Biomedical subjects

Paolo Ghia

Publications and source records attributed to Paolo Ghia.

At least 19 recordsLinked to original sources

PubMed2026

Final phase 2 study results of acalabrutinib in treatment-naive and relapsed/refractory chronic lymphocytic leukemia.

Acalabrutinib is a selective, covalent Bruton tyrosine kinase inhibitor approved for marketing in chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). We report final, long-term phase 1/2 study results in 99 patients with treatment-naive (TN) and 134 with relapsed/refractory (R/R) CLL/SLL. At final data cutoff, 71% and 31% of patients in the TN and R/R cohorts, respectively, remained on acalabrutinib treatment (median follow-up of 73.7 and 52.6 months). Among the events of clinical interest (any grade) in the TN and R/R cohorts, atrial fibrillation was reported in 6.1% and 9.0%, hypertension in 29.3% and 23.1%, other malignancies (excluding nonmelanoma skin cancer) in 14.1% and 17.2%, and major bleeding in 8.1% and 8.2% of patients, respectively. The incidence of the most common adverse events decreased over time. Overall response rates were 97.0% and 94.8% in the TN and R/R cohorts, respectively, with similar response findings among patients with standard and high-risk genomic features. In the TN cohort, median progression-free survival (PFS) was not reached and the 72-month PFS rate was 86.7% (95% confidence interval [CI], 77.0-92.5). For the R/R cohort, median PFS was 66.1 months (range, 0.4-87.8) and the 72-month PFS rate was 45.1% (95% CI, 35.6-54.1). This final analysis extends the duration of benefit observed with acalabrutinib, demonstrates that no new safety signals are apparent with longer follow-up, and confirms the safety and tolerability of acalabrutinib monotherapy for patients with CLL/SLL. This trial was registered at www.clinicaltrials.gov as #NCT02029443.

Humans↗

PubMed2022

The International Consensus Classification of Mature Lymphoid Neoplasms: a report from the Clinical Advisory Committee.

Since the publication of the Revised European-American Classification of Lymphoid Neoplasms in 1994, subsequent updates of the classification of lymphoid neoplasms have been generated through iterative international efforts to achieve broad consensus among hematopathologists, geneticists, molecular scientists, and clinicians. Significant progress has recently been made in the characterization of malignancies of the immune system, with many new insights provided by genomic studies. They have led to this proposal. We have followed the same process that was successfully used for the third and fourth editions of the World Health Organization Classification of Hematologic Neoplasms. The definition, recommended studies, and criteria for the diagnosis of many entities have been extensively refined. Some categories considered provisional have now been upgraded to definite entities. Terminology for some diseases has been revised to adapt nomenclature to the current knowledge of their biology, but these modifications have been restricted to well-justified situations. Major findings from recent genomic studies have impacted the conceptual framework and diagnostic criteria for many disease entities. These changes will have an impact on optimal clinical management. The conclusions of this work are summarized in this report as the proposed International Consensus Classification of mature lymphoid, histiocytic, and dendritic cell tumors.

Advisory Committees↗

PubMed2006

Over 20% of patients with chronic lymphocytic leukemia carry stereotyped receptors: Pathogenetic implications and clinical correlations.

The chronic lymphocytic leukemia (CLL) immunoglobulin repertoire is biased and characterized by the existence of subsets of cases with closely homologous ("stereotyped") complementarity-determining region 3 (CDR3) sequences. In the present series, 201 (21.9%) of 916 patients with CLL expressed IGHV genes that belonged to 1 of 48 different subsets of sequences with stereotyped heavy chain (H) CDR3. Twenty-six subsets comprised 3 or more sequences and were considered "confirmed." The remaining subsets comprised pairs of sequences and were considered "potential"; public database CLL sequences were found to be members of 9 of 22 "potential" subsets, thereby allowing us to consider them also "confirmed." The chance of belonging to a subset exceeded 35% for unmutated or selected IGHV genes (eg, IGHV1-69/3-21/4-39). Comparison to non-CLL public database sequences showed that HCDR3 restriction is "CLL-related." CLL cases with selected stereotyped immunoglobulins (IGs) were also found to share unique biologic and clinical features. In particular, cases expressing stereotyped IGHV4-39/IGKV1-39-1D-39 and IGHV4-34/IGKV2-30 were always IgG-switched. In addition, IGHV4-34/IGKV2-30 patients were younger and followed a strikingly indolent disease, contrasting other patients (eg, those expressing IGHV3-21/IGLV3-21) who experienced an aggressive disease, regardless of IGHV mutations. These findings suggest that a particular antigen-binding site can be critical in determining the clinical features and outcome for at least some CLL patients.

ADP-ribosyl Cyclase 1↗

PubMed2006

Evaluation of ZAP-70 expression by flow cytometry in chronic lymphocytic leukemia: A multicentric international harmonization process.

The clinical course of patients with chronic lymphocytic leukemia (CLL) is heterogeneous with some patients requiring early therapy whereas others will not be treated for years. The evaluation of an individual CLL patient's prognosis remains a problematic issue. The presence or absence of somatic mutations in the IgVH genes is currently the gold-standard prognostic factor, but this technique is labor intensive and costly. Genomic studies uncovered that 70 kDa zeta-associated protein (ZAP-70) expression was associated with unmutated IgVH genes and ZAP-70 protein expression was proposed as a surrogate for somatic mutational status. Among the available techniques for ZAP-70 detection, flow cytometry is most preferable as it allows the simultaneous quantification of ZAP-70 protein expression levels in CLL cells and residual normal lymphocyte subsets. However, several factors introduce variability in the results reported from different laboratories; these factors include the anti-ZAP-70 antibody clone and conjugate, the staining procedure, the gating strategy, and the method of reporting the results. The need for standardization of the approach led to the organization of an international working group focused on harmonizing all aspects of the technique. During this workshop, a technical consensus was reached on the methods for cell permeabilization and immunophenotyping procedures. An assay was then designed that allowed comparison of two clones of anti-ZAP-70 antibody and the identification of the expression of this molecule in B, T, and NK cells identified in a four multicolor analysis. This procedure was applied to three stabilized blood samples, provided by the UK NEQAS group to all participating members of this study, in order to minimize variability caused by sample storage and shipment. Analysis was performed in 20 laboratories providing interpretable data from 14 centers. Various gating strategies were used and the ZAP-70 levels were expressed as percentage positive (POS) relative to isotype control or normal B-cells or normal T-cells; in addition the levels were reported as a ratio of expression in CLL cells relative to T-cells. The reported level of ZAP-70 expression varied greatly depending on the antibody and the method used to express the results. The CLL/T-cell ZAP-70 expression ratio showed a much lower interlaboratory variation than other reporting strategies and is recommended for multicenter studies. Stabilization results in decreased expression of CD19 making gating more difficult and therefore stabilized samples are not optimal for multicentric analysis of ZAP-70 expression. We assessed the variation of ZAP-70 expression levels in fresh cells according to storage time, which demonstrated that ZAP-70 is labile but sufficiently stable to allow comparison using fresh samples distributed between labs in Europe. These studies have demonstrated progress toward a consensus reporting procedure, and further work is underway to harmonize the preparation and analysis procedures.

Antibodies, Monoclonal↗

PubMed2006

IGHV gene insertions and deletions in chronic lymphocytic leukemia: "CLL-biased" deletions in a subset of cases with stereotyped receptors.

Nucleotide insertions/duplications or deletions in immunoglobulin heavy chain genes have been found in 24/760 patients (3.15%) with chronic lymphocytic leukemia (CLL). In 21/24 cases, the inserted/duplicated or lost nucleotides occurred in multiples of 3; therefore, the original reading frame was maintained and a potentially intact receptor was coded. The pattern and location of insertions/duplications or deletions in CLL and their restriction to mutated IGHV rearranged genes strongly suggests that they resulted from somatic hypermutation. Their incidence in CLL is consistent with previous reports in normal, auto-reactive and neoplastic human B cells, thus seemingly indicating that these modifications generally arise without any particular disease-specific associations. A striking exception to this rule was identified in CLL IGHV3-21-expressing cases: one amino acid was deleted from the CDR2 region in 16/63 (25.4%) mutated CLL IGHV3-21 sequences (including public database-derived IGHV3-21 CLL cases + the present series) vs. only 2/257 (0.78%) public database-derived mutated non-CLL IGHV3-21 sequences; 15/16 CLL IGHV3-21 sequences carrying this deletion belonged to a subset with unique, shared HCDR3 and light chain CDR3 motifs. This finding further supports the idea of selective antigenic pressures playing a pathogenetic role in some CLL cases.

Amino Acid Sequence↗

PubMed2006

The origin of B-cell chronic lymphocytic leukemia.

An immunobiologic approach has led to substantial changes in our current view of chronic lymphocytic leukemia (CLL). Several questions remain unsolved and the definition of the cell origin of CLL is still prominent. The presence of somatic mutations of IGHV genes indicates that, at least in a portion of cases, CLL cells had encountered an antigen during the natural history of the disease. Unmutated (UM) cases show a remarkable skewing in IGHV gene usage. In addition, all CLL cases, both mutated (M) and UM, show a common surface phenotype which is significantly activated and similar to the surface phenotype of antigen (Ag)-experienced B cells. The properties of CLL B-cell receptors (BCR) resemble those observed in normal B cells upon Ag interaction, and gene profiling analyses revealed that both subsets share striking similarities with the so-called memory B cells. The detailed analyses of the complementary determining region 3 (CDR3) sequences of the leukemic immunoglobulin (Ig) receptors showed that unrelated patients in different parts of the world express very similar if not identical BCR. Remarkably, similar V(H)DJ(H) rearrangements have been identified in both UM- and M-CLL, suggesting an antigenic selection in both subsets of the disease. From all this evidence, the concept has arisen that the cell of origin, regardless its mutational status, has to be "an Ag-experienced" B cell that gives rise to a malignant clone that appears to be more dynamic than previously appreciated and whose progression is favored by a number of molecular and cellular interactions that occur in tissues.

Animals↗

PubMed2005

Gene expression profiling identifies BAX-delta as a novel tumor antigen in acute lymphoblastic leukemia.

The identification of new tumor-associated antigens (TAA) is critical for the development of effective immunotherapeutic strategies, particularly in diseases like B-cell acute lymphoblastic leukemia (B-ALL), where few target epitopes are known. To accelerate the identification of novel TAA in B-ALL, we used a combination of expression profiling and reverse immunology. We compared gene expression profiles of primary B-ALL cells with their normal counterparts, B-cell precursors. Genes differentially expressed by B-ALL cells included many previously identified as TAA in other malignancies. Within this set of overexpressed genes, we focused on those that may be functionally important to the cancer cell. The apoptosis-related molecule, BAX, was highly correlated with the ALL class distinction. Therefore, we evaluated BAX and its isoforms as potential TAA. Peptides from the isoform BAX-delta bound with high affinity to HLA-A*0201 and HLA-DR1. CD8+ CTLs specific for BAX-delta epitopes or their heteroclitic peptides could be expanded from normal donors. BAX-delta-specific T cells lysed peptide-pulsed targets and BAX-delta-expressing leukemia cells in a MHC-restricted fashion. Moreover, primary B-ALL cells were recognized by BAX-delta-specific CTL, indicating that this antigen is naturally processed and presented by tumor cells. This study suggests that (a) BAX-delta may serve as a widely expressed TAA in B-ALL and (b) gene expression profiling can be a generalizable tool to identify immunologic targets for cancer immunotherapy.

Adolescent↗

PubMed2005

Diagnostic criteria for monoclonal B-cell lymphocytosis.

Very low levels of circulating monoclonal B-cell subpopulations can now be detected in apparently healthy individuals using flow cytometry. We propose the term 'monoclonal B-cell lymphocytosis' (MBL) to describe this finding. The aim of this document is to provide a working definition of MBL for future clinical, epidemiological and laboratory studies. We propose that the detection of a monoclonal B-cell population by light chain restriction is sufficient to define this condition in individuals not meeting the diagnostic criteria for other B-lymphoproliferative disorders. The majority of individuals with MBL will have cells that are indistinguishable from chronic lymphocytic leukaemia (CLL). However, this blood cell clonal expansion of CD5+ or CD5- B-lymphocytes is age-dependent and immunophenotypic heterogeneity is common. Longitudinal studies are required to determine whether MBL is a precursor state to CLL or other B-lymphoproliferative disease in a situation analogous to a monoclonal gammopathy of undetermined significance and myeloma. Future studies of MBL should be directed towards determining its relationship to clinical disease, particularly in individuals from families with a genetic predisposition to developing CLL.

Adolescent↗

PubMed2005

HS1 protein is differentially expressed in chronic lymphocytic leukemia patient subsets with good or poor prognoses.

We used a proteomic approach for identifying molecules involved in the pathogenesis of chronic lymphocytic leukemia (CLL). We investigated 14 patients who were completely concordant for IgV(H) mutational status (unmutated vs. mutated), CD38 expression (positive vs. negative), and clinical behavior (progressive vs. stable); these patients were characterized as having either poor or good prognoses. The 2 patient subsets differed in the expression of hematopoietic lineage cell-specific protein 1 (HS1). In patients with poor prognoses, most HS1 protein was constitutively phosphorylated, whereas only a fraction was phosphorylated in patients with good prognoses. This difference was investigated in a larger cohort of 26 unselected patients. The survival curve of all 40 patients analyzed revealed that patients with predominately phosphorylated HS1 experience a significantly shorter median survival time. As HS1 is a protein pivotal in the signal cascade triggered by B cell receptor (BCR) stimulation, we studied its pattern of expression following BCR engagement. Normal mature B cells stimulated by anti-IgM shifted the non- or less-phosphorylated form of HS1 toward the more phosphorylated form. Naive B cells showed both HS1 forms while memory B cells expressed mainly the phosphorylated fraction. These data indicate a central role for antigen stimulation in CLL and suggest a new therapeutic target for patients with aggressive disease.

ADP-ribosyl Cyclase↗

PubMed2004

Vdelta1 T lymphocytes from B-CLL patients recognize ULBP3 expressed on leukemic B cells and up-regulated by trans-retinoic acid.

We analyzed 38 untreated patients with chronic lymphocytic leukemia of B-cell type (B-CLL): 24 low-, 8 intermediate-, and 6 high-risk stage. In 15 patients (13 low risk and 2 intermediate risk), circulating Vdelta1 T lymphocytes were significantly increased (100 to 300 cells/muL) compared with most intermediate, all high-risk stage, and 15 healthy donors (50 to 100 cells/muL). We studied these Vdelta1 T lymphocytes and observed that they proliferated in vitro and produced tumor necrosis factor alpha or IFN-gamma in response to autologous leukemic B cells but not to normal lymphocytes. However, they were unable to kill resting autologous B cells, which lack the MHC-related MIC-A antigen and express low levels of the UL16-binding protein (ULBP) 3 and undetectable levels of ULBP1, ULBP2, and ULBP4. All these molecules are reported ligands for the NKG2D receptor, which is expressed by gammadelta T cells and activates their cytolytic function. The Vdelta1 T lymphocytes studied were able to lyse the ULBP3(+) C1R B-cell line upon transfection with MIC-A. More importantly, they also lysed autologous B-CLL cells when transcription and expression of MIC-A or up-regulation of ULBP3 were achieved either by activation or by exposure to trans-retinoic acid. The NKG2D receptor expressed on Vdelta1 T cells was involved in the recognition of B-CLL. Finally, in six patients with low numbers of circulating Vdelta1 T cells and undetectable ULBP3, the disease progressed over 1 year, whereas no progression occurred in patients with high Vdelta1 T lymphocytes and detectable/inducible ULBP3. These data suggest that Vdelta1 T lymphocytes may play a role in limiting the progression of B-CLL.

Aged↗

PubMed2004

Geographic patterns and pathogenetic implications of IGHV gene usage in chronic lymphocytic leukemia: the lesson of the IGHV3-21 gene.

We studied immunoglobulin variable heavy-chain (IGHV) repertoire and mutational status in 553 patients with chronic lymphocytic leukemia (CLL) from the Mediterranean area to gain insight into the potential pathogenetic role of antigenic stimulation. The most commonly represented IGHV genes mirrored the usage of normal B cells, with the exception of IGHV1-18, IGHV3-30.3, and IGHV4-59 that were underrepresented. The IGHV3-21 gene, frequently expressed in Northern European CLL, was present only in 16 cases (2.9%). Based on HCDR3 cluster analysis, cases using IGHV3-21 could be grouped in 2 subsets of similar frequency. The first one (7 of 16 cases) carried a similar HCDR3 amino acid sequence (common-HCDR3 subset), virtually identical to the Scandinavian IGHV3-21 CLL. These cases used the IGHJ6 gene; 4 of 7 were unmutated; 6 of 7 carried the V(lambda)2-14 (IGLV3-21) light-chain gene with a similar LCDR3. All expressed CD38 and had a progressive disease. The second subset (9 of 16) was characterized by heterogeneous HCDR3 rearrangements (nonhomogeneous-HCDR3 subset), diverse IGHJ and IGV light-chain gene usage, variable IGHV mutational status (5 of 9 unmutated), variable CD38 expression, and variable clinical course (4 of 9 progressed). The first subset suggests a potential antigenic element rarely encountered in the Mediterranean area, possibly responsible for a negative outcome. The second subset may reflect the physiologic heterogeneity of expression of IGHV3-21 rearrangements in the normal repertoire and is characterized by a variable clinical outcome.

Adult↗

PubMed2004

Leukemia-derived immature dendritic cells differentiate into functionally competent mature dendritic cells that efficiently stimulate T cell responses.

Primary acute myeloid leukemia cells can be induced to differentiate into dendritic cells (DC). In the presence of GM-CSF, TNF-alpha, and/or IL-4, leukemia-derived DC are obtained that display features of immature DC (i-DC). The aim of this study was to determine whether i-DC of leukemic origin could be further differentiated into mature DC (m-DC) and to evaluate the possibility that leukemic m-DC could be effective in vivo as a tumor vaccine. Using CD40L as maturating agent, we show that leukemic i-DC can differentiate into cells that fulfill the phenotypic criteria of m-DC and, compared with normal counterparts, are functionally competent in vitro in terms of: 1) production of cytokines that support T cell activation and proliferation and drive Th1 polarization; 2) generation of autologous CD8(+) CTLs and CD4(+) T cells that are MHC-restricted and leukemia-specific; 3) migration from tissues to lymph nodes; 4) amplification of Ag presentation by monocyte attraction; 5) attraction of naive/resting and activated T cells. Irradiation of leukemic i-DC after CD40L stimulation did not affect their differentiating and functional capacity. Our data indicate that acute myeloid leukemia cells can fully differentiate into functionally competent m-DC and lay the ground for testing their efficacy as a tumor vaccine.

CD40 Ligand↗

PubMed2004

The nature and origin of the B-chronic lymphocytic leukemia cell: a tentative model.

Chronic lymphocytic leukemia cells have the profile of antigen (Ag) activated memory B cells but also show a constellation of T-cell-associated properties. We suggest that the early transforming events may occur in an early lymphoid progenitor. This precursor differentiates into a mature B cell that, though retaining T-cell features, has a functional B-cell receptor that may allow Ag intervention to trigger clonal expansion. This model has to cope with the existence of at least two subsets of the disease as defined by their IgVH genes mutational status. Mutated cases have a lower capacity to interact with Ag and are reminiscent of anergic cells. This explains their less harmful behavior as compared with unmutated case, which have a more aggressive potential likely because they had the opportunity to acquire additional chromosomal aberrations after repeated rounds of Ag stimulation and replication.

Humans↗

PubMed2003

Monoclonal CD5+ and CD5- B-lymphocyte expansions are frequent in the peripheral blood of the elderly.

The responsiveness and diversity of peripheral B-cell repertoire decreases with age, possibly because of B-cell clonal expansions, as suggested by the incidence of serum monoclonal immunoglobulins and of monoclonal chronic lymphocytic leukemia (CLL)-like B lymphocytes in clinically silent adults. We phenotyped peripheral blood cells from 500 healthy subjects older than 65 years with no history or suspicion of malignancies and no evidence of lymphocytosis. In 19 cases (3.8%) a kappa/lambda ratio of more than 3:1 or less than 1:3 was found: 9 were CD5+, CD19+, CD23+, CD20low, CD79blow, sIglow (classic CLL-like phenotype); 3 were CD5+, CD19+, CD23+, CD20high, CD79blow, sIglow (atypical CLL-like), and 7 were CD5-, CD19+, CD20high, CD23-, CD79bbright, FMC7+, sIgbright (non-CLL-like). In 2 subjects, 2 phenotypically distinct unrelated clones were concomitantly evident. No cases were CD10+. Polymerase chain reaction (PCR) analysis demonstrated a monoclonal rearrangement of IgH genes in 15 of 19 cases. No bcl-1 or bcl-2 rearrangements were detected. Using a gating strategy based on CD20/CD5/CD79 expression, 13 additional CLL-like B-cell clones were identified (cumulative frequency of classic CLL-like: 5.5%). Thus, phenotypically heterogeneous monoclonal B-lymphocyte expansions are common among healthy elderly individuals and are not limited to classic CLL-like clones but may have the phenotypic features of different chronic lymphoproliferative disorders, involving also CD5- B cells.

Aged↗

PubMed2003

IL-12 regulates an endothelial cell-lymphocyte network: effect on metalloproteinase-9 production.

IL-12 is key cytokine in innate immunity and participates in tumor rejection by stimulating an IFN-gamma-mediated response characterized by CD8(+) mediated-cytotoxicity, inhibition of angiogenesis, and vascular injury. We previously demonstrated that activated lymphocytes stimulated with IL-12 induced an angiostatic program in cocultured vascular endothelial cells. In this study, we have extended this observation showing that a reciprocal modulation of cellular responses occurs. Actually, the presence of endothelial cells enhanced the inhibitory effect of IL-12 on metalloproteinase-9 expression in activated PBMC as well as their ability to transmigrate across an extracellular matrix. IL-12 triggered intracellular signaling, as indicated by STAT-1 activation, appeared to mainly operative in activated CD4 (+) cells challenged with IL-12, but it was also initiated in CD8(+) lymphocytes in the presence of endothelial cells. On the other hand, stimulated PBMC reduced the expression and the activity of metalloproteinase-9, up-regulated that of tissue inhibitor metalloproteinase-1, and stimulated the STAT-1 pathway in cocultured endothelial cells. We used neutralizing Abs to show that the IFN-inducible protein 10 (CXCL10) and monokine-induced by IFN-gamma (CXCL9) chemokines produced by both PBMC and endothelial cells are pivotal in inducing these effects. Altogether these results suggest the existence of an IL-12-regulated circuit between endothelium and lymphocytes resulting in a shift of proteolytic homeostasis at site of tissue injury.

Basement Membrane↗

PubMed2003

Expansion of tumor-specific CD8+ T cell clones in patients with relapsed myeloma after donor lymphocyte infusion.

Donor lymphocyte infusions (DLI) provide effective therapy for patients with multiple myeloma who have relapsed after allogeneic bone marrow transplantation. However, the immunological mechanisms of the graft-versus-myeloma (GVM) effect have not been defined, and the target antigens of this response have not been identified. Molecular analysis of CDR3 Vbeta repertoire after CD4+ DLI demonstrated previously that the development of GVM and graft-versus-host-disease (GVHD) were associated with the clonal expansion of distinct T-cell populations in patient peripheral blood. In the current study, we undertook a molecular and functional characterization of GVM- and GVHD-associated T-cell clones. T-cell clones associated with GVM were detectable by clone-specific PCR at a low level in peripheral blood before DLI and expanded approximately 10-fold after DLI. In contrast, T-cell clones associated with GVHD were not detectable before DLI or before the development of clinical GVHD. Two T-cell clones associated with GVM were isolated and expanded in vitro, allowing their phenotypic and functional characterization. Both GVM clones were derived from donor cells and had a CD3+CD8+CD4- phenotype. One GVM clone specifically recognized patient myeloma cells in an HLA class I-restricted manner, but was not reactive with patient normal bone marrow cells or patient EBV transformed B cells. Taken together, these findings suggest that the GVM response is mediated by donor-derived CD8+ T-cell clones with antimyeloma specificity that may be present before DLI. In contrast, T-cell clones associated with GVHD are expanded de novo after DLI.

Adult↗

PubMed2003

The characterization of chemokine production and chemokine receptor expression reveals possible functional cross-talks in AML blasts with monocytic differentiation.

OBJECTIVE: The mechanisms regulating the trafficking of leukemic myeloid blasts are poorly understood. A differential expression of chemokines and chemokine receptors might account for some aspects of the pattern of invasion and accumulation of leukemic cells. We aimed at defining the pattern of chemokine and chemokine receptor expression of acute myeloid leukemia (AML) blasts in comparison with their putative normal cell counterparts. PATIENTS AND METHODS: Twenty-five cases of AML were analyzed by flow cytometry for the expression of several chemokine receptors and by RT-PCR for the expression of relevant chemokines. For selected chemokines, the production was confirmed by ELISA. AML blasts were also assessed for their migration capacity in response to autologous supernatants and recombinant chemokines. RESULTS: Undifferentiated AML (MO-M1 and some M2) express only CXCR4 on their surface and produce mainly inflammatory chemokines, resembling normal CD34+ progenitors. More differentiated AML (M4-M5 and some M2) have a more diversified receptor repertoire and, besides CXCR4, express the receptors for inflammatory chemokines and produce both constitutive and inflammatory chemokines, resembling resting and activated monocytes. In particular, M4-M5 blasts produce MCP-1 and MIP-3alpha and also express their specific receptors (CCR2 and, to a lesser extent, CCR6) and migrate in vitro in response to MCP-1 and MIP-3alpha and to their own supernatant. A significant correlation between extramedullary involvement and coexpression of MCP-1/CCR2 was found. CONCLUSIONS: These data suggest that chemokines and their receptors segregate within the different FAB subtypes and, by allowing cross-talk among members of the malignant clone, might help to explain some aspects of the pattern of invasion in AML with monocytic differentiation.

Acute Disease↗

PubMed2002

CD100/Plexin-B1 interactions sustain proliferation and survival of normal and leukemic CD5+ B lymphocytes.

Growth and survival of chronic B-cell tumors are favored by the malignant cell's capacity to respond to selected microenvironmental stimuli provided by nontumoral bystander cells. To investigate which mechanisms operate in these crosstalks and whether they are malignancy-related or reproduce the mechanisms used by normal B cells we have studied the expression and functional role of semaphorin CD100 (now called Sema4D) in chronic lymphocytic leukemia (CLL) cells and normal CD5+ B cells. We demonstrate here that (1) leukemic and normal CD5+ B lymphocytes uniformly express CD100; (2) the CD100 high-affinity receptor Plexin-B1 is expressed by bone marrow stromal cells, follicular dendritic cells, and activated T lymphocytes, and is thus available to CD100+ lymphocytes in different specific microenvironments; and (3) upon interaction between CD100 and Plexin-B1 both CLL and normal CD5+ B cells increase their proliferative activity and extend their life span. These findings establish that Plexin-B1 is an easily accessible receptor for CD100 within the immune system. The encounter of CD100+ leukemic cells with Plexin-B1 may promote the proliferation and survival of malignant cells. The crosstalk operated by the CD100/Plexin-B1 interaction is not malignancy related but reproduces a mechanism used by normal CD5+ B cells.

Animals↗