Inter-laboratory method validation of CD34+ flow-cytometry assay: the experience of Turin Metropolitan Transplant Centre.

The Turin Metropolitan Transplant Centre (CIC 305) includes four flow-cytometry laboratories assessing quality control on hematopoietic stem cells (HSC) with different instruments and operators. Therefore, the CD34+ enumeration assay should be validated on a regular basis. We describe here the validation plan to test the inter-laboratory reproducibility of CD34+ enumeration assay, based on the risk analysis. Stabilized blood samples were analysed using Stem-Kit reagent according to manufacturer's instructions and acquired using the Beckman Coulter Navios at Regina Margherita Children's' Hospital (305-1), Beckman Coulter FC500 at Candiolo Cancer Institute FPO-IRCCS (305-2), BD Biosciences FACSLyric™ at S. Luigi Hospital (305-3), and Beckman Coulter Navios EX at Mauriziano Hospital (305-4). The ISHAGE guidelines were followed for estimating % and absolute number of CD34+ cells in single-platform method. For each sample repeatability limit (r), reproducibility error, uncertainty of reproducibility error and coefficient of variation (CV) were reported. The repeated measurements from each laboratory or instrument have a variability, expressed as reproducibility error, lower than the repeatability limit for that single parameter. The corrected reproducibility error is always lower than the repeatability limit except for the percentage value of the "low" count. The analysis of inter-laboratory variance is within the maximum acceptable variance value, and the CV of all measurements for each parameter is less than 8%, indicating low measurement variability among laboratories. Evaluating the overall data, we can conclude that the four laboratories are perfectly aligned and the results are reproducible.

International standardized approach for flow cytometric residual disease monitoring in chronic lymphocytic leukaemia.

The eradication of minimal residual disease (MRD) in chronic lymphocytic leukaemia (CLL) predicts for improved outcome. However, the wide variety of MRD techniques makes it difficult to interpret and compare different clinical trials. Our aim was to develop a standardized flow cytometric CLL-MRD assay and compare it to real-time quantitative allele-specific oligonucleotide (RQ-ASO) Immunoglobulin heavy chain gene (IgH) polymerase chain reaction (PCR). Analysis of 728 paired blood and marrow samples demonstrated high concordance (87%) for patients off-therapy. Blood analysis was equally or more sensitive than marrow in 92% of samples but marrow analysis was necessary to detect MRD within 3 months of alemtuzumab therapy. Assessment of 50 CLL-specific antibody combinations identified three (CD5/CD19 with CD20/CD38, CD81/CD22 and CD79b/CD43) with low inter-laboratory variation and false-detection rates. Experienced operators demonstrated an accuracy of 95.7% (specificity 98.8%, sensitivity 91.1%) in 141 samples with 0.01-0.1% CLL. There was close correlation and 95% concordance with RQ-ASO IgH-PCR for detection of CLL above 0.01%. The proposed flow cytometry approach is applicable to all sample types and therapeutic regimes, and sufficiently rapid and sensitive to guide therapy to an MRD-negativity in real time. These techniques may be used as a tool for assessing response and comparing the efficacy of different therapeutic approaches.

ZAP-70 is expressed by normal and malignant human B-cell subsets of different maturational stage.

ZAP-70 tyrosine kinase is involved in signalling pathways following T-cell receptor stimulation and was originally described only in T cells and natural killer cells. ZAP-70 expression has been reported in normal mouse B lineage cells and in human malignant B lymphocytes, mainly in chronic lymphocytic leukemia (CLL) where it correlates with clinical outcome. We analyzed several B-cell lines and ex vivo malignant B cells, ranging from acute lymphoblastic leukemia to multiple myeloma and reflecting different stages of B-cell differentiation, and they showed ZAP-70 expression regardless their maturation stage. We then analyzed by Western blot and flow cytometry different human normal B-lymphocyte subpopulations: naïve, germinal center and memory B cells from tonsils, CD19+ CD5+ cells from cord blood and CD19+ lymphocytes from peripheral blood. All expressed ZAP-70 protein, though at different levels depending on their differentiation, activation and tissue localization. In addition, ZAP-70 expression levels could be modulated following stimulation via the B-cell receptor. These findings implicate a potential role of ZAP-70 in the signalling pathway of B lymphocytes at different maturational stages, indicate that ZAP-70 expression is not a CLL-specific feature among B-cell malignancies and suggest that the absence of ZAP-70 rather than its presence should be considered abnormal for malignant B lymphocytes.

p53 evaluation in gastric mucosa of patients with chronic Helicobacter pylori infection.

Gastric cancer is often associated with p53 over-expression and Helicobacter pylori (HP) infection. In this study we have investigated the production of the p53 protein and mutation of its gene in precancerous gastric lesions with HP infection. For this purpose 130 patients who underwent endoscopy for dyspepsia were enrolled in the study. To assess p53 production and mutation of the p53 gene we employed an immunoluminometric assay and polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) analysis, respectively. Histologically, 52 of the 130 enrolled patients showed intestinal metaplasia type I (IM) (90.4% of these were also HP positive), 47 had HP-related gastritis and 31 were normal. p53 cytosol levels were significantly higher in patients with IM or HP-related gastritis than in normal patients (p = 0.0137 and p = 0.0411, respectively). All DNAs extracted from gastric mucosa samples with higher p53 values and examined for p53 mutations by PCR-SSCP analysis were characterized by a normal run. Our data indicate, that irreversible genetic changes in the p53 protein has not yet occurred in morphologically non-neoplastic gastric mucosa with IM and HP-related chronic gastritis. In conclusion, the increase in p53 cytosolic levels found in our study is due to an increased production of the wild-type protein probably related to an inflammatory response induced by HP infection.

Survivin is expressed on CD40 stimulation and interfaces proliferation and apoptosis in B-cell chronic lymphocytic leukemia.

In B-cell chronic lymphocytic leukemia (B-CLL), defective apoptosis causes the accumulation of mature CD5(+) B cells in lymphoid organs, bone marrow (BM), and peripheral blood (PB). These cells are the progeny of a proliferating pool that feeds the accumulating compartment. The authors sought to determine which molecular mechanisms govern the proliferating pool, how they relate to apoptosis, and what the role is of the microenvironment. To begin to resolve these problems, the expression and modulation of the family of inhibitor of apoptosis proteins (IAPs) were investigated, with consideration given to the possibility that physiological stimuli, such as CD40 ligand (CD40L), available to B cells in the microenvironment, might modulate IAP expression. The in vitro data on mononuclear cells from PB or BM of 30 patients demonstrate that B-CLL cells on CD40 stimulation express Survivin and that Survivin is the only IAP whose expression is induced by CD40L. Through immunohistochemistry, in vivo Survivin expression in lymph node (LN) and BM biopsies was evaluated. In reactive LN, Survivin was detected only in highly proliferating germinal center cells. In LN from patients with B-CLL, Survivin was detected only in pseudofollicles. Pseudofollicle Survivin(+) cells were actively proliferating and, in contrast to Survivin(+) B cells found in normal GC, were Bcl-2(+). In B-CLL BM biopsies, CD5(+), Survivin(+) cells were observed in clusters interspersed with T cells. These findings establish that Survivin controls the B-CLL proliferative pool interfacing apoptosis and that its expression may be modulated by microenvironmental stimuli.

IL-12 inhibition of endothelial cell functions and angiogenesis depends on lymphocyte-endothelial cell cross-talk.

In vivo IL-12-dependent tumor inhibition rests on the ability of IL-12 to activate a CD8-mediated cytotoxicity, inhibit angiogenesis, and cause vascular injury. Although in vivo studies have shown that such inhibition stems from complex interactions of immune cells and the production of IFN-gamma and other downstream angiostatic chemokines, the mechanisms involved are still poorly defined. Here we show that IL-12 activates an anti-angiogenic program in Con A-activated mouse spleen cells (activated spc) or human PBMC (activated PBMC). The soluble factors they release in its presence arrest the cycle of endothelial cells (EC), inhibit in vitro angiogenesis, negatively modulate the production of matrix metalloproteinase-9, and the ability of EC to adhere to vitronectin and up-regulate ICAM-1 and VCAM-1 expression. These effects do not require direct cell-cell contact, yet result from continuous interaction between activated lymphoid cells and EC. We used neutralizing Abs to show that the IFN-inducible protein-10 and monokine-induced by IFN-gamma chemokines are pivotal in inducing these effects. Experiments with nu/nu mice, nonobese diabetic-SCID mice, or activated spc enriched in specific cell subpopulations demonstrated that CD4(+), CD8(+), and NK cells are all needed to mediate the full anti-angiogenetic effect of IL-12.

Human CD38 and its ligand CD31 define a unique lamina propria T lymphocyte signaling pathway.

CD38, a nonlineage-restricted surface glycoprotein, is an ecto-enzyme (ADP ribosyl cyclase/cADPR hydrolase/EC 3.2.2.6) that regulates cytoplasmic Ca2+ and cell-cell interactions. The molecule also delivers trans-membrane signals, despite a structural ineptitude to the scope. To reconcile these issues in a unitarian model, we compared the effects of CD38 signaling in circulating and residential T lymphocytes, the latter represented by those colonizing the intestinal lamina propria. Results are as follows: 1) LP T cells express an enzymatically active form of CD38, characterized by a modified ratio between cyclase and hydrolase functions; 2) LP T cells do not mobilize Ca2+ upon CD38 ligation, as seen in PB T cells (this condition is due to a lack in activation of PLC- g, constantly observed in PB T lymphocytes); 3) The early steps of CD38 signaling involve activation of lck, syk, and LAT; 4) Late events include synthesis and release of IL-2, IL-4, IL-5, IL-10, IFN-g and GM-CSF; 5) The uniqueness of the CD38 pathway in LP T cells is not caused by impaired interactions with the CD31 ligand. The differences observed concern the signaling machinery that CD38 exploits for its own use and not the interplay with its ligand.

Prolactin in autoimmunity and antitumor defence.

Prolactin (PRL) enhances inflammatory and antitumor responses in vitro and thus exhibits Th1-type cytokine-like effects. Evidence from experimental models indicates that inhibition of PRL release by bromocriptine downregulates immune reactions and ameliorates autoimmune diseases in which Th1 responses are predominant. A direct effect of locally produced PRL in some Th1 diseases, such as rheumatoid arthritis, supports this concept. Paradoxically, however, hyperprolactinemia can also be associated with conditions such as pregnancy, where remission of Th1-mediated diseases is known to occur in the context of a Th2-dominated milieu. This reversal of the Th1-promoting effect of PRL may be due to major changes in the levels of other hormones that can annul and/or override the PRL-mediated proinflammatory state. Nevertheless, PRL, as an immunopotentiating agent, may have a powerful therapeutic role in cancer and other immunocompromised patients.

Gene transfer by lentiviral vectors is limited by nuclear translocation and rescued by HIV-1 pol sequences.

Gene-transfer vectors based on lentiviruses are distinguished by their ability to transduce non-dividing cells. The HIV-1 proteins Matrix, Vpr and Integrase have been implicated in the nuclear import of the viral genome in non-dividing cells. Here we show that a sequence within pol is also required in cis. It contains structural elements previously associated with the progress of reverse transcription in target cells. We restored these elements in cis within late-generation lentiviral vectors. The new vector transduced to a much higher efficiency several types of human primary cells, when both growing and growth-arrested, including haematopoietic stem cells assayed by long-term repopulation of NOD/SCID mice. On in vivo administration into SCID mice, the vector induced higher plasma levels of human clotting factor IX (F.IX) than non-modified vector. Our results indicate that nuclear translocation of the genome is a rate-limiting step in lentiviral infection of both dividing and non-dividing cells, and that it depends on protein and nucleic acid sequence determinants. Full rescue of this step in lentivirus-based vectors improves performance for gene-therapy applications.

Individual and combined effect of granulocyte-macrophage colony-stimulating factor and prolactin on maturation of dendritic cells from blood monocytes under serum-free conditions.

Prolactin (PRL) shares structural and functional features with haemopoietic factors and cytokine peptides. Dendritic cells (DC) are involved in both initiating the primary and boosting the secondary host immune response and can be differentiated in vitro from precursors under the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) plus other factors. Because PRL has been shown to functionally interact with GM-CSF, we have addressed its role on GM-CSF-driven differentiation of DC. Monocytic DC precursors from peripheral blood mononuclear cells (PBMC) were enriched either by adhesion to a plastic surface or CD14-positive selection and cultured for 7 days in serum-free medium containing GM-CSF, interleukin (IL)-4 and PRL, alone or in combination. Cells with large, veiled cytoplasm, expressing major histocompatibility complex (MHC) class II and the costimulatory molecules CD80, CD86 and CD40 and lacking the monocyte marker CD14, were considered as having the phenotype of cytokine-generated DC. Functional maturation was assessed by proliferation and interferon-gamma (IFN-gamma) release of allogeneic T lymphocytes. Physiological (10-20 ng/ml) concentrations of PRL interacted synergistically with GM-CSF and the effect was similar to that induced by IL-4 on GM-CSF-driven DC maturation. When used alone, the physiological concentrations of PRL were inhibitory, whereas higher concentrations (80 ng/ml) were stimulatory. The synergistic effect of PRL may in part be caused by its ability to counteract the down-modulation of the GM-CSF receptor observed in serum-free conditions. These data provide further evidence of the significance of PRL in the process of T lymphocyte activation.

Expression of prolactin and prolactin receptors by non-Hodgkin's lymphoma cells.

Prolactin (PRL) interacts with lymphocyte-signaling molecules and cytokines. Previous work has shown independent and synergistic effects of PRL on the generation of IL-2-driven anti-tumor lymphokine activated killer (LAK) activity by peripheral blood mononuclear cells (PBMC). The potential importance of PRL as a biological immunomodifier, however, is challenged by its ability to influence normal lymphocyte mitogenesis and hence lymphoid tumor growth. Since non-Hodgkin's lymphoma (NHL) cell lines were efficiently killed by LAK generated with native (n) or recombinant (r) human PRL combined with low, per se ineffective doses of IL-2, we have addressed here the question of whether PRL acts as a growth factor for LAK targets. NHL cells were analyzed for: 1. expression of the PRL receptor (PRL-R); 2. responsiveness to nPRL or rPRL; 3. constitutive expression and release of PRL; 4. existence of a PRL autocrine loop. PRL-R, defined by multiple antibodies, was detected in 3 of 12 NHL cell lines. However, nPRL or rPRL, in a wide range of concentrations (0.75-50 ng/ml), were not mitogenic for growth-arrested, PRL-R positive NHL cell lines. PRL mRNA was detected by RT-PCR in 10 of the 12 cell lines examined with a higher frequency among AIDS-related NHL cell lines. PRL protein in the immunoprecipitate of (35)S-methionine-labeled cell lysates and supernatants paralleled mRNA expression, and Western blotting analysis showed the presence of the pituitary/lymphocyte non-glycosylated (23.5 kDa) and glycosylated (25 kDa) isoforms. Experiments with blocking antibodies showed the independence from endogenous PRL for NHL cell growth.

Flow cytometry in breast cancer: prognostic and surgical indications of the sparing of axillary lymph node dissection.

The lymph node status is still regarded as the most important prognostic factor in breast cancer. However, the utility of axillary lymph node dissection in clinically node-negative patients with breast cancer as a therapeutic approach rather than a pathologic staging procedure has been recently discussed. DNA index (DI) and S-phase fraction (SPF), evaluated by flow cytometric analysis, are two prognostic factors used especially in the assessment of the adjuvant therapy in stage N0 tumors. By studying a large number of cases, the authors aimed to assess the potential role of flow cytometry in predicting lymph node status. Two hundred eleven patients with breast cancer were included. Each tumor specimen was freshly analyzed by flow cytometry to assess DI and SPF. The authors also evaluated TNM status of patients, estrogen- and progesterone-receptor (ER and Pgr) status, and histologic grades. A group of patients with negative axillary lymph nodes was identified by means of association of tumor size of 2 cm or less, DI of 1, and SPF less than 7%. The ER and PgR status as well as histologic grade were significantly more favorable in this group of patients. These findings indicate that association of DI, SPF value, and tumor size may be predictive of axillary lymph node status in breast cancer.

Prolactin is an autocrine growth factor for the Jurkat human T-leukemic cell line.

Despite convincing evidence of cooperation between IL-2 and endogenous prolactin (PRL) during T cell activation, the individual role of PRL as a T-cell lineage cytokine remains to be defined. We have examined the production and function of PRL on the Jurkat human T-leukemic cell line, which does not constitutively produce IL-2. The majority of Jurkat cells expressed PRL receptor (R) under standard culture conditions, whereas appearance of the alpha chain of the IL-2-R required PHA-PMA stimulation, as did IL-2 synthesis. Western blotting revealed a predominant band at 23.5 kDa and a weaker band at 25.5 kDa in both Jurkat cell lysates and human (h) pituitary PRL. Metabolic labeling of the cell lysates with 35S-methionine and immunoprecipitation with an antiserum against hPRL showed that both forms of PRL are actively synthesized by the Jurkat cell line. PRL released in the medium was biologically active in the rat Nb2 lymphoma mitogenic assay. Depletion of medium PRL with two polyclonal anti-hPRL antisera inhibited the growth of Jurkat cells in a dose-dependent manner, as evaluated by cell number and 3H-TdR uptake. Purified pituitary or recombinant hPRL at a wide range of concentrations had no significant effect on their growth, but reversed the blocking activity of the anti-hPRL antibody. Recombinant IL-2 had no effect on the antibody-induced growth inhibition. Taken as a whole, these results demonstrate that PRL can act as an autocrine T cell growth factor independently of IL-2 and are the first evidence of its involvement in human leukemic growth and possibly in leukemic transformation.

Cell proliferation, bcl-2, c-myc, p53 and apoptosis as indicators of different aggressiveness in small lymphocytic lymphoma (SLL).

Cell proliferation activity, by MIB1 mAb, expression of bcl-2, c-myc and p53 gene proteins and apoptotic index (AI) were assessed in 54 cases of SLL and compared to the morphological subtypes of this disorder, defined by Lennert on the basis of amount and distribution of small and larger activated lymphocytes as diffuse, tumor-forming and pseudofollicular subtypes (DS, TFS, PFS). MIB1 scores showed significant differences between DS, PFS and TFS (5.5%, 16.61% and 24.14%, respectively; p < 0.0001). Worth noting, the MIB1 score did not differ significantly when comparing DS with the diffuse areas of PFS, or TFS with the pseudofollicles of PFS. The mean bcl-2 gene protein score was displayed to a high extent in all subtypes, but less extensively by larger activated lymphocytes that, conversely, expressed c-myc. MIB1 score correlated negatively with bcl-2 and positively with c-myc protein scores. These findings suggest that lymphocytes protected from apoptosis by bcl-2 would be exponed to cell activation and growth acceleration provided by c-myc. This condition would account for a different aggressiveness of morphologically activated subtypes, such as TFS and PFS with larger pseudofollicles. The survival analysis, performed in 23 cases, showed a trend of association of cell proliferation and c-myc expression with a more aggressive progression of the disease. Overexpression of p53 and apoptosis were found only in a minority of cases, unrelated to the subtypes. In conclusion, cell growth fraction, bcl-2 and c-myc assessment may be of help in predicting the aggressiveness of different subtypes of SLL. This approach should be most conveniently applied to PFS, which represents a continuum between DS and TFS, in order to distinguish, in this heterogeneous subtype, more indolent from more aggressive disorders.

Growth stimulation of colorectal carcinoma cells via the c-kit receptor is inhibited by TGF-beta 1.

Activation of the receptor tyrosine kinase c-kit by the kit-ligand, also known as stem cell factor (SCF), is essential to melanocyte and germ cell development and during the early stages of hematopoiesis. Deregulated expression of c-kit has been reported in malignancies affecting these lineages, i.e., myeloid leukemias, melanomas, and germ cell tumors. In addition, c-kit and SCF are coexpressed in some breast and colorectal cancer (CRC) cells, raising the question of whether c-kit serves an autocrine role in normal or malignant epithelial tissues. In this study, we demonstrate that human colorectal carcinomas, but not normal colorectal mucosa cells, coexpress SCF and c-kit in situ. Expression of c-kit was also observed in mucosa adjacent to colorectal tumor tissue. Consistent with a growth-regulatory role of SCF in CRC cells, exogenous SCF stimulated anchorage-dependent and anchorage-independent growth in four out of five CRC cell lines. Exogenous transforming growth factor (TGF)-beta 1 added at nanomolar concentrations to HT-29 CRC cells, which express the type I, II, and III TGF-beta receptors, downregulated c-kit expression to background levels and inhibited c-kit-dependent proliferation. Similarly, TGF-beta 1 inhibited SCF-dependent proliferation of three first-passage CRC cell lines. In summary, expression of the potential autocrine SCF/ c-kit axis is a tumor-associated phenomenon in colorectal cancer that can be suppressed by TGF-beta 1 in TGF-beta-responsive CRC cells.

A case-control study on lymphocytic subsets in elderly bearing a gastroenteric cancer.

The aim of this work is to evaluate the differences in lymphocytic sub-classes between elderly patients with gastroenteric cancer and elderly patients with a non neoplastic disease. A group of 88 patients over 60, consecutively admitted to the III Division General Surgery for gastro-enteric cancer has been collected for the study, the control group consisted of 74 patients also over 60, consecutively admitted over the same period for benign abdominal diseases. In all patients the following data were measured: body mass index (BMI), white blood cells (WBC), total lymphocytes, total T lymphocytes (CD3+), helper T lymphocytes (CD4+), suppressor T lymphocytes (CD8+), CD4+/CD8+ ratio, B lymphocytes, CD5+ B lymphocytes, activated T lymphocytes (CD3+ HLA-DR+), CD4+ "naive" lymphocytes (CD4+ CD45 RA+), CD4+ "memory" lymphocytes (CD4+ CD45 RO+), NK lymphocytes (CD16+ 56+), red blood cells (RBC), total serum cholesterol, albumin, total serum proteins. The main lymphocytic subsets were on an average lower in the cancerous elderly group with respect to the non cancerous. As the tumour progressively increases in size (T), total lymphocytes significantly decrease, while CD4+ progressively decreases with nodal involvement (N). In the cancerous elderly, we found a lower immune response. The immune system appears to be less efficient also in association with tumor growth, especially when T and N get worse. The response of effector cells to the tumour seems not specific.

CD56-positive cutaneous lymphoma: a poorly recognized entity in the spectrum of primary cutaneous disease.

CD56-positive (CD56+) lymphomas, characterized by the expression of the neural cell adhesion molecule on pathological lymphocytes, share a frequent extranodal involvement and a generally aggressive course. Five CD3- CD56+ lymphoma patients presenting with nodular lesions were identified among 180 immunophenotyped cutaneous lymphomas. All the patients were men, with ages ranging from 55 to 78 years. After staging, two patients were diagnosed as having primary cutaneous lymphomas; the remaining three had the secondary cutaneous type. The clinical course was aggressive and four patients died within 8 months from diagnosis. The remaining patient is still alive after a 17-month follow-up. The histological diagnosis was immunoblastic lymphoma in two patients, and medium and large cell pleomorphic lymphoma in three. The angiocentric infiltrate was located mainly in the dermis; azurophilic granules were present in three of the five patients. Immunogenotypic analyses suggested the natural killer cell origin of these neoplasias: all cases exhibited a CD56+ CD3- CD5- T-cell receptor (TCR) silent phenotype, and Southern blot analysis showed a germline configuration of the TCR beta-chain gene.