-IV) and none presented pancytopenia. At a mean follow-up of 585 days (range 89-1103), 14 patients were alive in CR, one patient was alive in relapse, four patients had died of relapse and three had died of transplant-related complication. Individually adjusted prophylactic DLI at the doses we used with an escalating schedule allowed an acceptable GVHD rate and a good engraftment of donor hematopoiesis.

In a retrospective study, we compared 15 patients who received cyclosporine (CsA), methotrexate (MTX) and prednisone (PDN) and 15 patients who received CsA-MTX for GVHD prophylaxis after allogeneic BMT (HLA-identical sibling (n = 22), related one HLA mismatch (n = 1), unrelated matched donors (n = 6), unrelated one HLA mismatch (n = 1)). The primary objectives of this study were to compare the incidence of GVHD and post-transplantation complications. Secondary objectives were to compare relapse rate, transplant-related mortality and overall survival. The incidence of acute GVHD grade III-IV was similar between the two groups (P = 0.66), as was the incidence of chronic GVHD (P = 0.67). Incidence of arterial hypertension was significantly higher in patients who received prophylactic PDN, (P = 0.03) and more insulin treatment was required in this group (P = 0.003). We observed no differences in the incidence of infections or upper digestive tract bleeding. Musculoskeletal complications appeared earlier in the group which received PDN. With a median follow-up of 4.4 years, patients in the CsA-MTX group had better overall survival, 46.7% vs 13.3% (P = 0.026). Relapse was a more frequent cause of death in the CsA-MTX group, whereas procedure-related mortality was more frequent in the CsA-MTX-PDN group (P = 0.013). These results suggest that prophylactic prednisone when combined with cyclosporine and methotrexate adds no benefit in acute or chronic GVHD prevention and may increase the morbidity of allogeneic transplantation. Corticosteroids may be reserved for GVHD treatment.

HLA matching in bone marrow transplantation has an important role in determining successful outcome. However HLA typing of both potential related and unrelated donors can be both time-consuming and laborious, and does not always resolve accurately the true level of histocompatibility. We have utilised a method, reference strand mediated conformation analysis (RSCA), which is technically simple and allows high resolution matching for all HLA loci, for the typing of 48 patients and their potential 120 donors. The results indicate that RSCA can detect many mismatches that are not routinely identified by conventional HLA typing methods. In addition, RSCA can be applied for the simultaneous analysis of multiple potential BM donor samples in order to quickly identify the best match for each patient.

Based on previous experiences in animals and humans, low doses of CD8+ lymphocytes infused together with the marrow graft seem to enhance engraftment after allogeneic T cell-depleted marrow transplantation. From April 1994 to February 1997, 12 patients with chronic myelogenous leukemia in first chronic phase receiving a bone marrow transplant (BMT) from an HLA-identical sibling were included in a pilot study of T cell subset depletion. Total depletion of CD4+ cells of the marrow graft and partial depletion of CD8+ cells was performed by immunomagnetic separation. In order to improve the engraftment rate, we infused a low fixed number of CD8+ lymphocytes (0.25 x 10(6)/kg). All the patients were at high risk of developing acute graft-versus-host disease (GVHD), with a recipient age of >30 years, and/or donor sensitized by previous pregnancies or transfusions. All of them received cyclosporin A and methotrexate post-BMT. No graft failure was observed. The grade III-IV GVHD rate was 16.6%, and the actuarial survival at 3 years is 81.8%. Immunological recovery showed persistent CD8+ HLA-DR+ lymphocytosis 8 months after transplant. Relapses were not observed. This experience shows the importance of CD8+ cells to ensure correct engraftment, decreasing the GVHD rate.

TNF-alpha (Tumor necrosis factor-alpha) is involved in many immunological and inflammatory processes, and might be expected to play an important role in the development of BMT-related complications. Triple therapy (pentoxifylline, ciprofloxacin and prednisone) with known anti-TNF activity was tested in 37 patients undergoing a hematopoietic progenitor transplant (HPT). A control group of 16 patients with similar characteristics was selected among consecutive patients receiving a HTP in a neighboring center who did not receive anti-TNF prophylaxis. Major transplant-related complications were registered (VOD, acute GVHD, infectious episodes, renal failure and mucositis) and survival status. TNF plasma concentrations were determined by ELISA, and pentoxifylline plasma concentrations were determined by HPLC. Among patients treated with pentoxifylline (PTX), ciprofloxacin and steroids, no difference in the mean survival time was observed compared with the control group. The incidence of procedure-related death up to day +35 was 11% in the study group and 6% in the control group. In spite of a tendency to a lower incidence of mucositis there was a higher incidence of infections (positive blood cultures) in the study group (49%) than in the control group (16.7%) (P = 0.16). This difference achieved statistical significance in patients receiving an allogeneic HPT (P = 0.05). It is likely that the use of steroids in the early period after transplant increases infectious episodes and makes control of GVHD difficult. The combined administration of steroids with pentoxifylline and ciprofloxacin has not proved beneficial in preventing mucositis, renal failure, VOD or GVHD, or in improving patient survival.

Neurological complications are not usually considered among the most important complications that may appear after allogeneic bone marrow transplantation (BMT). We have analyzed the occurrence of neurological manifestation in 27 recipients of allogeneic BMT. Ten patients (37%) developed neurological symptoms, and 14 episodes were registered. The most frequent manifestations were due to the use of cyclosporin A or prednisone for prophylaxis or treatment of graft-versus-host disease (GVHD). Cerebrovascular events (infarction or hemorrhage) and CNS infections were the most severe complications: they represented 26% of cause of death in our series. In conclusion, neurological complications are frequent in these patients, and represent an important cause of morbidity and mortality.

We report a young woman with acute promyelocytic leukemia who showed primary resistance to chemotherapy and who responded to ATRA treatment. During the neutropenic period she developed Curvularia sp infection and was finally successfully consolidated with autologous bone marrow transplantation.