Lymphokine-activated killer (LAK) cells from human intestinal mucosa: cytotoxic activity against tumor cell lines and modified self but not autologous and allogeneic colon cancer cells

Proinflammatory cytokines differentially modulate their own expression in human intestinal mucosal mesenchymal cells

BACKGROUND & AIMS

Intestinal homeostasis is coordinated through the response of different cell types, including the interaction of immune with nonimmune cells. This study investigated the effect of immune cell-derived proinflammatory cytokines on mesenchymal cell proliferation and gene product expression.

METHODS

Primary cultures of human mucosal mesenchymal cells were activated with interleukin (IL)-1 beta, IL-6, and tumor necrosis factor alpha (TNF-alpha). Proliferation was measured by thymidine incorporation, messenger RNA (mRNA) expression was assessed by Northern blot analysis, and IL-1 receptor type was identified by reverse-transcription polymerase chain reaction.

RESULTS

Mesenchymal cells dose-dependently proliferated in response to IL-1 beta, IL-6, and TNF-alpha. Each cytokine differentially induced mRNA expression in a dose-dependent and selective fashion: IL-1 beta was the most potent inducer, TNF-alpha was weaker, and IL-6 induced little or no mRNA; in contrast, IL-6 mRNA was the most abundantly induced, followed by IL-1 beta mRNA, whereas TNF-alpha mRNA was weakly and infrequently expressed. The IL-1 receptor antagonist inhibited cytokine mRNA expression, and mesenchymal cells expressed the type II, but not the type I, IL-1 receptor.

CONCLUSIONS

The ability of intestinal mesenchymal cells to express proinflammatory gene products implicates them as regulators of local immune cells through immune-nonimmune interactions. Thus, mesenchymal cells should be considered as active regulators of intestinal immunity under normal and inflammatory conditions.

T cell killing of human colon carcinomas by monoclonal-antibody-targeted superantigens

The bacterial superantigen staphylococcal enterotoxin A (SEA) induces T cell activation as well as directing activated T cells to kill major-histocompatibility-complex-class-II-expressing tumours such as freshly prepared leukemia cells. We now report that conjugates of SEA and the colon-carcinoma-reactive mAb C215 mediate T-cell-dependent killing of freshly isolated cells obtained from surgical specimens of human colon carcinomas. Cytotoxicity was observed at nanomolar concentrations of conjugate while no or very low effects were seen with the mAb C215 or SEA alone. Tumour-infiltrating lymphocytes (TIL) did not exert any cytotoxicity against conjugate-treated tumour cells immediately after isolation. In vitro culture of TIL with interleukin-2 and SEA resulted in SEA-mAb-conjugate-dependent killing of freshly isolated tumour cells. This suggests that mAb-SEA conjugates may be of potential use to target T lymphocytes, including TIL, against colon carcinoma cells in vivo.

Substance P increases in vitro lymphokine-activated-killer (LAK) cell cytotoxicity against fresh colorectal cancer cells

Gut-associated lymphoid cells are modulated by several gut hormones. We postulated that lymphokine-associated-killer (LAK) cell cytotoxicity of lymphocytes isolated from the gut mucosa may be increased by substance P (SP). Intestinal lamina propria mononuclear cells (LPMC) and colonic cancer cells were isolated from operative specimens by successive mechanical and enzymatic dissociation methods. Effector LAK cells were induced by culturing LPMC with recombinant interleukin-2 at a concentration of 250 U/ml. Substance P (10(-5) M) was added to the culture medium. Targets consisted of fresh colon cancer cells, HT-29 (cultured human colon cancer cell line), and control cell lines. After 4 days of incubation, cytotoxicity was measured using a 4-h 51Cr release assay. LAK cells alone showed moderate cytotoxicity against HT-29 and none against fresh colon cancer cells. LAK cells generated in the presence of substance P showed moderate cytotoxicity against HT-29 and strong cytotoxicity against fresh colorectal cancer cells. The percentage of cytotoxicity +/- SEM at various effector to target ratios was [(*) denotes P < 0.05 compared with above]: [table: see text] We conclude that substance P significantly increases LAK cell cytotoxicity against fresh colon cancer cells, but not against cultured cells.

Effect of anti-CD3 antibody on the generation of interleukin-2-activated lymphocytes from tumor tissues of gastrointestinal cancer

BACKGROUND

The efficiency of anti-CD3 antibody (OKT3) for adoptive immunotherapy using lymphokine-activated killer (LAK) cells generated from tumor-infiltrating lymphocytes (TIL), regional lymph node lymphocytes (RLNL), and peripheral blood lymphocytes (PBL) was investigated.

METHODS

TIL, RLNL, and PBL derived from 39 patients with gastrointestinal cancers (16 gastric cancers, 17 colorectal cancers, and 6 esophageal cancers) were cultured for 4 weeks with 200 U/ml of recombinant interleukin-2. To one group, solid-phase 10 micrograms/ml OKT3 was added during the initial culture period (day 2 or 4). Cytotoxicity against K562 cells (NK-like activity) and Daudi cells (LAK activity) and the phenotypes of effector cells generated after culturing for 2-3 weeks were studied.

RESULTS

Proliferative responses were significantly increased by OKT3 in each type of effector cell (P less than 0.01); in particular, TIL expanded more by OKT3 than PBL and RLNL (P less than 0.01). The population of CD8+ CD11b- cytotoxic T-cells in OKT3-stimulated groups was significantly larger than that in unstimulated groups (P less than 0.01), whereas no differences were observed with CD4+ cells (helper/inducer T-cells) and CD8+ CD11b+ cells (suppressor T-cells). OKT3 enhanced the NK-like activity of TIL and PBL but did not affect their LAK activity. OKT3 suppressed the NK and LAK activity of RLNL.

CONCLUSIONS

OKT3 stimulation did not significantly enhance the LAK activity, but the authors propose that OKT3 could be an effective addition to adoptive immunotherapy using TIL due to an increased proliferation and generation of a large cytotoxic T-cell population.

Resident research award: tumor necrosis factor alpha selectively enhances growth and cytotoxic activity of tumor infiltrating lymphocytes from human colorectal cancer

Adoptive immunotherapy with tumor-infiltrating lymphocytes (TIL) and interleukin-2 (IL2) can induce regression of tumor metastases in animal models and in human metastatic malignant melanoma. We investigated the potential of colorectal cancer TIL as a source of killer cells and the effect of tumor necrosis factor alpha (TNF alpha) in combination with IL2 on their cytotoxic activity. Tumor-infiltrating lymphocytes were isolated from surgical specimens using a mechanical and enzymatic dissociation process. Autologous lamina propria mononuclear cells (LPMC) were used as control. Tumor-infiltrating lymphocytes and LPMC were cultured in the presence of IL2 with/without TNF alpha (1000 U/ml each) for 5 to 8 weeks. Cytotoxicity (% lysis) was tested against Daudi target cells in a 4-hr 51Cr-release assay. The combination of IL2 and TNF alpha resulted in a significantly greater-fold expansion of TIL than IL2 alone (P less than 0.01). Lamina propria mononuclear cells expanded less than TIL, and TNF alpha had an inhibitory effect on their growth (P less than 0.05). Tumor-infiltrating lymphocytes and LPMC showed comparable cytotoxicity when cultured with IL2 alone. However, the addition of TNF alpha augmented the killer activity of TIL while inhibiting that of LPMC (P = 0.035). These results indicate that TNF alpha selectively increases the IL2-induced growth and cytotoxic function of colorectal cancer TIL, but not those of gut mucosal lymphoid cells, suggesting that TIL and LMPC differ in their response to TNF alpha. Therefore, this combination of cytokines may hold more promise than single agents for the immunotherapy of colorectal cancers with TIL.

Intestinal lymphokine-activated killer cells in inflammatory bowel disease

The role of non-specific cytotoxicity in the pathogenesis of inflammatory bowel disease (IBD) was investigated by assaying the natural killer (NK) and lymphokine-activated killer (LAK) cell activity of lamina propria mononuclear cells (LPMC) from 22 specimens of intestinal mucosa affected by IBD. Only minimal levels of NK activity were detected against K562 cells, as well as colon carcinoma cells, adenoma cells and fibroblasts freshly isolated from the intestinal mucosa. Culture of LPMC from IBD in the presence of interleukin-2 (IL-2) generated LAK cells that mediated high levels of activity against K562 cells and against neoplastic epithelial cells and fibroblasts derived from the intestinal mucosa. A group of 20 histologically normal specimens of intestinal mucosa showed similar levels of LAK activity against the K562 and intestinal cell targets. The minimal mucosal NK activity in IBD suggests that the cytotoxic properties of NK cells are not important in the pathogenesis of IBD. The presence of LAK precursor cells in the inflamed mucosa of IBD and their ability to lyse biologically relevant targets in vitro suggests that LAK cells have the potential to contribute to intestinal mucosal injury in IBD.

Intestinal immune reactivity to interleukin 2 differs among Crohn's disease, ulcerative colitis, and controls

When stimulated by the lymphokine interleukin 2, human intestinal mucosal mononuclear cells mediate lymphokine-activated killer cell activity. When supplied with optimal doses of exogenous interleukin 2, lamina propria mononuclear cells isolated from inflammatory bowel disease and control tissue display comparable levels of cytotoxicity in vitro. However, cultures of Crohn's disease- and ulcerative colitis-derived cells contain significantly decreased interleukin 2 activity, suggesting that in vivo the availability of interleukin 2 may be limited, perhaps resulting in impaired cytotoxic function. To test this hypothesis, lamina propria mononuclear cells from inflammatory bowel disease and control patients were stimulated to produce endogenous interleukin 2, which was then used to induce autologous lymphokine-activated killer cells. When tested against K562 and Daudi target cells, Crohn's disease cells, despite producing only one-third of the amount of interleukin 2 generated by control cells, exhibited comparable levels of cytotoxicity. In contrast, ulcerative colitis cells produced substantially less interleukin 2 and exhibited remarkably low lymphokine-activated killer cell activity. When the same cells were supplied with an amount of human recombinant interleukin 2 equivalent to the average titer found in control cultures, similar results were obtained, and Crohn's disease cells even showed a significantly greater cytolytic activity than controls. These results suggest that the observed differences in lymphokine-activated killer cell activity cannot be attributed to the level of interleukin 2 alone, and that response to this lymphokine is different among Crohn's disease, ulcerative colitis, and control intestine. In Crohn's disease, there is either an increased number of interleukin 2-responsive cells or an exacerbated reactivity to interleukin 2. In ulcerative colitis, a loss of interleukin 2-responsive cells, a hyporesponsiveness to interleukin 2, or both might be present. In conclusion, this study demonstrates that reactivity to interleukin 2 distinguishes inflammatory bowel disease from control intestinal mononuclear cells, and, under appropriate experimental conditions, it can be used to uncover abnormalities of intestinal immunity.

Lymphokines and the intestinal immune response. Role in inflammatory bowel disease

The study of production of and response to various soluble mediators by gut-derived mucosal mononuclear cells has contributed significantly to a better understanding of the regulation of the intestinal immune system. So far, a number of factors have been investigated in some detail or in a preliminary fashion: interleukin 1, interleukin 2, interleukin 4, interferon gamma and colony-stimulatory factors. Their level of activity, and their effect on the intestinal mucosal immune system are discussed, particularly in regard to their potential role in the pathogenesis of inflammatory bowel disease.