Peripheral blood natural killer cell activity in human breast cancer patients and its modulation by T-cell growth factor and autologous plasma

Serum Levels of Interleukin-18 and sICAM-1 in Patients Affected by Breast Cancer: Preliminary Considerations

Interleukin-18 (IL-18), a cytokine that plays an important role in the T-cell-helper type 1 response, acts as an angiogenesis and tumor suppressor. Intercellular adhesion molecule-1 (ICAM-1) has a potential role in immunoregulation by mediating immune cell infiltration into the tissue. The aim of this study was to evaluate IL-18 and soluble (s) ICAM-1 serum levels in breast cancer (BCa) patients with liver (BCaM1h) or bone (BCaM1b) metastases compared to BCa patients without metastases (BCaM0) and healthy donors (HDs). Furthermore, since IL-18 enhances ICAM-1 expression, we investigated whether there was a direct correlation between sICAM-1 and IL-18 serum levels. Serum IL-18 and sICAM-1 levels were assayed by immunoenzymatic methods. The serum sICAM-1 levels in the three groups of cancer patients were significantly higher (p<0.05) than those of HDs. Serum IL-18 levels were significantly higher (p<0.05) in BCaM1h and BCaM1b patients compared to BCaM0 patients and HDs. sICAM-1 proved to be closely correlated with serum IL-18 levels in HDs, whereas a weaker correlation was found in BCaM1h, BCaM1b and BCaM0 patients. The defective correlation between sICAM-1 and IL-18 found in cancer patients may contribute to our understanding of the immunity upset occurring in cancer. Our data suggest that IL-18, irrespective of its biological activity, could represent a marker for metastatic breast cancer.

Association of NK cell dysfunction with changes in LDH characteristics of peripheral blood lymphocytes (PBL) in breast cancer patients

The cytotoxic activity of NK (natural killer) cells is very important in immunological surveillance against the appearance and especially the spread of malignant disease. The aim of this study was to investigate the function of this subpopulation of cells in breast cancer patients in different clinical stages of disease prior to therapy. NK cell activity was determined in breast cancer patients and healthy controls by three different methods: standard 51-chromium-release assay and by the original colorimetric uncorrected and corrected lactate dehydrogenase (LDH) release assay. A discrepancy was shown between the assays, as the uncorrected LDH assay showed, not only, much higher values, but no stage-dependent depression in NK cell activity compared to the chromium-release assay. Further analyses of separately cultured peripheral blood lymphocytes (PBL) revealed that this difference arose from an increasing, clinical stage-dependent, spontaneous LDH release from PBL of breast cancer patients. Furthermore, a stage-dependent increase in intracellular LDH activity of PBL was found, although without difference in LDH-H and LDH-M isotype ratio, compared to controls. Increased spontaneous LDH release and intracellular LDH activity was more evident in young patients, under 40 years. Correction of the original LDH-release assay for the spontaneous LDH release activity from PBL present in the assay, gave values of NK cell activity comparable to those determined by the chromium assay and indicated that breast cancer patients have a significant depression in NK cell activity which correlates with the stage-dependent increase in spontaneous LDH release. Moreover, as both assays measure the secretory, perforin-mediated, NK cell cytotoxic pathway against tumor cells, it can be concluded that the appearance of spontaneous LDH release is an indicator of cell membrane damage which not only allows the loss of LDH, but also of the components of the secretory killing pathway, resulting in NK cell dysfunction with the progression of disease. The novel findings obtained in this work reveal the association of PBL membrane damage with clinical stage of breast cancer that can, aside from reflecting NK cell depression, underlie the defect in other PBL subsets and subsequently facilitate progression of the malignant process.

Interleukin-2-inducible natural immune (lymphokine-activated killer cell) responses as a functional correlate of progression to AIDS

The functions of natural killer (NK) cells and their interleukin-2-deducible counterparts, lymphokine-activated killer (LAK) cells, are often impaired in human immunodeficiency virus (HIV)-infected individuals. A statistical approach was used to establish if changes in LAK activity were associated with antiviral drug therapy, HIV-1 burden, or lymphocyte subset alterations. Our study group included 61 HIV-positive subjects without any opportunistic infections (OI-), 16 of whom received zidovudine (AZT), and 97 HIV-positive individuals with AIDS-related infection (OI+), 50 of whom received AZT. As expected, there was a stepwise decrease in total lymphocyte numbers in OI+ groups as a result of the selective loss of CD4+ cells. The groups receiving AZT therapy had fewer CD4+ cells but lower circulating p24 antigen levels than corresponding untreated groups did. No significant changes in the relative proportions or absolute numbers of CD56+ subsets in HIV-positive groups could be ascribed to OI status or AZT intervention. LAK cell cytotoxic responses, measured as LU20 values (which give a measure of 20% cytolysis of target cells), lysis per unit CD56+ NK cell, or lysis per unit blood volume, declined in OI+ groups. No main or interactive effects of AZT therapy on LAK activities were observed. Multivariate general linear models were used to determine the interactive effects of NK- and T-cell subsets on measured LAK cell numbers were added negative and positive predictors of LAK activity, respectively. These findings indicate that declines in NK-mediated LAK cell responses serve as functional correlates of progression in HIV-infected individuals.

Changes in natural immunity during the course of HIV-1 infection

The role of natural killer (NK) and lymphokine-activated killer (LAK) cell-mediated cytotoxicity in AIDS has yet to be established. The objective of this study was to determine inducible LAK cell responses at different stages of HIV-1 infection, and specifically to establish the participation of CD8 lymphocytes in these responses. Peripheral blood lymphocytes (PBL) were isolated from healthy seronegative (CDC-0) subjects and HIV-1+ individuals who were clinically asymptomatic (Centre for Disease Control group 2, CDC-2) or symptomatic (CDC-4) with regard to secondary opportunistic infection (OI). LAK cells were generated upon incubation of PBL with IL-2 and their cytolysis of K562 and U-937 targets was determined using chromium release assays. The role of CD8+ lymphocytes as progenitors and effectors of these LAK cell responses was determined by immunomagnetic depletion of CD8+ cells from precursor PBL and LAK cells, respectively. LAK cell-mediated cytotoxicities in HIV-1-infected individuals were reduced compared with seronegative controls without any corresponding changes in the relative proportions of CD56+ (NK) cells among groups. Depletions of CD8+ subsets from either PBL or LAK cells dramatically reduced total LAK cytotoxic responses and LAK activities per unit CD56+ cell in the OI-/CDC-2 seropositive population. No corresponding changes in LAK activities in seronegative control or HIV+/OI+/CDC-4 groups were observed. Levels of LAK activity against K562 targets in CDC-0/HIV- and CDC-4/HIV+ groups correlated with the percentage of CD56+ LAK cells; corresponding LAK activity in the CDC-2/HIV+ group correlated with the percentage of both CD56+ and CD8+ subsets. These findings suggest that adaptive changes in non-MHC restricted cytotoxic responses occur in HIV-1 individuals at early stages post-HIV infection, before the onset of opportunistic infection.

Increased LAK activity against HIV-infected cell lines in HIV-1+ individuals

The role of natural killer (NK) cells and their inducible counterparts, lymphokine-activated killer (LAK) cells in AIDS with regard to HIV-1 viral immunosurveillance and the control of secondary opportunistic disease has yet to be established. In this study, we have demonstrated that LAK cells derived from all HIV-1+ groups showed striking increases in their capacity to lyse HIV-1-infected U-937 cells relative to their uninfected U-937 counterparts. Surprisingly, similarly derived LAK cells from healthy seronegative controls showed no differences in their lysis of HIV-1-infected versus uninfected U-937 cells. The differential ability of LAK effectors from seropositive donors to lyse HIV-1-infected targets was demonstrable using a number of U-937 subclones and their HIV-1-infected counterparts. Again, no differences in LAK cell-mediated lysis of HIV-1-infected and uninfected U-937 subclones were observed in seronegative individuals. Our findings that HIV-1+ individuals show selective expansion of non-MHC restricted, HIV-1-directed cytotoxic LAK cells indicate that natural immunity may indeed play a role in HIV-1 viral immunosurveillance.

Natural killer cell tumoricidal activity in cigarette smokers and in silicotics

Cigarette smoking and asbestos exposure have been reported to alter the tumor-killing activity of blood natural killer (NK) cells. However, NK cell function in relation to silica dust exposure has not been examined. We studied blood NK cell number, percentage, and tumoricidal activity in 120 hardrock miners, 57 of whom had radiographic evidence of silicosis, and in 33 community controls. There was a significant increase in leukocyte count and lymphocyte count in current smokers compared with former and never smokers, but these cell counts were normal in silicotics and those with silica dust exposure. No significant differences in NK cell (CD16+) number or percentage were found by flow cytometric analysis of smoking or dust exposure groups. Surprisingly, NK tumoricidal activity was significantly higher in cigarette smokers compared with former smokers and never smoker control subjects. Although tumoricidal activity was elevated in silicotics, this was accounted for by their cigarette smoking. These results suggest that cigarette smoking is associated with elevation of blood NK cell tumoricidal activity on a per cell basis, in the absence of any alteration in the absolute number of NK cells in blood.

The relationship of chemotherapeutic and endocrine intervention on natural killer cell activity in human breast cancer

Peripheral blood natural killer (NK) activity against K562 target tumor cells was monitored in patients with breast cancer receiving no treatment, combination chemotherapy, and/or endocrine therapy. NK activity in untreated Stage I patients with no evidence of disease (ned) was significantly higher than in healthy controls. NK activity was shown to decline in individuals with cytotoxic drug therapy (P equals 0.036). There also were reduction in lymphocyte recoveries concomitant with chemotherapeutic intervention (P less than 0.001). Lymphocyte counts were incorporated in a calculation of absolute NK activity that more accurately reflected the significant reduction in NK activity that occurred in patients with localized and systemic disease on chemotherapy. Different chemotherapeutic agents were found to selectively affect NK activity. Stage II patients on phenylalanine mustard (P)/5-fluorouracil (F) (PF) and cyclophosphamide (C)/methotrexate (M)/5-fluorouracil (F) (CMF) protocols showed significant reductions in overall NK activity relative to healthy controls and Stage I patients with ned. Patients on P/doxorubicin (A)/F/tamoxifen (Tx) (PAFT) protocols showed reduced NK activity relative to Stage I patients. Patients on the short-dose C/A (CA) protocol showed normal levels of overall NK activity. High-risk Stage I patients on methotrexate (M)/F (MF)with sequential leucovorin rescue and patients with metastatic disease on endocrine therapy, i.e., Tx or megestrol acetate (Meg) showed overall NK activities in the range of healthy controls. Patients with systemic disease on CMF, CMF/vincristine/prednisone (CMFVP), vinblastine/A/thiotepa/fluoxymesterone (VATH), mitomycin/mitoxantrone (MtMx), and A regimens showed overall levels of absolute NK that were significantly less than either healthy controls or metastatic patients undergoing endocrine therapy. NK cytolytic data, monitored at multiple effector to target ratios, were subjected to exponential regression analysis. The elevation of NK cell responses in Stage I patients with ned and the decline of NK cell responses with cytotoxic chemotherapy were due to alterations in the maximal plateau levels of NK cell cytotoxicity represented by the A (asymptote) values. The k values obtained on regression analysis and indices of the relative killing capacities of individual NK cells remained unaltered in all populations. These results suggest that the cytolytic lymphocyte NK pool, elevated in Stage I patients with cancer, selectively declines as a result of cytotoxic therapy.

Sera from patients with colon, breast and lung cancer induce resistance to lysis mediated by NK cytotoxic factors (NKCF)

Natural killer (NK) cells are involved in the antitumoral immunologic mechanism. These cells act through the release of cytotoxic molecules defined as NK cytotoxic factors (NKCF). Inhibitory factors of NK and NKCF mediated lysis have been described in in vitro assays. This study evaluates the induction of resistance to NKCF cytotoxicity by sera from 27 patients with colon, breast and lung cancer. Addition of these sera to the cytolytic assay where K562 cells and concentrated NKCF were used, induced resistance to NKCF mediated cytotoxicity in 21 cases (77%). The sera from the group with metastasis blocked NKCF lysis more markedly than the group with local tumours. However, no differences were observed when the groups with colon, breast and lung cancers were compared. This blocking effect was not found to be related to gamma interferon (IFN) levels. In a previous study, we described a tumour factor (NK-RIF) produced by human cell lines derived from metastatic adenocarcinomas. This factor blocked lysis of tumour target cells by NK cells. Consequently, it is proposed that the release of similar tumour factors with a capacity to induce resistance to NKCF may be involved in tumour growth and metastatic spreading in in vivo.

Natural cytotoxicity and serum blocking in malignant cervical neoplasia

Peripheral blood lymphocytes from 100 patients with various stages and histological types of squamous cell carcinoma of the uterine cervix were assayed for natural killer (NK) cell activity against K562 cells using the single cell cytotoxicity assay in agarose. The effect of autologous serum on NK cell activity and a quantitation of soluble antigen-antibody complexes was also carried out. The cancer patients showed reduced NK activity compared with normal controls, the reduction increasing with tumor load. Another observation was that patients with poorly differentiated tumours showed lower levels of NK activity. Addition of autologous serum resulted in further depression of NK activity in all groups of patients. An increase in circulating immune complexes was also evident in all groups of patients. Here again increase in tumor load and poorly differentiated tumors showed the highest levels. The results point toward a possible disturbance in NK cell activity that could be further depressed by autologous serum factors.

Interleukin-2 induces cytotoxic activity in lymphocytes from regional axillary nodes of breast cancer patients

Natural killer (NK) cells and lymphokine-activated killer (LAK) cells have been involved in immunosurveillance against tumors. A normal NK activity was observed in peripheral blood (PB) mononuclear cells (MNC) from women with breast cancer, but a very low or absent NK cytotoxicity was found in the regional lymph node (RLN) MNC. However, strong cytotoxic activity against NK-resistant and NK-sensitive target cells can be induced in RLN MNC by long-term (5-day) incubation with recombinant interleukin-2 (rIL-2). This cytotoxic inducer effect of rIL-2, not observed with recombinant interferon gamma, was dose and time-dependent and was not associated with modifications in the low number of Leu 11+ or Leu 7+ cells present in the population. Both the lack of NK activity and the generation of rIL-2-activated killer cells can be readily demonstrated in either histologically affected or unaffected RLN. These results stress the value of the immunomodulators inducing cytotoxic activity in RLN MNC of patients with tumors, and are discussed in association with their possible therapeutical role.