Constitutive activation of Wnt signaling favors generation of memory CD8 T cells.

T cell factor-1 (TCF-1) and lymphoid enhancer-binding factor 1, the effector transcription factors of the canonical Wnt pathway, are known to be critical for normal thymocyte development. However, it is largely unknown if it has a role in regulating mature T cell activation and T cell-mediated immune responses. In this study, we demonstrate that, like IL-7Ralpha and CD62L, TCF-1 and lymphoid enhancer-binding factor 1 exhibit dynamic expression changes during T cell responses, being highly expressed in naive T cells, downregulated in effector T cells, and upregulated again in memory T cells. Enforced expression of a p45 TCF-1 isoform limited the expansion of Ag-specific CD8 T cells in response to Listeria monocytogenes infection. However, when the p45 transgene was coupled with ectopic expression of stabilized beta-catenin, more Ag-specific memory CD8 T cells were generated, with enhanced ability to produce IL-2. Moreover, these memory CD8 T cells expanded to a larger number of secondary effectors and cleared bacteria faster when the immunized mice were rechallenged with virulent L. monocytogenes. Furthermore, in response to vaccinia virus or lymphocytic choriomeningitis virus infection, more Ag-specific memory CD8 T cells were generated in the presence of p45 and stabilized beta-catenin transgenes. Although activated Wnt signaling also resulted in larger numbers of Ag-specific memory CD4 T cells, their functional attributes and expansion after the secondary infection were not improved. Thus, constitutive activation of the canonical Wnt pathway favors memory CD8 T cell formation during initial immunization, resulting in enhanced immunity upon second encounter with the same pathogen.

Plasmacytoid Dendritic Cells Are Productively Infected and Activated through TLR-7 Early after Arenavirus Infection.

The antiviral response is largely mediated by dendritic cells (DCs), including conventional (c) DCs that function as antigen-presenting cells, and plasmacytoid (p) DCs that produce type I interferons, making them an attractive target for viruses. We find that the Old World arenaviruses lymphocytic choriomeningitis virus clone 13 (LCMV Cl13) and Lassa virus bind pDCs to a greater extent than cDCs. Consistently, LCMV Cl13 targets pDCs early after in vivo infection of its natural murine host and establishes a productive and robust replication cycle. pDCs coproduce type I interferons and proinflammatory cytokines, with the former being induced in both infected and uninfected pDCs, demonstrating a dissociation from intrinsic virus replication. TLR7 globally mediates pDC responses, limits pDC viral load, and promotes rapid innate and adaptive immune cell activation. These early events likely help dictate the outcome of infections with arenaviruses and other DC-replicating viruses and shed light on potential therapeutic targets.

A pro-inflammatory role of lymphoid cells in acute pleurisy in rats

The effect of viable splenic lymphoid cells and their constituents (filtrate) on carrageenan-induced acute pleurisy was investigated in rats. Suspensions of lymphoid cells administered intravenously to recipients just prior to initiation of pleurisy enhance both the volume of exudate and cell accumulation in the pleural cavity 3 h after the irritation. Similar results were observed when filtrate of disrupted lymphoid cells was injected either 30 or 5 min before the carrageenan, but not when administered 30 min afterwards. Suspensions of bone marrow cells, on the contrary, were ineffective in producing an enhancement of the parameters studied. When administered into the pleural cavity together with carrageenan, the lymphoid cell filtrate augmented the inflammatory response to the irritant. Nevertheless, it was ineffective, per se, to elicit any local change. It is suggested that lymphoid cells may play a pro-inflammatory role in the initiation of the process by enhancing both the fluid and the cellular components of inflammation.

Co-existence of t(6;13)(p21;q14.1) and trisomy 12 in chronic lymphocytic leukemia

We report a case of a 57-year-old man diagnosed with chronic lymphocytic leukemia (CLL) and presence of a rare t(6;13)(p21;q14.1) in association with an extra copy of chromosome 12. Classical cytogenetic analysis using the immunostimulatory combination of DSP30 and IL-2 showed the karyotype 47,XY,t(6;13)(p21;q14.1), +12 in 75% of the metaphase cells. Spectral karyotype analysis (SKY) confirmed the abnormality previously seen by G-banding. Additionally, interphase fluorescence in situ hybridization using an LSI CEP 12 probe performed on peripheral blood cells without any stimulant agent showed trisomy of chromosome 12 in 67% of analyzed cells (134/200). To the best of our knowledge, the association of t(6;13)(p21;q14.1) and +12 in CLL has never been described. The prognostic significance of these new findings in CLL remains to be elucidated. However, the patient has been followed up since 2009 without any therapeutic intervention and has so far remained stable.

Differentiating between tuberculosis-related and lymphoma-related lymphocytic pleural effusions by measuring clinical and laboratory variables: Is it possible?

Objective: To describe clinical and laboratory characteristics in patients with tuberculosis-related or lymphoma-related lymphocytic pleural effusions, in order to identify the variables that might contribute to differentiating between these diseases. Methods: This was a retrospective study involving 159 adult HIV-negative patients with tuberculosis-related or lymphoma-related lymphocytic effusions (130 and 29 patients, respectively), treated between October of 2008 and March of 2010 at the Pleural Diseases Outpatient Clinic of the University of Sao Paulo School of Medicine Hospital das Clinicas Heart Institute, in the city of Sao Paulo, Brazil. Results: Mean age and the mean duration of symptoms were lower in the tuberculosis group than in the lymphoma group. The levels of proteins, albumin, cholesterol, amylase, and adenosine deaminase (ADA) in pleural fluid, as well as the serum levels of proteins, albumin, and amylase, were higher in the tuberculosis group, whereas serum cholesterol and triglycerides were higher in the lymphoma group. Pleural fluid leukocyte and lymphocyte counts were higher in the tuberculosis group. Of the tuberculosis group patients, none showed malignant cells; however, 4 showed atypical lymphocytes. Among the lymphoma group patients, cytology for neoplastic cells was positive, suspicious, and negative in 51.8%, 24.1%, and 24.1%, respectively. Immunophenotyping of pleural fluid was conclusive in most of the lymphoma patients. Conclusions: Our results demonstrate clinical and laboratory similarities among the patients with tuberculosis or lymphoma. Although protein and ADA levels in pleural fluid tended to be higher in the tuberculosis group than in the lymphoma group, even these variables showed an overlap. However, none of the tuberculosis group patients had pleural fluid ADA levels below the 40-U/L cut-off point.

Monoclonal B-cell lymphocytosis (MBL), CD4(+)/CD8(weak) T-cell large granular lymphocytic leukemia (T-LGL leukemia) and monoclonal gammopathy of unknown significance (MGUS): molecular and flow cytometry characterization of three concomitant hematological disorders

The diagnosis of T-cell large granular lymphocytic leukemia in association with other B-cell disorders is uncommon but not unknown. However, the concomitant presence of three hematological diseases is extraordinarily rare. We report an 88-year-old male patient with three simultaneous clonal disorders, that is, CD4+/CD8(weak) T-cell large granular lymphocytic leukemia, monoclonal gammopathy of unknown significance and monoclonal B-cell lymphocytosis. The patient has only minimal complaints and has no anemia, neutropenia or thrombocytopenia. Lymphadenopathy and hepatosplenomegaly were not present. The three disorders were characterized by flow cytometry analysis, and the clonality of the T-cell large granular lymphocytic leukemia was confirmed by polymerase chain reaction. Interestingly, the patient has different B-cell clones, given that plasma cells of monoclonal gammopathy of unknown significance exhibited a kappa light-chain restriction population and, on the other hand, B-lymphocytes of monoclonal B-cell lymphocytosis exhibited a lambda light-chain restriction population. This finding does not support the antigen-driven hypothesis for the development of multi-compartment diseases, but suggests that T-cell large granular lymphocytic expansion might represent a direct antitumor immunological response to both B-cell and plasma-cell aberrant populations, as part of the immune surveillance against malignant neoplasms.

Infiltration of a mixture of immune cells may be related to good prognosis in patients with differentiated thyroid carcinoma

Objective Immune responses against differentiated thyroid carcinomas (DTC) have long been recognized. We aimed to investigate the role of immune cell infiltration in the progression of DTC. Design We studied 398 patients 253 with papillary and 13 with follicular thyroid cancers, as well as 132 with nonmalignant tissues. Patients and measurements Immune cell infiltration was identified using CD3, CD4, CD8, CD20, CD68 and FoxP3 immunohistochemical markers. In addition, we assessed colocalization of CD4 and IL-17 to identify Th17 lymphocytic infiltration and colocalization of CD33 and CD11b to identify infiltration of myeloid-derived suppressor cells (MDSC). Results Immune cells infiltrated malignant tissues more often than benign lesions. The presence of chronic lymphocytic thyroiditis (CLT) concurrent to DTC, CD68+, CD4+, CD8+, CD20+, FoxP3+ and Th17 lymphocytes but not MDSCs was associated with clinical and pathological features of lower tumour aggressiveness and a more favourable patient outcome. A log-rank test confirmed an association between concurrent CLT, tumour-associated macrophage infiltration, and CD8+ lymphocytes and an increased in disease-free survival, suggesting that evidence of these immune reactions is associated with a favourable prognosis. Conclusion Our data suggest that the tumour or peri-tumoural microenvironment may act to modify the observed pattern of immune response. Immune cell infiltration and the presence of concurrent CLT helped characterize specific tumour histotypes associated with favourable prognostic features.

Telomeres and prognosis in patients with chronic lymphocytic leukaemia

In the present study, telomere length, telomerase activity, the mutation load of immunoglobulin variable heavy chain (IGHV) genes, and established prognostic factors were investigated in 78 patients with chronic lymphocytic leukaemia (CLL) to determine the impact of telomere biology on the pathogenesis of CLL. Telomere length was measured by an automated multi-colour flow-FISH, and an age-independent delta telomere length ( TL) was calculated. CLL with unmutated IGHV genes was associated with shorter telomeres (p = 0.002). Furthermore, we observed a linear correlation between the frequency of IGHV gene mutations and elongation of telomeres (r = 0.509, p < 0.001). With respect to prognosis, a threshold TL of -4.2 kb was the best predictor for progression-free and overall survival. TL was not significantly altered over time or with therapy. The correlation between the mutational load in IGHV genes and the TL in CLL might reflect the initial telomere length of the putative cell of origin (pre- versus post-germinal center B cells). In conclusion, the TL is a reliable prognostic marker for patients with CLL. Short telomeres and high telomerase activity as occurs in some patients with CLL with a worse prognosis might be an ideal target for treatment with telomerase inhibitors.

Efficacy of rituximab and cladribine in patients with chronic lymphocytic leukemia and feasibility of stem cell mobilization: a prospective multicenter phase II trial (protocol SAKK 34/02)

This phase II trial investigated rituximab and cladribine in chronic lymphocytic leukemia. Four induction cycles, comprising cladribine (0.1 mg/kg/day days 1-5, cycles 1-4) and rituximab (375 mg/m(2) day 1, cycles 2-4), were given every 28 days. Stem cell mobilization (rituximab 375 mg/m(2) days 1 and 8; cyclophosphamide 4 g/m(2) day 2; and granulocyte colony-stimulating factor 10 microg/kg/day, from day 4) was performed in responders. Of 42 patients, nine achieved complete remission (CR), 15 very good partial remission, and two nodular partial remission (overall response rate 62%). Stem cell mobilization and harvesting (> or = 2 x 10(6) stem cells/kg body weight) were successful in 12 of 20 patients. Rituximab infusion-related adverse events were moderate. The main grade 3/4 adverse events during induction were neutropenia and lymphocytopenia. Rituximab plus cladribine was effective; however, the CR rate was modest and stem cell harvest was impaired in a large number of responding patients.

Chronic myelogenous leukemia maintains specific CD8(+) T cells through IL-7 signaling

Chronic myelogenous leukemia (CML) is a malignant myeloproliferative disease of hematopoietic stem cells. The disease progresses after several years from an initial chronic phase to a blast phase. Leukemia-specific T cells are regularly detected in CML patients and may be involved in the immunological control of the disease. Here, we analyzed the role of leukemia-specific CD8(+) T cells in CML disease control and the mechanism that maintains CD8(+) T-cell immunosurveillance in a retroviral-induced murine CML model. To study antigen-specific immune responses, the glycoprotein of the lymphocytic choriomeningitis virus was used as model leukemia antigen. Leukemia-specific CTL activity was detectable in vivo in CML mice and depletion of CD8(+) T cells rapidly led to disease progression. CML-specific CTL were characterized by the expression of the IL-7 receptor -chain. In addition, leukemia cells produced IL-7 that was crucial for the maintenance of leukemia-specific CTL and for disease control. Therefore, CML cells maintain the specific CD8(+) T-cell-mediated immune control by IL-7 secretion. This results in prolonged control of disease and probably contributes to the characteristic chronic phase of the disease.

Development of replication-defective lymphocytic choriomeningitis virus vectors for the induction of potent CD8+ T cell immunity

Lymphocytic choriomeningitis virus (LCMV) exhibits natural tropism for dendritic cells and represents the prototypic infection that elicits protective CD8(+) T cell (cytotoxic T lymphocyte (CTL)) immunity. Here we have harnessed the immunobiology of this arenavirus for vaccine delivery. By using producer cells constitutively synthesizing the viral glycoprotein (GP), it was possible to replace the gene encoding LCMV GP with vaccine antigens to create replication-defective vaccine vectors. These rLCMV vaccines elicited CTL responses that were equivalent to or greater than those elicited by recombinant adenovirus 5 or recombinant vaccinia virus in their magnitude and cytokine profiles, and they exhibited more effective protection in several models. In contrast to recombinant adenovirus 5, rLCMV failed to elicit vector-specific antibody immunity, which facilitated re-administration of the same vector for booster vaccination. In addition, rLCMV elicited T helper type 1 CD4+ T cell responses and protective neutralizing antibodies to vaccine antigens. These features, together with low seroprevalence in humans, suggest that rLCMV may show utility as a vaccine platform against infectious diseases and cancer.

Destruction of lymphoid organ architecture and hepatitis caused by CD4+ T cells

Immune responses have the important function of host defense and protection against pathogens. However, the immune response also causes inflammation and host tissue injury, termed immunopathology. For example, hepatitis B and C virus infection in humans cause immunopathological sequel with destruction of liver cells by the host's own immune response. Similarly, after infection with lymphocytic choriomeningitis virus (LCMV) in mice, the adaptive immune response causes liver cell damage, choriomeningitis and destruction of lymphoid organ architecture. The immunopathological sequel during LCMV infection has been attributed to cytotoxic CD8(+) T cells. However, we now show that during LCMV infection CD4(+) T cells selectively induced the destruction of splenic marginal zone and caused liver cell damage with elevated serum alanin-transferase (ALT) levels. The destruction of the splenic marginal zone by CD4(+) T cells included the reduction of marginal zone B cells, marginal zone macrophages and marginal zone metallophilic macrophages. Functionally, this resulted in an impaired production of neutralizing antibodies against LCMV. Furthermore, CD4(+) T cells reduced B cells with an IgM(high)IgD(low) phenotype (transitional stage 1 and 2, marginal zone B cells), whereas other B cell subtypes such as follicular type 1 and 2 and germinal center/memory B cells were not affected. Adoptive transfer of CD4(+) T cells lacking different important effector cytokines and cytolytic pathways such as IFNγ, TNFα, perforin and Fas-FasL interaction did reveal that these cytolytic pathways are redundant in the induction of immunopathological sequel in spleen. In conclusion, our results define an important role of CD4(+) T cells in the induction of immunopathology in liver and spleen. This includes the CD4(+) T cell mediated destruction of the splenic marginal zone with consecutively impaired protective neutralizing antibody responses.

Imatinib mesylate selectively impairs expansion of memory cytotoxic T cells without affecting the control of primary viral infections

Imatinib mesylate (imatinib) is a potent inhibitor of defined tyrosine kinases (TKs) and is effective in the treatment of malignancies characterized by constitutive activation of these TKs such as chronic myeloid leukemia and gastrointestinal stromal tumors. TKs also play an important role in T-cell receptor (TCR) signal transduction. Inhibitory as well as stimulating effects of imatinib on T cells and dendritic cells have been described. Here, we analyzed the effects of imatinib treatment on antiviral immune responses in vivo. Primary cytotoxic T-cell (CTL) responses were not impaired in imatinib-treated mice after infection with lymphocytic choriomeningitis virus (LCMV) or after immunization with a tumor cell line expressing LCMV glycoprotein (LCMV-GP). Similarly, neutralizing antibody responses to vesicular stomatitis virus (VSV) were not affected. In contrast, secondary expansion of LCMV-specific memory CTLs was reduced in vitro and in vivo, resulting in impaired protection against reinfection. In addition, imatinib treatment delayed the onset of diabetes in a CTL-induced diabetes model. In summary, imatinib treatment in vivo selectively inhibits the expansion of antigen-experienced memory CTLs without affecting primary T- or B-cell responses. Therefore, imatinib may be efficacious in the suppression of CTL-mediated immunopathology in autoimmune diseases without the risk of acquiring viral infections.

Folliculo-stellate cells of "true dendritic" type are involved in the inflammatory microenvironment of tumor immunosurveillance of pituitary adenomas

Folliculo-stellate cells are a nonendocrine, sustentacular-like complementary population of the anterior pituitary. They currently are considered as functionally and phenotypically heterogeneous, with one subpopulation of folliculo-stellate cells possibly representing resident adenohypophyseal macrophages. We took advantage of a limited T-cell mediated inflammatory reaction selectively involving tumor tissue in three cases of pituitary adenoma (2 prolactin cell adenomas, and 1 null cell adenoma) to test the hypothesis whether some folliculo-stellate cells within inflammatory foci would also assume monocytic/dendritic properties. Immunohistochemical double labeling for S-100 protein and the class II major histocompatibility antigen HLA-DR indeed showed several arborized cells to coexpress both epitopes. These were distributed both amidst adenomatous acini and along intratumoral vessels, and were morphologically undistinguishable from conventional folliculo-stellate cells. On the other hand, markers of follicular dendritic cells (CD21) and Langerhans' cells (CD1a) tested negative. Furthermore, no S-100/HLA-DR coexpressing folliculo-stellate cells were seen in either peritumoral parenchyma of the cases in point nor in control pituitary adenomas lacking inflammatory reaction. These findings suggest that a subset of folliculo-stellate cells may be induced by an appropriate local inflammatory microenvironment to assume a dendritic cell-like immunophenotype recognizable by their coexpression of S-100 protein and HLA-DR. By analogy with HLA-DR expressing cells in well-established extrapituitary inflammatory constellations, we speculate that folliculo-stellate cells with such immunophenotype may actually perform professional antigen presentation. A distinctly uncommon finding in pituitary adenomas, lymphocytic infiltrates may therefore be read as a manifestation of tumoral immunosurveillance.

"Exterritorial" lymphocytic hypophysitis within an ovarian teratoma during pregnancy: a possible sentinel lesion?

Pituitary tissue is rarely to be found among the constituents of ovarian teratomas (dermoid cysts). In some exceptional cases, however, such ectopic pituitary anlagen may even give rise to secondary organ-specific pathologies. Akin to those of the pituitary in its natural location, these tend to be adenomas. We describe a unique example of lymphocytic hypophysitis incidentally encountered in a mature left ovarian teratoma from a 30-year-old woman in the 19th week of pregnancy. Amidst various fully differentiated derivatives of all three embryonic layers, the cyst wall also included a miniature replica of the anterior pituitary lobe 0.5 cm in diameter. While a full set of adenohypophyseal hormone-producing cell types could be identified, there was characteristic pregnancy-related hyperplasia of lactotrophs. This was further overlaid by prominent mononuclear inflammation, including infiltration by T lymphocytes, follicular aggregates of B cells, and attendant destruction of parenchyma. There was no significant inflammatory reaction elsewhere. Discounting the non-standard location, the ensemble of the clinical setting and histology were felt to be indistinguishable from the classical paradigm of lymphocytic hypophysitis complicating pregnancy. To date, lymphocytic thyroiditis is the sole form of organ-specific inflammatory process within an ovarian teratoma on record. By analogy, we hypothesize that this ectopic manifestation of immune-mediated inflammation of pituitary parenchyma may possibly be read as a preclinical sentinel lesion of lymphocytic hypophysitis.