Immunological changes in peripheral blood mononuclear cells of patients with metastatic renal cell carcinoma after low doses of subcutaneous immunotherapy with IFN-alpha-2b and IL-2

NK Response Correlates with HIV Decrease in Pegylated IFN-α2a-Treated Antiretroviral Therapy-Suppressed Subjects

We previously reported that pegylated IFN-α2a (Peg-IFN-α2a) added to antiretroviral therapy (ART)-suppressed, HIV-infected subjects resulted in plasma HIV control and integrated HIV DNA decrease. We now evaluated whether innate NK cell activity or PBMC transcriptional profiles were associated with decreases in HIV measures. Human peripheral blood was analyzed prior to Peg-IFN-α2a administration (ART, baseline), after 5 wk of ART+Peg-IFN-α2a, and after 12 wk of Peg-IFN-α2a monotherapy (primary endpoint). After 5 wk of ART+Peg-IFN-α2a, immune subset frequencies were preserved, and induction of IFN-stimulated genes was noted in all subjects except for a subset in which the lack of IFN-stimulated gene induction was associated with increased expression of microRNAs. Viral control during Peg-IFN-α2a monotherapy was associated with 1) higher levels of NK cell activity and IFN-γ-induced protein 10 (IP-10) on ART (preimmunotherapy) and 2) downmodulation of NK cell KIR2DL1 and KIR2DL2/DL3 expression, transcriptional enrichment of expression of genes associated with NK cells in HIV controller subjects, and higher ex vivo IFN-α-induced NK cytotoxicity after 5 wk of ART+Peg-IFN-α2a. Integrated HIV DNA decline after immunotherapy was also associated with gene expression patterns indicative of cell-mediated activation and NK cytotoxicity. Overall, an increase in innate activity and NK cell cytotoxicity were identified as correlates of Peg-IFN-α2a-mediated HIV control.

Natural killer cells: the journey from puzzles in biology to treatment of cancer

Natural Killer (NK) cells are innate immune effectors that are primarily involved in immunosurveillance to spontaneously eliminate malignantly transformed and virally infected cells without prior sensitization. NK cells trigger targeted attack through release of cytotoxic granules, and secrete various cytokines and chemokines to promote subsequent adaptive immune responses. NK cells selectively attack target cells with diminished major histocompatibility complex (MHC) class I expression. This "Missing-self" recognition by NK cells at first puzzled researchers in the early 1990s, and the mystery was solved with the discovery of germ line encoded killer immunoglobulin receptors that recognize MHC-I molecules. This review summarizes the biology of NK cells detailing the phenotypes, receptors and functions; interactions of NK cells with dendritic cells (DCs), macrophages and T cells. Further we discuss the various strategies to modulate NK cell activity and the practice of NK cells in cancer immunotherapy employing NK cell lines, autologous, allogeneic and genetically engineered cell populations.

Changes in Lymphocyte Count Induced by Repeated Cycles with Low-Dose Interleukin-2 and Interferon-α in 146 Patients with Renal Cell Carcinoma

Aims and Background

The exact mechanism by which recombinant interleukine-2 and interferon-a modulate the immunological response, inducing long-term responses in metastatic renal cell carcinoma, is still not clear. The aim of the study was to analyze the modifications in peripheral blood lymphocytes during cycles of low-dose immunotherapy as a marker of the biological response to the treatment in 146 patients with renal cell carcinoma (advanced and localized disease).

Methods and Study Design

Peripheral blood lymphocytes were evaluated before and after every cycle of treatment.

Results

We found a statistically significant overall difference between pre- and post-cycle values (mean increase of 39%). The differences between pre- and post-cycle lymphocyte counts for each cycle were significant. Also, the post-cycle lymphocyte count of each cycle remained higher than the baseline value. Furthermore, pre-cycle lymphocyte counts of each cycle were still higher than the baseline value, with no difference between a pre-cycle lymphocyte mean value and the other one (except that between the first and second cycle). From the end of each cycle, but before starting the next one, the absolute value of lymphocytes fell on the average by 15–30%, concurring with the fact that, even starting from pre-cycle values higher than baseline, the immune system remains sensitive to chronically repeated stimulation by immunotherapy. We also found that non-metastatic patients had a higher number of peripheral blood lymphocytes than metastatic patients, whereas the latter had a lower immune response to therapy.

Conclusions

The results support the idea that “maintenance” immunotherapy may not develop resistance over time in terms of biological response and thus may have a role as chronic therapy in combination with other drugs such as target therapy. We suppose that the immune system of patients with metastases is in a state of relative impairment, resulting in less sensitivity to immunostimulating agents.

Development and application of a multiplexable flow cytometry-based assay to quantify cell-mediated cytolysis

Although target cell cytolysis has been widely employed to describe effector function of cells, cytolysis assays as commonly employed do not generate quantitative data. In this report we describe the development and application of a statistically supported flow cytometry-based assay to quantify cell-mediated cytolysis. The assay depends on the use of the fluorescent dye CFSE to distinguish target from effector cells, the DNA intercalating dye 7AAD to distinguish dead from live cell events, and on the establishment of a cytolysis curve that allows for the derivation of statistically robust data. We demonstrate that the cytolysis curve is well described by a four parameter logistic regression model provided that (i) the range of effector to target (E:T) ratios studied allows for full description of the logistic curve, and (ii) an adequate number of data points are collected to estimate the model parameters. We show that the assay is highly reproducible and accurate, and comparable in sensitivity with the standard (51)Cr assay. We report on the potential for this assay to generate quantitative data on the cytolytic activity of both CD8 T and NK cells; describe a relationship between the efficiency of effector cell degranulation and target cell cytolysis throughout a range of E:T ratios, and demonstrate the potential to multiplex with other platforms to obtain broader datasets for the effector phenotype of cells. Appropriate use of this assay will enhance the ability to derive quantitative and integrated correlative datasets from basic, translational, and clinical studies.

Natural killer cell-based immunotherapy in cancer: current insights and future prospects

As our understanding of the molecular mechanisms governing natural killer (NK) cell activity increases, their potential in cancer immunotherapy is growing increasingly prominent. This review analyses the currently available preclinical and clinical data regarding NK cell-based immunotherapeutic approaches in cancer starting from a historical background and an overview of molecular mechanisms taking part in NK cell responses. The status of NK cells in cancer patients, currently investigated clinical applications such as in vivo modulation of NK cell activity, ex vivo purification/expansion and adoptive transfer as well as future possibilities such as genetic modifications are discussed in detail.

Inhaled IL-2 induces systemic immunomodulation in patients with renal cell carcinoma and lung metastasis

The peripheral blood lymphocytes of eight patients with metastatic renal cell carcinoma, and of eight healthy volunteers were analyzed by four-color flow cytometry to characterize the immunophenotypic alterations manifested, determine the prevalence of lymphocyte apoptosis, and detect evidence of the systemic effect of inhaled IL-2. The T, B and NK lymphocytes of untreated patients were found to have undergone profound changes characterized by an increase in susceptibility to both spontaneous and mitogen-induced ex vivo apoptosis, a modified distribution of the main lymphocyte populations in the peripheral blood, and alterations in activation status. An increase in the proportion of regulatory T cells was also seen in these patients. Treatment with inhaled IL-2, however, normalized the rate of apoptosis in all the lymphocyte subpopulations studied, as well as their distribution and activation status. These findings demonstrate that inhaled IL-2 has systemic immunomodulatory effects.

Interferon-alpha restores HIV-induced alteration of natural killer cell perforin expression in vivo

OBJECTIVE

The percentage and the activity of natural killer (NK) cells are known to be decreased in HIV-infected patients. However, the mechanisms responsible for this NK deficiency are poorly understood. Because of the role of NK cells in the host defence against microbial infections, this defect contributes to the virus-induced immune deficiency. The aim of the present study was to better understand this defect in order to be able to restore NK function in HIV infection.

DESIGN AND METHODS

The expression of the cytolytic mediators perforin and granzyme A was analysed by flow cytometry, the lytic activity of peripheral blood NK cells of HIV-infected patients was analysed by cytotoxic assay, and the expression of perforin was followed during administration of interferon (IFN)alpha attached to polyethylene glycol (PEG)-IFNalpha.

RESULTS

The lytic activity and the expression of perforin and granzyme A was low in NK cells of infected individuals in comparison with normal control volunteers. In both groups NK cytotoxic capacity was linked to perforin expression. The low perforin expression in HIV-infected subjects negatively correlated with HIV RNA plasma level. administration of PEG-IFNalpha restored perforin expression even in patients whose viral load was not reduced by this treatment.

CONCLUSIONS

These results suggest that HIV-induced NK deficiency could be partly mediated by a defect in perforin and granzyme A expression, and that PEG-IFNalpha could be used in infected subjects to directly improve their natural immunity in addition to eventually reducing their viraemia.

Prognostic factors for biologic therapy in kidney cancer

Renal cell cancer is resistant to most forms of therapy. Cytokine therapy with either interleukin-2 or interferon-alpha yields the best results, with response rates from 10% to 20%. Therapy is not without toxicity, which means that the majority of patients treated with cytokines suffer toxicity without any therapeutic benefit. Recent endeavors have tried to find new ways to identify responders to cytokine therapy. Prognostic factors, such as good performance status, lack of anemia, normal calcium, normal lactate dehydrogenase, and prior nephrectomy, correlate with an increased likelihood of responding to cytokine therapy. Recent studies have examined whether altered subpopulations of lymphocytes, the presence of eosinophils, or altered levels of cytokines can predict response to cytokine therapy. Although prior nephrectomy does correlate with improved survival while the patient is receiving cytokine therapy, it is unclear if this is due to a significant alteration in the tumor's response to cytokine or some unrelated benefit from surgery. Further studies are needed to confirm the current immune parameters and disease characteristics that suggest a better response to cytokine therapy.

Different rates of CD4+ and CD8+ T-cell proliferation in interleukin-2-treated human immunodeficiency virus-positive subjects

BACKGROUND

Interleukin-2 (IL-2) has been used successfully to increase CD4 cell counts in patients who are human immunodeficiency virus (HIV) positive. The mechanisms involved in this phenomenon are unknown. We hypothesized that a differential proliferation rate of CD4+ compared with CD8+ lymphocytes could be related to the increase of CD4 counts and of CD4/CD8 ratios that occur in HIV+ patients during IL-2 treatment.

METHODS

We enrolled in our study 14 HIV+ patients treated with IL-2 or with highly active antiretroviral therapy (HAART) during a 96-week observation period. Using flow cytometry, we measured longitudinally the expression of the Ki67 antigen in peripheral blood CD4+ and CD8+ lymphocyte subsets.

RESULTS

Compared with HAART alone, IL-2 produced a rapid increase of Ki67+ proliferating CD4 cells and a concomitant increase of the CD4/CD8 ratios, whereas the corresponding CD8 proliferation increased slightly. On the contrary, HAART alone was effective in suppressing equally both CD4 and CD8 proliferation.

CONCLUSIONS

Our results suggest a selective activity of IL-2 on CD4 T-cell proliferation; on the contrary, CD8-specific proliferation is affected minimally during treatment. This information may offer the potential to plan correctly immune activating regimens.