Human lymphokine-activated killer cells (LAK cells) as a potential immunotherapeutic modality

Application Of Adoptive Immunotherapy In Ovarian Cancer

Ovarian cancer (OC) has been the most fatal gynecological disease that threatens women's health. Surgery and platinum-based chemotherapy are the basic ovarian cancer treatments that can improve survival, but the five-year survival rate has not improved because of delayed diagnosis, drug resistance, and recurrence. Novel treatments are needed to improve the prognosis and survival rate of ovarian cancer patients. In recent years, adoptive cell therapy (ACT) has received increasing attention as an emerging therapeutic strategy in the treatment of solid tumors including OC. ACT has shown promising results in many preclinical and clinical trials of OC. The application of ACT depends on different effector cells, such as lymphokine-activated killer (LAK) cells, tumor-infiltrating lymphocytes (TILs), and genetically modified T cells. In this review, we focus on adoptive immunotherapies in ovarian cancer and summarize completed and ongoing preclinical/clinical trials. The future development directions and obstacles for ACT in OC treatment are discussed.

Adoptive immunotherapy using lymphokine-activated killer (LAK) cells and interleukin-2 for recurrent malignant primary brain tumors

Ten patients with recurrent malignant primary brain neoplasms were treated with adoptive immunotherapy using lymphokine-activated killer (LAK) cells and interleukin-2 (IL-2). Nine patients had supratentorial glioma and they received multiple intratumoral instillations of LAK cells through reservoir-catheter system or burrhole. The other patients with disseminated subarachnoid metastases from posterior fossa medulloblastoma received immunotherapy via lumbar subarachnoid route. A partial and transient clinical response was observed in two patients. following the therapy, and a cystic transformation of the essentially solid tumour was noted on the CT scans of these two patients. No significant clinical or radiological response to the treatment was observed in the remaining 8 patients. The results of this preliminary study reveal limitations of the regional intratumoral adoptive immunotherapy using currently available techniques and provide sufficient evidence of its effectiveness to warrant further investigations.

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.

Studies of serum-free medium for the generation of lymphokine-activated killer cells

We examined a serum-free medium (designated as TYI 101) for the generation of lymphokine-activated killer (LAK) cells from human lymphocytes, regional lymph node lymphocytes (RLNL) and peripheral blood lymphocytes (PBL). TYI 101 medium consisted of, in addition to nutrient mixture, transferrin, insulin, fetuin, sodium selenite, 2-mercaptoethanol, o-phosphorylethanolamine, chick egg yolk and porcine kidney extract. These hormones were effective for supporting RLNL proliferation as assessed by (3H)-thymidine uptake. When human lymphocytes from two different sources were cultivated with recombinant interleukin 2 (rIL-2) in TYI 101 medium, LAK activity was generated. In cultures of PBL from a healthy donor, LAK cells were generated in TYI 101 medium as efficiently as in RPMI 1640 medium supplemented with 10% human AB-type serum (RPMI-AB). In cultures of RLNL from lung cancer patients, LAK activity obtained in TYI 101 medium was about sixty-five percent of that in RPMI-AB. However, the addition of a small amount of AB-type serum improved the generation of LAK activity, LAK cell expansion, and cell viability in TYI 101 medium. We conclude that TYI 101 medium can be used for the generation of LAK cells from human lymph node lymphocytes with supplementation of none or only a reduced amount of human serum.

Natural killer and lymphokine activated killer cell functions in Hodgkin's disease

We report the natural killer (NK) and lymphokine activated killer (LAK) cell activities in peripheral blood lymphocytes (PBL) from untreated patients with Hodgkin's disease (HD) and from healthy donors. The frequency of LAK cell precursors was also studied using limiting dilution analysis (LDA). About 75% of the HD patients had normal NK activity. There was a higher percentage of low NK responders (mean percent NK activity of healthy donors--2 SD) in patients with lymphocyte depletion histologic grade of the disease and those who were in clinical stage IV, suggesting a correlation of decrease in NK activity with poor prognosis. We found efficient LAK activity against the NK-sensitive K562 cells and NK-resistant VIP (melanoma) and T-24 (bladder carcinoma) tumour targets in both low and normal NK responder HD patients, irrespective of the histopathological grade and clinical stage of the disease. In concordance with their good LAK cell activity, HD patients showed a frequency distribution of LAK cell progenitors in the PBL comparable to that of healthy donors.

Two populations of mouse lymphokine-activated killer cells separated by use of soybean agglutinin

We separated lymphokine-activated killer (LAK) cells induced from spleen cells of BALB/c mice by culturing with recombinant interleukin-2 (rIL-2) into soybean agglutinin-positive (SBA+) and soybean agglutinin-negative (SBA-) fractions with a cell sorter at the time when LAK activity reached a maximum (day 3). We found that the cells with LAK activity were enriched in the SBA+ fraction. Analysis of cell surface phenotypes revealed that the SBA+ cells are of non-T cell origin, while the SBA- fraction consists of T cells. We also found that the large granular lymphocyte (LGL) fraction of spleen cells obtained with a Percoll gradient became SBA+ after culture for 3 days with rIL-2, whereas cells of high density did not. The change in SBA binding sites was also examined on C57BL/6 mouse spleen cells and we found that NK1.1+ non-T cells selectively acquire SBA binding sites at an early stage of activation with rIL-2. On the other hand, sorted SBA- cells gradually acquired SBA binding sites on extended culturing with rIL-2. These results suggest that the expression of SBA binding sites is related to the stage of cell activation with rIL-2, though cells of the NK-lineage became SBA+ at an earlier period of a culture with rIL-2 than cells of the T-lineage. Utilizing these findings, we separated NK-derived LAK cells by means of SBA-binding, and used the separated cells for adoptive immunotherapy for experimental pulmonary metastasis. We found that SBA(+)-NK cell-derived LAK cells showed stronger activity for the inhibition of experimental pulmonary metastasis than SBA(-)-T cell-derived LAK cells.

Differential activation of lymphokine-activated killer cells with different surface phenotypes by cultivation with recombinant interleukin 2 or T-cell growth factor in gastric cancer patients

Fourteen days' culture of human peripheral blood lymphocytes (PBL) with recombinant interleukin 2 (rIL 2) or T cell growth factor (TCGF) results in the generation of lymphokine-activated killer (LAK) effector cells which have the unique property of lysing natural killer (NK)-resistant human tumor cells, Daudi, as well as NK-sensitive, K562 cells. LAK cells were generated from both normal and gastric cancer patients' PBL. However, LAK cell activities induced by rIL 2 or TCGF decreased with the progress of the tumor growth. In addition, TCGF-induced LAK cell activities were found to be lower than the rIL 2-induced LAK cell activities. Different mechanisms may be involved in the decreases of the rIL 2-induced and TCGF-induced LAK cell activities. This study further demonstrates that the cell types involved are also heterogeneous, as determined by phenotypic characteristics. The LAK-effector cell type was analyzed by two-color flow cytometry. RIL 2-induced LAK cells showed increased proportions of CD4+Leu 8- and Leu 7+CD16-, and a decreased proportion of CD8+CD11- cells, which are believed to be associated with killer T cell functions. In contrast, TCGF-induced LAK cells revealed significantly increased proportions of CD8+CD11- and CD4+Leu8- cells, and a decreased proportion of Leu 7+CD16- cells. Thus, LAK cells with different surface phenotypes were induced by the cultivations with rIL 2 and with TCGF.