John F. Daley

CD40-activated human B cells: an alternative source of highly efficient antigen presenting cells to generate autologous antigen-specific T cells for adoptive immunotherapy.

Multiple clinical trials have shown the efficacy of adoptively transferred allogeneic antigen-specific T cells for the treatment of viral infections and relapsed hematologic malignancies. In contrast, the therapeutic potential of autologous antigen-specific T cells has yet to be established since it has been technically difficult to generate sufficient numbers of these T cells, ex vivo. A major obstacle to the success of this objective derives from our inability to simply and rapidly isolate and/or expand large numbers of highly efficient antigen presenting cells (APCs) for repetitive stimulations of antigen-specific T cells in vitro. We show that autologous CD40-activated B cells represent a readily available source of highly efficient APC that appear to have several important advantages over other APCs for ex vivo T cell expansion including: (a) methodological simplicity necessary to generate continuously large numbers of APCs from just 50 cm3 of peripheral blood without loss of APC function; (b) capacity to induce high peak T cell proliferation and interferon-gamma production without IL-10 production; (c) ease in cryopreservation; and (d) markedly reduced cost. We, therefore, contend that CD40-activated B cells are an alternative source of highly efficient APCs with which to generate antigen-specific T cells ex vivo for autologous adoptive immunotherapy.

Selective loss of the suppressor-inducer T-cell subset in progressive multiple sclerosis: analysis with anti-2H4 monoclonal antibody

The T4+ lymphocyte population includes a subset that induces suppressor T lymphocytes (T8+ cells) and can be distinguished by dual-color fluorescence analysis with anti-2H4 and anti-T4 monoclonal antibodies. To investigate the possible role of these cells in multiple sclerosis, we used anti-2H4 antibody to characterize peripheral-blood lymphocyte subsets in 63 patients with multiple sclerosis that was progressive, stable, or acute (relapsing-remitting). Twenty-three of 37 patients with progressive multiple sclerosis had a selective decrease in the number and percentage of peripheral-blood T cells that induce suppressor cells (T4+2H4+ cells), whereas only 3 of 16 patients with stable disease and 2 of 10 patients in the midst of an acute attack had a significant decrease. These selective decreases of circulating T4+2H4+ cells occurred in only 1 of 34 patient controls with other neurologic diseases and in 2 of 50 healthy controls (P less than 0.0001 by Fishers exact test). The absolute number of T4+2H4+ cells and the percentage of reactivity in the populations studied were 187 +/- 28 per cubic millimeter and 8.3 +/- 1 percent in patients with progressive multiple sclerosis; 353 +/- 60 per cubic millimeter and 14.5 +/- 2 percent in patients with stable disease; 368 +/- 72 and 14.6 +/- 2.1 percent in patients with acute disease; 402 +/- 64 and 15.6 +/- 2 percent in controls with other neurologic diseases; and 519 +/- 44 and 19.7 +/- 1 percent in healthy controls. Functional studies using a pokeweed mitogen-driven IgG assay demonstrated a correlation between decreased numbers of T4+2H4+ cells and increased production of IgG in vitro. Family studies showed that the 2H4 antigen was not part of an inherited polymorphic antigenic determinant. Our results suggest that in progressive multiple sclerosis decreases in inducers of suppressor T cells may permit the activation of cells reactive with elements of the central nervous system.

A defect of immunoregulatory T cell subsets in systemic lupus erythematosus patients demonstrated with anti-2H4 antibody.

The cell surface phenotype of peripheral blood lymphocytes (PBL) of systemic lupus erythematosus (SLE) patients was characterized with the anti-2H4 monoclonal antibody that defines the human suppressor inducer subset. The T4+2H4+ population of cells has been shown to be critical for the activation of T8+ suppressor cells. Patients with SLE has a markedly decreased percentage of T4+2H4+ cells (13 +/- 2%) in their PBL compared with normal controls (21 +/- 1%) (P less than 0.001). This reduction was greatest in patients with active SLE, especially those with renal disease. Serial analysis of patients with SLE and renal disease showed a correlation between percent positive circulating T4+2H4+ cells and disease activity. Moreover, there was a significant correlation between a low percentage of T4+2H4+ cells and decreased suppressor-inducer function in autologous mixed lymphocyte reaction-activated T4+ cells from SLE patients. Thus, a deficiency exists in SLE patients with active renal disease in the T4+2H4+ suppressor-inducer T cell subset.

Elevated IL-17 produced by Th17 cells promotes myeloma cell growth and inhibits immune function in multiple myeloma

Elevated cytokines in bone marrow (BM) micro-environment (interleukin-6 [IL-6], transforming growth factor-beta [TGF-beta], and IL-1beta) may play an important role in observed immune dysfunction in multiple myeloma (MM). As IL-6 and TGF-beta are important for the generation of T-helper 17 (T(H)17) cells, we evaluated and observed a significantly elevated baseline and induced frequency of T(h)17 cells in peripheral blood mononuclear cells (PBMCs) and BM mononuclear cells (BMMCs) from MM patients compared with healthy donors. We observed significant increase in levels of serum IL-17, IL-21, IL-22, and IL-23 in blood and BM in MM compared with healthy donors. We also observed that myeloma PBMCs after T(H)17 polarization significantly induced IL-1alpha, IL-13, IL-17, and IL-23 production compared with healthy donor PBMCs. We next observed that IL-17 promotes myeloma cell growth and colony formation via IL-17 receptor, adhesion to bone marrow stromal cells (BMSCs) as well as increased growth in vivo in murine xenograft model of human MM. Additionally, we have observed that combination of IL-17 and IL-22 significantly inhibited the production of T(H)1-mediated cytokines, including interferon-gamma (IFN-gamma), by healthy donor PBMCs. In conclusion, IL-17-producing T(h)17 cells play an important role in MM pathobiology and may be an important therapeutic target for anti-MM activity and to improve immune function.

Combination immunotherapy with rituximab and interleukin 2 in patients with relapsed or refractory follicular non-Hodgkin's lymphoma.

Summary.  Rituximab has significant activity as a single agent in the treatment of follicular non‐Hodgkins lymphoma (NHL). Interleukin 2 (IL‐2) is a lymphokine that increases effector cell number. In an effort to augment antibody‐dependent cell‐mediated cytotoxicity (ADCC) associated with rituximab therapy, low‐dose IL‐2 was added to a standard rituximab regimen and patients were evaluated for safety and efficacy. Twenty patients with relapsed or refractory follicular NHL were treated with IL‐2 (1·2 MIU/m2/d for 56 d subcutaneously) as outpatients. Rituximab (375 mg/m2) was given on d 15, 22, 29 and 36. The regimen was well tolerated and only three patients required dose adjustments in IL‐2. Infusional toxicity associated with rituximab was not exacerbated by IL‐2. Peripheral blood immunophenotyping demonstrated significant increases in circulating CD8+ and CD56+ lymphocytes in all evaluable patients (P = 0·0002). Increases in total eosinophil number were observed in all patients. Eleven patients responded to therapy, for an overall response rate of 55%. Four additional patients had stable disease. For these 15 patients, the median time to progression exceeded 13 months. We conclude concomitant cytokine therapy to enhance ADCC with monoclonal antibody therapy was well tolerated and did not exacerbate antibody‐related infusional toxicity. Further studies of this rational combination are warranted and ongoing.

Lenalidomide targets clonogenic side population in multiple myeloma: pathophysiologic and clinical implications

Recurrence of multiple myeloma (MM) after therapy suggests the presence of tumor-initiating subpopulations. In our study, we performed flow cytometry-based Hoechst 33342 staining to evaluate the existence of a MM population with stem-like features known as side population (SP) cells. SP cells exhibit substantial heterogeneity in MM cell lines and primary MM cells; express CD138 antigen in MM cell lines; display higher mRNA expression and functional activity of ABCG2 transporter; and have a higher proliferation index compared with non-SP cells. We observed evidence for clonogenic potential of SP cells, as well as the ability of SP cells to regenerate original population. Moreover, SP cells revealed higher tumorigenicity compared with non-SP cells. Importantly, lenalidomide decreased the percentage and clonogenicity of SP cells, and also induced phosphorylation changes in Akt, GSK-3α/β, MEK1, c-Jun, p53, and p70S6K in SP cells. Adherence to bone marrow stromal cells (BMSCs) increased the percentage, viability, and proliferation potential of SP cells. Lenalidomide and thalidomide abrogated this stimulatory effect of BMSCs and significantly decreased the percentage of SP cells. Our studies demonstrate a novel mechanism of action for lenalidomide, namely targeting SP fraction, providing the framework for new therapeutic strategies targeting subpopulations of MM cells including presumptive stem cells.

Smac mimetics: implications for enhancement of targeted therapies in leukemia

Drug resistance is a growing concern with clinical use of tyrosine kinase inhibitors. Utilizing in vitro models of intrinsic drug resistance and stromal-mediated chemoresistance, as well as functional mouse models of progressive and residual disease, we attempted to develop a potential therapeutic approach designed to suppress leukemia recurrence following treatment with selective kinase inhibitors. The novel inhibitor of apoptosis (IAP), LCL161, was observed to potentiate the effects of tyrosine kinase inhibition against leukemic disease both in the absence and presence of a stromal protected environment. LCL161 enhanced the proapoptotic effects of nilotinib and PKC412, against leukemic disease in vitro and potentiated the activity of both kinase inhibitors against leukemic disease in vivo. In addition, LCL161 synergized in vivo with nilotinib to reduce leukemia burden significantly below the baseline level suppression exhibited by a moderate-to-high dose of nilotinib. Finally, LCL161 displayed antiproliferative effects against cells characterized by intrinsic resistance to tyrosine kinase inhibitors as a result of expression of point mutations in the protein targets of drug inhibition. These results support the idea of using IAP inhibitors in conjunction with targeted tyrosine kinase inhibition to override drug resistance and suppress or eradicate residual disease.

Differential expression of CD8α and CD8β associated with MHC-restricted and non-MHC-restricted cytolytic effector cells

The differential expression of the alpha and beta chains of the CD8 glycoprotein was examined in three functionally distinct cytolytic effector cell populations: (i) T cells (CD3+ CD56-), (ii) NK cells (CD56+ CD3-), and (iii) non-MHC-restricted T cells (CD56+ CD3+). Twenty-four percent of T cells were CD8+, and they consistently coexpressed both CD8 alpha and CD8 beta. Moreover, CD8+ T cells uniformly expressed high-density CD8 alpha. Forty percent of NK cells were CD8+ but the vast majority (approximately 75%) expressed only CD8 alpha without CD8 beta. In addition, CD8+ NK cells uniformly expressed low-density CD8 alpha. In comparison, 75% of non-MHC-restricted T lymphocytes were CD8+ but they displayed an intermediate phenotype: 60% coexpressed CD8 alpha and CD8 beta while 40% expressed only CD8 alpha. Within this population, CD8 alpha was expressed at high density, similar to that of T cells. Following IL-2 activation, enhancement of non-MHC-restricted cytotoxicity was not associated with any changes in either the quantitative or qualitative pattern of expression of CD8 alpha or CD8 beta by these cells. Addition of either anti-CD8 alpha or anti-CD8 beta mAb did not alter non-MHC-restricted cytotoxicity of either CD56+ CD3- or CD56+ CD3+ effector cells. However, within the CD56+ cell population, non-MHC-restricted cytotoxicity was almost entirely found within the CD8- and CD8 alpha + beta- populations, and both subsets displayed a similar level of killing. In contrast, CD8 alpha+ beta+ cells exhibited very little non-MHC-restricted cytotoxicity. Thus, the coexpression of CD8 alpha and CD8 beta in conjunction with the TCR/CD3 complex appears to characterize MHC restricted cells while the expression of CD8 alpha alone is associated with non-MHC-restricted cytotoxicity. Taken together, these findings suggest that neither CD8 alpha nor CD8 beta is involved in the initial phases of target cell binding or recognition during NK cell-mediated lysis. However, the selective expression of CD8 alpha by a large fraction of non-MHC-restricted effector cells suggests that this antigen may play a different functional role in this unique subset of cytolytic lymphocytes.

Myeloma-specific multiple peptides able to generate cytotoxic T lymphocytes: A potential therapeutic application in multiple myeloma and other plasma cell disorders

Purpose: The efficacy of peptide vaccines may be enhanced by stimulating immune cells with multiple peptides derived from distinct tumor-associated antigens. We have evaluated the heteroclitic XBP1-US184–192 (YISPWILAV), heteroclitic XBP1-SP367–375 (YLFPQLISV), native CD138260–268 (GLVGLIFAV), and native CS1239–247 (SLFVLGLFL) peptides, which have strong HLA-A2 affinity and immunogenicity in combination, for their ability to elicit multiple myeloma antigen–specific responses. Experimental Design: Multipeptide-specific cytotoxic T lymphocytes (MP-CTL) were generated by the stimulation of CD3+ T lymphocytes from HLA-A2+ individuals with either autologous mature dendritic cells or T2 cells pulsed with a cocktail of these four peptides. Results: The peptide cocktail did not compromise tumor antigen–specific activity of CTLs. MP-CTLs displayed increased total, effector memory (CCR7−CD45RO+), and activated (CD69+) CD3+CD8+ T lymphocytes. In addition, MP-CTL showed IFN-γ production, cell proliferation, and cytotoxicity against HLA-A2+ multiple myeloma cells, including cells of HLA-A2+ patients with multiple myeloma. Importantly, MP-CTLs showed specific responses in functional assays to each relevant peptide but not to an irrelevant HLA-A2–specific CMV pp65 (NLVPMVATV) peptide. Conclusions: These results highlight the potential therapeutic application of vaccination with a cocktail of HLA-A2–specific peptides to induce CTLs with a broad spectrum of immune responses against multiple myeloma antigens. Clin Cancer Res; 18(17); 4850–60. ©2012 AACR.

CD4+CD45RA+ and CD4+CD45RA− T cell subsets in man maintain distinct function and CD45RA expression persists on a subpopulation of CD45RA+ cells after activation with Con A☆

We have previously shown that Con A-induced suppressor T cells belong to the CD45RA+ subset. After unseparated T cells are activated with Con A, CD45RA expression increases to a maximum (Day 2), and then decreases significantly, but does not disappear entirely (Day 9), while CD29 expression increases steadily. In the present study, we examined the fate of these cell surface molecules on isolated CD4+CD45RA+ and CD4+CD45RA- cells following activation with Con A, and their relationship to the regulatory functions of these subsets. After activation of CD4+CD45RA+ cells with Con A, CD45RO and CD29 antigen expression rapidly increases (greater than 90%). While CD45RA expression is downregulated, approximately 40% of the cells continue to express low-density CD45RA in a stable fashion through Day 21. Despite these phenotypic changes, cells originally CD45RA+ continue to suppress IgG synthesis and provide only minimal B cell help. Furthermore, when cells originally CD45RA+ were sorted on the basis of continued presence, or loss of CD45RA antigen 14 days after activation, both populations demonstrated potent suppression and minimal help. In contrast, after activation with Con A, CD4+CD45A- cells maintain stable phenotype and provide significant help and minimal suppression. Immunoprecipitation of the CD45RA antigen from Day 14 activated CD4+CD45RA+ cells confirms the continued presence of the 205-kDa isoform, but reveals a significant decrease in the 220-kDa isoform. These results suggest that after activation with Con A, cells originally CD45RA+ remain functionally distinct from cells originally CD45RA-, and that CD45RA antigen persists on a subpopulation of CD45RA+ cells after activation with Con A.