Detection of cytotoxicity of freshly obtained lymphocytes and of lymphocytes activated with recombinant interleukin II (rIL-2) against lung cancer cell lines by human tumor clonogenic assay (HTCA)

CD44 stimulation down-regulates Fas expression and Fas-mediated apoptosis of lung cancer cells

Cytotoxic T lymphocytes (CTL) play a major role in the rejection of tumor cells, but tumor rejection does not always occur in vivo, indicating that defects in anti-tumor immune responses may be common. We here document a novel function for CD44--using lung cancer cells, we showed that stimulation of CD44 reduced Fas expression and Fas-mediated apoptosis: (i) lung cancer cells expressed high levels of CD44; (ii) engagement of CD44 on the cells by a specific antibody or fragmented hyaluronan reduced Fas expression; (iii) CD44 cross-linking reduced Fas-mediated apoptosis; (iv) stimulation of CD44 on lung cancer cells decreased IFN-gamma production by autologous CTL; and (v) CD44 stimulation prevented killing of lung cancer cells by autologous CTL. Based on these findings, we postulate a new concept--that interaction of CD44 on lung cancer cells with fragments of extracellular hyaluronan present in the surrounding extracellular matrix reduces Fas expression as well as Fas-mediated apoptosis of cancer cells. This leads to reduced susceptibility of the cells to CTL-mediated cytotoxicity through the Fas-Fas ligand pathway.

Subcutaneous interleukin-2 as initial therapy for patients with extensive small cell lung cancer: a phase II trial of Cancer and Leukemia Group B

In a prior Cancer and Leukemia Group B (CALGB), 16% of a small cohort of patients with extensive small call lung cancer who had failed to obtain a complete remission with chemotherapy did obtain a complete remission after therapy with interleukin-2 (IL-2). In this current trial, 10 patients with extensive small cell lung cancer who had had no prior therapy were treated with subcutaneous IL-2 as induction therapy and then standard chemotherapy with etoposide/cisplatin. Only one patient experienced an objective response to the IL-2 administered prior to chemotherapy. The factors governing response to IL-2 in the first trial but not in this trial are discussed.

Interleukin-2-inducible killer activity and its regulation by blood monocytes from autologous lymphocytes of lung cancer patients

The ability of blood lymphocytes of newly diagnosed lung cancer patients to respond to interleukin 2 (IL-2) to become IL-2-activated killer (LAK) cells and its regulation by autologous monocytes were examined. LAK activity was measured by 51Cr release assay. The abilities of lymphocytes among blood mononuclear cells (MNC) of subjects of different ages without malignancies to generate LAK activity against NK-cell resistant Daudi cells and lung adenocarcinoma (PC-9) cells were very similar. The LAK activity of blood MNC of lung cancer patients was also nearly the same as that of blood MNC of control subjects. There was no significant difference in IL-2-inducible LAK activity between MNC of patients with small cell lung cancer (SCLC) and those of patients with non-SCLC. Monocytes and lymphocytes were separated from blood MNC on a one-step Percoll gradient. Monocytes of lung cancer patients were found to augment in vitro induction of LAK activity by IL-2 of autologous blood lymphocytes. In contrast, endotoxin-stimulated monocytes suppressed LAK induction of autologous lymphocytes of cancer patients. These findings suggest that administration of IL-2 and LAK cells induced in vitro may be of benefit in the treatment of lung cancer.

Inhibition of colony formation of drug-resistant human tumor cell lines by combinations of interleukin-2-activated killer cells and antitumor drugs

The cytotoxicity of interleukin-2-activated killer (LAK) cells with or without anticancer drugs against cell lines with acquired drug resistance was evaluated in vitro by colony assay. Human non-small cell lung cancer cell lines, PC-9 and PC-14, human leukemia cell line, K-562, and their sublines resistant to cisplatin (CDDP), PC-9/CDDP and PC-14/CDDP, and to adriamycin (ADM), K-562/ADM, were used as target cells. PC-9/CDDP demonstrated a marked increase in susceptibility to killing by both peripheral blood lymphocytes (PBL) and LAK cells, as compared to the parental cell line, PC-9. The cytotoxicity of PBL and LAK cells against PC-14/CDDP and K-562/ADM was similar to that against their parental cell lines. Moreover, the combination of LAK and CDDP had a synergistic effect on PC-14 and PC-14/CDDP.

Three schedules of recombinant human interleukin-2 in the treatment of malignancy: side effects and immunologic effects in relation to serum level

Recombinant human interleukin-2 (rIL-2) was administered to 34 patients with advanced malignancy. Three schedules of rIL-2 administration employed were as follows: (A) 2-hr iv infusion of 6.7 X 10(5) U/m2/day (A1, 6 cases) or 2.2 X 10(6) U/m2/day (A2, 8 cases) for five consecutive days; (B) 24-hr continuous iv infusion of 3.3 X 10(5) U/m2/day (B1, 3 cases), 6.7 X 10(5) U/m2/day (B2, 7 cases) or 1.1 X 10(6) U/m2/day (B3, 5 cases) for 28 consecutive days; and (C) 24-hr continuous iv infusion of 6.7 X 10(5) U/m2/day (C, 5 cases) for 5 consecutive days per week for four weeks. The common side effects were fever (79%), eosinophilia (61%), malaise (56%), erythema or rash (50%), chills (38%) and nausea or vomiting (35%), with the dose-limiting toxicities being hypotension in group A, and renal dysfunction with fluid retention in groups B and C. In the case of 2-hr iv infusion, rIL-2 was rapidly cleared from the plasma, with a half life of about 30 min, while in the case of 24-hr continuous infusion, more than 1 U/ml serum IL-2 activity was maintained for 14 days in group B3. Natural killer (NK) and lymphokine-activated killer (LAK) activities were augmented by rIL-2 administration in patients of groups A, B3 and C. In eight patients of group B, NK and LAK activities transiently decreased after rIL-2 administration, and recovered by day 3. The percentage of IL-2 receptor and Leu HLA-DR positive cells reached the peak level on day 7 in group B. In patients of group C, the percentage of Leu HLA-DR positive cells as well as NK and LAK activities increased upon rIL-2 administration and decreased during an intermission of two days. However, the percentage of rIL-2 receptor positive cells increased during the intermission of rIL-2. The most effective schedule of rIL-2 administration was considered to be the schedule of group C on the basis of this study.

The human tumor clonogenic assay as a model system in cell biology

The human tumor stem cell (clonogenic) assay (HTCA) is a soft agar system designed for growing fresh human tumor specimens in vitro. The assay has been extensively used in studies both of individual patients' response to chemotherapy and for screening new agents. The technical limitations of this assay have been extensively discussed. The use of this test as a model system to study fundamentals of tumor cell growth has not been stressed. The potentials and limitations of this assay for the study of the regulation of tumor growth are presented.