Addition of Anti-thymocyte Globulin in Allogeneic Stem Cell Transplantation With Peripheral Stem Cells From Matched Unrelated Donors Improves Graft-Versus-Host Disease and Relapse Free Survival.

Anti-thymocyte globulin (ATG) is commonly used to prevent graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). To evaluate the impact of ATG as part of the GvHD prophylaxis in our institution, we report the outcome of 415 patients with matched unrelated donors (MUD) transplanted for hematological malignancies with or without ATG from 2005 to 2019 at Oslo University Hospital, Norway. The following groups were compared: (1) 154 patients transplanted with peripheral blood stem cells (PBSC) without ATG 2005-2014. (2) 137 patients transplanted with bone marrow stem cells (BMSC) 2005-2019. (3) 124 patients transplanted with PBSC and ATG (PBSC + ATG) 2014-2019. Three years survival was similar in the groups, 61% following allografting with PBSC, 54% with BMSC, and 59% with PBSC + ATG. Acute GvHD grade III-IV was 14%, 14%, and 7%; chronic GvHD was 81%, 32, and 26%; and extensive cGvHD 44%, 15%, and 6% in the corresponding groups. Both acute and chronic GvHD were significantly reduced in the PBSC + ATG-versus the PBSC group (p < 0.05 and p < 0.001 respectively).Transplant-related mortality (TRM) was 33%, 25%, and 17% (p = 0.18). Graft versus host disease and relapse free survival (GRFS) at 3 years was 43 %, 43%, and 64% in the groups. Adding ATG to the GvHD prophylaxis regimen of MUD allo-HSCT with PBSC resulted in a substantial reduction of both acute and chronic GvHD without compromising the disease control, reflected in a superior 3 years GRFS.

The CD34+ Cell Dose Matters in Hematopoietic Stem Cell Transplantation with Peripheral Blood Stem Cells from Sibling Donors.

The effect of CD34+ cell dose in allogeneic hematopoietic stem cell transplantation (HSCT) on overall survival (OS) and incidence of acute and chronic graft-versus-host disease (GvHD) has not been established and few studies have been performed. Our single center analysis included 189 patients with hematological malignancies who received peripheral blood stem cell (PBSC) grafts from sibling donors. Myeloablative conditioning was used in 88 cases and 101 received reduced intensity conditioning. The median CD34+ cell dose was 5.6 × 106/kg (0.6-17.0). In the multivariate analysis, a CD34 cell dose of 6-7 × 106/kg was associated with better OS and lower transplant-related mortality (TRM), while a dose of <5 × 106/kg led to increased relapse and reduced chronic GVHD (cGVHD). A high CD34 cell-dose (>6.5 × 106/kg) correlated with less acute GVHD (aGVHD) II-IV. We conclude that the CD34 cell dose has an impact on the outcome of HSCT from sibling donor PBSCs.

Targeting B cell leukemia with highly specific allogeneic T cells with a public recognition motif.

The possibility that allogeneic T cells may be targeted to leukemia has important therapeutic implications. As most tumor antigens represent self-proteins, high-avidity tumor-specific T cells are largely deleted from the repertoire of the patient. In contrast, T cells from major histocompatibility complex (MHC)-mismatched donors provide naïve repertoires wherein such cells have not been systematically eliminated. Yet, evidence for peptide degeneracy or poly-specificity warrants caution in the use of foreign human leukocyte antigen (HLA) or peptide complexes as therapeutic targets. Here, we cocultured HLA-A(*)0201-negative T cells with autologous dendritic cells engineered to present HLA-A(*)0201 complexed with a peptide from the B cell antigen CD20 (CD20p). HLA-A(*)0201/CD20p pentamer-reactive CD8(+) T cells were readily obtained from all donors. The polyclonal cells showed exquisite peptide and MHC specificity, and efficiently killed HLA-A(*)0201-positive B cells, including primary chronic lymphocytic leukemia cells. The T cell receptor (TCR) sequences displayed a novel type of conservation, with extensive homology in the TCR ß chain complementarity-determining region 3 and in J, but not V, region. This is surprising, as the donors were HLA disparate and their TCR repertoires are expected to show little overlap. The results demonstrate the first public recognition motif for an allogeneic HLA/peptide complex. The allo-restricted T cells or TCRs could provide graft-versus-leukemia in the absence of graft-versus-host disease.

Dendritic cells engineered to express defined allo-HLA peptide complexes induce antigen-specific cytotoxic T cells efficiently killing tumour cells.

Most tumour-associated antigens (TAA) are non-mutated self-antigens. The peripheral T cell repertoire is devoid of high-avidity TAA-specific cytotoxic T lymphocytes (CTL) due to self-tolerance. As tolerance is major histocompatibility complex-restricted, T cells may be immunized against TAA presented by a non-self human leucocyte antigen (HLA) molecule and transferred to cancer patients expressing that HLA molecule. Obtaining allo-restricted CTL of high-avidity and low cross-reactivity has, however, proven difficult. Here, we show that dendritic cells transfected with mRNA encoding HLA-A*0201, efficiently present externally loaded peptides from the antigen, Melan-A/MART-1 to T cells from HLA-A*0201-negative donors. CD8(+) T cells binding HLA-A*0201/MART-1 pentamers were detected already after 12 days of co-culture in 11/11 donors. The majority of cells from pentamer(+) cell lines were CTL and efficiently killed HLA-A*0201(+) melanoma cells, whilst sparing HLA-A*0201(+) B-cells. Allo-restricted CTL specific for peptides from the leukaemia-associated antigens CD33 and CD19 were obtained with comparable efficiency. Collectively, the results show that dendritic cells engineered to express defined allo-HLA peptide complexes are highly efficient in generating CTL specifically reacting with tumour-associated antigens.

Bacteriology of normal and infected conjunctiva.

The conjunctivas of 273 inflamed eyes were cultured by both aerobic and anaerobic techniques. Isolations were obtained from 267 (97.8%) of the eyes. Aerobic organisms were isolated from 237 (86.8%) of the conjunctivas. Staphylococcus aureus from 63 (23.1%) of the diseased eyes was the aerobic pathogen most often isolated. Anaerobic bacteria were isolated from 172 (63.0%) of the conjunctivas. Propionibacterium acnes was isolated from 126 (46.2%) of the conjunctivas, and Peptostreptococcus species were isolated from 80 (29.3%) of the conjunctivas. Comparison with the bacteriology of 96 normal eyes showed that anaerobes play a much greater role as etiological agents of conjunctivitis than formerly believed. When anaerobic bacteria were isolated, they appeared on the average in 7 days, indicating that they may be missed by ordinary bacteriological culturing.