Induction of potent antitumour natural-killer cells from peripheral blood of patients with advanced prostate cancer

"Adherent" versus Other Isolation Strategies for Expanding Purified, Potent, and Activated Human NK Cells for Cancer Immunotherapy

Natural killer (NK) cells have long been hypothesized to play a central role in the development of new immunotherapies to combat a variety of cancers due to their intrinsic ability to lyse tumor cells. For the past several decades, various isolation and expansion methods have been developed to harness the full antitumor potential of NK cells. These protocols have varied greatly between laboratories and several have been optimized for large-scale clinical use despite associated complexity and high cost. Here, we present a simple method of "adherent" enrichment and expansion of NK cells, developed using both healthy donors' and cancer patients' peripheral blood mononuclear cells (PBMCs), and compare its effectiveness with various published protocols to highlight the pros and cons of their use in adoptive cell therapy. By building upon the concepts and data presented, future research can be adapted to provide simple, cost-effective, reproducible, and translatable procedures for personalized treatment with NK cells.

Reduction of the CD16(-)CD56bright NK cell subset precedes NK cell dysfunction in prostate cancer

Background

Natural cytotoxicity, mediated by natural killer (NK) cells plays an important role in the inhibition and elimination of malignant tumor cells. To investigate the immunoregulatory role of NK cells and their potential as diagnostic markers, NK cell activity (NKA) was analyzed in prostate cancer (PCa) patients with particular focus on NK cell subset distribution.

Methods

Prospective data of NKA and NK cell subset distribution patterns were measured from 51 patients initially diagnosed with PCa and 54 healthy controls. NKA was represented by IFN-γ levels after stimulation of the peripheral blood with Promoca®. To determine the distribution of NK cell subsets, PBMCs were stained with fluorochrome-conjugated monoclonal antibodies. Then, CD16⁺CD56^dim and CD16⁻CD56^bright cells gated on CD56⁺CD3⁻ cells were analyzed using a flow-cytometer.

Results

NKA and the proportion of CD56^bright cells were significantly lower in PCa patients compared to controls (430.9 pg/ml vs. 975.2 pg/ml and 2.3% vs. 3.8%, respectively; p<0.001). Both tended to gradually decrease according to cancer stage progression (p for trend = 0.001). A significantly higher CD56^dim-to-CD56^bright cell ratio was observed in PCa patients (41.8 vs. 30.3; p<0.001) along with a gradual increase according to cancer stage progression (p for trend = 0.001), implying a significant reduction of CD56^bright cells in relation to the alteration of CD56^dim cells. The sensitivity and the specificity of NKA regarding PCa detection were 72% and 74%, respectively (best cut-off value at 530.9 pg/ml, AUC = 0.786).

Conclusions

Reduction of CD56^bright cells may precede NK cell dysfunction, leading to impaired cytotoxicity against PCa cells. These observations may explain one of the mechanisms behind NK cell dysfunction observed in PCa microenvironment and lend support to the development of future cancer immunotherapeutic strategies.

Comparative study of frequency of different lymphocytes subpopulation in peripheral blood of patients with prostate cancer and benign prostatic hyperplasia

PURPOSE

Benign prostatic hyperplasia (BPH) and prostate cancer (PC) are the most common urologic diseases among men over fifty and, until recently, they were considered to be caused by the impaired immune response. Despite many studies designed to investigate T-cell-based antitumor immunity, the role of innate immune cells in BPH and PC is still poorly understood. In this study the frequency of different leukocytes subpopulation in peripheral blood of BPH, PC patients and in healthy volunteers was analysed and compared.

METHODS

In a cross-sectional study 60 subjects were enrolled (20 patients with BPH or with PC and 20 healthy volunteers). Peripheral blood mononuclear cells (PBMC) were isolated and the percentage of T lymphocytes, natural killer (NK) and NKT cells, as well as subsets of T lymphocytes [CD3(+)CD56(-)CD4(+), T(regs) (CD4(+)CD25(+)FoxP3(+)) and CD3(+)CD56(-)CD8(+)] and NK cells (CD3(-)CD56(+dim) and CD3(-)CD56(+bright)) were analysed by flow cytometry. Intracellular content of interleukin-4 (IL-4) and interferon gamma (IFNγ in T lymphocytes, NK and NKT cells were also detected.

RESULTS

The percentage of T lymphocytes and their subsets in peripheral blood lymphocytes did not differ among investigated groups, while the frequency of Tregs was the highest in PC patients. The percentage of NK cell and their subsets did not differ among investigated groups. Negative correlation between PSA value, percentage of T lymphocytes and NK cells was observed only in PC patients. Highly positive correlation between the PSA value and the percentage of Tregs was found in PC patients.

CONCLUSION

Different frequencies in distinctly lymphocyte subpopulation in peripheral blood of healthy men, BPH and PC patients could be responsible for occurrence and progression of prostatic hyperplasia or tumour. Due to the ability of tumours to suppress the cognate T cell immune response, the cells of innate immunity (NKT and Tregs) may be playing a key role in the immunopathogenesis of PC and BPH.

The liposome-incorporating cell wall skeleton of Mycobacterium bovis bacillus Calmette-Guéin can directly enhance the susceptibility of cancer cells to lymphokine-activated killer cells through up-regulation of natural-killer group 2, member D ligands

OBJECTIVE

• To conduct a preclinical evaluation of the ability of natural killer cells to cytolyze bladder cancer cells that were modified to show enhanced expression of natural-killer group 2, member D (NKG2D) ligands by R8-liposome-bacillus Calmette-Guéin (BCG)-cell wall skeleton (CWS) treatment.

MATERIALS AND METHODS

• The T24 cells and RT-112 cells were co-cultured with R8-liposome-BCG-CWS and BCG for 2, 4, or 6 h, and then the surface expression of NKG2D ligands was analyzed using TaqMan real-time quantitative RT-PCR. • Peripheral blood mononuclear cells were obtained with a conventional preparation kit, and then lymphokine-activated killer (LAK) cells were generated from these purified peripheral blood mononuclear cells via interleukin-2 stimulation. • The anti-tumour effect of LAK cells against untreated and R8-liposome-BCG-CWS co-cultured with cells of the human bladder cancer cell lines T24 and RT-112 was analyzed using the cytotoxic WST-8 assay method at 4 h of culture at various effector/target (E : T) ratios.

RESULTS

• Major histocompatibility complex class I-related chain B (MICB) expression was increased ≈1.5-fold on T24 cells and RT-112 cells with BCG. • UL-16-binding protein (ULBP) 1 expression was also increased ≈1.5-fold on T24 cells and RT-112 cells with BCG. R8-liposome-BCG-CWS increased the surface expression of MICB 2.2-fold on T24 cells but did not increase it significantly on RT-112 cells. • ULBP1 expression was increased ≈2.2-fold on RT-112 cells, although no differences were observed between the expression of ULBP2 and 3 with R8-liposome-BCG-CWS. • T24 cells that were co-cultured with R8-liposome-BCG-CWS showed an ≈1.3-fold increase in sensitivity to cytolysis by LAK cells at an E : T ratio of 4 and RT-112 cells showed an ≈1.4-fold increase at an E : T ratio of 2.

CONCLUSIONS

• In the present study, the induction of surface NKG2D ligands by R8-liposome-BCG-CWS rendered cancer cells more susceptible to cytolysis by LAK cells. • T24 cells and RT-112 cells, even when cultured singly in the absence of immune cells, can directly respond to R8-liposome-BCG-CWS. • The results obtained in the present study may therefore indicate a novel adoptive immunotherapy against bladder cancers.

Differential CTLs specific for prostate-specific antigen in healthy donors and patients with prostate cancer

Induction of CTL responses specific for prostate-specific antigen (PSA)-derived peptides in healthy individuals and patients with prostate cancer (PC) was investigated. Eight PSA-derived peptides that have the potential to bind HLA-A2 molecules were examined. Peripheral blood lymphocytes isolated from HLA-A2-positive volunteers were expanded using autologous mature, PSA-derived peptide-pulsed dendritic cells. The expansion of IFN-gamma-secreting CD8+ T cells specific for three of the eight PSA-derived peptides (PSA-2(108-117), PSA-4(141-150) and PSA-6(146-154)) was detected in healthy individuals, but not in patients with PC. Using HLA-A2/peptide tetramers, the PSA-specific CD8+ T cells were detectable at low frequency both in healthy individuals and patients with PC. Using flow cytometric cytotoxicity assays, the expanded effectors from healthy individuals were able to kill the PSA-expressing epithelial cell line LNCaP and the peptide-pulsed T2 cells in a MHC class I-restricted manner without involving NK activity. However, such killing by effectors expanded from prostatectomized patients involved a complete or a significant NK activity. Specific recognition of PSA-derived peptides in healthy individuals may occur by an adaptive CTL immune response, while such recognition in PC patients may additionally or alternatively be mediated by an innate NK immune response. In conclusion, our work indicates that the PSA-specific CD8+ T cells exist in both healthy individuals and PC patients, but they have impaired function in patients as they failed to release IFN-gamma and to kill targets without involving NK activity.

A Wilms tumor cell line, HFWT, can greatly stimulate proliferation of CD56+ human natural killer cells and their novel precursors in blood mononuclear cells

OBJECTIVE

A Wilms tumor cell line, HFWT, selectively stimulates expansion of natural killer (NK) cells from human peripheral blood mononuclear cells (PBMC). In this study, we attempted to identify NK precursors in PBMC or in cord blood mononuclear cells (CBMC) that preferentially respond to feeder HFWT cells.

MATERIALS AND METHODS

Human NK cells or candidate precursor cells were fractionated from PBMC or CBMC by magnetic antibody cell sorting or by flow cytometry and applied to limiting dilution analysis to determine the proportion of NK/NK precursor cells, which are able to proliferate on irradiated HFWT cells. NK and NK precursor cells were cultured in medium containing interleukin-2 (IL-2). Expansion of NK cells from both resting NK cells and NK precursor cells was examined using proliferation from single cells, expression of NK cell markers, and cytotoxic activity.

RESULTS

In the limiting dilution analysis, NK cells expanded on irradiated HFWT cells not only from CD3-CD56bright and CD3-CD56dim NK cells, but also from CD16+/-CD122+ cells in the lineage-negative (Lin-, CD3-CD14-CD19-CD56-) cell fraction. The feeder HFWT cells stimulated Lin-CD122+ cell proliferation more strongly than feeder cells from the well-known human NK target cell line K562. CBMC contained significantly higher percentages of Lin-CD122+ cells than PBMC.

CONCLUSION

CD3-CD14-CD19-CD56- cells expressing CD122+ (a subunit of the IL-2 receptor) preferentially respond to HFWT feeder cells and are novel precursors of CD3-CD56+ NK cells in human PBMC and CBMC.