Chronic lymphocytic leukemia (CLL) is IntroductionThe most common leukemia among white adults, B-cell chronic lymphocytic leukemia (CLL), remains incurable and its pathogenesis poorly defined. 1 Currently no system permits differentiation and long-term growth of CLL cells in vitro; therefore, an in vivo animal model that reproducibly supports engraftment and growth of human CLL cells would help elucidate key features of CLL cell biology and lead to better treatments.Previous attempts to engraft human CLL cells into mice have been hampered for 2 reasons. First, xenogeneic recipients were not sufficiently immune deficient to prevent human cell rejection. [2][3][4][5] Although Dü rig et al 5 successfully transferred CLL cells into nonobese diabetes/severe combined immunodeficiency (NOD/SCID) mice, apparently the level of CLL cell growth was not sufficient to correlate kinetics with essential interactions with different cell subpopulations. Second, optimal engraftment and growth may have been impaired by the inability of a murine microenvironment to support CLL cells in vivo. Indeed, in vitro studies suggest at least 3 cell lineages are involved in CLL survival and growth: lymphoid (T cells 6,7 ), myeloid (monocytes and monocyte-derived nurse-like cells 8 ), and mesenchymal ("stromal cells" 9,10 ).To provide a more physiologic microenvironment for CLL cells within highly immune incompetent recipients, we introduced precursors of human hematopoietic and mesenchymal lineages into NOD/Shi-scid,␥c null (NSG) mice, a NOD/SCID-derived strain that lacks the IL-2 family common cytokine receptor gamma chain gene (␥c), rendering animals completely deficient in lymphocytes, including natural killer (NK) cells. We found activated autologous T cells were essential for leukemia cells to successfully engraft, survive, and proliferate in vivo and to recapitulate cardinal features of human CLL cells: kinetics, CD38 expression, and growth in secondary lymphoid tissues. This adoptive transfer model may facilitate the definition of leukemic and nonleukemic elements involved in the interactions and kinetics of CLL cells in patients. Methods Patients and samplesThe Institutional Review Board and the Institutional Animal Care and Utilization Committee of the North Shore-LIJ Health System sanctioned these studies. After obtaining informed consent, in accordance with the Submitted December 10, 2010; accepted February 17, 2011. Prepublished online as Blood First Edition paper, March 8, 2011 DOI 10.1182 DOI 10. /blood-2010 An Inside Blood analysis of this article appears at the front of this issue.The online version of this article contains a data supplement.The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked ''advertisement'' in accordance with 18 USC section 1734. For personal use only. on June 7, 2019. by guest www.bloodjournal.org From Declaration of Helsinki, we collected blood from 37 CLL patients for whom clinical information, la...

The antibody that we identified was detected in most patients with autoimmune pancreatitis but also in some patients with pancreatic cancer, making it an imperfect test to distinguish between these two conditions.

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Cytotoxic T lymphocyte antigen-4 (CTLA-4) is the major negative regulator of T-cell responses, although growing evidence supports its wider role as an immune attenuator that may also act in other cell lineages. Here, we have analyzed the expression of CTLA-4 in human monocytes and monocyte-derived dendritic cells (DCs), and the effect of its engagement on cytokine production and T-cell stimulatory activity by mature DCs. CTLA-4 was highly expressed on freshly isolated monocytes, then down-modulated upon differentiation toward immature DCs (iDCs) and it was markedly upregulated on mature DCs obtained with different stimulations (lipopolysaccharides [LPS], Poly:IC, cytokines). In line with the functional role of CTLA-4 in T cells, treatment of mDCs with an agonistic anti-CTLA-4 mAb significantly enhanced secretion of regulatory interleukin (IL)-10 but reduced secretion of IL-8/IL-12 pro-inflammatory cytokines, as well as autologous CD4+ T-cell proliferation in response to stimulation with recall antigen purified protein derivative (PPD) loaded-DCs. Neutralization of IL-10 with an anti-IL-10 antibody during the mDCs-CD4+ T-cell co-culture partially restored the ability of anti-CTLA-4-treated mDCs to stimulate T-cell proliferation in response to PPD. Taken together, our data provide the first evidence that CTLA-4 receptor is expressed by human monocyte-derived mDCs upon their full activation and that it exerts immune modulatory effects.

Aging is commonly associated with immune deficiency and dysregulation. The aging of the immune system involves a progressive reduction in naïve T cell output associated with thymic involution and peripheral expansion of oligoclonal memory T cells. We have investigated frequency, phenotype, and function of CD3+CD8+CD28(-)CD25+ T cells in healthy volunteers over a wide age range. We demonstrate that the frequency of CD3+CD8+CD28(-)CD25+ T cells in healthy volunteers increases with age. Peripheral CD3+CD8+CD28(-)CD25+ T cells share phenotypic and functional features with CD3+CD4+CD25+ regulatory T cells (Tregs): In particular, they strongly express CTLA-4 and forkhead box P3. We observed that in vitro, functional titration assays of CD3+CD8+CD28(-)CD25+ T cells show equivalent regulatory function in young and elderly donors, with suppression of proliferation and cytokine production in response to polyclonal T cell stimulation. Finally, CD3+CD8+CD28(-)CD25+ T cells seem to specifically express the CD122 receptor. Altogether, these observations demonstrate an increase in peripheral blood CD8+ Tregs associated with aging.

Celiac disease (CD) is a multifactorial disorder influenced by environmental, genetic and immunological factors. Increasing evidence showed CTLA-4 gene as an important susceptibility locus for autoimmune disorders. A native soluble cytotoxic T-lymphocyte-associated protein-4 (sCTLA-4), lacking of transmembrane sequence, has been described in several autoimmune diseases. We aimed to evaluate the presence of increased sCTLA-4 concentration in the serum of patients with CD and the possible immunoregulatory function. Blood samples were collected from 160 CD patients; sCTLA-4 levels were evaluated by ELISA, western blot and reverse transcription-PCR. The capability of serum sCTLA-4 to modulate T-lymphocyte proliferation in vitro was evaluated by two-way mixed leukocyte reaction assay. We demonstrated high levels of sCTLA-4 in serum of untreated celiac patients. Additionally, we observed that sCTLA-4 concentrations are related to gluten intake and that a correlation between autoantibodies to tissue transglutaminase and sCTLA-4 concentration exists. Moreover, sCTLA-4 levels correlate with the degree of mucosal damage. Conversely, no correlation between sCTLA4 levels and the HLA-related risk was observed. Finally, we show that sCTLA-4 from sera of CD patients displays functional activities. These results strongly suggest a regulation of sCTLA-4 synthesis depending on the presence or absence of dietary gluten and imply a possible immunomodulatory effect on cytotoxic T lymphocyte functions. In gluten-exposed patients, serum sCTLA-4 levels might provide insight about mucosal injury.

CTLA-4, initially described as a membranebound molecule, is a costimulatory receptor transducing a potent inhibitory signal. Increasing evidence shows the CTLA-4 gene to be an important susceptibility locus for autoimmune endocrinopathies and other autoimmune disorders. A soluble form of cytotoxic T-lymphocyte-associated antigen-4 (sCTLA-4) has been established and shown to possess CD80/CD86 binding activity and in vitro immunoregulatory functions. sCTLA-4 is generated by alternatively spliced mRNA. Whereas low levels of sCTLA-4 are detected in normal human serum, increased serum levels are observed in several autoimmune diseases (e.g. Graves’ disease, myasthenia gravis, systemic lupus erythematosus, type 1 diabetes, systemic sclerosis, coeliac disease, autoimmune pancreatitis and primary biliary cirrhosis). The biological significance of increased sCTLA-4 serum levels is not fully clarified yet. On the one hand, it can be envisaged that sCTLA-4 specifically inhibits early T-cell activation by blocking the interaction of CD80/CD86 with the costimulatory receptor CD28. On the other hand, higher levels of sCTLA-4 could compete for the binding of the membrane form of CTLA-4 with CD80/CD86 in the later phases of T-lymphocyte activation, causing a reduction in inhibitory signalling. This double-edged nature of sCTLA-4 to block the binding of CD28 to CD80/CD86 may result in different outcomes during the clinical course of an autoimmune disease.

Xenografting primary tumor cells allows modeling of the heterogeneous natures of malignant diseases and the influences of the tissue microenvironment. Here, we demonstrate that xenografting primary chronic lymphocytic leukemia (CLL) B lymphocytes with activated autologous T cells into alymphoid mice results in considerable CLL B cell division and sizable T cell expansion. Nevertheless, most/all CD5+CD19+ cells are eventually lost, due in part to differentiation into antibody-secreting plasmablasts/plasma cells. CLL B cell differentiation is associated with isotype class switching and development of new IGHV-D-J mutations and occurs via an activation-induced deaminase-dependent pathway that upregulates IRF4 and Blimp-1 without appreciable levels of the expected Bcl-6. These processes were induced in IGHV-unmutated and IGHV-mutated clones by Th1-polarized T-bet+ T cells, not classical T follicular helper (Tfh) cells. Thus, the block in B cell maturation, defects in T cell action, and absence of antigen-receptor diversification, which are often cardinal characteristics of CLL, are not inherent but imposed by external signals and the microenvironment. Although these activities are not dominant features in human CLL, each occurs in tissue proliferation centers where the mechanisms responsible for clonal evolution operate. Thus, in this setting, CLL B cell diversification and differentiation develop by a nonclassical germinal center–like reaction that might reflect the cell of origin of this leukemia.