Tumor-Infiltrating B Lymphocyte Profiling Identifies IgG-Biased, Clonally Expanded Prognostic Phenotypes in Triple-Negative Breast Cancer

In breast cancer, humoral immune responses may contribute to clinical outcomes, especially in more immunogenic subtypes. Here, we investigated B lymphocyte subsets, immunoglobulin expression, and clonal features in breast tumors, focusing on aggressive triple-negative breast cancers (TNBC). In samples from patients with TNBC and healthy volunteers, circulating and tumor-infiltrating B lymphocytes (TIL-B) were evaluated. CD20+CD27+IgD- isotype-switched B lymphocytes were increased in tumors, compared with matched blood. TIL-B frequently formed stromal clusters with T lymphocytes and engaged in bidirectional functional cross-talk, consistent with gene signatures associated with lymphoid assembly, costimulation, cytokine-cytokine receptor interactions, cytotoxic T-cell activation, and T-cell-dependent B-cell activation. TIL-B-upregulated B-cell receptor (BCR) pathway molecules FOS and JUN, germinal center chemokine regulator RGS1, activation marker CD69, and TNFα signal transduction via NFκB, suggesting BCR-immune complex formation. Expression of genes associated with B lymphocyte recruitment and lymphoid assembly, including CXCL13, CXCR4, and DC-LAMP, was elevated in TNBC compared with other subtypes and normal breast. TIL-B-rich tumors showed expansion of IgG but not IgA isotypes, and IgG isotype switching positively associated with survival outcomes in TNBC. Clonal expansion was biased toward IgG, showing expansive clonal families with specific variable region gene combinations and narrow repertoires. Stronger positive selection pressure was present in the complementarity determining regions of IgG compared with their clonally related IgA in tumor samples. Overall, class-switched B lymphocyte lineage traits were conspicuous in TNBC, associated with improved clinical outcomes, and conferred IgG-biased, clonally expanded, and likely antigen-driven humoral responses. SIGNIFICANCE: Tumor-infiltrating B lymphocytes assemble in clusters, undergoing B-cell receptor-driven activation, proliferation, and isotype switching. Clonally expanded, IgG isotype-biased humoral immunity associates with favorable prognosis primarily in triple-negative breast cancers.

CD44 and CD27 expression pattern in B cell precursor acute lymphoblastic leukemia and its clinical significance

The expression of CD44 and CD27 molecules correlates with the differentiation stage of B cell precursors. The present study was designed to investigate the prognostic relevance of CD44 and CD27 molecules in patients with B cell acute lymphoblastic leukemia (ALL). CD27 and CD44 expression was determined in 58 patients by flow cytometry and their relation to established prognostic factors and response to therapy was investigated. Four patterns of expression were found; CD27 single positive (SP) in 20.7 % of patients, CD44SP in 25.8 %, CD27CD44 double positive (DP) in 20.7 %, and CD27CD44 double negative (DN) in 32.8 %. CD27 expression and the CD27SP pattern correlated directly with TEL/AML1 genotype (P = 0.012). Conversely, CD44 expression and the CD44SP pattern correlated inversely with this genotype (P = 0.016). Patients with the DP pattern had a lower WBC count (P = 0.03), lower percentage of blasts in their bone marrow (P = 0.028), and higher platelet count, whereas CD44SP patients had a higher WBC count and higher percentage of bone marrow blasts. Moreover, a negative association between DN pattern and complete remission (CR) rate was detected (P = 0.03). Mean CD27 expression was significantly higher in low-risk group and in patients who achieved CR (P = 0.001), and in those with a higher platelet number (P = 0.046) and less extramedullary involvement (P = 0.008). Although survival and CR duration were longer in patients with DP pattern and shorter in those with DN pattern, the result did not reach statistical significance. The expression of CD27 together with CD44 showed a relationship with several established risk factors as well as response to therapy, indicating the biological significance of these molecules in ALL.

Unlike αβ T cells, γδ T cells, LTi cells and NKT cells do not require IRF4 for the production of IL-17A and IL-22

Apart from conventional CD4(+) Th17 cells, the cytokines IL-17A and IL-22 can also be produced by γδ T cells, NK cells and lymphoid tissue inducer (LTi) cells. Th17 cells develop from precursor cells after T-cell receptor stimulation in the presence of TGF-β, IL-6 and IL-23. In contrast, a subset of γδ T cells ("γδT17") is committed for fast IL-17 production already in the thymus; however, γδ T cells can also produce IL-17 after prolonged in vitro stimulation via their γδ T-cell receptor plus IL-23. Here, we show that γδ T-, LTi- and NKT cells differ extensively from Th17 cells in their signalling requirements for the generation of IL-17A and IL-22. While production of these cytokines by Th17 cells totally depends on the transcription factor interferon regulatory factor 4 (IRF4), IRF4 is irrelevant in the other cell types. As for γδ T cells, this finding pertains to both thymic commitment and prolonged in vitro culture. Furthermore, IL-17A-producing γδ T cells accumulate in the central nervous system of IRF4 deficient (Irf4(-/-)) mice during experimental autoimmune encephalomyelitis. IL-17A-producing WT and Irf4(-/-) γδ T cells equally express CCR6 and lack CD27. The underlying IRF4-independent pathway partially involves STAT3 during in vitro stimulation.

Dissociating markers of senescence and protective ability in memory T cells

No unique transcription factor or biomarker has been identified to reliably distinguish effector from memory T cells. Instead a set of surface markers including IL-7Rα and KLRG1 is commonly used to predict the potential of CD8 effector T cells to differentiate into memory cells. Similarly, these surface markers together with the tumor necrosis factor family member CD27 are frequently used to predict a memory T cell's ability to mount a recall response. Expression of these markers changes every time a memory cell is stimulated and repeated stimulation can lead to T cell senescence and loss of memory T cell responsiveness. This is a concern for prime–boost vaccine strategies which repeatedly stimulate T cells with the aim of increasing memory T cell frequency. The molecular cues that cause senescence are still unknown, but cell division history is likely to play a major role. We sought to dissect the roles of inflammation and cell division history in developing T cell senescence and their impact on the expression pattern of commonly used markers of senescence. We developed a system that allows priming of CD8 T cells with minimal inflammation and without acquisition of maximal effector function, such as granzyme expression, but a cell division history similar to priming with systemic inflammation. Memory cells derived from minimal effector T cells are fully functional upon rechallenge, have full access to non-lymphoid tissue and appear to be less senescent by phenotype upon rechallenge. However, we report here that these currently used biomarkers to measure senescence do not predict proliferative potential or protective ability, but merely reflect initial priming conditions.

Characterization of T-cell memory phenotype after in vitro expansion of tumor-infiltrating lymphocytes from melanoma patients

Memory T-cell populations in human antitumor tumor-infiltrating lymphocytes (TILs) for adoptive cell transfer have not been fully characterized. Our studies demonstrated that CD62L, CD27 and CD28 positive effector memory T-cells were present in the TIL samples from the tumor tissues of melanoma patients and T-cell expansion led to the significant loss of memory T-cells. CD27- and CD28-positive T-cells had high levels of CD44 expression. T-Cell expansion resulted in significant down-regulation of CD44 expression. Interleukin-2 (IL-2) and anti-CD3 antibody stimulation may be responsible for CD44 down-regulation on CD8(+) T-cells during expansion. Furthermore, CD44 down-regulation using small interfering RNA (siRNA) on TILs dramatically reduced interferon-gamma and IL-2 release upon tumor stimulation. These results suggest that the regulation of CD44 expression in TILs may play an important role in memory T-cell maintenance and antitumor immune response.

Mouse natural killer (NK) cells express the nerve growth factor receptor TrkA, which is dynamically regulated

BACKGROUND

Nerve growth factor (NGF) is a neurotrophin crucial for the development and survival of neurons. It also acts on cells of the immune system which express the NGF receptors TrkA and p75(NTR) and can be produced by them. However, mouse NK cells have not yet been studied in this context.

METHODOLOGY/PRINCIPAL FINDINGS

We used cell culture, flow cytometry, confocal microscopy and ELISA assays to investigate the expression of NGF receptors by NK cells and their secretion of NGF. We show that resting NK cells express TrkA and that the expression is different on NK cell subpopulations defined by the relative presence of CD27 and CD11b. Expression of TrkA is dramatically increased in IL-2-activated NK cells. The p75(NTR) is expressed only on a very low percentage of NK cells. Functionally, NGF moderately inhibits NK cell degranulation, but does not influence proliferation or cytokine production. NK cells do not produce NGF.

CONCLUSIONS/SIGNIFICANCE

We demonstrate for the first time that mouse NK cells express the NGF receptor TrkA and that this expression is dynamically regulated.

Significantly higher percentage of circulating CD27(high) plasma cells in systemic lupus erythematosus patients with infection than with disease flare-up

PURPOSE

To distinguish lupus flare-up from infection in systemic lupus erythematosus (SLE), we analyze the expression of circulating CD27(high) plasma cells in SLE patients with and without infection, in comparison to non-SLE patients with infection.

MATERIALS AND METHODS

The percentage of circulating CD27(high) plasma cells was measured by flow cytometry in the following four groups: 36 SLE patients without infection, 23 SLE patients with infection, eight non-SLE patients with infection, and 26 healthy controls.

RESULTS

The frequency of CD27(high) plasma cells had a correlation with the SLE disease activity index (SLEDAI) (r = 0.866, p < 0.05), level of anti-dsDNA (r = 0.886, p < 0.05), C3 (r = - 0.392, p < 0.05), and C4 (r = - 0.337, p < 0.05) in SLE patients without infection, but there was no correlation with disease activity in SLE patients with infection. Among three groups in particular-SLE without infection, SLE with infection, and non-SLE with infection- the percentages of CD27(high) plasma cells were elevated. The percentage of CD27(high) plasma cells was higher in SLE patients with infection, when compared to SLE patients without infection.

CONCLUSION

The percentage of CD27(high) plasma cells is a biomarker for disease activity of SLE without infection, under correlation with SLEDAI, anti-dsDNA, and C3 and C4 level. However, when the SLE patients have an infection, the percentage of CD27(high) plasma cells is not an adequate biomarker for the survey of disease activity. The percentage of CD27(high) plasma cells may serve as a potential parameter to distinguish a lupus flare-up from infection.

Down-regulation of CD72 and increased surface IgG on B cells in patients with lupus nephritis

The significance of both the acceleratory and inhibitory functions of the CD72 molecule was investigated among patients with systemic lupus erythematosus (SLE) during modification of B cell differentiation. Expression of the CD72 molecule and mRNA on B cells was decreased in SLE with lupus nephritis, while CD100 expression on both CD4+ T cells and CD8+ T cells was not significant in comparison with the controls. When the relationship between CD72 expression and other B cell markers was examined, decreased expression of CD72 was associated with differences in the stage of differentiation. In patients with decreased expression of CD72, switching to IgG was evident, and the disease stage was started to severe. In patients with lupus nephritis, the decreased expression of CD72 was related to class switching on B cells, suggesting that CD72 is a useful marker for determining class switching of B cells in lupus nephritis.

Alterations in peripheral blood memory B cells in patients with active rheumatoid arthritis are dependent on the action of tumour necrosis factor

INTRODUCTION

Disturbances in peripheral blood memory B cell subpopulations have been observed in various autoimmune diseases, but have not been fully delineated in rheumatoid arthritis (RA). Additionally, the possible role of tumour necrosis factor (TNF) in regulating changes in specific peripheral blood memory B cell subsets in RA is still unclear.

METHODS

The frequency and distribution of B cell subsets in the peripheral blood and synovial membrane of active RA patients with long-standing disease have been analysed. Additionally, the possible role of TNF in causing disturbances in memory B cell subsets in RA patients was assessed in a clinical trial with the specific TNF-neutralising antibody, infliximab.

RESULTS

RA patients, independent of disease duration, have a significantly lower frequency of peripheral blood pre-switch IgD+CD27+ memory B cells than healthy individuals, whereas post-switch IgD-CD27+ accumulate with increased disease duration. Notably, both pre-switch IgD+CD27+ and post-switch IgD-CD27+ memory B cells accumulate in the synovial membrane of RA patients. Finally, anti-TNF therapy increased the frequency of pre-switch IgD+CD27 memory B cells in the peripheral blood.

CONCLUSIONS

The data suggest that decreases in peripheral blood IgD+CD27+ pre-switch memory B cells in RA reflect their accumulation in the synovial tissue. Moreover, the significant increase in the peripheral blood pre-switch memory B cells in patients who underwent specific TNF-blockade with infliximab indicates that trafficking of memory B cells into inflamed tissue in RA patients is regulated by TNF and can be corrected by neutralising TNF.

A splenic marginal zone-like peripheral blood CD27+B220- B cell population is preferentially depleted in HIV type 1-infected individuals

Peripheral blood CD27(+) B cells are reduced in HIV-1-infected individuals. In healthy individuals, the human peripheral blood CD27(+) B cell pool consists of two subsets defined by the expression, or lack thereof, of the CD45 isoform B220. We investigated the presence of circulating B220(+) and B220(-) memory B cells in HIV(+) individuals and found that the reduction in CD27(+) memory B cells occurs primarily among CD27(+)B220(-) B cells. Studies conducted using healthy controls indicate that CD27(+)B220(-) B cells have a splenic marginal zone like the immunophenotype IgM(hi)IgD(lo)CD21(+)CD23(-), express TLR9, and proliferate and secrete IgG and IgM in response to B cell-specific ODN. CD27(+)B220(+) B cells have the immunophenotype IgM(lo)IgD(hi)CD21(+)CD23(+), express activation-induced cytidine deaminase, and proliferate in response to SAC but do not secrete immunoglobulin. The AICD expression, along with CD86 expression, by CD27(+)B220(+) suggests these cells are of germinal center origin. The preferential depletion of CD27(+)B220(-) B cells mirrors alterations in spleen morphology and resident B cell populations due to HIV infection reported by other investigators and may play an important role in the defective B cell immunity against T-independent pathogens such as pneumococcus observed in HIV-1-infected individuals.

Impaired induction of CD27 and CD28 predicts naive CD4 T cell proliferation defects in HIV disease

Many immunological defects have been described in HIV disease, including a diminished capacity of naive CD4+ T cells to expand after TCR stimulation. The mechanisms underlying impaired naive CD4+ T cell expansion in HIV disease are not well described. Using a rigorous phenotypic definition of naive T cells, we found that cell cycle entry after TCR engagement was restricted to cells that increased surface expression of costimulatory molecules CD27 and CD28. Induction of these receptors, however, was not sufficient to result in cell cycle entry among the CD4+CD31- naive T cell subset. Analyses of cells from HIV-infected persons indicated that naive CD4+CD31+ T cells from these subjects were impaired in their ability to enter the cell cycle after stimulation and this impairment was predicted by the relatively poor induction of costimulatory molecules on these cells. Thus, failure to increase surface expression of costimulatory molecules may contribute to the naive T cell expansion failure that characterizes HIV infection.

The impact of a boosting immunogen on the differentiation of secondary memory CD8+ T cells

While recent studies have demonstrated that secondary CD8+ T cells develop into effector-memory cells, the impact of particular vaccine regimens on the elicitation of these cells remains poorly defined. In the present study we evaluated the effect of three different immunogens--recombinant vaccinia, recombinant adenovirus, and plasmid DNA--on the generation of memory cellular immune responses. We found that vectors that induce the rapid movement of CD8+ T cells into the memory compartment during a primary immune response also drive a rapid differentiation of these cells into effector-memory CD8+ T cells following a secondary immunization. In contrast, the functional profiles of both CD8+ and CD4+ T cells, assessed by measuring antigen-stimulated gamma interferon and interleukin-2 production, were not predominantly shaped by the boosting immunogen. We also demonstrated that the in vivo expression of antigen by recombinant vectors was brief following boosting immunization, suggesting that antigen persistence has a minimal impact on the differentiation of secondary CD8+ T cells. When used in heterologous or in homologous prime-boost combinations, these three vectors generated antigen-specific CD8+ T cells with different phenotypic profiles. Expression of the memory-associated molecule CD27 on effector CD8+ T cells decreased following heterologous but not homologous boosting, resulting in a phenotypic profile similar to that seen on primary CD8+ T cells. These data therefore suggest that the phenotype of secondary CD8+ T cells is determined predominantly by the boosting immunogen whereas the cytokine profile of these cells is shaped by both the priming and boosting immunogens.

Human IgM+CD27+ B cells: memory B cells or "memory" B cells?

Memory B cells are generated in germinal centers (GC) and contribute to serological immunity by rapidly differentiating into plasma cells. Human memory B cells can be identified by the expression of CD27. These cells exhibit more rapid responses than naive (CD27-) B cells following stimulation in vitro, consistent with the heightened kinetics of secondary responses in vivo. CD27+ B cells express mutated Ig V region genes; however a significant proportion continue to express IgM, suggesting the existence of IgM+ memory B cells. The observation that mutated IgM+CD27+ B cells are generated in humans who cannot form GC led to the conclusions that these cells are generated independently of GC and thus are not memory cells and that they mediate responses to T cell-independent Ag. Although some studies support the idea that IgM+CD27+ B cells participate in T cell-independent responses, many others do not. In this review we will provide alternate interpretations of the biology of IgM+CD27+ B cells and propose that they are indeed memory cells.

Cutting edge: migration to nonlymphoid tissues results in functional conversion of central to effector memory CD8 T cells

Memory CD8 T cells, essential for defense against intracellular pathogens, are heterogeneous with respect to phenotype and function. Constitutively lytic effector memory cells primarily reside in nonlymphoid tissues, whereas secondary lymphoid tissues contain functionally quiescent central memory cells. However, the mechanism by which functionally distinct memory populations are maintained is unknown. In this study, we show that resting CD8 memory cells modified their functional abilities upon entry into nonlymphoid tissues, as exemplified by the induction of granzyme B and lytic activity. Contemporaneously, the costimulator CD27 was down-regulated. These findings hold important implications for memory cell lineage development and tissue-specific immunity.

Analyses of CD27++ plasma cells in peripheral blood from patients with bacterial infections and patients with serum antinuclear antibodies

The number of CD27⁺⁺ plasma cells (PCs) in peripheral blood may be a valuable biomarker for systemic lupus erythematosus (SLE) disease management. More insights into the behavior of the PC population are, however, required to validate CD27 as a reliable biomarker. In the current study, we have monitored the PC compartment of patients with acute bacterial infections and patients with SLE and, in addition, examined the relationship between the presence of serum antinuclear antibodies (ANAs) and the number of peripheral PCs. Kinetic analyses in patients with bacterial infection revealed a 10–60-fold expansion of the CD27⁺⁺ PC compartment that peaked at day 2–5 and returned toward normal values at day 7–9 after hospital admission. The transient expansion of the PC population appeared to be a late phenomenon in the process of recovering from a bacterial infection. SLE subjects had significantly increased frequencies of PCs compared with patients suspected of a connective tissue disease and healthy controls. In patients suspected of a connective tissue disease, no relationship was found between the presence of serum ANAs and the number of CD27⁺⁺ PCs. Additionally, the presence of serum ANAs was not associated with abnormalities in other peripheral B-cell subsets. It remains to be established at which stage of SLE development the expansion of the PC compartment is initiated.

A New Subset of Human Naive CD8+T Cells Defined by Low Expression of IL-7Rα

Concomitant with an increased number of memory-type cells, the amount of naive T cells steadily declines with age. Although the regulatory mechanisms behind this conversion are not fully understood, the suggestion is that both alterations in thymic output and homeostatic signals mold the naive T cell pool. In this study, we identify a new subset of circulating CD27(high)CD45RA(high) CD8+ T cells characterized by low IL-7Ralpha message and protein expression. Analysis of TCR repertoire and TCR excision circle content together with ex vivo recovery of IL-7Ralpha expression indicated that these cells should be placed into the naive T cell pool. Compared with conventional IL-7Ralpha(high) naive T cells, this subset displayed significantly lower levels of CD28 and higher levels of HLA-DR. Proliferative responses to anti-CD3/CD28 mAbs were indistinguishable from conventional naive T cells, but the responsiveness to IL-7 was limited. Strikingly, IL-7Ralpha(low) naive T cells were particularly increased in circumstances of naive CD8+ T cells shortage, as in the elderly, in patients early after hemopoietic stem cell transplantation, and in HIV-infected individuals. As common gamma chain cytokines induce rapid down-regulation of IL-7Ralpha, we propose that this new subset of naive T cells may encompass cells that have recently received homeostatic signals.

A new population of cells lacking expression of CD27 represents a notable component of the B cell memory compartment in systemic lupus erythematosus

Human memory B cells comprise isotype-switched and nonswitched cells with both subsets displaying somatic hypermutation. In addition to somatic hypermutation, CD27 expression has also been considered a universal memory B cell marker. We describe a new population of memory B cells containing isotype-switched (IgG and IgA) and IgM-only cells and lacking expression of CD27 and IgD. These cells are present in peripheral blood and tonsils of healthy subjects and display a degree of hypermutation comparable to CD27+ nonswitched memory cells. As conventional memory cells, they proliferate in response to CpG DNA and fail to extrude rhodamine. In contrast to other recently described CD27-negative (CD27neg) memory B cells, they lack expression of FcRH4 and recirculate in the peripheral blood. Although CD27neg memory cells are relatively scarce in healthy subjects, they are substantially increased in systemic lupus erythematosus (SLE) patients in whom they frequently represent a large fraction of all memory B cells. Yet, their frequency is normal in patients with rheumatoid arthritis or chronic hepatitis C. In SLE, an increased frequency of CD27neg memory cells is significantly associated with higher disease activity index, a history of nephritis, and disease-specific autoantibodies (anti-dsDNA, anti-Smith (Sm), anti-ribonucleoprotein (RNP), and 9G4). These findings enhance our understanding of the B cell diversification pathways and provide mechanistic insight into the immunopathogenesis of SLE.

Metalloprotease inhibitors block release of soluble CD27 and enhance the immune stimulatory activity of chronic lymphocytic leukemia cells

OBJECTIVE

Chronic lymphocytic leukemia (CLL) B cells from most patients express both membrane-bound CD27 (mCD27) and soluble CD27 (sCD27). Expression of sCD27 inhibits CD27-dependent T-cell or CLL-cell activation mediated by its ligand, CD70. In this study, we evaluated whether protease inhibitors could inhibit the release of sCD27 from CLL cells and enhance T-cell activation mediated by CD27-CD70 interaction.

METHODS

CLL cells exposed to hydroxamic acid-based matrix metalloprotease (MMP) inhibitors were evaluated for the release of sCD27 by sandwich enzyme-linked immunosorbent assay and immunoprecipitation. We examined for phenotypic changes in CLL cells treated with MMP inhibitors by flow cytometry and T-cell activation by CLL cells was assessed by [(3)H] thymidine incorporation assay and the production of interferon-gamma.

RESULTS

Treatment of CLL cells with MMP inhibitors blocked the release of sCD27 to the culture supernatant. In contrast, a non-hydroxamic acid control compound or inhibitors of other proteases, including serine, cysteine, and aspartyl proteases, were ineffective. Furthermore, CLL cells treated with MMP inhibitors expressed significantly higher levels of accessory molecules, such as CD54, CD80, and CD95. Consistent with such changes, we found that CLL cells treated with MMP inhibitors, but not control treated cells, could stimulate allogeneic and autologous T cells in mixed lymphocyte reactions.

CONCLUSION

These data reveal that metalloprotease inhibitors can block production of sCD27, which can interfere with mCD27-CD70 interactions that induce expression of immune costimulatory molecules on CLL B cells. Conceivably, treatment of CLL cells with metalloprotease inhibitors may enhance their potential for stimulating cellular immune recognition of leukemia-associated antigens.

Eradication of lymphoma by CD8 T cells following anti-CD40 monoclonal antibody therapy is critically dependent on CD27 costimulation

Growing evidence points to the potential of agonistic anti-CD40 mAbs as adjuvants for vaccination against cancer. These appear to act by maturing dendritic cells (DCs) and allowing them to prime CD8 cytotoxic T lymphocytes (CTLs). Although it is well established that optimal T-cell priming requires costimulation via B7:CD28, recent studies emphasize the contribution of TNF receptors to this process. To understand how anti-CD40 mAbs trigger effective antitumor immunity, we investigated the role of TNFR superfamily members CD27 and 4-1BB in the generation of this immunity and showed that, although partially dependent on 4-1BB:4-1BBL engagement, it is completely reliant on CD27:CD70 interactions. Importantly, blocking CD70, and to some extent 4-1BBL, during anti-CD40 treatment prevented accumulation of tumor-reactive T cells and subsequent tumor protection. However, it did not influence changes in DC number, phenotype, nor the activity of CTLs once immunity was established. We conclude that CD27:CD70 and 4-1BB:4-1BBL interactions are needed for DC-driven accumulation of antitumor CTLs following anti-CD40 mAb treatment. Finally, in support of the critical role for CD70:CD27, we show for the first time that agonistic anti-CD27 mAbs given without a DC maturation signal completely protect tumor-bearing mice and provide a highly potent reagent for boosting antitumor T-cell immunity.

The gene expression profile of nodal peripheral T-cell lymphoma demonstrates a molecular link between angioimmunoblastic T-cell lymphoma (AITL) and follicular helper T (TFH) cells

The molecular alterations underlying the pathogenesis of angioimmunoblastic T-cell lymphoma (AITL) and peripheral T-cell lymphoma, unspecified (PTCL-u) are largely unknown. In order to characterize the ontogeny and molecular differences between both entities, a series of AITLs (n = 18) and PTCLs-u (n = 16) was analyzed using gene expression profiling. Unsupervised clustering correlated with the pathological classification and with CD30 expression in PTCL-u. The molecular profile of AITLs was characterized by a strong microenvironment imprint (overexpression of B-cell- and follicular dendritic cell-related genes, chemokines, and genes related to extracellular matrix and vascular biology), and overexpression of several genes characteristic of normal follicular helper T (T(FH)) cells (CXCL13, BCL6, PDCD1, CD40L, NFATC1). By gene set enrichment analysis, the AITL molecular signature was significantly enriched in published T(FH)-specific genes. The enrichment was higher for sorted AITL cells than for tissue samples. Overexpression of several T(FH) genes was validated by immunohistochemistry in AITLs. A few cases with molecular T(FH)-like features were identified among CD30(-) PTCLs-u. Our findings strongly support that T(FH) cells represent the normal counterpart of AITL, and suggest that the AITL spectrum may be wider than suspected, as a subset of CD30(-) PTCLs-u may derive from or be related to AITL.

Immune escape for renal cell carcinoma: CD70 mediates apoptosis in lymphocytes

Tumors can escape immune recognition and destruction through the induction of apoptosis in lymphocytes. Although renal cell carcinoma (RCC) is able to prevent immune recognition, only a few genes (such as FasL) that are relevant for RCC immune escape have been identified so far. We have previously shown that some apoptosis-inducing genes are overexpressed in RCC. We hypothesized that these genes could be part of the immune-escape strategy of these tumors. Here we report that CD70, a cytokine overexpressed in RCC, promotes lymphocyte apoptosis through interaction with its receptor CD27 and with the intracellular receptor-binding protein SIVA. Apoptosis increased after cocultivating lymphocytes with the RCC cell lines A498 and CAKI2. The addition of recombinant soluble CD70 to both native lymphocytes and a T-cell cell line resulted in increased lymphocyte apoptosis as well. Furthermore, induced apoptosis could be partially blocked with anti-CD27 and anti-CD70 antibodies. Our results strongly indicate a role for CD70 and CD27 receptor in lymphocyte apoptosis within the tumor environment. Apoptosis mediated by exposure to the CD70 secreted by tumor cells may contribute to the failure of RCC patients to develop an effective lymphocyte-mediated antitumor response.

A new memory CD27-IgG+ B cell population in peripheral blood expressing VH genes with low frequency of somatic mutation

In humans, up to 40% of peripheral B cells express CD27 and have hypermutated variable regions in their Ig genes. The CD27+ B cells are considered to be derived from germinal center following specific antigenic stimulation. Actually, somatic hypermutation in Ig genes and CD27 expression are hallmarks of memory B cells. However, the blood IgM+ IgD+ CD27+ B cells were recently associated to splenic marginal zone B cells and proposed to be a subset distinct from germinal center-derived memory B cells showing premutated Igs. The results presented herein further weaken this bona fide association because B cells expressing surface IgG, but not CD27, were found in human blood. Representing 1-4% of all peripheral B cells and approximately 25% of the IgG+ blood B cells, this population expressed mutated IgG genes showing antigenic selection characteristics but with lower mutation frequencies than that of CD27+ IgG+ B cells. However, their morphology and phenotype were similar to that of CD27+ IgG+ cells. Interestingly, the proportion of IgG2 over IgG3 transcripts was opposite in CD27- IgG+ and CD27+ IgG+ cells, suggesting distinct functions or origins. Overall, these findings extend the memory B cell reservoir beyond the CD27+ compartment and could provide further insights into B cell disorders of unknown etiology.

Expression of TCL1 and CD27 in primary cutaneous B-cell lymphomas

AIMS

To investigate by immunohistochemical analysis the expression of the TCL1 oncogene product and of CD27 in 25 cases of primary cutaneous B-cell lymphomas (PCBCL) classified according to the World Health Organization-European Organization for Research and Treatment of Cancer classification of cutaneous lymphomas. In B-cell ontogenesis TCL1 is mainly expressed by 'naive' B lymphocytes and by a subset of germinal centre B cells, whereas CD27 is expressed by a subset of germinal centre B cells, 'memory' B lymphocytes and plasma cells, suggesting that their expression in physiological conditions is mutually exclusive.

METHODS AND RESULTS

Overall, TCL1 was expressed in 5/25 cases (20%) and CD27 in 15/25 cases (60%). Furthermore, 7/25 cases (28%) were TCL1- and CD27- and 2/25 cases (8%) were TCL1+ and CD27+. In particular, primary cutaneous follicle-centre lymphomas (10 cases) showed a variable expression of both TCL1 and CD27, whereas primary cutaneous marginal-zone B-cell lymphomas (eight cases) showed, with the exception of a single case, a definite CD27+/TCL1- profile.

CONCLUSIONS

These findings indicate: (i) the TCL1 oncogene product is uncommonly expressed in PCBCL (20% of cases, mainly of the follicle-centre subtype); (ii) in contrast, CD27 is often expressed in PCBCL (60% of cases), mainly of the marginal-zone subtype; (iii) the coexpression of TCL1 and CD27 may be seldom observed in PCBCL (8% of cases); (iv) PCBCL does not seem to show, in terms of either TCL1 or CD27 expression, significant differences compared with its systemic counterparts.

Modulation by IL-2 of CD70 and CD27 expression on CD8+ T cells: importance for the therapeutic effectiveness of cell transfer immunotherapy

Proper T cell function relies on the integration of signals delivered by Ag, cytokine, and costimulatory receptors. In this study, the interactions between IL-2, CD27, and its ligand CD70 and their effects on human T cell function were examined. Unstimulated CD8(+) T cells expressed relatively low levels of CD70 and high levels of CD27. Incubation in vitro with high doses of IL-2 (3,000 IU/ml) or administration of IL-2 in vivo resulted in substantial up-regulation of CD70 expression and the concomitant loss of cell surface CD27 expression on CD8(+) cells. Withdrawal of IL-2 from activated CD8(+) T cells that had been maintained in IL-2 resulted in a reversal of the expression of these two markers, whereas reciprocal changes were seen following treatment of PBMCs with IL-2. The proliferation observed in cells stimulated with IL-2 primarily occurred in a subset of the CD70(+)CD8(+) T cells that up-regulated IL-2 receptor expression but did not occur in CD70(-)CD8(+) T cells. Blocking CD70 resulted in a significant reduction of T cell proliferation induced by high-dose IL-2, indicating that the interaction of CD70 with CD27 played a direct role in T cell activation mediated by IL-2. Finally, studies conducted on tumor-infiltrating lymphocyte (TIL) samples that were administered to melanoma patients indicated that the size of the pool of CD27(+)CD8(+) T cells in bulk TILs was highly associated (p = 0.004) with the ability of these TILs to mediate tumor regression following adoptive transfer.

Detailed Analysis of Intrahepatic CD8 T Cells in the Normal and Hepatitis C-Infected Liver Reveals Differences in Specific Populations of Memory Cells with Distinct Homing Phenotypes

In hepatitis C virus (HCV) infection the immune response is ineffective, leading to chronic hepatitis and liver damage. Primed CD8 T cells are critical for antiviral immunity and subsets of circulating CD8 T cells have been defined in blood but these do not necessarily reflect the clonality or differentiation of cells within tissue. Current models divide primed CD8 T cells into effector and memory cells, further subdivided into central memory (CCR7+, L-selectin+), recirculating through lymphoid tissues and effector memory (CCR7-, L-selectin-) mediating immune response in peripheral organs. We characterized CD8 T cells derived from organ donors and patients with end-stage HCV infection to show that: 1) all liver-infiltrating CD8 T cells express high levels of CD11a, indicating the effective absence of naive CD8 T cells in the liver. 2) The liver contains distinct subsets of primed CD8+ T cells including a population of CCR7+ L-selectin- cells, which does not reflect current paradigms. The expression of CCR7 by these cells may be induced by the hepatic microenvironment to facilitate recirculation. 3) The CCR7 ligands CCL19 and CCL21 are present on lymphatic, vascular, and sinusoidal endothelium in normal liver and in patients with HCV infection. We suggest that the recirculation of CCR7+/L-selectin- intrahepatic CD8 T cells to regional lymphoid tissue will be facilitated by CCL19 and CCL21 on hepatic sinusoids and lymphatics. This centripetal pathway of migration would allow restimulation in lymph nodes, thereby promoting immune surveillance in normal liver and renewal of effector responses in chronic viral infection.