Characterization of natural cytotoxic effector cells isolated from rat liver

Nonparenchymal liver cells (NPC) from normal untreated female Wistar/Furth rats were tested for natural cytotoxicity in a 4-hour 51Cr release assay against the murine lymphoma YAC-1, the murine mastocytoma P815, and the syngeneic rat mammary carcinoma TMT-081 tumor cell lines. NPC exerted strong cytotoxicity against all three target cells. In contrast, fresh spleen cells displayed cytotoxicity only against YAC-1, although after culture for 24 h at 37 degrees C cytotoxicity was displayed against all three target cells. Fresh spleen cells contained 2-15% large granular lymphocytes (LGL) as assessed by Giemsa staining whereas NPC contained 10-23% LGL and 10-25% Kupffer cells. Centrifugal elutriation produced fractions that were increased in one or the other of the cell types. More cytotoxic activity was observed in the fraction containing more LGL. The cytolytic activity of fresh spleen cells could be eliminated by either in vivo or in vitro treatment with anti-asialo-GM1 antiserum. On the other hand, the cytolytic activity of NPC was resistant to in vivo treatment, but was partially sensitive to in vitro treatment. Furthermore, the activity of cultured spleen cells was also partially sensitive to in vitro treatment. NPC and cultured spleen cells also were more resistant to suppression by prostaglandin E2 and nordihydroguaiaretic acid than fresh spleen cells. We conclude that LGL is mainly responsible for natural cytotoxicity of NPC and that some effector cells in NPC may be highly activated.     

Generation of cytotoxic effector cells against human melanoma

Metastatic or tumor-draining lymph nodes from six of nine melanoma patients undergoing lymph node dissection for metastatic melanoma generated cytotoxic T cells against autologous melanoma when these lymph node cells were treated by in vitro sensitization and recombinant interleukin-2 (IL-2). During the initial lymphocyte culture (2–6 weeks), cross-reactivity with autologous tumor cells, K562 and Daudi cells was usually noted. Cold-target inhibition assay with K562 and Daudi showed K562/Daudi-associated antigens on melanoma cells. During the later phase of lymphocyte culture with repeated in vitro sensitization (over 6–10 weeks), cytotoxicity was noted against autologous and allogeneic melanoma cells but not against K562, Daudi cells or autologous fibroblasts. Repeated in vitro sensitization resulted in the selection of specific cytotoxic lymphocytes against melanoma. Cold-target inhibition assay with autologous and allogeneic melanoma cells revealed shared and individual antigens. Using blocking monoclonal antibodies, MHC-restricted killing was noted in the autologous system. Further, both the autologous and allogeneic systems could be mediated through adhesion molecules such as ICAM-1 and LFA-3 on melanoma cells and LFA-1 on T cells. This study suggests that a constellation of cytotoxic effector cells and melanoma-associated antigens may be pivotal in tumor killing. Thus, future adoptive immunotherapy should modulate and enhance this complex interaction.This work was supported by an Elsa, U. Pardee Foundation grant, the Arizona Chronic Disease Research Commission grant and partly by grant CA23074 from the National Institutes of Health, Bethesda, MD, 20892     

Cell-mediated amplification and down regulation of cytotoxic immune response against autologous human cancer

The cytotoxic host immune response toward autologous human cancer may be regulated by the immunoregulatory network. Here we show that helper T cells, cloned from peripheral blood lymphocytes that were sensitized in vitro against an autologous human malignant paraganglioma, proliferated against and made interleukin 2 when cocultured with the tumor-associated antigen in the presence of autologous accessory cells. Furthermore, the helper cell clones amplified cytotoxic immune response by peripheral blood lymphocytes against the paraganglioma cells in coculture with the blood lymphocytes and the paraganglioma cells. An autologous T cell line bearing suppressor phenotype, established from a lymph node that had been infiltrated with the paraganglioma tumor cells, in contrast to the helper cells, selectively suppressed the cytotoxic immune response by the blood lymphocytes against the paraganglioma cells in identical coculture. These results, therefore, demonstrate the existence of cell-mediated immunologic regulations of the cytotoxic immune response (concurrent amplification and suppression in the same host) against an autologous human tumor.     

Suppressor cells in the effector phase of autologous cytotoxic reactions in cancer patients

Summary Cytotoxicity was induced in lymphocytes (CL) from 10 out of 15 patients by autologous mixed lymphocyte tumor cell culture and further cultivation with recombinant interleukin-2. In cells from 3 of the 10 patients, cytotoxicity was suppressed by more than 50% when autologous peripheral blood mononuclear cells (PBMC) from the patients with large tumors were added to the autologous killing system. The cells responsible for suppressing the cytotoxicity in the effector phase were adherent or nonadherent to plastic depending on the patient examined. The T cell fraction from 1 patient significantly suppressed the cytotoxic activity, and this suppression was seen only in the autologous system. On the other hand, plastic adherent cells but not T cells from PBMC of 2 subjects suppressed the cytotoxic activity of CL. The reason why the main cell population suppressing the CL activity differed among the patients is unclear. However, the findings that the suppression was mostly abrogated following resection of the tumor mass suggested that suppressor cells, either of macrophage lineage or T cells, are induced in patients with a large tumor mass. This speculation is supported by the finding that the PBMC from a patient with tumor recurrence regained the suppressive activity.     

Sensitivity of ovarian tumor cells to effector cells generated by various biological response modifiers

The sensitivity of freshly derived human ovarian tumors (FOT) to various allogeneic cytotoxic effector cells stimulated by recombinant interleukin 2 (rIL-2), recombinant interferon alpha 2 (rIFN-alpha 2), OK-432, and concanavalin A was examined using the 51Cr release assay. Peripheral blood lymphocytes (PBL) of normal female donors were used as source of effector cells. Incubation of PBL with these biological response modifiers for 24 h generated effector cells with high natural killer activity, and only 20% (1/5) of the FOT examined were susceptible to lysis. By contrast, 83% (5/6) of the FOT were sensitive to lymphokine-activated killer (LAK) cells generated by rIL-2. OK-432 and concanavalin A activation of PBL also generated cytotoxic cells, though the cytotoxic activity against FOT was much less than that obtained by LAK cells. The addition of OK-432 to LAK culture medium containing rIL-2 generated effector cells with higher cytotoxicity against FOT than cultures with IL-2 alone. However, the addition of rIFN-alpha 2 in LAK culture medium resulted in the generation of effector cells with lower cytotoxicity. The addition of rIL-2, rIFN-alpha 2, or OK-432 to LAK cells during the in vitro cytotoxicity assay had no significant effect. When FOT target cells were pretreated with OK-432 they became more sensitive to LAK than nontreated tumor cells. However, pretreatment with rIL-2 or rIFN-alpha 2 did not influence cytolysis. These results suggest that the generation of LAK cells in vitro using rIL-2 plus OK-432 may be a more effective way to prepare these cells for adoptive immunotherapy in the treatment of ovarian cancer.     

Proliferative response of lymphocytes from ovarian cancer patients to autologous tumor cells

Summary Peripheral blood lymphocytes (PBL) from 43 patients with histologically confirmed ovarian carcinoma were stimulated in mixed lymphocyte-tumor culture (MLTC) with purified autologous tumor cells. Positive results, assessed as lymphocyte proliferation, were observed in 21 cases (48.8%). Lymphoid cells associated with ascitic fluid or infiltrating solid masses were in general less reactive than PBL as only 3/11 cases had positive MLTC. Tumor cells isolated from peritoneal effusions showed no significant difference in stimulatory potential as compared to the primary tumor. These results suggest that in an appreciable proportion of ovarian carcinoma patients (approximately 50%), lymphocytes have the potential to react to autologous tumor cells. Comprehension of the immunological mechanisms of antitumor resistance may have direct practical relevance for more effective treatment of neoplasms.     

Expression and release of HLA-E by melanoma cells and melanocytes: potential impact on the response of cytotoxic effector cells

HLA-E are nonclassical MHC molecules with poorly characterized tissue distribution and functions. Because of their capacity to bind the inhibitory receptor, CD94/NKG2A, expressed by NK cells and CTL, HLA-E molecules might play an important role in immunomodulation. In particular, expression of HLA-E might favor tumor cell escape from CTL and NK immunosurveillance. To address the potential role of HLA-E in melanoma immunobiology, we assessed the expression of these molecules ex vivo in human melanoma biopsies and in melanoma and melanocyte cell lines. Melanoma cell lines expressed no or low surface, but significant intracellular levels of HLA-E. We also report for the first time that some of them produced a soluble form of this molecule. IFN-gamma significantly increased the surface expression of HLA-E and the shedding of soluble HLA-E by these cells, in a metalloproteinase-dependent fashion. In contrast, melanocyte cell lines constitutively expressed HLA-E molecules that were detectable both at the cell surface and in the soluble form, at levels that were poorly affected by IFN-gamma treatment. On tumor sections, a majority of tumor cells of primary, but a low proportion of metastatic melanomas (30-70 and 10-20%, respectively), expressed HLA-E. Finally, HLA-E expression at the cell surface of melanoma cells decreased their susceptibility to CTL lysis. These data demonstrate that HLA-E expression and shedding are normal features of melanocytes, which are conserved in melanoma cells of primary tumors, but become dependent on IFN-gamma induction after metastasis. The biological significance of these findings warrants further investigation.     

Primary culture of ovarian surface epithelial cells and ascites-derived ovarian cancer cells from patients

Our laboratory has refined the technique for isolating primary cultures of normal human ovarian surface epithelial (OSE) cells by combining two different protocols involving the enzymatic and mechanical removal of OSE cells from ovarian biopsies. A simple protocol of obtaining primary epithelial ovarian cancer (EOC) cells from the ascites fluid removed from patients with high-grade ovarian cancer is also described. These methods allow for the direct application of many molecular and cellular analyses of normal versus cancer cells isolated freshly from patients, with the added potential for retrospective analyses of archived cells and tissues. Thus, we have included optional steps for the immediate preparation of ascites-derived EOC cells to be used for subsequent cytological analyses. Initial isolation of OSE or EOC cells can be completed in 1 h, and primary cells are further expanded in culture for several weeks.     

Activity of antibodies recovered from immune complexes of ovarian cancer patients

Summary Ascites fluids from ovarian cancer patients contain immune complexes (IC). Attempts were made to characterize those antigens to which the patient is reacting using antibody recovered from these complexes. Polyethylene glycol (PEG) precipitation and protein A Sepharose 4B affinity chromatography were used to isolate IC. Dissociation of the IC was achieved by G-150 gel filtration in 0.1 M acetic acid, 0.15 M NaCl. Activity of antibody preparations was measured using a binding assay with ¹²⁵I-labeled staphylococcal protein A. Confluent monolayers of various cell lines (including human ovarian and cervical carcinoma lines, human lymphoblastoid cell lines, human and chick embryo fibroblasts) were used. Six of nine antibody preparations isolated from ovarian cancer patient IC contained at least some reactivity against all cell types.Specificity was further defined using cell adsorption assays and polyacrylamide gel electrophoresis. These results indicate what appears to be autoreactivity directed against a normal component(s) of many cells. No evidence for an ovarian cancer-restricted response was shown. Immunoprecipitation analyses showed several polypeptide bands on autoradiograms (49K, 46K, 33K, 25K), which deviated distinctly from the pattern obtained for whole cell extracts.     

Enhanced effector function of cytotoxic cells in the induced sputum of COPD patients

Background

We have previously shown that NK (CD56⁺CD3^-) and NKT-like (CD56⁺CD3⁺) cells are reduced in both numbers and cytotoxicity in peripheral blood. The aim of the present study was to investigate their numbers and function within induced sputum.

Methods

Induced sputum cell numbers and intracellular granzyme B and perforin were analysed by flow cytometry. Immunomagnetically selected CD56⁺ cells (NK and NKT-like cells) were used in an LDH release assay to determine cytotoxicity.

Results

The proportion of NK cells and NKT-like cells in smokers with COPD (COPD subjects) was significantly higher (12.7% and 3%, respectively) than in healthy smokers (smokers) (5.7%, p < 0.01; 1%, p < 0.001) and non-smoking healthy subjects (HNS) (4.2%, p < 0.001; 0.8%, p < 0.01). The proportions of NK cells and NKT-like cells expressing both perforin and granzyme B were also significantly higher in COPD subjects compared to smokers and HNS. CD56⁺ cells from COPD subjects were significantly more cytotoxic (1414 biological lytic activity) than those from smokers (142.5; p < 0.01) and HNS (3.8; p < 0.001) and were inversely correlated to FEV₁. (r = -0.75; p = 0.0098).

Conclusion

We have shown an increased proportion of NK and NKT-like cells in the induced sputum of COPD subjects and have demonstrated that these cells are significantly more cytotoxic in COPD subjects than smokers and HNS.     

Multidimensional flow-cytometric analysis of dendritic cells in peripheral blood of normal donors and cancer patients

 We studied the potential of multidimensional flow cytometry to evaluate the frequency and maturation/activation status of dendritic cells in minimally manipulated peripheral blood mononuclear cell preparations (i.e., only separated on Ficoll-Hypaque) of normal donors and cancer patients. A rare subset of HLA-DR⁺ leukocytes (less than 1% mononuclear cells) was detected in blood of normal donors that displayed all the features of dendritic cells: these cells had high forward-light-scatter characteristics and coexpressed CD4, CD86 and CD54 surface antigens, but lacked the lineage-associated surface markers of T cells, B cells, monocytes, granulocytes or NK i.e. they were CD3^–, CD19^–, CD20^–, CD14^–, CD11b^–, CD16^–, CD56^–). These physical and phenotypic properties were virtually identical to those of immunomagnetically sorted leukocytes characterized as dendritic-cells on the basis of morphology, phenotype and high stimulatory activity in allogeneic mixed-lymphocyte cultures. Using this flow-cytometric approach we observed that the frequency of dendritic cell-like cells in peripheral blood mononuclear cell specimens of cancer patients receiving chemotherapy alone or those recovering from stem cell transplantation was significantly lower than that of normal individuals (mean ± SE: 0.36 ± 0.05%, 0.14 ± 0.06%, and 0.75 ± 0.04% respectively). Multidimensional flow-cytometric analysis of dendritic cells might represent an important new tool for assessing immunocompetence, and for monitoring the effects of therapeutic regimens on the immune system. Received: 20 June 1997 / Accepted: 14 August 1997     

Impaired proliferative response of V alpha 24 NKT cells from cancer patients against alpha-galactosylceramide

Human invariant V alpha 24(+) NKT cells are a relatively new subpopulation of lymphocytes. It has been reported that V alpha 24 NKT cells are significantly involved in some human diseases. We have evaluated the number and function of V alpha 24 NKT cells in both healthy volunteers and cancer patients. In this study we found that V alpha 24 NKT cells in unfractionated PBMCs obtained from cancer patients did not respond efficiently to alpha-galactosylceramide (alpha-GalCer) in vitro. Thus, their proportion after stimulation with alpha-GalCer was smaller than that found in healthy volunteers. However, the cancer patients' V alpha 24 NKT cells retained cytotoxic activity against malignant target cells, and they could efficiently proliferate to alpha-GalCer when fractionated by sorting. Furthermore, we found that addition of G-CSF to the culture could restore the low proliferative response of V alpha 24 NKT cells from cancer patients. These results suggest that some functions of NKT cells in cancer patients are impaired, and this observation carries significant implications for immunotherapy-based cancer treatments.     

Differential behavior of cytotoxic effector cells against HLA antigens in strong genetic linkage disequilibrium

Five sets of cytotoxic effector cells were generated, using haploidentical, first degree relatives in five different families, against the HLA-A3; B7 serological determinants combined with different DR antigens. When tested against a panel of cells bearing combinations of the HLA-A, -B and -DR antigens it was shown that the HLA-B7 antigen was as strong a CML target determinant alone as it was in the presence of HLA-A3. The strength of the HLA-A3 antigen as target determinant varied. With effector cells primed to the HLA-A3; B7; DR2 haplotype, the A3 antigen alone behaved as a weak target determinant. When the same target cells were tested with the effector cells generated against HLA-A3; B7 without DR2, the A3 antigen behaved as a strong target determinant. A number of target cells lacking the serologically detectable HLA determinants present on the sensitizing HLA haplotype were identified as being killed by specific effector cells. These data suggest either a number of new CML target determinants controlled by different loci or the presence of a single, new locus with multiple alleles controlling CML targets.     

T cells from naive mice suppress the in vitro cytotoxic response against endogenous Gross virus-induced tumor cells

Syngeneic normal lymphoid cells added in co-culture of immune lymphocytes and tumor cells reveal a suppressive activity inhibiting the generation of cytolytic T lymphocytes. The suppression was specific for the response directed against endogenous virus-induced or x-ray-induced tumor cells expressing endogenous C type virus antigens. Thymocytes, spleen cells, or lymph node cells from naive mice were able to express this suppressive activity. The same cells displayed no suppressive activity on killer cells directed against exogenous C type virus-induced tumor cells. The suppressor cells were Thy-1+, Lyt-1- 2+. Our results strongly suggested that the spontaneous suppressor cells exert their activity by interacting with an early step on the CTL response, probably at the level of the helper T cell function. The suppressive activity was mediated by soluble factor(s) that were antigen specific and possibly H-2 restricted. The possible implications of these spontaneous suppressor T lymphocytes in the development of endogenous virus-induced tumors and their possible implications in tolerance to self antigens are discussed.     

Characterization of rat preadipocytes from normal rat adipose tissue by their effector response.

We isolated from normal rat adipose tissue, by a Percoll-density-gradient procedure, two populations of adipocyte precursors. These preadipocytes undergo morphological and biochemical adipose conversion in primary culture. For full adipose conversion, these precursor cells, in addition to the adipogenic factor present in fetal-calf serum, require other effectors differentially. One population completes terminal differentiation in the presence of physiological concentrations of insulin. The second population requires a pre-sensitization with isobutylmethylxanthine at a critical period of the culture in order to respond to insulin. The fact that dibutyryl cyclic AMP could not be substituted for isobutylmethylxanthine suggests that the effect of the latter agent is not through its inhibition of particulate phosphodiesterase activity. These two populations further differ in their response to exogenously added haemin. Thus the existence of at least two developmentally regulated rat adipose-precursor compartments is demonstrated.     

T helper cells in immune mice amplify the primary anti-tumor cytotoxic response

In this report we examine the influence of splenic helper cells in the primary cytotoxic T lymphocyte (CTL) response against syngeneic murine leukemia virus-(MuLV) induced tumor cells. We identify an Lyt-1+ 800 R radiation-resistant helper T cell that will amplify the in vitro generation of CTL against syngeneic tumor cells from nonimmune spleen cells.