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T and B lymphocyte subsets have been not univocally associated to Graft-versus-host disease (GVHD) and relapse of hematological malignancies after stem cell transplantation (SCT). Their sequential assessment together with B and T cell neogenesis indexes has been not thoroughly analysed in relation to these changing and interrelated immunologic/clinic events yet. Lymphocyte subsets in peripheral blood (PB) and B and T cell neogenesis indexes were analysed together at different time points in a prospective study of 50 patients. Principal component analysis (PCA) was used as first step of multivariate analysis to address issues related to a high number of variables versus a relatively low number of patients. Multivariate analysis was completed by Fine-Gray proportional hazard regression model. PCA identified 3 clusters of variables (PC1-3), which correlated with acute GVHD: PC1 (pre-SCT: KRECs≥6608/ml, unswitched memory B 44%, CD8+TCM cells>4%; HR 1.9, p = 0.01), and PC3 (at aGVHD onset: CD4+TEMRA69%, switched memory CD19+ = 0 cells and KRECs

Background A normal number of T-cell receptor excision circles (TRECs) and K-deleting recombination excision circles (KRECs) is considered a biomarker for adequate new T- and B-cell production. In newborns, detection of TRECs and KRECs by real time PCR from dried blood spotted on filter paper is used for the screening of severe immunodeficiency. In adults, elderly and during diseases, where the number of TRECs is lower than in newborns and children, a large amount of DNA and a sensitive method of amplification are necessary to identify newly produced lymphocytes. Methods DNA was prepared from blood of 203 healthy adults (range: 18–91 years old) absorbed for 10 s on flocked swabs and let to dry, or from peripheral blood mononuclear cells. DNA was subjected to digital PCR and to well established conventional real time PCR-based method using TREC- and KREC-specific primers and probes. The number of TRECs and KRECs was expressed per mL of blood. Statistical analysis was performed by nested ANOVA, Pearson coefficient of determination, and by linear regression tests. Results The novel method for the storage of dried blood on nylon flocked swabs and the use of digital PCR allow quantification of TRECs and KRECs with high degree of sensitivity, specificity, accuracy, and precision. TRECs and KRECs were amplified by digital PCR in all tested blood samples, including those obtained from elderly individuals (>70 years old) and that were negative by real time PCR. Furthermore, values of TRECs and KRECs obtained by digital PCR were in the range of those acquired by real time PCR. Conclusions Our findings demonstrate that DNA isolation from dried blood on flocked swabs followed by digital PCR-based analysis represents a useful tool for studying new lymphocyte production in adults and elderly individuals. This suggests the potential use of the methodology when monitoring of clinical variables is limited by the number of molecules that can be amplified and detected, such as in patients with immunodeficiency or under immunosuppressive therapies. Electronic supplementary material The online version of this article (doi:10.1186/s12967-017-1169-9) contains supplementary material, which is available to authorized users.

Herein we dissect mechanisms behind the dissemination of cancer cells from primary tumor site to the bone marrow, which are necessary for metastasis development, with a specific focus on multiple myeloma. The ability of tumor cells to invade vessels and reach the systemic circulation is a fundamental process for metastasis development; however, the interaction between clonal cells and the surrounding microenvironment is equally important for supporting colonization, survival, and growth in the secondary sites of dissemination. The intrinsic propensity of tumor cells to recognize a favorable milieu where to establish secondary growth is the basis of the “seed and soil” theory. This theory assumes that certain tumor cells (the “seeds”) have a specific affinity for the milieu of certain organs (the “soil”). Recent literature has highlighted the important contributions of the vascular niche to the hospitable “soil” within the bone marrow. In this review, we discuss the crucial role of stromal cells and endothelial cells in supporting primary growth, homing, and metastasis to the bone marrow, in the context of multiple myeloma, a plasma cell malignancy with the unique propensity to primarily grow and metastasize to the bone marrow.

Combination of chemotherapy and immunotherapy to increase the effectiveness of an antitumor immune response is currently regarded as an attractive antitumor strategy. In a pilot clinical trial, we have recently documented an increase of melanoma antigen A (Melan-A)–specific, tumor-reactive, long-lasting effector-memory CD8+ T cells after the administration of dacarbazine (DTIC) 1 day before peptide vaccination in melanoma patients. Global transcriptional analysis revealed a DTIC-induced activation of genes involved in the immune response and leukocyte activation. To identify the possible mechanisms underlying this improved immune response, we have compared the endogenous and the treatment-induced anti–Melan-A response at the clonal level in patients treated with the vaccine alone or with DTIC plus vaccine. We report a progressive widening of T-cell receptor (TCR) repertoire diversity, accompanied by high avidity and tumor reactivity, only in Melan-A–specific T-cell clones of patients treated with chemoimmunotherapy, with a trend toward longer survival. Differently, patients treated with vaccine alone showed a tendency to narrowing the TCR repertoire diversity, accompanied by a decrease of tumor lytic activity in one patient. Collectively, our findings indicate that DTIC plus vaccination shapes the TCR repertoire in terms of diversity and antitumor response, suggesting that this combined therapy could be effective in preventing melanoma relapse. Cancer Res; 70(18); 7084–92. ©2010 AACR.

Background: As new biomarkers are validated and their significance in the natural history of specific diseases is established, these technologies can be rapidly transferred to clinical application. Since it has been shown that a single post-interferon-β (IFNβ) injection measurement of myxovirus-protein-A (MxA) mRNA correlates with IFNβ bioactivity in IFNβ treated patients with multiple sclerosis (MS), we had previously validated an assay for its quantification. Methods: We introduced a real-time PCR relative quantification assay into routine clinical practice and measured MxA mRNA expression in 564 samples from 500 unselected IFNβ treated MS patients over a 4-year period. Results: We confirmed that the assay is reproducible over time, and found that the percentage of patients lacking MxA mRNA induction is comparable to that described in studies performed worldwide after patient selection by pre-screening for the presence of anti-IFNβ antibodies. Conclusions: In view of its simplicity and reproducibility, this MxA assay is an alternative to anti-IFNβ antibody determinations for use in routine clinical practice. Clin Chem Lab Med 2010;48:1235–8.

A major problem in the field of stem cell transplantation is the difficulty to monitor the efficacy of immune reconstitution. By modifying the widely used method of measuring T-cell receptor excision circles (TRECs) and the recently proposed kappa-deleting recombination excision circles (KRECs) assay, we set up a duplex Real-Time PCR that allowed the simultaneous quantification of newly produced T and B cells in children with primary immunodeficiency undergone to transplantation. We found that lymphocyte recovery involves the mobilization of both new T and B cells from production and maturation sites, and that the increase of TRECs and KRECs can be or strictly associated or independent one from the other. Some patients showed a "lymphocyte rebound" which is followed by a progressive decrease of newly produced T and B lymphocytes starting about 2years after transplantation. In other patients, TRECs and KRECs number remained very low for the entire period of study.

Reduced CD4+ lymphocytes have been recently found in peripheral blood of children with active opsoclonus-myoclonus syndrome. The authors identified 2 children who recovered from this syndrome, one of whom showed reduced CD4+ lymphocytes 2 years after the disease onset. Except for a decrease of "naive" CD45RA+ CD4+ population and a mild restriction of T-cell heterogeneity in this patient, probably related to the immune response to viral infections, no alterations of T-cell homeostasis and function were found in either child. Therefore, the decrease of CD4+ cells may persist after clinical recovery, but the causes of this abnormality cannot be ascribed to intrinsic T-cell defects.

The presence of myxovirus resistance protein A (MxA) RNA was studied in 55 febrile children with primary immunodeficiency, 27 of whom underwent hematopoietic cell transplantation, and in 28 age-matched controls. The level of MxA RNA was above the cutoff, established as the 95th percentile found in controls, with primary immunodeficiency either undergoing transplantation or not in febrile patients, and with a documented diagnosis of infection by adenovirus, cytomegalovirus, Epstein-Barr virus, respiratory syncytial virus, and rotavirus. The presence of rare viral infections, unrecognized among those that more frequently occur in patients with primary immunodeficiency and in patients undergoing transplantation, may explain the high MxA RNA levels observed in some patients with fever but undetectable genomes or antibodies for the more common viruses. The level of MxA in febrile patients with acute graft versus host disease was below the cutoff, with a median level comparable with that observed in patients with primary immunodeficiency, who did not undergo transplantation and were without fever and infections, but significantly lower compared with controls. The level of MxA was well correlated with viral infections in follow-up samples. These data indicate that the measurement of MxA RNA is simple and useful to detect viral infections and in distinguishing them from acute graft versus host disease after allogeneic cell transplantation.

The lack of adenosine deaminase (ADA) leads to the accumulation of toxic metabolites, resulting in SCID. If the disease is left untreated, it is likely to have a fatal outcome in early infancy. Because hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy with pegylated bovine ADA (PEG-ADA) are both provided in our hospital, we undertook a retrospective longitudinal comparative study of the extent of lymphocyte recovery in two groups of treated ADA-SCID children. Together with classical immunological parameters, we quantified the output of the new B and T cells from the production sites using the κ-deleting recombination excision circle and TCR excision circle assay, and we monitored T cell repertoire diversification. We found that immune reconstitution was different following the two treatments. The stable production of κ-deleting recombination excision circle+ lymphocytes sustained an increase in B cell number in HSCT-treated patients, whereas in PEG-ADA–treated patients, it was accompanied by a significant and progressive decrease in circulating CD19+ lymphocytes, which never reached the levels observed in age-matched children. The mobilization of TCR excision circle+ cells, though lower than in controls, was stable with time after HSCT treatment, leading to a constant peripheral T cell number and to the diversification of the T cell repertoire; however, it was compromised in children receiving prolonged PEG-ADA therapy, whose T cells showed progressively narrowing T cell repertoires.

Background: The immune defects occurring in chronic lymphocytic leukemia are responsible for the frequent occurrence of infections and autoimmune phenomena, and may be involved in the initiation and maintenance of the malignant clone. Here, we evaluated the quantitative defects of newly produced B and T lymphocytes. Methods: The output of B and T lymphocytes from the production and maturation sites was analyzed in chronic lymphocytic leukemia patients and healthy controls by quantifying kappa-deleting recombination excision circles (KRECs) and T-cell receptor excision circles (TRECs) by a Real-Time PCR assay that simultaneously detects both targets. T-lymphocyte subsets were analyzed by six-color flow cytometric analysis. Data comparison was performed by two-sided Mann-Whitney test. Results: KRECs level was reduced in untreated chronic lymphocytic leukemia patients studied at the very early stage of the disease, whereas the release of TRECs + cells was preserved. Furthermore, the observed increase of CD4 + lymphocytes could be ascribed to the accumulation of CD4 + cells with effector memory phenotype. Conclusions: The decreased number of newly produced B lymphocytes in these patients is likely related to a homeostatic mechanism by which the immune system balances the abnormal B-cell expansion. This feature may precede the profound defect of humoral immunity characterizing the later stages of the disease. Background Profound defects of both humoral and cell-mediated immunity have been described in patients with chronic lymphocytic leukemia (CLL), a disease characterized by the accumulation of mature, malignant, monoclonal B lymphocytes in blood, lymph nodes, spleen, liver, and bone marrow [1]. The disease is characterized by the presence of immune defects, responsible for the frequent occurrence of infections and autoimmune phenomena, that may be involved in the initiation and maintenance of the malignant clone. The immune abnormalities include reduced immunoglobulin (Ig) levels, as well as qualitative and quantitative defects of B, T, NK cells, neutrophils, and the monocyte/

The immunomodulating activity of glatiramer acetate on T-cells of multiple sclerosis patients has only been partially clarified. The objective of this work was to investigate whether glatiramer acetate modifies thymic release of newly produced T-cells and the peripheral composition of the T-cell repertoire. T-cell receptor excision circles, thymic naive (CD4+CD45RA+CCR7 +CD31+) T helper cells, and central (CD4+CD45RA -CCR7+) and effector (CD4+CD45RA-CCR7 -) memory T-cells were evaluated in 89 untreated patients, 84 patients treated for at least 1 year, and 31 patients beginning treatment at the time of inclusion in the study and then followed-up for 12 months; controls were 81 healthy donors. The T-cell repertoire was analysed in selected samples. The percentage of thymicnaive T helper cells was diminished in untreated patients, but rose to control values in treated subjects; a decrease in central memory T-cells was also observed in treated patients. Follow-up patients could be divided into two subgroups, one showing unmodified thymicnaive T helper cells and T-cell diversity, the other in which the increased release of new T-cells was accompanied by modifications of the T-cell repertoire. Glatiramer acetate modifies the peripheral T-cell pool by activating a thymopoietic pathway of T-cell release that leads to a different setting of T-cell diversity and, likely, to a dilution of autoreactive T-cells.

Background To determine the role of interferon-alpha in controlling HIV infection we phenotypically and functionally analyzed circulating plasmacytoid dendritic cells (pDC), which are known to be the highest interferon-alpha producing cells, in 33 perinatally infected HIV+ patients undergoing standard antiretroviral therapy. Methods Circulating pDC were identified by flow cytometry using anti-BDCA-2 monoclonal antibody and by measuring BDCA-2 mRNA by real-time PCR, while tissue-resident pDC were identified by immunohistochemistry. mRNA for interferon-alpha and MxA, a gene that is specifically induced by interferon-alpha, was quantified in peripheral blood cells by real-time PCR, while serum interferon-alpha protein was measured by ELISA. Results While median values of pDC, both in terms of percentage and absolute number, were not statistically different from age-matched controls, interferon-alpha mRNA was increased in HIV-infected patients. However, in a group of patients with long disease duration, having a low number of both pDC and CD4+ lymphocytes and a significant increase of serum interferon-alpha, MxA mRNA was produced at high level and its expression directly correlated with HIV RNA copy numbers. Furthermore in patients displaying a low CD4+ blood cell count, a severe depletion of pDC in the tonsils could be documented. Conclusion HIV replication unresponsive to antiretroviral treatment in perinatal-infected patients with advanced disease and pDC depletion may lead to interferon-alpha expression and subsequent induction of MxA mRNA. Thus, the latter measurement may represent a valuable marker to monitor the clinical response to therapy in HIV patients.

We developed a real-time PCR assay to simultaneously measure the mRNA level of type I interferon (IFN) receptor (IFNAR) components in peripheral blood cells of children with chronic immune stimulation due to HIV infection. All patients were undergoing antiretroviral therapy and were divided into two groups on the basis of the induction of MxA mRNA, a marker of type I IFN bioactivity. We found that IFNAR-2 subunit mRNA was higher than that of the IFNAR-1 subunit, that the mRNA for the IFNAR-2.2 functional isoform was more expressed than that for the truncated IFNAR-2.1 isoform, and both were much more represented than that of the IFNAR-2.3 soluble isoform. We also demonstrated that soluble isoform mRNA was significantly diminished in the subgroup of patients with MxA mRNA below the cutoff value (determined as the 99th percentile of MxA measured in healthy controls). These results suggest that downregulation of the soluble receptor isoform, which would not compete with the functional isoform for binding to the target cytokine, would give type I IFN, eventually induced in these patients in the case of viral reactivation, the opportunity to promptly exert its antiviral activity.

Interferon-beta receptor (IFNAR) is composed of 2 subunits, IFNAR1 and IFNAR2, the latter of which is expressed as functional (IFNAR2.2), non-functional (IFNAR2.1) and soluble (IFNAR2.3) isoform. Real-Time PCR analysis of mRNA for all IFNAR components in multiple sclerosis patients naive for therapy and undergoing long-term treatment with interferon-beta shows that IFNAR1 mRNA level is lower than in healthy controls. If long-term treated patients are divided according to the production of mRNA for Myxovirus protein-A, a marker of interferon-beta bioactivity, IFNAR1 mRNA reaches the values observed in controls only in Myxovirus protein-A-induced patients. Since chronic cell stimulation by interferon-beta induces IFNAR protein down-regulation, we suggest that the increase of IFNAR1 mRNA might serve as a mechanism for counterbalancing the loss of protein receptor, enhancing, at least in this sub-group of patients, cell responsiveness to interferon-beta.

ObjectiveTo examine whether myxovirus-resistance protein A (MxA) mRNA expression, commonly considered a reliable marker of Type I interferon (IFN) bioactivity, is modified in patients with systemic sclerosis (SSc); if it is associated to specific clinical features; and if its modulation is accompanied by modulation of mRNA for the Type I IFN receptor (IFNAR).MethodsQuantification of mRNA for MxA and the subunit IFNAR1 and isoforms of IFNAR2 was performed by real-time polymerase chain reaction in 50 patients with SSc. Results were compared with those obtained from healthy controls and patients with another autoimmune disease such as multiple sclerosis.ResultsLevels of MxA mRNA above the 99th percentile of values found in healthy controls were observed in 9 out of 50 patients with SSc (p < 0.001). Induced MxA expression was significantly associated with some features of more severe disease, such as lower forced vital capacity and the presence of ischemic digital ulcers. No differences in the levels of IFNAR were found within MxA-induced and MxA-non-induced patients, but there was a direct correlation between levels of MxA and the soluble isoform of IFNAR2.ConclusionOur results show induction of MxA expression in some patients with SSc, which correlates with the presence of ischemic ulcers and other signs of worse disease, suggesting a potential role of Type I IFN in the pathogenesis of this disease and/or its complications.

Introduction The long-term efficacy of allogeneic haematopoietic stem cell transplantation (SCT) relies primarily on the Graft-versus-tumor (GVT) effect, which partially overlaps with Graft versus Host disease (GvHD), the most common cause of morbidity and mortality in SCT. Researches on GVHD-biomarkers are still ongoing and a set of validate markers are still lacking, especially for chronic GVHD. Furthermore, immune parameters that univocally associate with GVHD or GVT have not been identified yet. In this study, lymphocyte subsets together with TCR-repertoire analysis, and index of thymic and bone marrow output were evaluated at different time points, in order to identify possible predictors of GVHD and ineffective GVT. Methods Prospective evaluations of lymphocyte subsets, thymic and bone marrow output were performed in 40 patients before SCT, at 30, 90, 180 days and 1 year after SCT. CD4+/CD8+ naïve, central memory, effector memory, terminally differentiated effector memory (TEMRA) cells, subsets of regulatory T-lymphocytes, immature B cells, naïve, switched and unswitched memory B cells, memory double negative (IgD-CD27-) B cells were analysed by flow cytometry. Analysis of thymic and bone marrow output was performed by detection of T cell receptor excision circles (TRECs) and kappa-deleting recombination circles (KRECs). TRECs and KRECs were simultaneously quantified by a duplex quantitative Real-Time PCR. Heteroduplex assay was used to perform TCR-repertoire analysis. A 2-step multivariate analysis was performed using principal component analysis (PCA) and Cox regression analysis, to solve the problem of the high number of variables (immunological, patients- and transplant related) in comparison with the relatively limited and heterogeneous pool of patients. Results Twenty patients developed acute GVHD (median time: 28 days, range 19-120). Chronic GVHD was observed in 9 patients (median time: 6 months, range 4-10). In multivariate analysis, acute GVHD correlated positively with pre-transplant percentage of CD4+ central memory cells, and with values of regulatory effector memory T-cells and CD4+TEMRA cell at day +30 (p=0,0006). Pre-transplant percentage of unswitched memory B cells was also associated with acute GVHD, whereas pre-transplant levels of KRECs were inversely correlated (p=0,0005). Chronic GVHD was associated with matched unrelated donor and with (p -values of regulatory effector memory T-cells at +30, percentage of CD8+TEMRA cells at +90, values of immature B cells and levels of KRECs at +180 (positive correlation) -percentage of CD4+ central memory and CD8+ effector memory cells at +90 (negative correlation). The relapse rate (27%; median time: 5,5 months, range 3-12) was used as clinical index of ineffective GVT. The following cluster of immunological parameters at day +90 correlated positively with relapse: CD8+ effector memory cells, immature B cells, naïve, switched memory B cells, memory double negative (IgD-CD27-) B cells (p=0,006). Discussion Different clusters of immunological parameters at different time points were evidenced as predictors of GVHD and ineffective GVT, allowing a clear-cut distinction between these immunological reactions. Changes in pre- and post-transplant B-lymphopoietic microenvironment and specific imbalances in the subset of B-cells may be involved in acute and chronic GVHD development. The atypical association of regulatory T-cells with GVHD may be explained by the relative efficiency of different subsets of regulatory T-cells (naïve>effector memory), as shown in some experimental models. Increased values of CD8+ effector memory cells could be an early sign of ineffective GVL. Imbalance toward a lymphocyte B-response, and especially toward "senescent" memory (IgD-CD27-) B cells, could promote tolerance to tumor cells. The validation of these clusters of immunological parameters as specific early predictors of GVHD or GVT, even before SCT, could potentially allow the development of pre-emptive and targeted therapies. Disclosures No relevant conflicts of interest to declare.

Introduction Phosphoinositide-3-kinases (PI3Ks) are pivotal in various cellular functions including proliferation and survival, cell differentiation, intracellular trafficking and immunity. The PI3Kδ isoform is highly expressed in cells of hematopoietic origin, and is often dysregulated in various hematologic malignancies. New drugs targeting PI3Ks have emerged as promising treatment options for patients (pts) with CLL and indolent NHL, but a clear understanding of their effects on pts' immunity is lacking. Herein we performed detailed immunological analysis in two follicular lymphoma (FL) pts treated with PI3K inhibitors and developing severe immune-mediated side effects. Patients and Methods Two of 9 pts with relapsed FL treated with PI3Kδ (pt1) and PI3Kα/δ (pt2) inhibitors developed severe adverse events (SAE). Both pts were heavily pretreated including autologous transplantation and discontinued therapy due to SAE. Pt1 showed grade 3 transaminase elevation, esophagitis and diarrhea requiring hospitalization after 3 cycles of therapy. Diarrhea worsened with fever and weight loss, in spite of transient discontinuation and dose reduction of PI3k inhibitor. Colonoscopic biopsy showed GVHD-like colitis. He died 3 months later. Pt2 has developed, after the first cycle and over a period of one year, febrile neutropenia, erythroderma, ulcerative keratitis requiring corneal transplant, pure red cell aplasia, endocrine abnormalities, grade 3 diarrhea with weight loss, and inflammatory bowel disease-like colitis. Detailed T-cell subpopulations immunophenotyping and T-cell receptor (TCR) spectratyping were performed in samples obtained at 6 months and 1 year after the start of treatment. Results Compared to healthy controls (HC) both pts showed marked abnormalities in T-cell subsets including a very low percentage of CD4+CD45RA+CCR7+CD31+ recent T-emigrants (RTE) and of CD4+CD45RA+CCR7+ naïve T cells in both CD4+ and CD8+ populations; CD4+CD45RA-CCR7+ central memory were significantly decreased, while CD4+CD45RA-CCR7- effector memory T cells were increased. Natural CD4+CD25+CD127low/- regulatory T cell (Treg) were low in both pts and the defect equally involved naïve, central and effector memory Treg. On the contrary, inducible Treg (Tr1) did not differ between FL pts and HC. The predominance of effector T cells strongly biased the TCR repertoire. Cells expressing all TCR beta variable (BV) chains were clonally or oligoclonally expanded at the spectratyping analysis because their profiles deviated from the Gaussian patterns found in polyclonal repertoires of HC. Discussion The clinical picture of the two FL pts was reminiscent of congenital immunodeficiencies with defects of Treg activity (e.g. IPEX caused by FoxP3 gene mutation). Similar symptoms and T-cell abnormalities are also present in pts with inadequate thymic function and immunologic reconstitution due to severe chronic GVHD. The associated T-cell immunological derangement was characterized by: 1) a marked reduction of the thymic output; 2) a clear defect in natural Treg; 3) an increase of peripheral oligoclonal effector memory T cells. Preclinical data on the role of PI3kδ support its possible pathogenetic involvement: PI3Kδ is known to play critical roles during thymopoiesis and its deletion/inactivation results in a block at the CD4 CD8 double negative stage of T-cell development. In mice with a mutation of PI3Kδ subunit, Treg were increased in the thymus but decreased in all peripheral immune organs, suggesting an impaired emigration of these cells from the thymus. Moreover, mice expressing an inactive form of PI3Kδ develop inflammatory bowel disease. These preliminary data suggest that small molecule-mediated inhibition of PI3Kδ may cause severe alterations within the T-cell compartment in selected pts, which may derive from a defect in the thymic output, including that of Treg. The generation of mature, oligoclonal T cells can be either the result of an homeostatic T-cell proliferation or of a strong (auto)antigenic stimulation. To better elucidate such mechanisms, further studies are in progress on a larger number of pts showing different levels of PI3k inhibitor toxicity. Nevertheless, we suggest that a close follow-up of lymphocyte subpopulation changes should be worthwhile since it may anticipate the onset of these severe clinical manifestations. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures No relevant conflicts of interest to declare.

Background. One of the major concern for high-dose chemotherapy and hematopoietic stem cell transplantation (HSCT) for HIV-associated lymphoma is that posttransplant immunosuppression might worsen immune defects of HIV+ individuals. Since the introduction of highly active antiretroviral therapy has made HSCT possible also in these patients, we analyzed whether the immune system already compromised by HIV infection might support an efficient T-cell recovery after HSCT. Methods. The kinetics and the extent of T-cell reconstitution were investigated before and after HSCT in four patients with HIV-related lymphoma (one with Hodgkin's Disease and three with non-Hodgkin's lymphoma) by measuring the thymic output, the level of IL-7 and the heterogeneity of T-cell repertoire. T-cell competence was gauged at two functional levels: by determining the number of T-cell divisions and by measuring IFN-γ production. Results. The thymus of transplanted patients can be capable of generating new T cells, but there is no relationship between increasing number of newly produced lymphocytes and modification of IL-7 level. Various T-cell subsets, expressing different T-cell receptor variable beta genes, were preferentially expanded in CD8 population and most of them showed a restricted diversity. Furthermore, CD3+ lymphocytes showed heterogeneous behaviors in terms of proliferative capability and IFN-γ production. Conclusions. High-dose therapy and HSCT in HIV+ patients under highly active antiretroviral therapy does not worsen the immune defects. On the contrary, in the presence of some conditions (including the type of hematologic malignancy, the therapy compliance, and the immune status before transplantation), high-dose therapy and HSCT might support the improvement of immune conditions.

Abstract 2353 Poster Board II-330 Background Chronic lymphocytic leukemia (CLL) results in accumulation of mature, malignant, monoclonal B cells in blood, lymph nodes, spleen, liver, and bone marrow. Patients with CLL have fundamental defects in both humoral and cell-mediated immunity that significantly impact on its clinical course. It is still not known if these immune abnormalities include a decrease of new B- and T-cell mobilization from their production sites. During early lymphocyte development and differentiation, occurring in bone marrow and in thymus, B- and T-cells undergo rearrangements of B-cell and T-cell receptor genes whereby specific chromosomal sequences are excised to produce episomal DNA products identified respectively as T-cell receptor excisional circles (TRECs) and Kappa-deleting recombination excision circles (KRECs). Being stable circular fragments of DNA, TRECs and KRECs do not replicate during the mitotic process required for cell proliferation and, therefore, they are diluted out by cell divisions and are lost when the cells die. Since T-cells leaving the thymus are 70% TRECs+ and KRECs are present randomly in about 50% of neo-produced normal B-cells, the quantification of TRECs and KRECs allows a good estimation of the thymic and bone marrow output. Aim To investigate the extent of neo-synthesis of normal B and T cells in untreated patients with CLL. Patients and Methods Twelve previously untreated CLL patients were enrolled in this study. M:F ratio was 5:1; median age was 66; 7 patients had mutated IgVH genes, while 5 patients had unmutated IgVH genes; all patients were stage A Binet; FISH analysis including del(13q), del(11q), del(17p) and trisomy 12 detected 13q deletion in 6 patients while the other 6 patients presented no abnormalities. TRECs and KRECs were measured in mononuclear cells isolated from peripheral blood by duplex quantitative Real-Time PCR. This new assay, based on the use of a standard curve prepared with a plasmid containing fragments of TRECs, KRECs and of a reference gene, allows to quantify neo-produced B and T lymphocytes. T-cell subpopulations were determined by flow cytometry as follows: recent thymic emigrants (RTE) as cells with CD4+CD45RA+CCR7+CD31+ phenotype, regulatory T cells (Treg), as CD4+CD25int/highCD127low, RTE-Treg as Treg expressing CCR7+CD31+CD25int/high markers, effector memory (TEM) and central memory (TCM) T cells as lymphocytes displaying CD4+CD45RA-CCR7- and CD4+CD45RA-CCR7+ phenotype. Results The overall number of CD4+ lymphocytes was increased in chemotherapy-naïve patients with CLL (1585/μl vs 953/μl; p=0.02). TRECs were significantly higher in CLL patients compared to age-matched healthy controls (2.9/ml vs 1.4/ml; p=0.04), while the proportion of RTE was lower (24.9% vs 32.4%; p=0.02). No significant differences were observed in the percentage of Treg and RTE-Treg as well as of TCM. On the contrary, the percentage of TEM was higher (22.4% vs 10.4%; p=0.01) in CLL patients. The number of KRECs was lower in CLL patients than in controls (3.8/ml vs 7.4/ml; p=0.004). No correlation between IgVH gene mutational status, Ig levels and KRECs was found. Conclusions The neo-synthesis of normal T, with the exception of Treg, and B cells is reduced in patients with CLL compared to controls, even in a good prognosis, chemotherapy-naïve subset. The increased number of TRECs+ cells and TEM together with low RTE could be ascribed to the increased number of circulating CD4+ lymphocytes which do not appear to be recently mobilized from the thymus (CD31- cells) or to undergo peripheral expansion, but to accumulate in the peripheral blood. The low number of KRECs compared to normal controls could be interpreted as a consequence of the abnormal leukemic B-cell expansion which may impair normal B cell neo-synthesis. The level of KRECs did not seem to correlate to the mutational status of IgVH genes or the Ig level but a larger number of patients is needed to confirm these preliminary data and to establish whether the analysis of TRECs and KRECs may help clarify the complex immune abnormalities in CLL. Disclosures: No relevant conflicts of interest to declare.