Use of IGK gene rearrangement analysis for clonality assessment of lymphoid malignancies: a single center experience

Diagnosis of B-non Hodgkin lymphomas (NHLs) is based on clinical, morphological and immunohistochemi-cal features. However, in up to 10-15% of cases, analysis of immunoglobulin heavy (IGH) or light (IGK/IGL) chains genes is required to discriminate between malignant and reactive lymphoid proliferations. In this study, we evaluated the feasibility and efficiency of IGK analysis in the routine diagnostic of B-cell lymphoproliferative disorders (B-LD) when applied to formalin-fixed paraffin-embedded (FFPE) tissues. Clonality patterns were studied in 59 B-LD using the BIOMED-2 protocol for IGK assays, after failure of the IGH assay. PCR products were evaluated by both heterodu-plex and GeneScan analysis. IGK analysis was technically successful in all cases. Overall, it supported the histopa-thological suspicion in 52/59 cases (88%), the sensitivity and specificity being 83% and 80%, respectively. Further, positive and negative predictive values were 95% and 50%, respectively. Interestingly, among various lymphoma subtypes, marginal zone lymphoma and follicular lymphoma most frequently required IGK analysis. In conclusion, IGK study according to the BIOMED-2 protocol resulted feasible and extremely useful in supporting challenging diagnosis of B-LD even if applied on FFPE samples. Accordingly, when NHL is suspected, negative results at IGH analysis should not be considered as conclusive and further investigation of IGK is appropriate.

Lymphoma classification: the quiet after the storm

The classification of malignant lymphomas remained controversial for over 30 years. The first scheme was proposed by Rappaport in the '60th and was based on incorrect histogenetic concepts. To overcome these limitations, several groups formulated new proposals in '70th. Among these two merited attention: the Lukes and Collins and the Kiel Classifications. They were based on the assumption that each lymphoma category might be related to a precise differentiation step of the lymphoid system, thus excluding any correlation with histiocytes, present on the Rappaport scheme. The Kiel Classification became very popular in Europe, while the one of Luke and Collins did not meet success in the United States (U.S.). In 1978, the National Cancer Institute proposed an international trial to compare the classifications used in Europe and U.S. The result was the genesis of the Working formulation, the tool for lymphoma classification in the U.S. up to the early '90th, but which was conversely rejected in Europe. In order to get over this lack of transatlantic communication, in 1994 the Revised European-American Lymphoma (REAL) Classification was proposed by the International Lymphoma Study Group. Its goal was to list "real" entities, each defined by the presence of homogeneous morphologic, phenotypic, cytogenetic, molecular, and clinical criteria, along with the possible recognition of its normal counterpart. The REAL Classification became the model for the WHO Classification of all haematopoietic tumours published in 2001. The present review aims to analyse future perspectives after the fourth edition of the WHO Classification released in 2008.

Pathobiology of acute lymphoblastic leukemia

In the present review, the authors described the pathobiological features of B- and T-ALL, which appear to be quite heterogeneous with regard to molecular pathogenesis. The last edition of the World Health Organization Classification considered this aspect by defining many entities based on genetic findings. This approach is not only important for prognostic stratification, but also in the near future will surely represent the basis for the definition of patient-specific therapeutic approaches. A striking example is Ph+ acute lymphoblastic leukemia (ALL), which until the advent of tyrosine kinase inhibitors (TKI) has been regarded as the most aggressive ALL. The use of imatinib, dasatinib, and possibly more recent inhibitors has dramatically changed the clinical scenario, offering new opportunities to patients, especially the elderly. Similarly, the use of FLT3 inhibitors in mixed lineage leukemia-positive cases, gamma-secretase inhibitors in T-ALL, novel TKI, and monoclonal antibodies may represent a successful approach in the future.

Peripheral T-cell lymphoma classification: the matter of cellular derivation

Peripheral T-cell lymphomas (PTCLs) represent approximately 12% of all non-Hodgkin's lymphomas in Western countries. They are quite heterogeneous as far as morphology and phenotype are concerned. Furthermore, until now, PTCLs could not be referred to specific normal counterparts, in contrast to B-cell-derived non-Hodgkin's lymphomas. In particular, in the last edition of the WHO classification of Tumors of the Hematopoietic and Lymphoid Tissues, for the majority of nodal PTCLs (including the not otherwise specified type and anaplastic large-cell lymphoma), the postulated cell of origin remained undefined. However, in the last few years, high-throughput genomic techniques, especially gene-expression profiling, have allowed us to better define the relationship between some entities and the different T-cell subpopulations. Consequently, it has become possible to clearly define, for example, the association between angioimmunoblastic T-cell lymphoma and T-follicular helper cells. In addition, within PTCLs/not otherwise specified, different subgroups were identified based on their similarity to different cellular counterparts, including T-helper, T-cytotoxic and T-follicular helper cells. In this article, based on their own experience as well as up-to-date literature, the authors revise the concept of PTCL classification by specially focusing on their cellular counterparts and discuss the possible clinical relevance of such an approach.

Primary cutaneous lymphomas: a reprisal

Primary cutaneous lymphomas (PCLs) are a group of lymphoid neoplasms provided with heterogeneous clinical, histological, immunohistochemical and molecular features. They can be classified in two groups: cutaneous T-cell lymphomas (CTCLs) and cutaneous B-cell lymphomas (CBCLs). Recent studies show an increase of the incidence of PCLs over the last three decades. Our aim is to evaluate the commonest types of PCL analysing the clinical characteristics, histology, phenotype, molecular biology, prognosis and therapy.

Anaplastic lymphoma kinase in human cancer

The receptor tyrosine kinases (RTKs) play a critical role, controlling cell proliferation, survival, and differentiation of normal cells. Their pivotal function has been firmly established in the pathogenesis of many cancers as well. The anaplastic lymphoma kinase (ALK), a transmembrane RTK, originally identified in the nucleophosmin (NPM)-ALK chimera of anaplastic large cell lymphoma, has emerged as a novel tumorigenic player in several human cancers. In this review, we describe the expression of the ALK-RTK, its related fusion proteins, and their molecular mechanisms of activation. Novel tailored strategies are briefly illustrated for the treatment of ALK-positive neoplasms.

Pathobiology of ALK-negative anaplastic large cell lymphoma

The authors revise the concept of ALK-negative anaplastic large cell lymphoma (ALCL) in the light of the recently updated WHO classification of Tumors of Hematopoietic and Lymphoid Tissues both on biological and clinical grounds. The main histological findings are illustrated as well as the phenotypic, molecular and clinical characteristics. Finally, the biological rationale for possible innovative targeted therapies is presented.

Follicular lymphoma: stillSix characters in search of an author?

Follicular lymphoma (FL) is regarded as a distinct entity in the literature as well as in the 2008 edition of the WHO classification of tumours of haematopoietic and lymphoid tissues. Nevertheless, there are still several issues that are matters of controversy such as the grading system or the exact biological location of grade 3B FL. This makes FL somewhat like the Six characters in search of an author of Pirandello's comedy. Here, we revise the morphology and pathobiology of FL by highlighting both the areas remaining critical and future perspectives. This review was inspired by the reappraisal of Professor Lennert's personal archive that represents a unique legacy for the entire scientific community.

Systemic Epstein-Barr-virus-positive T cell lymphoproliferative childhood disease in a 22-year-old Caucasian man: A case report and review of the literature

INTRODUCTION

Systemic Epstein-Barr-virus-positive T cell lymphoproliferative disease of childhood is an extremely rare disorder, characterized by clonal proliferation of Epstein-Barr-virus-infected T cells with an activated cytotoxic phenotype. The disease is more frequent in Asia and South America, with only few cases reported in Western countries. A prompt diagnosis, though often difficult, is a necessity due to the very aggressive clinical course of the disease.

CASE PRESENTATION

We report the clinicopathological features of fulminant T cell lymphoproliferative disease that arose in the setting of acute primary Epstein-Barr virus infection. Our patient, a 23-year-old man, presented to our facility with persisting fever, hepatosplenomegaly and severe pancytopenia. On bone marrow biopsy, an abundant lymphoid infiltrate was observed. Immunophenotypic and molecular studies revealed that the atypical lymphoid cells displayed a CD8+, Epstein-Barr-encoded-RNA-positive T cell phenotype with clonal rearrangement of the T cell receptor genes, the final diagnosis being systemic Epstein-Barr-virus-positive T cell lymphoproliferative disease. On reviewing the literature we found only 14 similar cases, all presenting with very aggressive clinical courses and requiring extensive phenotyping and molecular techniques for final diagnosis.

CONCLUSION

Though extremely rare, this disease can occur in Europe, and a comprehensive diagnostic approach is thus recommended in all case of Epstein-Barr-virus-positive lymphoproliferative disorders. Unfortunately, at present no specific treatment is available; however, prompt administration of anti- Epstein-Barr virus treatment and rapid attempts to control the hemophagocytic syndrome are indicated.

New mechanisms of resistance in Philadelphia chromosome acute lymphoblastic leukemia

The outcome for adults and children with Philadelphia chromosome acute lymphoblastic leukemia (ALL) has been improved dramatically with the use of tyrosine kinase inhibitors but relapse is an expected event in the majority of patients. We reviewed recent findings obtained from both gene-expression profiling analysis and single nucleotide polymorphism arrays and characterized by the identification of multiple novel genetic alterations targeting key cellular pathways, including lymphoid differentiation, cell cycle, tumor suppression, apoptosis and drug responsiveness. By gene-expression profiling analysis a new subtype known as 'BCR-ABL1-like' was identified, which includes 15-20% of all precursor B-ALL cases and is associated with an unfavorable outcome. By single nucleotide polymorphism array analysis, deletions of genes such as IKAROS, PAX5 and CDKN2A-CDKN2B were frequently identified. New therapeutic approaches are now available, such as dasatinib, nilotinib and bosutinib, and we highlight those that may be applicable to the treatment of adult BCR-ABL1-positive ALL.

The bone marrow stroma in hematological neoplasms--a guilty bystander

In the setting of hematological neoplasms, changes in the bone marrow (BM) stroma might arise from pressure exerted by the neoplastic clone in shaping a supportive microenvironment, or from chronic perturbation of the BM homeostasis. Under such conditions, alterations in the composition of the BM stroma can be profound, and could emerge as relevant prognostic factors. In this Review, we delineate the multifaceted contribution of the BM stroma to the pathobiology of several hematological neoplasms, and discuss the impact of stromal modifications on the natural course of these diseases. Specifically, we highlight the involvement of BM stromal components in lymphoid and myeloid malignancies, and present the most relevant processes responsible for remodeling the BM stroma. The role of bystander BM stromal elements in the setting of hematological neoplasms is discussed, strengthening the rationale for treatment strategies that target the BM stroma.

Biology and treatment of follicular lymphoma

Follicular lymphoma (FL) is the second most common lymphoid tumor. It is composed of elements resembling those of normal germinal centers. In particular, it is constituted by small centrocytes and large centroblasts, typically CD10+, CD19+, CD20+, CD79a+ and BCL6+, with follicular growth pattern. The molecular hallmark of FL is the t(14;18)(q32;q21) translocation, which leads to inappropriate BCL2 expression. This feature, other than representing a pathogenetic primary event, constitutes a suitable diagnostic marker, as well as a target for minimal residual disease monitoring and, hopefully, future therapies. Clinically, FL presents with indolent behavior, characterized by prompt response to initial therapy but almost invariably subsequent relapses. Novel approaches, including stem cell transplantation, monoclonal antibodies and innovative agents, should be then considered for improving long-term results.

Evaluation of modified PEG-anilinoquinazoline derivatives as potential agents for EGFR imaging in cancer by small animal PET

Purpose

The in vivo evaluation of three modified polyethylene glycol (PEG)-anilinoquinazoline derivatives labeled with ¹²⁴I, ¹⁸F, and ¹¹C as potential positron emission tomography (PET) bioprobes for visualizing epidermal growth factor receptor (EGFR) in cancer using small animal PET.

Procedures

Xenograft mice with the human glioblastoma cell lines U138MG (lacking EGFR expression) and U87MG.wtEGFR (transfected with an overexpressing human wild-type EGFR gene) were used. Static and dynamic PET imaging was conducted for all three PEGylated compounds. Tumor necrosis, microvessel density, and EGFR levels were evaluated by histopathology and enzyme-linked immunosorbent assay.

Results

Nineteen animal models were generated (two U138MG, three U87MG, 14 with both U138MG and U87MG bilateral masses). In static images, a slight increase in tracer uptake was observed in tumors, but in general, there was no retention of tracer uptake over time and no difference in uptake between U138MG and U87MG masses. In addition, no significant uptake was demonstrated in dynamic scans of the ¹⁸F-PEG tracer. No necrosis was present except in four animals. MVD was 9.6 and 48 microvessels/×400 field in the U138GM and U87GM masses, respectively (p = 0.00008). Similarly, the microvessel grades were generally higher in the U87GM group (p = 0.002). Total EGFR amount was higher in U87MG than U138MG masses (p = 0.001), but the ratio of activated (pY1068) to total EGFR did not differ (p = 0.95).

Conclusions

PEGylated tracers labeled with ¹¹C, ¹²⁴I, and ¹⁸F showed no significant difference in uptake between U138MG and U87MG glioblastoma xenograft mice. The tracer binding with EGFR could be influenced by activation of the tyrosine kinase portion of the receptor which was similar in U138MG and U87MG. Despite these results, these tracers should be investigated in animal models with mutant EGFR genes to determine whether aberrant receptor function plays a role in tumor uptake.

Primary effusion lymphoma associated with Human Herpes Virus-8 and Epstein Barr virus in an HIV-infected woman from Kampala, Uganda: a case report

INTRODUCTION

Primary effusion lymphoma is a recently recognized entity of AIDS related non-Hodgkin lymphomas. Despite Africa being greatly affected by the HIV/AIDS pandemic, an extensive MEDLINE/PubMed search failed to find any report of primary effusion lymphoma in sub-Saharan Africa. To our knowledge this is the first report of primary effusion lymphoma in sub-Saharan Africa. We report the clinical, cytomorphologic and immunohistochemical findings of a patient with primary effusion lymphoma.

CASE PRESENTATION

A 70-year-old newly diagnosed HIV-positive Ugandan African woman presented with a three-month history of cough, fever, weight loss and drenching night sweats. Three weeks prior to admission she developed right sided chest pain and difficulty in breathing. On examination she had bilateral pleural effusions.Haematoxylin and eosin stained cytologic sections of the formalin-fixed paraffin-embedded cell block made from the pleural fluid were processed in the Department of Pathology, Makerere University, College of Health Sciences, Kampala, Uganda. Immunohistochemistry was done at the Institute of Haematology and Oncology "L and A Seragnoli", Bologna University School of Medicine, Bologna, Italy, using alkaline phosphatase anti-alkaline phosphatase method. In situ hybridization was used for detection of Epstein-Barr virus.The tumor cells were CD45+, CD30+, CD38+, HHV-8 LANA-1+; but were negative for CD3-, CD20-, CD19-, and CD79a- and EBV RNA+ on in situ hybridization. CD138 and Ki-67 were not evaluable. Our patient tested HIV positive and her CD4 cell count was 127/μL.

CONCLUSIONS

A definitive diagnosis of primary effusion lymphoma rests on finding a proliferation of large immunoblastic, plasmacytoid and anaplastic cells; HHV-8 in the tumor cells, an immunophenotype that is CD45+, pan B-cell marker negative and lymphocyte activated marker positive. It is essential for clinicians and pathologists to have a high index of suspicion of primary effusion lymphoma when handling HIV positive patients who have effusions without palpable tumor masses. Basic immunohistochemistry is essential for definitive diagnosis.

Pathobiology of anaplastic large cell lymphoma

The authors revise the concept of anaplastic large cell lymphoma (ALCL) in the light of the recently updated WHO classification of Tumors of Hematopoietic and Lymphoid Tissues both on biological and clinical grounds. The main histological findings are illustrated with special reference to the cytological spectrum that is indeed characteristic of the tumor. The phenotype is reported in detail: the expression of the ALK protein as well as the chromosomal abnormalities is discussed with their potential pathogenetic implications. The clinical features of ALCL are presented by underlining the difference in terms of response to therapy and survival between the ALK-positive and ALK-negative forms. Finally, the biological rationale for potential innovative targeted therapies is presented.

Partial nodal involvement by marginal zone lymphoma. Use of IGK gene rearrangement analysis in diagnostic work-up

Nodal marginal zone lymphoma (NMZL) is an indolent B-cell lymphoma that originates from the marginal zone of B-cell follicles. The tumour is rather uncommon, and shares some morphologic and immunophenotypic similarities with the extranodal form of marginal zone lymphomas. However, diagnosis of NMZL implies the exclusion of lymphoplasmacytic lymphoma, follicular lymphoma, and lymph node involvement by extra nodal or splenic marginal zone B-cell lymphoma In addition, its distinction from reactive conditions, including T-zone hyperplasia, are sometimes problematic based on morphologic grounds. We describe a patient who presented with cervical and inguinal lymphadenopathies and high inflammation indexes. Bone marrow and lymph node biopsies were performed for definitive diagnosis. Bone marrow histological and immunophenotypic examinations were normal and excluded haematological disease. In contrast, lymph node evaluation showed some features compatible with a possible lymphoproliferative disorder, even though no definite diagnosis could be made based on morphologic and immunohistochemical investigation. In particular, the problem of a differential diagnosis between NMZL and a florid hyperplasia of monocytoid B-elements was posed. Thus, in order to assess the nature (neoplastic vs. reactive) of the lesion, molecular analysis of the immunoglobulin genes was performed by PCR. Notably, although no clonal rearrangements were revealed by IGHV@ analysis, further evaluation of the immunoglobulin light chain (IGKV@) confirmed the presence of a clonal B-cell population. Accordingly, a final diagnosis of NMZL was made. In conclusion, this case is a good example of the crucial role of complete molecular analysis in the diagnostic work up of lymphoproliferative disorders.

Gene expression analysis uncovers similarity and differences among Burkitt lymphoma subtypes

Burkitt lymphoma (BL) is classified into 3 clinical subsets: endemic, sporadic, and immunodeficiency-associated BL. So far, possible differences in their gene expression profiles (GEPs) have not been investigated. We studied GEPs of BL subtypes, other B-cell lymphomas, and B lymphocytes; first, we found that BL is a unique molecular entity, distinct from other B-cell malignancies. Indeed, by unsupervised analysis all BLs clearly clustered apart of other lymphomas. Second, we found that BL subtypes presented slight differences in GEPs. Particularly, they differed for genes involved in cell cycle control, B-cell receptor signaling, and tumor necrosis factor/nuclear factor κB pathways. Notably, by reverse engineering, we found that endemic and sporadic BLs diverged for genes dependent on RBL2 activity. Furthermore, we found that all BLs were intimately related to germinal center cells, differing from them for molecules involved in cell proliferation, immune response, and signal transduction. Finally, to validate GEP, we applied immunohistochemistry to a large panel of cases and showed that RBL2 can cooperate with MYC in inducing a neoplastic phenotype in vitro and in vivo. In conclusion, our study provided substantial insights on the pathobiology of BLs, by offering novel evidences that may be relevant for its classification and possibly future treatment.

Prognostic markers in peripheral T-cell lymphoma

Based on their own experience and knowledge of the literature, the authors review the pathobiological characteristics of peripheral T-cell lymphomas (PTCLs), focusing on the available prognostic indicators. The International Prognostic Index (IPI), which is based on age, performance status, lactate dehydrogenase [LDH], stage, and extranodal involvement, appears to be efficient as a prognostic index for PTCLs, at least in part and especially for certain PTCL subtypes. However, it is not so satisfactory for the two commonest PTCLs, PTCL not otherwise specified (PTCL/NOS) and angioimmunoblastic T-cell lymphoma (AITL), for which novel scores, possibly based on the biologic features of the tumors, have been explored. An Italian cooperative group proposed a revision of the IPI for PTCL unspecified (PTCL-U), the Prognostic Index for PTCL-U (PIT), which includes age, performance status, LDH, and bone marrow involvement. The PIT apparently offered some advantages, but they were not confirmed in subsequent studies. A clinical-biological score (the Bologna score) was then proposed, including tumor proliferation and clinical features (age, LDH, and performance status). This score appears promising and offers the intriguing advantage of integrating biological and clinical elements, but independent validation on a large series is still warranted. More recently, gene expression profiling has been used to identify novel molecular prognostic factors. In particular, inactivation of the NFκB pathway, high expression of proliferation-associated genes, and cytotoxic molecular phenotype seem to be associated with a worse outcome. So far, however, none of these indicators has been validated in an independent series. Finally, various reports have dealt specifically with the prognostication of NK-derived tumors, including nasal and nasal-type lymphomas. Both the IPI and dedicated models have turned out to be of prognostic relevance for these tumors. In conclusion, although the IPI is somewhat effective for PTCL prognostication, novel scores that are more refined and possibly disease-specific are warranted. The validation process for several models, including clinical-pathological and molecular models, is now ongoing.

Pathobiology of hodgkin lymphoma

Despite its well-known histological and clinical features, Hodgkin's lymphoma (HL) has recently been the object of intense research activity, leading to a better understanding of its phenotype, molecular characteristics, histogenesis, and possible mechanisms of lymphomagenesis. There is complete consensus on the B-cell derivation of the tumor in most cases, and on the relevance of Epstein-Barr virus infection and defective cytokinesis in at least a proportion of patients. The REAL/WHO classification recognizes a basic distinction between lymphocyte predominance HL (LP-HL) and classic HL (cHL), reflecting the differences in clinical presentation and behavior, morphology, phenotype, and molecular features. cHL has been classified into four subtypes: lymphocyte rich, nodular sclerosing, with mixed cellularity, and lymphocyte depleted. The borders between cHL and anaplastic large-cell lymphoma have become sharper, whereas those between LP-HL and T-cell-rich B-cell lymphoma remain ill defined. Treatments adjusted to the pathobiological characteristics of the tumor in at-risk patients have been proposed and are on the way to being applied.

Characterization of a New Monoclonal Antibody Against PAX5/BASP in 1525 Paraffin-embedded Human and Animal Tissue Samples

INTRODUCTION

We describe the newly generated DAK-PAX5 monoclonal antibody raised against a fixation-resistant epitope of the human PAX5/BSAP molecule.

MATERIALS AND METHODS

Following Western-blot, absorption, and chess-board titration tests, and optimization of antigen-retrieval and detection methods, DAK-Pax5 was used in parallel with a reference antibody (clone 24) on tissue micro-arrays (TMAs) constructed from normal human and animal tissues and from hematologic and nonhematologic human malignancies. Such TMAs were also tested with an anti-PAX2 antibody.

RESULTS

DAK-Pax5 reacted with normal human and animal B-cells and with 460/473 B-cell non-Hodgkin lymphomas (B-NHLs). All plasmacytomas/plasmablastic tumors (n=13) and T/NK-cell neoplasms (n=264) turned out consistently negative as did acute myelogenous leukaemias (n=19) except 2 carrying t(8;21). Positivity was found in 6/6 and 155/169 lymphocyte predominant and classical HLs, respectively, although the staining intensity varied through cases. Among 521 nonhematologic malignancies, DAK-Pax5 reacted with 22/399 carcinomas (4/11 neuroendocrine, 2/4 Merkel-cell, 4/21 prostatic, 1/11 urothelial, 1/26 renal, 2/12 cervical squamous-cell, 3/13 ovarian, and 5/75 colonic). When compared with clone 24, DAK-Pax5 produced a stronger positivity in most if not all B-NHLs and HLs. No cross-reactivity with the anti-PAX2 antibody was recorded.

DISCUSSION

DAK-Pax5 represents a new reliable tool for diagnostics and research.

CDKN1B/p27 expression in peripheral T cell lymphoma not otherwise specified

AIMS

Peripheral T cell lymphoma not otherwise specified (PTCL/NOS) is the commonest PTCL subtype. Recently, proliferation pathways have been found to be commonly altered in PTCL/NOS. CDKN1B/p27, a critical regulator of cell cycle and proliferation, has been suggested to be involved in T cell lymphomagenesis. This study aimed to evaluate the possible occurrence of CDKN1B/p27 aberrations in PTCL/NOS.

METHODS

CDKN1B/p27 expression at RNA and protein level by DNA and tissue microarrays, in 28 and 98 cases, respectively, was studied. Additionally, direct sequencing of CDKN1B in 81 PTCL/NOS was performed.

RESULTS

CDKN1B mRNA was similarly expressed in PTCL/NOS and normal T lymphocytes. In addition, structural abnormalities were not found; these included mutations and deletions in any exons, exon-intron junctions or regulatory regions. Furthermore, physiological expression of p27 in neoplastic cells was demonstrated by immunohistochemistry; this was mutually exclusive with Ki-67, as expected when the system is intact. Consistently, the expression of other molecules that are functionally related to CDKN1B/p27 in controlling cell cycle (including CCNE1) did not appear to be affected at either the mRNA or protein level. Finally, it was found that p27 expression was not significantly related with overall survival.

CONCLUSION

CDKN1B/p27 aberrations seem to be uncommon in PTCL/NOS pathogenesis.

Mast cells and Th17 cells contribute to the lymphoma-associated pro-inflammatory microenvironment of angioimmunoblastic T-cell lymphoma

Reports focusing on the immunological microenvironment of peripheral T-cell lymphomas (PTCL) are rare. Here we studied the reciprocal contribution of regulatory (Treg) and interleukin-17-producing (Th17) T-cells to the composition of the lymphoma-associated microenvironment of angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified on tissue microarrays from 30 PTCLs not otherwise specified and 37 AITLs. We found that Th17 but not Treg cells were differently represented in the two lymphomas and correlated with the amount of mast cells (MCs) and granulocytes, which preferentially occurred in the cellular milieu of AITL cases. We observed that MCs directly synthesized interleukin-6 and thus contribute to the establishment of a pro-inflammatory, Th17 permissive environment in AITL. We further hypothesized that the AITL clone itself could be responsible for the preferential accumulation of MCs at sites of infiltration through the synthesis of CXCL-13 and its interaction with the CXCR3 and CXCR5 receptors expressed on MCs. Consistent with this hypothesis, we observed MCs efficiently migrating in response to CXCL-13. On these bases, we conclude that MCs have a role in molding the immunological microenvironment of AITL toward the maintenance of pro-inflammatory conditions prone to Th17 generation and autoimmunity.