Oligoclonal TCRBV Gene Usage in B-Cell Chronic Lymphocytic Leukemia: Major Perturbations Are Preferentially Seen Within the CD4 T-Cell Subset

CD20+ T cells in monoclonal B cell lymphocytosis and chronic lymphocytic leukemia: frequency, phenotype and association with disease progression

Introduction

In monoclonal B cell lymphocytosis (MBL) and chronic lymphocytic leukemia (CLL), the expansion of malignant B cells disrupts the normal homeostasis and interactions between B cells and T cells, leading to immune dysregulation. CD20+ T cells are a subpopulation of T cells that appear to be involved in autoimmune diseases and cancer.

Methods

Here, we quantified and phenotypically characterized CD20+ T cells from MBL subjects and CLL patients using flow cytometry and correlated our findings with the B-cell receptor mutational status and other features of the disease.

Results and discussion

CD20+ T cells were more represented within the CD8+ T cell compartment and they showed a predominant memory Tc1 phenotype. CD20+ T cells were less represented in MBL and CLL patients vs healthy controls, particularly among those with unmutated IGVH gene. The expansion of malignant B cells was accompanied by phenotypic and functional changes in CD20+ T cells, including an increase in follicular helper CD4+ CD20+ T cells and CD20+ Tc1 cells, in addition to the expansion of the TCR Vβ 5.1 in CD4+ CD20+ T cells in CLL.

Distinct immune signatures in chronic lymphocytic leukemia and Richter syndrome

Richter syndrome (RS) refers to transformation of chronic lymphocytic leukemia (CLL) to an aggressive lymphoma, most commonly diffuse large B-cell lymphoma. RS is known to be associated with a number of genetic alterations such as TP53 and NOTCH1 mutations. However, it is unclear what immune microenvironment changes are associated with RS. In this study, we analyzed expression of immune checkpoint molecules and infiltration of immune cells in nodal samples, and peripheral blood T-cell diversity in 33 CLL and 37 RS patients. Compared to CLL, RS nodal tissue had higher PD-L1 expression in histiocytes and dendritic cells (median 16.6% vs. 2.8%, P < 0.01) and PD1 expression in neoplastic B cells (median 26.0% vs. 6.2%, P < 0.01), and higher infiltration of FOXP3-positive T cells (median 1.7% vs. 0.4%, P < 0.01) and CD163-positive macrophages (median 23.4% vs. 9.1%, P < 0.01). In addition, peripheral blood T-cell receptor clonality was significantly lower in RS vs. CLL patients (median [25th–75th], 0.107 [0.070–0.209] vs. 0.233 [0.111–0.406], P = 0.046), suggesting that T cells in RS patients were significantly more diverse than in CLL patients. Collectively these data suggest that CLL and RS have distinct immune signatures. Better understanding of the immune microenvironment is essential to improve immunotherapy efficacy in CLL and RS.

T Cells in Chronic Lymphocytic Leukemia: A Two-Edged Sword

Chronic lymphocytic leukemia (CLL) is a malignancy of mature, antigen-experienced B lymphocytes. Despite great progress recently achieved in the management of CLL, the disease remains incurable, underscoring the need for further investigation into the underlying pathophysiology. Microenvironmental crosstalk has an established role in CLL pathogenesis and progression. Indeed, the malignant CLL cells are strongly dependent on interactions with other immune and non-immune cell populations that shape a highly orchestrated network, the tumor microenvironment (TME). The composition of the TME, as well as the bidirectional interactions between the malignant clone and the microenvironmental elements have been linked to disease heterogeneity. Mounting evidence implicates T cells present in the TME in the natural history of the CLL as well as in the establishment of certain CLL hallmarks e.g. tumor evasion and immune suppression. CLL is characterized by restrictions in the T cell receptor gene repertoire, T cell oligoclonal expansions, as well as shared T cell receptor clonotypes amongst patients, strongly alluding to selection by restricted antigenic elements of as yet undisclosed identity. Further, the T cells in CLL exhibit a distinctive phenotype with features of “exhaustion” likely as a result of chronic antigenic stimulation. This might be relevant to the fact that, despite increased numbers of oligoclonal T cells in the periphery, these cells are incapable of mounting effective anti-tumor immune responses, a feature perhaps also linked with the elevated numbers of T regulatory subpopulations. Alterations of T cell gene expression profile are associated with defects in both the cytoskeleton and immune synapse formation, and are generally induced by direct contact with the malignant clone. That said, these abnormalities appear to be reversible, which is why therapies targeting the T cell compartment represent a reasonable therapeutic option in CLL. Indeed, novel strategies, including CAR T cell immunotherapy, immune checkpoint blockade and immunomodulation, have come to the spotlight in an attempt to restore the functionality of T cells and enhance targeted cytotoxic activity against the malignant clone.

T-Cell Dynamics in Chronic Lymphocytic Leukemia under Different Treatment Modalities

PURPOSE

Using next-generation sequencing (NGS), we recently documented T-cell oligoclonality in treatment-naïve chronic lymphocytic leukemia (CLL), with evidence indicating T-cell selection by restricted antigens.

EXPERIMENTAL DESIGN

Here, we sought to comprehensively assess T-cell repertoire changes during treatment in relation to (i) treatment type [fludarabine-cyclophosphamide-rituximab (FCR) versus ibrutinib (IB) versus rituximab-idelalisib (R-ID)], and (ii) clinical response, by combining NGS immunoprofiling, flow cytometry, and functional bioassays.

RESULTS

T-cell clonality significantly increased at (i) 3 months in the FCR and R-ID treatment groups, and (ii) over deepening clinical response in the R-ID group, with a similar trend detected in the IB group. Notably, in constrast to FCR that induced T-cell repertoire reconstitution, B-cell receptor signaling inhibitors (BcRi) preserved pretreatment clones. Extensive comparisons both within CLL as well as against T-cell receptor sequence databases showed little similarity with other entities, but instead revealed major clonotypes shared exclusively by patients with CLL, alluding to selection by conserved CLL-associated antigens. We then evaluated the functional effect of treatments on T cells and found that (i) R-ID upregulated the expression of activation markers in effector memory T cells, and (ii) both BcRi improved antitumor T-cell immune synapse formation, in marked contrast to FCR.

CONCLUSIONS

Taken together, our NGS immunoprofiling data suggest that BcRi retain T-cell clones that may have developed against CLL-associated antigens. Phenotypic and immune synapse bioassays support a concurrent restoration of functionality, mostly evident for R-ID, arguably contributing to clinical response.

CD1d expression on chronic lymphocytic leukemia B cells affects disease progression and induces T cell skewing in CD8 positive and CD4CD8 double negative T cells

Chronic lymphocytic leukemia develops within a complex network driven by genetic mutations and microenvironmental interactions. Among the latter a complex interplay with the immune system is established by the clone. Next to a proposed recruitment of support from T and myeloid cells, potential anti-CLL immune reactions need to be subverted. By using TCL1 mice as a CLL model, we show that TCR-Vβ7+ NK1.1+ T cells are overrepresented in this disease model and constitute a main subset of peripheral CD3+ cells with biased TCR usage, showing that these cells account for a major part for T cell skewing in TCL1 mice. Moreover, we show that overrepresentation is dependent on CD1d expression in TCL1 mice, implicating that these cells belong to a NKT-like cell fraction which are restricted to antigen presented by the MHC-like surface marker CD1d. Accordingly, we observed a high fraction of CD161+ cells within overrepresented T cells in CLL patients and we found downregulation of CD1d on the surface of CLL cells, both in TCL1 mice and patients. Finally, we show that in TCL1 mice, CD1d deficiency resulted in shortened overall survival. Our results point to an interaction between CLL and CD161+ T cells that may represent a novel therapeutic target for immune modulation.

Restricted T cell receptor repertoire in CLL-like monoclonal B cell lymphocytosis and early stage CLL

Analysis of the T cell receptor (TR) repertoire of chronic lymphocytic leukemia-like monoclonal B cell lymphocytosis (CLL-like MBL) and early stage CLL is relevant for understanding the dynamic interaction of expanded B cell clones with bystander T cells. Here we profiled the T cell receptor β chain (TRB) repertoire of the CD4⁺ and CD8⁺ T cell fractions from 16 CLL-like MBL and 13 untreated, Binet stage A/Rai stage 0 CLL patients using subcloning analysis followed by Sanger sequencing. The T cell subpopulations of both MBL and early stage CLL harbored restricted TRB gene repertoire, with CD4⁺ T cell clonal expansions whose frequency followed the numerical increase of clonal B cells. Longitudinal analysis in MBL cases revealed clonal persistence, alluding to persistent antigen stimulation. In addition, the identification of shared clonotypes among different MBL/early stage CLL cases pointed towards selection of the T cell clones by common antigenic elements. T cell clonotypes previously described in viral infections and immune disorders were also detected. Altogether, our findings evidence that antigen-mediated TR restriction occurs early in clonal evolution leading to CLL and may further increase together with B cell clonal expansion, possibly suggesting that the T cell selecting antigens are tumor-related.

Ibrutinib Therapy Increases T Cell Repertoire Diversity in Patients with Chronic Lymphocytic Leukemia

The Bruton's tyrosine kinase inhibitor ibrutinib is a highly effective, new targeted therapy for chronic lymphocytic leukemia (CLL) that thwarts leukemia cell survival, growth, and tissue homing. The effects of ibrutinib treatment on the T cell compartment, which is clonally expanded and thought to support the growth of malignant B cells in CLL, are not fully characterized. Using next-generation sequencing technology, we characterized the diversity of TCRβ-chains in peripheral blood T cells from 15 CLL patients before and after 1 y of ibrutinib therapy. We noted elevated CD4⁺ and CD8⁺ T cell numbers and a restricted TCRβ repertoire in all pretreatment samples. After 1 y of ibrutinib therapy, elevated peripheral blood T cell numbers and T cell-related cytokine levels had normalized, and T cell repertoire diversity increased significantly. Dominant TCRβ clones in pretreatment samples declined or became undetectable, and the number of productive unique clones increased significantly during ibrutinib therapy, with the emergence of large numbers of low-frequency TCRβ clones. Importantly, broader TCR repertoire diversity was associated with clinical efficacy and lower rates of infections during ibrutinib therapy. These data demonstrate that ibrutinib therapy increases diversification of the T cell compartment in CLL patients, which contributes to cellular immune reconstitution.

Antigen Selection Shapes the T-cell Repertoire in Chronic Lymphocytic Leukemia

PURPOSE

The role of antigen(s) in shaping the T-cell repertoire in chronic lymphocytic leukemia, although relevant for understanding malignant cell interactions with cognate T cells, is largely unexplored.

EXPERIMENTAL DESIGN

Here we profiled the T-cell receptor β chain gene repertoire in 58 chronic lymphocytic leukemia patients, focusing on cases assigned to well-characterized subsets with stereotyped clonotypic B-cell receptor immunoglobulins, therefore those cases most evidently selected by antigen (subsets #1, #2, and #4).

RESULTS

Remarkable repertoire skewing and oligoclonality were observed, and differences between subsets were noted regarding both T-cell receptor β chain gene usage and the extent of clonality, with subset #2 being the least oligoclonal. Longitudinal analysis of subset #4 cases revealed that although the repertoire may fluctuate over time, certain clonotypes persist, thus alluding to persistent antigenic stimulation. Shared ("stereotyped") clonotypes were found between different patients, reflecting selection by common antigenic elements. Cross-comparison of our dataset with public databases showed that some T-cell clonotypes may have expanded secondary to common viral infections; however, the majority of clonotypes proved to be disease-specific.

CONCLUSIONS

Overall, the T-cell receptor β chain repertoire in chronic lymphocytic leukemia is likely shaped by antigen selection and the implicated antigenic elements may concern epitopes that also select the malignant B-cell progenitors or, more intriguingly, chronic lymphocytic leukemia-derived epitopes.

Enhancement of the TCRζ expression, polyclonal expansion, and activation of t cells from patients with acute myeloid leukemia after IL-2, IL-7, and IL-12 induction

Defective T cell receptor (TCR) signaling resulting in lower T cell function plays a crucial role in the pathogenesis of T cell immunodeficiency in leukemia. Previous studies have indicated that lower TCRζ levels are a common characteristic of patients with leukemia, and upregulating TCRζ could partially recover T cell function. In this study, we characterized the effect of the stimulating factor induction on the TCRζ, Zap-70, and FcɛRIγ levels, IFN-γ secretion, and the distribution and clonal expansion of TCR Vβ subfamilies in CD3(+) T cells sorted from peripheral blood from acute myeloid leukemia (AML) patients. The induction included single stimulating factor or a combination with different cytokines (IL-2, IL-7, IL-2+IL-7, IL-7+IL-12, CD3, CD3+CD28 antibody, CD3+CD28 antibody+IL-2, and CD3+CD28 antibody+IL-7) at 72 h. The results showed that increased TCRζ and Zap-70 levels with deceased FcɛRIγ in T cells after induction, and different responses to cytokine in T cell from different cases may indicate the heterogeneity of T cells and different immune statuses in different AML cases. Increased IFN-γ levels in T cells from AML patients were detected after induction in the IL-12+IL-7, CD3+CD28+IL-2, and CD3+CD28+IL-7 groups. Moreover, the number of TCR Vβ subfamily T cells expressed was increased; however, all of the TCR Vβ subfamily T cells in the AML patients could not be completely recovered after induction. In conclusion, the cytotoxicity and activation function of T cells could be enhanced after induction by different stimuli accompanied by an increase in TCRζ and Zap-70 and recovery of the TCR Vβ repertoire in AML patients.

A novel method using blinatumomab for efficient, clinical-grade expansion of polyclonal T cells for adoptive immunotherapy

Current treatment of chronic lymphocytic leukemia (CLL) patients often results in life-threatening immunosuppression. Furthermore, CLL is still an incurable disease due to the persistence of residual leukemic cells. These patients may therefore benefit from immunotherapy approaches aimed at immunoreconstitution and/or the elimination of residual disease following chemotherapy. For these purposes, we designed a simple GMP-compliant protocol for ex vivo expansion of normal T cells from CLL patients' peripheral blood for adoptive therapy, using bispecific Ab blinatumomab (CD3 × CD19), acting both as T cell stimulator and CLL depletion agent, and human rIL-2. Starting from only 10 ml CLL peripheral blood, a mean 515 × 10(6) CD3(+) T cells were expanded in 3 wk. The resulting blinatumomab-expanded T cells (BET) were polyclonal CD4(+) and CD8(+) and mostly effector and central memory cells. The Th1 subset was slightly prevalent over Th2, whereas Th17 and T regulatory cells were <1%. CMV-specific clones were detected in equivalent proportion before and after expansion. Interestingly, BET cells had normalized expression of the synapse inhibitors CD272 and CD279 compared with starting T cells and were cytotoxic against CD19(+) targets in presence of blinatumomab in vitro. In support of their functional capacity, we observed that BET, in combination with blinatumomab, had significant therapeutic activity in a systemic human diffuse large B lymphoma model in NOD-SCID mice. We propose BET as a therapeutic tool for immunoreconstitution of heavily immunosuppressed CLL patients and, in combination with bispecific Ab, as antitumor immunotherapy.

The role of PD-1 and PD-L1 in T-cell immune suppression in patients with hematological malignancies

T-cell activation and dysfunction relies on direct and modulated receptors. Based on their functional outcome, co-signaling molecules can be divided as co-stimulators and co-inhibitors, which positively and negatively control the priming, growth, differentiation and functional maturation of a T-cell response. We are beginning to understand the power of co-inhibitors in the context of lymphocyte homeostasis and the pathogenesis of leukemia, which involves several newly described co-inhibitory pathways, including the programmed death-1 (PD-1) and PD-1 ligand (PD-L1) pathway. The aim of this review is to summarize the PD-1 and PD-L1 biological functions and their alterative expression in hematological malignancies. The role of PD-1 and PD-L1 in T-cell immune suppression and the potential for immunotherapy via blocking PD-1 and PD-L1 in hematological malignancies are also reviewed.

Understanding the immunodeficiency in chronic lymphocytic leukemia: potential clinical implications

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Although significant advances have been made in the treatment of CLL in the last decade, it remains incurable. Treatments may be too toxic for some elderly patients, who constitute most of the individuals with this disease, and there remain subgroups of patients for which this therapy has minimal activity. This article summarizes the current understanding of the immune defects in CLL. It also examines the potential clinical implications of these findings.

Leukemia Associated Clonal Expansion of TCR Vβ Subfamily T Cells

The analysis of the T cell receptor (TCR) Vbeta repertoire is one of the most sensitive methods to identify the clonal expansion T cells which respond to tumor associated antigens. Recently, studies have focused on clonally expanded T cells from patients or normal donors induced by leukemia associated antigens in vivo or in vitro. Understanding such clonality and restricted usage of TCR Vbeta repertoire of leukemia-associated expanded T cells may be useful for the design of new immuno-therapeutic strategy for leukemia.

Expression feature of CD3, FcεRIγ, and Zap-70 in patients with chronic lymphocytic leukemia

In leukemia patients, T-cell function has been suppressed with the disease progress. Patients with chronic lymphocytic leukemia (CLL) are all to a degree immunodeficient. In order to elucidate the feature of T-cell receptor signal transduction in CLL, the expression levels of CD3γ, δ, ε, and ζ chain, FcεRIγ, and Zap-70 genes in peripheral blood mononuclear cells (PBMCs) were analyzed. Real-time polymerase chain reaction with SYBR Green technique was used for detecting the gene expression level in PBMCs from 13 patients with CLL, 13 healthy individuals, and 10 B-cell acute lymphocytic leukemia (B-ALL) served as control. The β2-microglobulin gene was used as an endogenous reference. Relative mRNA expression level of genes was analyzed by using the 2(-ΔCt) × 100% method. Significant lower expression levels of CD3γ, ε, and ζ chain genes, as well as FcεRIγ gene were found in CLL samples. Moreover, there was lost the negative correlation of the expression levels between CD3ζ and FcεRIγ genes. The expression level of Zap-70 in CLL was lower than those from healthy controls, while higher than those from B-ALL group. There was no significant correlation between the expression levels of CD3ζ and Zap-70 genes neither in the healthy group nor in the CLL group. In conclusion, the results provide a global gene expression profile of CD3γ, δ, ε, and ζ chains, and the CD3ζ-related genes FcεRIγ and Zap-70 in CLL. Deficiency of these gene expression levels might represent the feature related to T-cell immunodeficiency. The study might contribute to better understand the cellular immune features in CLL patients.

T-cell receptor repertoire usage in hematologic malignancies

Over the last few years several studies have addressed the possible influence of different immune mechanisms on the evolution of hematologic malignancies. More specifically, a fundamental role of reactive T-cells has now been demonstrated in the pathogenesis of many of these disorders as well as in the typical immunological milieu observed after stem cell transplantation in patients affected by these malignancies. In this context the study of the T-cell receptor (TCR) repertoire performed by different techniques, such as for instance flow cytometry and spectratyping, has undoubtedly provided a fundamental contribution. More recently, these seminal observations have even opened new potential therapeutic avenues based on the employment of adoptive T-cells somehow engineered toward potential neoplastic targets. This review will run through the most relevant studies which have tried to dissect the TCR repertoire usage in patients with different hematologic malignancies, especially focusing on the possible pathogenetic and therapeutic implications.

Upregulated TCRζ enhances interleukin-2 production in T-cells from patients with CML

T-cell immunodeficiency is a common feature in patients with chronic myeloid leukemia (CML), and deficiency in CD3 levels was detected in T cells from these patients, which may represent a characteristic that is related to a lower T cell activation. In this study, we explored the possibility that forced TCRζ gene expression may upreg-u-late T cell receptor (TCR) signaling activation and reverse interleukin-2 (IL-2) production in T cells from patients with CML. A recombinant eukaryotic vector expressing TCRζ was transfected into T cells by nucleofection. Phosphorylated TCRζ, phosphorylated NF-κB, and the IL-2 level in TCRζ-transfected CD3+T cells that were activated with anti-CD3 and anti-CD28 antibodies were measured by Western blot and enzyme-linked immunosorbent assay (ELISA). Significantly increased TCRζ levels were found in TCRζ-transfected CD3+T cells. After CD3 and CD28 antibody stimulation, a significantly higher phosphorylated TCRζ chain level was demonstrated, and an increased IL-2 production in TCRζ-upregulated T cells was associated with the increased expression of the phosphorylated NF-κB. In conclusion, TCRζ gene transfection could restore TCRζ chain deficiency and enhance IL-2 production in T cells from patients with CML. It is possible that TCRζ chain reconstitution in leukemia-specific, clonally expanded T cells will effectively increase their activation of antileukemia cytotoxicity.

Expansion of effector T cells associated with decreased PD-1 expression in patients with indolent B cell lymphomas and chronic lymphocytic leukemia

In patients with chronic lymphocytic leukemia (CLL), numbers of CD8 + CD45RA +/- CD27- effector T cells are expanded. We investigated whether this expansion is also present in other B cell malignancies and the possible mechanism underlying these changes. Whereas an increase in total CD4+and CD8+ T cell numbers was found only in CLL, numbers of CD4+ and CD8+ effector T cells were significantly increased in both CLL and indolent lymphoma, but not aggressive lymphoma and myeloma. Interestingly, PD-1 expression was decreased on effector T cells and inversely correlated with effector T cell numbers, suggesting a functional role for PD-1 in regulating T cell homeostasis. In vitro experiments revealed impaired up-regulation of PD-1 upon T cell activation in the presence of malignant but also healthy B cells. Our data suggest that in CLL and indolent lymphoma, the malignant B cells affect PD-1 expression on effector T cells, resulting in an expansion of these subsets.

Immune reconstitution in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is associated with a profound immune defect, which results in increased susceptibility to recurrent infections as well as a failure to mount effective antitumor immune responses. Current chemotherapy-based regimens are not curative and often worsen this immune suppression, so their usefulness is limited, particularly in the frail and elderly. This article reviews the immune defect in CLL and discusses strategies aimed at repairing or circumventing this defect. In particular, it focuses on recent developments in the areas of CD40 ligand (CD40L/CD154) gene therapy, immunomodulatory agents such as lenalidomide, and adoptive transfer of T cells bearing chimeric antigen receptors.

Restricted TRBV repertoire in CD4+ and CD8+ T-cell subsets from CML patients

T-cell immunodeficiency is a common feature in cancer patients, which may relate to initiation and development of tumor. In expanding our previous observations in this area, we studied the repertoire of T-cell receptor beta variable region (TRBV) and T-cell proliferative history in CD4+ and CD8+ T cells from chronic myeloid leukemia (CML) patients. The expression and clonality analysis were performed by reverse transcription-polymerase chain reaction (RT-PCR) and GeneScan technique in peripheral blood mononuclear cells (PBMCs), CD4+ and CD8+ subsets of T cells. Nineteen CML cases in chronic phase were selected for this study and 17 healthy individuals served as controls. Marked restriction of TRBV repertoire was observed in both CD4+ and CD8+ T cells from CML. In most CML samples, clonally expanded T cells were identified in CD4+ and CD8+ T cells, predominantly in TRBV19 and TRBV21 (5/19) subfamilies. In conclusion, the restricted expression of TRBV subfamilies indicates the T-cell immunodeficiency in CML patients; however, clonally expanded T cells suggest a specific immune response to leukemia associated antigens.

Deficiency of CD3gamma, delta, epsilon, and zeta expression in T cells from AML patients

In order to elucidate the feature of T-cell receptor (TCR) signal transduction in T-cells from acute myeloid leukemia (AML), the expression levels of CD3gamma, delta, epsilon and zeta chain genes in CD3+ T cells were analyzed using real-time PCR. CD3+ T cells sorted from peripheral blood of 10 AML patients and 10 healthy donors were used in the study. Significantly lower expression levels of all four CD3gamma, delta, epsilon, and zeta chain genes were found in the AML samples. The expression pattern of the four CD3 chains was epsilon>gamma>delta>zeta in CD3+ T cells from AML samples, which was different from the healthy control group. In conclusion, the results provide a global gene expression profile of CD3gamma, delta, epsilon, and zeta chains in AML patients. Deficiency of all four CD3 gene expression levels might represent the feature related to T-cell immunodeficiency.

Development of CLL in the TCL1 transgenic mouse model is associated with severe skewing of the T-cell compartment homologous to human CLL

Chronic lymphocytic leukemia (CLL) cells require complex microenvironmental and immunologic interactions to survive and proliferate. Such interactions might be best recreated in animal models; however, this needs extensive verification. We therefore investigated the composition of the T-cell compartment in the Eμ-TCL1 transgenic mouse, currently the most widely used murine model for CLL. Immunophenotyping and transplant approaches were used to define T-cell subsets at various stages of CLL. Analogous to human CLL, we observed a skewing of T-cell subsets from naive to antigen-experienced memory T cells that was more pronounced in lymph nodes than in blood. Transplantation of CLL into non-transgenic recipients was feasible without immunosuppression in a pure C57BL/6 background and resulted in the prominent skewing of the T cells of the recipient mice. Both in spontaneously developed CLL and in the transplantation setting, a loss in T-cell receptor diversity was observed, with a relevant number of clonal T-cell populations arising. This suggests that antigen-dependent differentiation toward the T memory pool is initiated by murine CLL cells. In summary, we validate the TCL1 transgenic mouse model for analysis of T-cell phenotypes and suggest a CLL-dependent antigen-driven skewing of T cells in these mice.

Multiple myeloma patients at peripheral blood stem cell harvest: restricted usage of TCR beta variable families

The immune systems of multiple myeloma patients are suppressed by the disease itself, and this immunosuppression is further enhanced by standard therapies. The aim of our study was to evaluate the effects of initial chemotherapy and a peripheral blood mobilisation regimen on T-cell population diversity. Reverse transcription-polymerase chain reaction (RT-PCR) with a new set of primers, in combination with capillary electrophoresis, was established. The methodology was used to analyse the relative expression of 27 T-cell receptor beta variable gene families (BV families) in multiple myeloma patients undergoing peripheral blood stem cell harvest. We found that the overall BV family usage in these patients was restricted; the relative expression of 10 BV families was significantly depressed in patients compared to healthy donors. These findings demonstrate that the preparative regimen for autologous stem cell transplantation affects the T-cell population in terms of the restriction of its T-cell receptor diversity.

Evolution of T-cell clonality in a patient with Ph-negative acute lymphocytic leukemia occurring after interferon and imatinib therapy for Ph-positive chronic myeloid leukemia

Introduction

The development of Philadelphia chromosome (Ph) negative acute leukemia/myelodysplastic syndrome (MDS) in patients with Ph-positive chronic myeloid leukemia (CML) is very rare. The features of restrictive usage and absence of partial T cell clones have been found in patients with CML. However, the T-cell clonal evolution of Ph-negative malignancies during treatment for CML is still unknown.

Objective

To investigate the dynamic change of clonal proliferation of T cell receptor (TCR) Vα and Vβ subfamilies in one CML patient who developed Ph-negative acute lymphoblastic leukemia (ALL) after interferon and imatinib therapy.

Methods

The peripheral blood mononuclear cells (PBMC) samples were collected at the 3 time points (diagnosis of Ph-positive chronic phase (CP) CML, developing Ph-negative ALL and post inductive chemotherapy (CT) for Ph-negative ALL, respectively). The CDR3 size of TCR Vα and Vβ repertoire were detected by RT-PCR. The PCR products were further analyzed by genescan to identify T cell clonality.

Results

The CML patient who achieved complete cytogenetic remission (CCR) after 5 years of IFN-α therapy suddenly developed Ph-negative ALL 6 months following switch to imatinib therapy. The expression pattern and clonality of TCR Vα/Vβ T cells changed in different disease stages. The restrictive expression of Vα/Vβ subfamilies could be found in all three stages, and partial subfamily of T cells showed clonal proliferation. Additionally, there have been obvious differences in Vα/Vβ subfamily of T cells between the stages of Ph-positive CML-CP and Ph-negative ALL. The Vα10 and Vβ3 T cells evolved from oligoclonality to polyclonality, the Vβ13 T cells changed from bioclonality to polyclonality, when Ph-negative ALL developed.

Conclusions

Restrictive usage and clonal proliferation of different Vα/Vβ subfamily T cells between the stages of Ph-positive CP and Ph-negative ALL were detected in one patient. These changes may play a role in Ph- negative leukemogenesis.

Effects of Preactivated Autologous T Lymphocytes on CD80, CD86 and CD95 Expression by Chronic Lymphocytic Leukemia B Cells

Profound immune dysfunction is a constant feature in B-cell chronic lymphocytic leukemia (B-CLL) patients. Immunological abnormalities include hypogammaglobulinemia, impaired immunoglobulin class switching and diminished germinal center formation. This state of immune suppression renders B-CLL patients highly susceptible to infections, which contribute greatly to morbidity and mortality in this disease. Impaired T cell function in B-CLL is well-documented and has been suggested to result from inhibitory effects exerted by malignant B lymphocytes. Because the presence of leukemic cells may represent a major obstacle to efficient T cell activation, T lymphocytes were separated from CLL B cells, stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin for 4h, and then cocultured with autologous leukemic B cells both at a 1:1 ratio or at the same ratio as in vivo for 24-40 h. CLL B cell expression of CD86 and CD95 was markedly upregulated using this approach, whereas CD80 expression was augmented only in a minority of patients; these effects were partially preserved even when preactivated T cells were rechallenged with CLL B cells at the same low T/B cell ratio as that observed in vivo. Finally, CD80 upregulation on CLL B cells appeared to be mainly dependent on CD40L-mediated stimulation, whereas CD86 and CD95 expression was efficiently augmented by soluble factors released by preactivated T lymphocytes. In conclusion, efficient activation of T lymphocytes in B-CLL may be achieved which, in turn, may result in enhanced antigen-presenting capacity and susceptibility to apoptosis of leukemic cells via CD86 and CD95 upregulation, respectively.

Difference in the relative distribution of CD4+ T-cell subsets in B-CLL with mutated and unmutated immunoglobulin (Ig) VH genes: implication for the course of disease

B-cell chronic lymphocytic leukemia (B-CLL) is a clinically heterogeneous disease in which the clinical course is influenced by the presence or absence of immunoglobulin (Ig) variable heavy chain (VH) gene mutations. The poor clinical outcome of the subgroup with unmutated Ig VH genes has been linked to the persistent ability of the B-cell receptor in tumor cells from these cases to respond to antigen. As B-cell receptor signaling generally relies on T-cell help, we hypothesized that the course of B-CLL might not only be influenced by the Ig VH mutational status but also by the activation/differentiation status of T cells. We assessed the relative distribution of naive and memory T-cell subsets in peripheral blood from patients with mutated (M-CLL, n=71) and unmutated Ig VH genes (UM-CLL, n=42) and correlated it with the course of disease. We also compared the prosurvival potential of naive and memory T cells cocultured with B-CLL cells in vitro. A significant increase in relative numbers of central and effector memory T cells was observed in the CD4 T-cell pool from UM-CLL as compared with M-CLL cases and was associated with high Rai stage, progressive disease and shorter treatment-free survival (TFS). In a multivariate analysis, the relative number of CD4 central and effector memory T cells remained a significant prognostic parameter for TFS after correction for CD38 expression, Ig VH status, genomic aberrations, and Rai stage. The inverse correlation of memory CD4 T cells with TFS might be explained by their potential to support survival of B-CLL cells.

A polyvalent cellular vaccine induces T-cell responses against specific self-antigens overexpressed in chronic lymphocytic B-cell leukemia

B cell-derived chronic lymphocytic leukemia (CLL) is an incurable disease that requires innovative therapeutic regimens. Experimental approaches of immunotherapy aiming at induction of systemic T-cell responses have been developed. Trioma cells provide a potent vaccine derived from malignant B cells that allows multiple antigens (Ags) from the parental tumor to be ingested by Ag-presenting cells. Like other strategies using modified whole tumor cells, this approach induces polyvalent responses. Using trioma cell-pulsed dendritic cells (DCs) for T-cell activation in vitro, we asked whether specific Ags overexpressed by CLL can be identified as target structures of such responses and what is the nature of these Ags. Expression levels of several genes in CLL samples were quantitated by reverse transcriptase-polymerase chain reaction. T lymphocytes were polyvalently stimulated by trioma-pulsed DCs and specificities were tested by determining cytokine secretion in the presence of target cells transfected with RNA coding for those Ags that were found to be overexpressed. We demonstrate that DCs pulsed with the modified tumor cells efficiently activate T lymphocytes against CLL and that overexpressed Ags related to leukemogenesis, such as BCL-2, MDM2, and ETV5, serve as targets for those T cells. Immune escape by Ag loss or mutation is less likely to occur if immunity is directed against altered self-proteins that are involved in malignant transformation. Therefore, vaccines based on modified tumor cells such as triomas hold promise for immunotherapy of CLL and other malignancies. Polyvalent vaccines originally designed as individualized therapeutics may be more broadly applicable, at least in patients showing similar Ag patterns.

Activated autologous T cells exert an anti-B-cell chronic lymphatic leukemia effect in vitro and in vivo

BACKGROUND AIMS

The impact of chronic lymphatic leukemia (CLL) tumor burden on the autologous immune system has already been demonstrated. This study attempted to elucidate the molecular mechanisms underlying T-cell immunologic deficiencies in CLL.

METHODS

Freshly isolated CD3(+) T cells from patients with a diagnosis of CLL and healthy donors were analyzed by gene expression profiling. Activated T cells from 20 patients with CLL were tested in vitro for cytotoxicity against mutated and unmutated autologous B cells and DAUDI, K562 and P815 cell lines. To investigate T-cell mediated cytotoxicity in vivo, we co-transplanted OKT3-activated T lymphocytes and autologous B-cell CLL (B-CLL) cells into NOD/SCID mice.

RESULTS

Gene expression profiles of peripheral blood T cells from B-CLL patients showed 25 down-regulated, and 31 up-regulated, genes that were mainly involved in cell differentiation, proliferation, survival, apoptosis, cytoskeleton formation, vesicle trafficking and T-cell activation. After culture, the T-cell count remained unchanged, CD8 cells expanded more than CD4 and a cytotoxicity index >30% was present in 5/20 patients. Cytotoxicity against B autologous leukemic cells did not correlate with B-cell mutational status. Only activated T cells exerting cytotoxicity against autologous leukemic B cells prevented CLL in a human-mouse chimera.

CONCLUSIONS

This study indicates that patients with CLL are affected by a partial immunologic defect that might be somewhat susceptible to repair. This study identifies the molecular pathways underlying T-cell deficiencies in CLL and shows that cytotoxic T-cell functions against autologous B-CLL can be rebuilt at least in part in vitro and in vivo.

Novel insights in chronic lymphocytic leukemia: are we getting closer to understanding the pathogenesis of the disease?

Chronic lymphocytic leukemia (CLL) has unique epidemiologic, biologic, and clinical features. The progressively emerging picture leads us to consider that the critical genes for malignant CLL cells are those regulated by a number of microRNAs revealed by refined cytogenetic and molecular studies, and that the key molecule is the B-cell receptor (BCR). The hypothesis that CLL cells might be selected by some sort of antigenic pressure is strengthened by numerous findings indicating that a BCR-mediated stimulation plays a relevant role in the natural history of the disease and that autoantigens, as well as molecular structures instrumental in eliminating and scavenging apoptotic cells and pathogenic bacteria, may be relevant in triggering and/or facilitating the evolution of CLL. An important question is whether the tiny monoclonal B-cell populations phenotypically similar to CLL (that occur in the peripheral blood of about 3.5% of healthy individuals and are termed monoclonal B lymphocytosis) might be a critical step in the development of CLL. All relevant events of CLL occur in tissues in which a number of cellular and molecular interactions shape a microenvironment conducive to the accumulation of malignant cells and favor the organization of proliferating cells in focal aggregates of variable size that form the pseudofollicular proliferation centers. Given the impact that understanding the pathogenesis of CLL might have on the development of new treatments, the purposes of this review are to discuss whether the novel insights in CLL are leading us closer to understanding the tenet of the disease; to define the emerging new, stimulating questions; and to unfold the major challenges that still need to be addressed.

Long-term effects of idiotype vaccination on the specific T-cell response in peripheral blood and bone marrow of multiple myeloma patients

OBJECTIVES

To elucidate long-term effects of idiotype (Id) vaccination on Id-specific T cells of multiple myeloma (MM) patients and compare Id-specific T-cell responses of peripheral blood with those of bone marrow (BM).

MATERIALS AND METHODS

Id-specific T-cell responses of peripheral blood mononuclear cells (PBMC) were compared with those of BM mononuclear cells (BMMC) in 10 MM patients vaccinated with the Id protein at a median time of 41 months since the last immunization. The PBMC responses at late follow-up were also compared with those during active immunization. The responses were assessed by a proliferation assay, enzyme-linked immunospot (ELISPOT) (gamma-interferon), cytometric bead array (CBA) for secreted cytokines and quantitative real-time polymerase chain reaction (QRT-PCR) for cytokine gene expression.

RESULTS

At the late testing time, an Id-specific response was detected in PBMC of five patients (ELISPOT, CBA, QRT-PCR) and in BMMC of four patients (CBA, QRT-PCR). A response in both compartments was noted only in three patients. The cytokines gene profile was consistent with a predominance of Th(2) cells [interleukin (IL)-4, IL-5, IL-10]. Comparison of the Id-specific responses of PBMC during active immunization with those at the late follow-up showed that the frequency and magnitude of the responses had decreased significantly by time (proliferation/ELISPOT) (P < 0.02) and shifted at the gene level from a Th(1) to a Th(2) profile (P < 0.05).

CONCLUSION

Id-specific T-cells may decline overtime and shift toward a Th(2) response and may be found at a similar frequency of patients in blood and BM.

High frequency of primary cutaneous lymphomas associated with lymphoproliferative disorders of different lineage

In patients suffering from primary cutaneous lymphomas, secondary malignancies of various origin may develop. However, the frequency of a second neoplasm deriving from another lymphoid lineage is still unclear and may be underestimated. We screened all our patients with primary cutaneous lymphomas from a 4-year recruitment period for a coexisting secondary lymphoproliferative disorder. The cohort comprised of a total of 82 patients with primary cutaneous lymphomas, 62 with primary cutaneous T-cell lymphoma (CTCL), 18 with primary cutaneous B-cell lymphomas, and two with CD4+/CD56+ hematodermic neoplasm/blastic lymphomas. Seven patients (8.5%) were identified with a coexisting lymphoma of a different lymphoid lineage. Four patients with Sézary syndrome (SS) suffered from systemic B-cell lymphoma. Two of these developed SS after chemotherapy of their B-cell lymphoma. The other three patients with various types of skin lymphomas (SS, Mycosis fungoides [MF], primary cutaneous marginal zone lymphoma) developed Hodgkin's disease (hairy cell leukemia). Our data indicate that patients with primary cutaneous lymphomas have an elevated risk for the development of a secondary lymphoproliferative disorder even without previous chemotherapy. Possible explanations for this association include a genetic predisposition, alterations in early progenitor cells, underlying viral infections, and/or stimulation of a B-cell clone by the malignant helper T cells of the primary CTCL and vice versa.

Reconstitution of the T-cell repertoire following treatment with alemtuzumab (anti-CD52 monoclonal antibody) in patients with B-cell chronic lymphocytic leukaemia

In this pilot study, T-cell receptor B-variable (TCR-BV) gene usage in CD4 and CD8 T cells was assessed, by real-time polymerase chain reaction, as well as complementarity-determining region 3 (CDR3)-length polymorphism, before and after therapy in five patients with B-cell chronic lymphocytic leukaemia who received alemtuzumab (anti-CD52 monoclonal antibody) as first-line therapy. A decline in expression of most BV family genes in both CD4 and CD8 T cells was observed after alemtuzumab treatment, which was followed by a gradual increase in most BV families during long-term follow-up. After treatment, CDR3-length polymorphism showed an even more restricted pattern in CD4 T cells compared with pretreatment, with a shift towards a monoclonal/oligoclonal pattern. The clonally restricted pattern was significantly reduced in CD4 (P < 0.01) but not in CD8 T cells. This was followed by a gradual increase in the number of peaks within the CDR3 region of the different TCR-BV families, i.e. a polyclonal repertoire, during long-term follow-up. A restricted CDR3 pattern became even more restricted after treatment, but normalised during unmaintained follow-up. These results indicate that perturbations in the T-cell alterations following alemtuzumab are complex and include not only changes in CD4/CD8 T-cell numbers but also a highly restricted T-cell repertoire especially in CD4 T cells.

Characterization of T-cell repertoire in hairy cell leukemia patients before and after recombinant immunotoxin BL22 therapy

We previously reported that hairy cell leukemia (HCL) patients have high percentages of CD56+/CD57+/CD3+ large granular lymphocytes consistent with cytotoxic T-lymphocytes (CTLs), and other investigators have reported skewing of the T-cell repertoire. In previous studies of up to seven HCL patients, many of the 22 established T-cell receptor (TCR) beta variable region (TRBV) families showed mono- or oligoclonal restriction. To determine whether percentages of CTLs are correlated with TRBV clonal excess, we studied 20 HCL patients with flow cytometry, PCR of TCR gamma and TRBV regions, and fractional gel electrophoresis of PCR-amplified TRBV CDR3 domains (CDR3 spectratyping). Increased percentages of CD3+/CD8+/CD57+ CTLs correlated with more mono/oligoclonal and fewer polyclonal TRBV families (r=0.53; P=0.016). Age correlated with number of mono/oligoclonal TRBV families (r=0.51; P=0.022). Time since last purine analog therapy correlated with number of polyclonal TRBV families (r=0.46; P=0.040), but treatment with the anti-CD22 recombinant immunotoxin BL22 was not related to clonal excess. We conclude that abnormalities in the T-cell repertoire in HCL patients may represent deficient immunity, and may be exacerbated by purine analogs. Increased CD3+/CD57+ T-cells may be a useful marker of abnormal TRBV repertoire in HCL patients, and might prove useful in deciding whether patients should receive biologic antibody-based treatment rather than repeated courses of purine analog for relapsed disease.

The TCR Vbeta repertoire usage of T-cells from cord blood induced by chronic myelogenous leukemia associated antigen

Understanding the clonality and restricted usage of the TCR Vbeta repertoire of expanded T-cells induced by the chronic myelogenous leukemia (CML) associated antigen may be useful in helping design new immunotherapeutic strategies specifically for CML. T-cells from cord blood that had been stimulated by different stimulators (IL-2, PHA, CML cells, K562 cells and bcr-abl peptide) were amplified in vitro by liquid T-cell culture and the mixed lymphocyte and tumor cell culture (MLTC) method. By using the RT-PCR, the CDR3 segments of 24 variable region genes of TCR beta was analyzed in T-cells from 22 cases of cord blood before and after T-cell culture, to observe the usage of TCR Vbeta repertoire. The PCR products were further labeled with fluorescence and analyzed by the Genescan technique for the CDR3 size, to evaluating clonality of the detectable TCR Vbeta T-cells. Only a part of 24 Vbeta subfamily T-cells (3-15 subfamilies) could be detected, however, all of the 24 TCR Vbeta subfamily of T-cells were detected after in vitro culture with PHA or IL-2+anti-CD3 antibody. The number of expressed TCR Vbeta subfamilies was gradually reduced by prolonging the time of culture with CML-associated antigens. The restricted expression of TCR Vbeta subfamilies and oligoclonal expansion of Vbeta21 T-cells were found in cultured T-cells induced by CML cells, K562 cells or bcr-abl peptide. In conclusion, T-cells from cord blood may have the potential capability of proliferation in different TCR Vbeta subfamily T-cells, and the ability for restricted expression and clonal expansion, when T-cells were induced by CML associated antigen.

T and B cells in B-chronic lymphocytic leukaemia: Faust, Mephistopheles and the pact with the Devil

A large number of human malignancies are associated with decreased numbers of circulating T cells. B-CLL, in this regard, represents an anomaly since there is not only high numbers of circulating B cells, characteristic of the malignancy, but also a massive expansion of both CD4 and CD8 T cells. These T cells for the most part may probably not represent a leukaemia-specific TCR-dependent expansion. On the contrary, these T cells, especially the CD4 subset, might support a "microenvironment" sustaining the growth of the leukaemic B cell clone. Conversely, the leukaemic B cells may produce membrane-bound as well as soluble factors that stimulate the proliferation of these T cells in an antigen independent manner. In addition to these T cells lacking anti-leukaemic reactivity, there exist spontaneously occurring leukaemia-specific T cells recognizing several leukaemia-associated antigens, e.g. the tumour derived idiotype, survivin and telomerase. Both CD4 and CD8 leukaemia-specific T cells have been identified using proliferation and gamma-IFN assays. These reactive T cells can lyse autologous tumour cells in an MHC class I and II restricted manner. Spontaneously occurring leukaemia-specific T cells are more frequently noted at an indolent stage rather than in progressive disease. Preliminary results from vaccination trials using whole tumour cell preparations as vaccine have demonstrated that vaccination may induce a leukaemia-specific T cell response, which might be associated with clinical benefits. Extended clinical trials are required to establish the therapeutic effects of vaccination in B-CLL. Studies in our laboratory as well as those of others indicate that whole tumour cell antigen in the form of apoptotic bodies or RNA loaded on to dendritic cells may be a suitable vaccine candidate. Patients with low stage disease may maximally benefit from this form of therapy.

Bcl-2 regulatory pathway is functional in chronic lymphocytic leukemia

BACKGROUND

Chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal, malignant CD5(+), CD23(+) B cells. In vivo, these cells have an antiapoptotic phenotype (high levels of Bcl-2 and low levels of proapoptotic Bcl-2 family proteins, such as Bax). Abnormal B cells accumulate due to altered apoptosis regulation rather than to increased proliferation. However, it is unclear whether there are inherent Bcl-2 apoptotic pathway defects. With in vitro culture, these B cells rapidly apoptosis.

METHODS

To investigate apoptosis regulation, Bcl-2, Bax, mitochondrial membrane potential, annexin V, and caspase activation were simultaneous monitored in individual cells during in vitro apoptosis.

RESULTS

With in vitro culture, 30% to 50% of B cells were apoptotic at 24 h compared with fewer than 10% of T cells. Apoptotic B cells showed dramatic Bax upregulation and slight Bcl-2 decreases accompanied by decreased mitochondrial membrane potential and increased activated caspase-3 protein levels. Caspase-3 and caspase-9 activities were increased 18- to 51-fold and 6- to 11-fold, respectively, after 24 h of culture. Caspase-8 showed limited or no activation (less than fourfold).

CONCLUSIONS

These data show that in vitro apoptosis of CLL B cells occurs through a well-characterized Bcl-2 regulatory pathway consistent with that pathway being functional. Further, these cells' antiapoptotic phenotype is dependent on the in vivo environment, potentially involving paracrine/autocrine interactions.

Activated marrow-infiltrating lymphocytes effectively target plasma cells and their clonogenic precursors

A major limitation of adoptive immunotherapy is the availability of T cells specific for both terminally differentiated tumor cells and their clonogenic precursors. We show here that marrow-infiltrating lymphocytes (MILs) recognize myeloma cells after activation with anti-CD3/CD28 beads with higher frequency than activated peripheral blood lymphocytes from the same patients. Furthermore, activated MILs target both the terminally differentiated CD138+ plasma cells and the myeloma precursor as shown by profound inhibition in a tumor clonogenic assay. The presence of antigen in the marrow microenvironment seems to be important for the maintenance of tumor specificity. Taken together, these results highlight the intrinsic tumor specificity of MILs and describe a novel approach for the generation of tumor-specific T-cell populations suitable for adoptive immunotherapy of multiple myeloma.

Clonal expanded TCR Vβ T cells in patients with APL

T-cell receptor Vss gene repertoire and clonality have been studied in patients with leukemia and solid tumors, by assaying the CDR3 size of TCR genes, using RT-PCR and genescan analysis. Few studies have studied leukemia-associated oligoclonal expanded T-cells in leukemia, therefore, the aim of this study was to investigate the distribution and clonal expansion of T-cell receptor, Vss subfamily T-cells in patients with acute promyelocytic leukemia (APL) with t(15;17). The CDR3 of TCR Vbeta24 subfamily genes were analyzed in peripheral blood mononuclear cells from 17 cases with PML-RARalpha+ APL using RT-PCR and genescan technique. Ten normal individuals served as controls. The results showed that the number of expressed Vss subfamilies (from 2 to 21 subfamilies) varied in different patients with APL. The most frequently expressed Vss subfamilies were Vbeta2 (64.7%), Vbeta15 (58.8%), Vbeta3 and Vbeta5 (47.1%), with a lower expression rate found in Vbeta11 and Vbeta20 (11.7%). Clonally expanded T-cells in the Vss subfamilies could be identified in patients with APL in all but two of the cases studied, predominantly in Vbeta10, Vbeta23, Vbeta3 and Vbeta21. In conclusion, skewed distribution and clonal expansion of TCR Vss subfamily T-cells could be found in patients with APL. The clonal expansion of T-cells were considered to be a specific anti-leukemic immune response by host T-cells activated by the leukemia-associated-antigen.

Tim-3+ T-bet+ tumor-specific Th1 cells colocalize with and inhibit development and growth of murine neoplasms

Although T cells infiltrate many types of murine and human neoplasms, in many instances tumor-specific cytotoxicity is not observed. Strategies to stimulate CTL-mediated antitumor immunity have included in vitro stimulation and/or genetic engineering of T cells, followed by adoptive transfer into tumor-bearing hosts. In this model of B cell lymphoma in SJL/J mice, we used Tim-3(+) T-bet(+) Th1 cells to facilitate the development of tumor-specific CTL. Tumor-specific Th1 cell lines were polarized with IL-12 during in vitro stimulation and long term maintenance. As few as 5 million Tim-3(+) T-bet(+) Th1 cells enabled recipients to resist growth of malignant transplantable cells. In addition, similar numbers of Th1 cells injected into 2- to 3-mo-old mice inhibited development of the spontaneous primary lymphomas, which normally arise in 90% of aging mice. CFSE(+) Th1 cells colocalized with injected tumor cells in vivo and formed conjugates with the tumor cells within follicles, whereas in nontumor-challenged recipients the CFSE(+) Th1 cells localized only within the T cell zones of the spleen. These results provide evidence that adoptive immunotherapy with Tim-3(+) T-bet(+) tumor-specific Th1 cells can be used to induce host cytotoxic responses that inhibit the development and growth of neoplastic cells.

Clonal T-cell Populations and Increased Risk for Cytotoxic T-cell Lymphomas in B-CLL Patients

Chronic lymphocytic leukemia (CLL) is associated with increased risk of malignancy, but the occurrence of other lymphomas, in particular T-cell lymphomas, is rare. We identified 7 cases of peripheral T-cell malignancy associated with B-cell-derived CLL from the files of two institutions over a 20-year period. The presence of both B and T lymphoproliferative disorders was confirmed in all cases by immunophenotype and in 6 cases by gene rearrangements. Six patients developed peripheral T-cell lymphoma (PTCL), unspecified, during the course of CLL (10-168 months). In all 5 evaluable cases, the cells had a cytotoxic T-cell phenotype; the sixth case was CD56+, but TIA-1 and Granzyme B could not be studied. A seventh patient with CLL developed mycosis fungoides, and an aggressive NK cell leukemia. To investigate possible risk factors for the development of PTCL, we screened 100 unselected peripheral blood samples from newly diagnosed CLL patients by PCR for the presence of clonal T cell populations. We found evidence of clonal T-cell expansion in 8 patients and increased lymphocytes with large granular lymphocyte morphology in 7 of 8 cases. The immunophenotype was assessed by multicolor flow cytometry and in 4 cases the T-cell expansion was composed of either CD3+/CD8+ or CD3+/CD4-/CD8- cells. The cytotoxic nature of the clonal T-cell expansions in the peripheral blood correlates with the cytotoxic nature of the PTCLs, but their role in the subsequent development of T-cell lymphomas is still unclear. PTCL following CLL should be distinguished from typical Richter syndrome, which it can mimic clinically.

Kinetics of cytokine gene expression in human CD4+ and CD8+ T-lymphocyte subsets using quantitative real-time PCR

The time kinetics of five cytokines [interleukin-2 (IL-2), IL-5, interferon-gamma (IFN-gamma), granulocyte macrophage-colony stimulating factor (GM-CSF) and tumour necrosis factor-alpha (TNF-alpha)] and one cytotoxic effector protein (granzyme B) was analysed by real-time quantitative polymerase chain reaction (PCR) following in vitro stimulation of human CD4 and CD8 T lymphocytes. Two stimuli were used, a mitogen [phytohemagglutinin (PHA)] and a recall antigen [purified protein derivative (PPD)]. The pattern of cytokine mRNA expression was found to be dependent on the T-cell subset and stimulus used. A wide interindividual variability in the cytokine gene expression pattern was demonstrated. Two expression patterns were observed. A bell-shaped expression profile was seen for most cytokines upon PHA activation in both subsets and PPD-activated CD4 T cells, whereas a biphasic/multiphasic expression pattern was noted in CD8 T cells upon PPD stimulation. For most cytokines, the time to induction was within 30 min of activation, and maximum accumulation seemed to be obtained after 4-8 h of activation. A sustained high level could, however, be noticed for up to 24 h. Granzyme B gene expression was also induced within 30 min of activation but showed a continuous gradual increase and late maximal accumulation (48-72 h). The findings of the present study are of importance when designing studies using the cytokine gene expression profile as a marker for antigen-specific T lymphocytes. It might be recommended that cytokine gene expression (IL-2, IL-5 and IFN-gamma) should be measured after 4-8 h of specific activation but also up to 24 h of stimulation is acceptable. Granzyme B should preferentially be measured after 48-72 h of activation.

Immunologic monitoring in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is characterized by progressive defects in humoral- and cell-mediated immunity. These defects are manifested as a propensity to develop infections with encapsulated bacteria, and less frequently, with gram-negative enterics. In addition, reactivation of viruses such as herpesvirus is not uncommon. Treatment of the disease further exacerbates immunosuppression by depleting immune effectors and broadening the spectrum of potentially offending pathogens. Risk of infection can potentially be reduced by administration of intravenous immunoglobulin and use of prophylactic antibiotics for individuals who are at high risk. Current work focuses on development of cellular and cytokine therapy to facilitate immune reconstitution in patients with CLL, thereby reducing morbidity and mortality and potentially improving survival.

Expansion of CMV-specific CD8+CD45RA+CD27- T cells in B-cell chronic lymphocytic leukemia

In patients with B-cell chronic lymphocytic leukemia (B-CLL), the absolute number of T cells is increased. Although it has been suggested that these T cells might be tumor specific, concrete evidence for this hypothesis is lacking. We performed a detailed immunophenotypic analysis of the T-cell compartment in the peripheral blood of 28 patients with B-CLL (Rai 0, n = 12; Rai I-II, n = 10; Rai III-IV, n = 6) and 12 healthy age-matched controls and measured the ability of these patients to mount specific immune responses. In all Rai stages a significant increase in the absolute numbers of CD3+ cells was observed. Whereas the number of CD4+ cells was not different from controls, patients with B-CLL showed significantly increased relative and absolute numbers of CD8+ cells, which exhibited a CD45RA+CD27- cytotoxic phenotype. Analysis of specific immune responses with tetrameric cytomegalovirus (CMV)-peptide complexes showed that patients with B-CLL had significantly increased numbers of tetramer-binding CMV-specific CD8+ T cells. The rise in the total number of CD8+ cytotoxic T cells was evident only in CMV-seropositive B-CLL patients. Thus, our data suggest that in patients with B-CLL the composition of T cells is shifted toward a CD8+ cytotoxic cell type in an effort to control infections with persistent viruses such as CMV. Moreover, they offer an explanation for the high incidence of CMV reactivation in CLL patients treated with T cell-depleting agents, such as the monoclonal antibody (mAb) alemtuzumab (Campath; alpha-CD52 mAb). Furthermore, because in CMV-seronegative patients no increase in cytotoxic CD8+ T cells is found, our studies do not support the hypothesis that tumor-specific T cells account for T-cell expansion in B-CLL.