The number of CD56^dim NK cells in the graft has a major impact on risk of disease relapse following allo-HSCT

Key Points A stem cell graft NK cell dose below 6.3 × 106 cells per kg associates with risk of disease relapse following T-cell–depleted allo-HSCT. Clinical outcomes of patients undergoing allo-HSCT may be improved by setting an NK cell threshold within donor stem cell grafts.</jats:p

Unique features and clinical importance of acute alloreactive immune responses

Allogeneic stem cell transplantation (allo-SCT) can cure some patients with hematopoietic malignancy, but this relies on the development of a donor T cell alloreactive immune response. T cell activity in the first 2 weeks after allo-SCT is crucial in determining outcome, despite the clinical effects of the early alloreactive immune response often not appearing until later. However, the effect of the allogeneic environment on T cells is difficult to study at this time point due to the effects of profound lymphopenia. We approached this problem by comparing T cells at week 2 after allograft to T cells from autograft patients. Allograft T cells were present in small numbers but displayed intense proliferation with spontaneous cytokine production. Oligoclonal expansions at week 2 came to represent a substantial fraction of the established T cell pool and were recruited into tissues affected by graft-versus-host disease. Transcriptional analysis uncovered a range of potential targets for immune manipulation, including OX40L, TWEAK, and CD70. These findings reveal that recognition of alloantigen drives naive T cells toward a unique phenotype. Moreover, they demonstrate that early clonal T cell responses are recruited to sites of subsequent tissue damage and provide a range of targets for potential therapeutic immunomodulation

Identification of Structural Elements in the Apoptosis Receptor Fas Which Contribute to Down-Regulation by the Adenovirus RID Complex

Adenoviruses contain the E3 region of genes which have immunomodulatory functions. One such protein is RID, the Receptor of Internalisation and Degradation which can target a small subset of structurally diverse membrane receptors for down~ modulation. This study focuses on the interactions(between RID molecules and two such target receptors, the Fas and the epidermal growth factor receptor (EGFR). Removal of Fas from the surface of Adenovirus infected cells protects them from adaptive immune responses. This study primarily focuses on the regions within the Fas receptor that are important for RID mediated down-modulation. The transmembrane and cytoplasmic tail are critical for the regulation, mutant Fas receptors have been generated and we have specifically identified the regions and amino acids involved with binding to RID, in the context of Adenovirus species 2 (Ad2) infection. Similarly, the EGFR is targeted by RID, this thesis studies the ability of Ad2 to target EGFR for down-regulation and destruction.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Human macrophage inflammatory protein-3α/CCL20/LARC/Exodus/SCYA20 is transcriptionally upregulated by tumor necrosis factor-α via a non-standard NF-κB site

AbstractThe 5′-flanking sequences of the human macrophage inflammatory protein-3α/CCL20 gene were cloned and transfected into G-361 human melanoma cells in a luciferase reporter construct. Tumor necrosis factor-α (TNF-α) treatment stimulated luciferase expression, and promoter truncations demonstrated that TNF-α inducibility is conferred by a region between nt −111 and −77, which contains a non-standard nuclear factor-κB (NF-κB) binding site. The requirement for NF-κB was demonstrated as follows: (i) mutations in this NF-κB site abrogated TNF-α responsiveness; (ii) TNF-α activated a construct containing two copies of the CCL20 NF-κB binding site; (iii) overexpression of NF-κB p65 activated the CCL20 promoter; (iv) NF-κB from nuclear extracts of TNF-α-stimulated cells bound specifically to this NF-κB site

CMV reactivation initiates long-term expansion and differentiation of the NK cell repertoire

INTRODUCTION: NK cells play an important role in suppression of viral replication and are critical for effective control of persistent infections such as herpesviruses. Cytomegalovirus infection is associated with expansion of ‘adaptive-memory’ NK cells with a characteristic CD56dimCD16bright NKG2C+ phenotype but the mechanisms by which this population is maintained remain uncertain. METHODS: We studied NK cell reconstitution in patients undergoing haemopoietic stem cell transplantation and related this to CMV reactivation. RESULTS: NK cells expanded in the early post-transplant period but then remained stable in the absence of viral reactivation. However, CMV reactivation led to a rapid and sustained 10-fold increase in NK cell number. The proportion of NKG2C-expressing cells increases on all NK subsets although the kinetics of expansion peaked at 6 months on immature CD56bright cells whilst continuing to rise on the mature CD56dim pool. Phenotypic maturation was observed by acquisition of CD57 expression. Effective control of viral reactivation was seen when the peripheral NK cell count reached 20,000/ml. DISCUSSION: These data show that short term CMV reactivation acts to reprogramme hemopoiesis to drive a sustained modulation and expansion of the NK cell pool and reveal further insight into long term regulation of the innate immune repertoire by infectious challenge

Progression of mycosis fungoides occurs through divergence of tumor immunophenotype by differential expression of HLA-DR.

Immunotherapy is a valuable treatment for many cancer patients, and there is considerable interest in understanding the mechanisms of immune evasion to guide appropriate management. Mycosis fungoides (MF) is a malignant disorder of skin-homing CD4 T cells, and it exhibits a highly variable clinical course during which the tumor-specific immune response may be an important determinant. An unusual feature of MF is that tumor-infiltrating lymphocytes (TILs) must attempt to control a malignant cell from within their own lineage. We obtained skin biopsies and blood from 43 patients with CD4 MF and undertook a detailed phenotypic and functional analysis of CD4 and CD8 T cells. Clonotypic TCRBV staining allowed delineation of malignant and reactive CD4 subsets. CD4 and CD8 TILs displayed a comparable "exhausted" phenotype that was characterized by expression of PD-1 and TIGIT but retained cytotoxic activity and production of interferon-γ and interleukin-17 in early-stage disease. In contrast, tumor cells were much more heterogeneous and were divided into 3 discrete subsets based on differential expression of HLA-DR: "cold" (DR), "exhausted" (DR PD-1), and "evasive" (DR PD-L1) phenotypes. Disease progression was associated with increasing divergence of the tumor phenotype away from that of TILs and reduced functional activity within TILs. These observations reveal that the phenotype and function of TIL populations are constrained at all stages of disease, whereas the tumor evolves discrete phenotypic profiles of escape during clinical progression. The findings should help to direct appropriate immunotherapeutic interventions for individual patients