Local adoptive immunotherapy using lymphokine-activated killer cells and interleukin-2 against malignant pleural mesothelioma: report of two cases

Malignant pleural mesothelioma is refractory to conventional therapy. We tried local adoptive immunotherapy using lymphokine-activated killer (LAK) cells and interleukin-2 (IL-2) to control malignant pleural effusion due to mesothelioma in two patients: Case 1 was that of a 69-year-old man, and Case 2 that of a 49-year-old woman with complicating chronic idiopathic thrombocytopenic purpura. A systemic survey revealed no sign of metastasis in either case. Intrapleural instillations of 6.7 x 10(9) autologous LAK cells in Case 1, or 11.3 x 10(9) allogeneic LAK cells in Case 2, with daily injections of IL-2 resulted in reductions of the pleural effusions in each case and in a decline in the level of hyaluronic acid in the effusion, in Case 1. The instillations of autologous and allogeneic LAK cells were well tolerated. The results suggest that local adoptive immunotherapy could be useful in the treatment of malignant effusion due to mesothelioma.

Lymphokine-activated killer cells are rejected in vivo by activated natural killer cells

A 4-h in vivo cytotoxicity assay was used to study the fate of implanted IL-2-generated, lymphokine-activated killer (LAK) cells in mice undergoing an activated NK cell response. 125Iododeoxyuridine-labeled LAK cells were rejected from selected organs of C57BL/6 mice infected with lymphocytic choriomeningitis virus or treated with IL-2 or the IFN inducer poly I:C. This rejection was abrogated by the selective depletion of NK cells with antibodies to asialo-GM1 and NK1.1 Ag. Similar results were noted when LAK cells were generated from the spleens of B and T cell-deficient severe combined immunodeficiency mice and when LAK cells were implanted into severe combined immunodeficiency mice. These data indicate that NK cells activated by virus infections or by IL-2 infusions directly or indirectly eliminate implanted LAK cells. Because LAK cells are used in the treatment of certain human cancers, the strategy of accompanying this therapy with IL-2 infusions should be reassessed in light of these results.

[Infusion of LAK cells and anticancer drugs with a total implantable port to a patient with metastatic liver and spleen tumors]

A case of hepatic and splenic metastases of lung cancer infused with LAK cells and anticancer drugs from hepatic artery with total implantable port (Port-A-Cath: Pharmacia, Incorp.) was reported. A 56-year-old male was admitted to our hospital because of general fatigue, jaundice, pleural effusion and elevation of transaminase caused by hepatic and splenic metastases of lung carcinoid. Abdominal ultrasonography revealed 6 hepatic metastatic foci 10-35 mm in diameter and splenic metastases. The patient received 5 courses of MMC infusion, CPA (2 courses) and epirubicin, CDDP (3 courses), and 5 courses of LAK cells (total 1.4 x 10(10)) with IL-2 and OK-432. Eight months after initiation of treatment, jaundice and pleural effusion disappeared, transaminase returned to the normal level and the condition of the patient improved. Although the response of hepatic metastases to the treatment was NC, the size of a splenic metastasis decreased from 35 x 55 mm to 24 x 35 mm (PR).

IL-2/LAK cell treatment for advanced cancers with emphasis on a novel administration

Interleukin-2 (IL-2) is a substance produced by activated blood cells called helper T-lymphocytes and has been shown to stimulate the body's immune system. IL-2 may cause certain tumors to regress when administered intravenously to laboratory animals and humans. Lymphokine activated killer (LAK) cells are white blood cells that have been stimulated with IL-2 in vitro. LAK cells are capable of killing tumor cells both in vitro and in vivo, especially when given along with IL-2. Although this form of treatment has been found to be effective in patients with certain cancers who no longer benefit from standard forms of therapy, the anti-cancer effects of IL-2/LAK cell treatment are limited by the serious, life-threatening side effects of high-dose intravenous administration, and by the high cost. A treatment program with low-dose, intralymphatically-administered LAK/IL-2 in patients with advanced cancer is a promising alternative which circumvents these major problems and concerns, while maintaining high response rates.

[Cancer therapy by using bispecific antibody]

This paper reviewed recent researches and clinical trials using bispecific antibodies. Antibodies with two distinct binding specificities have great potential for a wide range of clinical applications as targeting agents for in vitro and in vivo immunotherapy. They have shown great promise for targeting cytotoxic effector cells, cytotoxic drugs, delivering radionuclides or toxins to tumor cells. We introduced potential applications of bispecific antibodies, and discussed the theoretical basis and problems associated with their production and purification, cell fusion and chemical conjugation techniques, and proposed a new manufacturing strategy by genetic engineering. This approach will enable the wide clinical application of bispecific antibodies for cancer immunotherapy.

Adoptive immunotherapy using lymphokine-activated killer cells and recombinant interleukin-2 in preventing and treating spontaneous pulmonary metastases of syngeneic Dunning rat prostate tumor

Lymphokine-activated killer (LAK) cells were generated from splenocytes of rats bearing a weakly immunogenic Dunning prostate tumor (R-3227 AT-3) and activated with recombinant interleukin-2 (rIL-2). The maximal LAK activity was obtained from splenocytes of rats bearing tumors for 10 to 14 days after incubation with 1000 U/ml./day of rIL-2 for five to eight days. The majority of these LAK cells expressed high levels of asialo GM1 (89%), laminin (83%), OX-19 (80%) and OX-8 (88%) surface markers. LAK cells exhibited higher cytotoxicity to rat prostate tumor cells and mouse lymphoma in vitro than to other non-prostate tumor cells or normal rat splenocytes and thymocytes. Splenocytes of rats bearing prostate tumors have higher LAK activity than normal splenocytes. The Winn type assay showed that Dunning prostate tumor growth was inhibited effectively by LAK cells at a tumor cell:LAK cell ratio of 1:50. The therapeutic efficacy of LAK cells in the treatment of primary solid prostate tumors and pulmonary metastases of Dunning rats was evaluated. LAK cells in combination with rIL-2 showed a greater therapeutic benefit in 1) prevention of prostate tumor metastases to lung, 2) retardation of the primary tumor growth, 3) regression of spontaneously established pulmonary metastases, and 4) prolongation of survival as compared to untreated controls or those groups treated with LAK cells or rIL-2 alone. The results of this study indicate that the conjunctive therapeutic approach of using surgical therapy to remove primary solid tumors followed by adoptive immunotherapy with LAK cells plus in vivo administration of IL-2 may be potentially valuable in the treatment of prostate tumors, particularly for the spontaneous pulmonary metastases.

A regimen of surgical adjuvant immunotherapy for cancer with interleukin 2 and lymphokine-activated killer cells. Basis, clinical toxicity, and immunomodulatory effects

We designed a unique regimen of adoptive immunotherapy with lymphokine-activated killer (LAK) cells and recombinant interleukin 2 (rIL-2) for application with surgical adjuvant therapy of cancer. The regimen features the prolonged (6 consecutive days) s.c. administration of low-dose rIL-2 and the transfer of ex vivo generated LAK cells from regional lymph node lymphocytes, obtained at the time of surgical operation. According to this regimen, 5 patients with primary lung cancer received immunotherapy about 2 weeks after surgery (pulmonary lobectomy). Clinical toxicities included fever(5/5), fatigue(5/5), slight(less than 5%) weight gain(5/5), increase of pleural effusion at the lobectomy site(2/5), and edema formation(1/5). All toxicities reversed within 4 days after the completion of therapy. Rebound lymphocytosis after therapy ranged from 2.4 to 5.5-fold (mean, 4.3-fold) over the baseline. Peripheral blood lymphocytes obtained during this lymphocytosis exhibited in vitro LAK activity in 4 of 5 patients. Thus, the regimen is considered to be well-tolerable and immunologically active in regard to the postoperative state of the patients.

Phase II trial of high-dose interleukin-2 and lymphokine-activated killer cells in Hodgkin's disease and non-Hodgkin's lymphoma

Interleukin-2 (IL-2) plus lymphokine-activated killer (LAK) cell therapy has antineoplastic activity in renal cancer and malignant melanoma. In order to explore the activity of this therapy in Hodgkin's disease and non-Hodgkin's lymphoma, the Extramural IL-2/LAK Working Group (ILWG) treated 27 patients on two protocols using high-dose IL-2 and autologous LAK cells. Two of 12 patients with Hodgkin's disease experienced partial responses lasting 6 and 12 weeks. No patient with non-Hodgkin's lymphoma responded (p = NS). The toxicities of therapy were similar to those reported by the ILWG from trials of IL-2/LAK in solid tumors, consisting of transient hemodynamic, cardiopulmonary, renal and hepatic dysfunction, skin rash, fever, and flu-like symptoms. In view of the low response rate and the brief duration of these responses, we do not recommend the regimens reported here for further investigation in Hodgkin's disease or non-Hodgkin's lymphomas.

Interleukin-2 stimulated T cell receptor V gamma 3 positive thymocytes do not migrate to the skin

T cell receptor (TcR) V gamma 3+ thymocytes, which only develop in the fetal thymus, migrate to the skin. IL-2 stimulation of fetal day 18 murine thymocytes results in a cell population of which 45% of the cells express the TcR V gamma 3. In this study, we describe that those IL-2 cultured TcR V gamma 3+ thymocytes have the killing capacity of lymphokine activated killer cells: NK-susceptible as well as NK-resistant tumor cell lines were killed in an MHC-unrestricted manner. Because of these findings, IL-2-expanded TcR V gamma 3+ thymocytes could have a potential use in adoptive immunotherapy for skin-located tumors. Therefore, we analyzed the migration pattern of IL-2-cultured TcR V gamma 3+ thymocytes upon i.v. injection. We describe their initial entrapment in the lungs and subsequent accumulation in the liver. Localization in the skin was practically absent, and did not differ from that of IL-2 cultured adult thymocytes (mainly TcR alpha beta +). The migration pattern was identical in adult and newborn normal mice, and in adult nude mice. Analysis of the expression of asialo-GM1 revealed that it increased strongly after IL-2 culture. The relevance of this change in asialo-GM1 expression with reference to the migration upon i.v. injection is discussed. This study indicates that an improved understanding of the determinants of in vivo localization of IL-2 cultured cells may lead to improved strategies for adoptive immunotherapy of cancer.

[Effect of LAK cells on liver regeneration after partial hepatectomy]

Lymphokine activated killer (LAK) cells can destroy not only tumor cells but also syngeneic regenerating liver cells. This study was started to determine the effect of passive transfer of LAK cells on liver regeneration after partial hepatectomy. C3H mice were received 70% hepatectomy and LAK cells were injected intravenously at a dose of 5 X 10(7) cells/body. After 36 hours, 3H-thymidine uptake into the residual liver was measured. LAK cells transferred group showed 31% suppression compared with control group. In vitro, 24 hours addition of LAK cells to the primary culture of regenerating liver cells caused 97% suppression of 3H-thymidine uptake at effector to target ratio, 50/1. Then we examined the effects of IL-2 administration on liver regeneration. Though IL-2 showed no effect on cultured liver cells, intraperitoneal administration of IL-2 after hepatectomy at a dose of 1 X 10(4)u/body 5 times every 8 hours brought 38% suppression of 3H-thymidine uptake of the residual liver. Cyclosporine A, which can suppress the IL-2 production of lymphocytes, promoted liver regeneration 45% over the control at a dose of 10 mg/kg. These results suggest that LAK cells could regulate liver regeneration.

[Interferon-induced protection of renal cell cancer cell lines to lymphokine-activated killer (LAK) cells and effect of acid treatment on their susceptibility. Its relevance to expression of major histocompatibility complex class I antigens on tumor cells]

Renal cell cancer (RCC) cell lines, ACHN and KRC/Y, with or without exposure to interferons (IFNs), were examined for their susceptibility to lymphokine-activated killer (LAK) cells in relation to modulation of major histocompatibility complex (MHC) class I antigens on tumor cells. Flow cytometric analysis demonstrated constitutional expression of class I antigen on both cell lines, which was enhanced by IFN-alpha and -gamma, and was reduced by acid treatment at pH 3. A 4-h 51Cr-release cytotoxicity assay demonstrated that pretreatment of both cell lines with IFN-alpha and -gamma decreased their susceptibility to LAK cells. Although an inverse correlation between class I antigen expression and susceptibility to LAK cells has been reported by others, IFN and acid treatment demonstrated that the degree of class I antigen expression did not correlate with the susceptibility to LAK cells. These results suggest that clinically administered IFNs might induce protection of RCC to LAK cells, and that decrease of susceptibility might depend upon a mechanism different from the enhancement of class I antigens which is frequently expressed on RCC.

Interleukin-2 immunotherapy followed by resection of residual renal cell carcinoma

We administered 10 (E5) units per kg. interleukin-2, 3 times daily, with or without lymphokine-activated killer cells, to 10 patients with metastatic renal cell carcinoma. All patients had metastases to the lung, and 3 of 5 patients who had previously undergone nephrectomy had metastases to the renal fossa. Of the 9 patients who completed at least 1 course of therapy 3 had complete regression of disease outside the abdomen, including 2 who were rendered disease-free after subsequent cytoreductive surgery (nephrectomy in 1 and resection of the renal fossa recurrence in 1). Viable tumor comprised less than 1% of each surgical specimen. Our results support the view that initial treatment with interleukin-2 immunotherapy, followed by abdominal cytoreductive surgery if the peripheral metastases have regressed, may be preferable to the practice of performing abdominal cytoreductive surgery before administering interleukin-2 immunotherapy for patients with widely metastatic renal cell carcinoma.

A phase II study of high-dose continuous infusion interleukin-2 with lymphokine-activated killer cells in patients with metastatic melanoma

Thirty-three patients with metastatic melanoma were treated in a phase II study with an intravenous continuous infusion (IVCI) of interleukin-2 (IL2) given with lymphokine-activated killer (LAK) cells. The dose of IL2 was the optimal priming dose for LAK-cell induction, followed by the maximally tolerated LAK-cell dose that could be given by an IVCI schedule as determined by a previous phase I trial. The CI schedule was chosen for evaluation because of a postulated reduction in toxicity with the possibility of administering a more prolonged IL2 infusion and because greater rebound lymphocytosis and LAK-cell generation had been reported using this dose and schedule. The 33 patients were similar in age, performance status, and sites of disease to those treated in previous IL2 trials. All patients were assessable for response and toxicity. One patient (3%) achieved a partial response of 10 months duration. There were no other clinically significant responses. Significant toxicity included hypotension requiring pressors (45%), dyspnea (36%), renal insufficiency (24%), hepatic dysfunction (66%), and cardiac arrhythmias (18%). These toxicities reversed with cessation of the infusion. There were four deaths during the first 30 days of treatment, three from infection (one related to central line, one related to LAK cells, one related to tumor), and one from tumor-related hemorrhage. Toxicity was unexpectedly high and at least comparable to that seen in previous studies using a high-dose IV bolus schedule of IL2. When comparing the IVCI schedule with high-dose bolus IL2 to LAK cells in nonrandomized but sequential studies in patients with advanced melanoma, it appears that CI IL2 is less efficacious.

Therapy of recurrent high-grade gliomas with surgery, autologous mitogen-activated IL-2-stimulated (MAK) killer lymphocytes, and rIL-2: II. Correlation of survival with MAK cell tumor necrosis factor production in vitro

Seven patients with recurrent high-grade glioma were treated in a Phase I/II trial with surgical debulking, after which mitogen-activated IL-2-stimulated killer (MAK) lymphocytes and 10(5) units rIL-2 were implanted in the surgical defect. The therapy was well tolerated, and the mean survival of this group of patients was 29 weeks. Tumor necrosis factor (TNF) production by MAK lymphocytes stimulated with IL-2 in vitro was measured. A significant (r = .78, p = .04) correlation between survival of patients after therapy and the ability of the MAK lymphocytes to produce TNF in vitro was noted. A significant negative correlation (r = -.82, p = .02) was found when comparing TNF production and increasing tumor size measured on MRI. No correlation was found between TNF production in vitro and MAK lymphocytes lytic activity on K562 and U373 target cells. No correlation was found between survival and MAK cell lytic activity measured on K562 and U373 target cells. We conclude that TNF production in vitro and cytotoxic activity measured in vitro are measures of different antitumor activity in vivo and in vitro. TNF production during IL-2-stimulated proliferation may be an important in vitro assay in terms of predicting length of survival of recurrent high-grade gliomas.

[The value of interferons, interleukin-2 and tumor necrosis factor in the therapy of renal cell cancer]

The treatment of patients with metastasized renal cell carcinoma by biological response modifiers such as interferon (IFN), interleukin-2 (IL-2) and tumor necrosis factor (TNF) should at present only be carried out in prospective studies since there are still no generally accepted treatment regimens for these substances. In addition, one must remember that only interleukin-2 has been approved for the treatment of renal cell cancer by the Bundesgesundheitsamt (Federal Health Authority) in Berlin. Regarding interferons, IFN-alpha seems to be the most suitable substance for the treatment of renal cell cancer. However, objective response rates (almost exclusively partial responses) can only be expected in about 15% of the cases. By combining IL-2 with lymphokine-activated killer cells or IFN-alpha, objectively assessed remissions can be found in 35%. The approximate complete-response rate using this form of treatment, however, is in the range of 10%.

[Usefulness and limitation of immunotherapy of metastatic renal cell carcinoma with autologous lymphokine-activated killer cells and interleukin 2]

Fourteen patients with metastatic renal cell carcinoma (RCC) were treated by systemic administration of autologous lymphokine-activated killer (LAK) cells and interleukin-2 (IL-2). Pulmonary metastases alone were found in 9 cases, pulmonary and mediastinal nodal metastases in 3, and pulmonary and bone metastases in 2. LAK cells, generated by incubation in 2 units/ml of IL 2 for 3-4 days, were intravenously administered once or twice a week. In addition, beginning on the day of the first LAK cell infusion, 1000 units of IL 2 diluted in normal saline were intravenously infused once or twice a day with occasional supplementation of 1000 units of IL-2 on each day of LAK cell infusion. The total number of LAK cells and total amount of IL-2 administered per patient in this study ranged from 0.8 x 10(10) to 6.9 x 10(10) cells and from 3.3 x 10(4) to 21.4 x 10(4) units, respectively. As toxic effects caused by the infusion of LAK cells, headache, shaking chills, fever and leukocytosis were found in all 14 cases. Side effects possibly induced by IL-2 infusion were tolerable fever, fluid retention (body weight gain of 2-3 kg) and eosinophilia. No objective regression of mediastinal nodal or bone metastases was observed. In regard to lung metastases, however, partial and minor responses were observed in 3 and 2 cases, respectively. One of the 3 patients with a partial response was clinically free of disease after undergoing a thoracotomy for resection of residual lesions, but a brain metastasis was detected 10 months after the thoracotomy. The remaining 2 patients are being closely followed up at present. In 3 of 11 patients who showed a minor response, no change or progressive disease, brain metastases were observed during or after the immunotherapy. Furthermore, we examined the possibility of selection of suitable candidates for this therapy on the basis of the degree of in vitro LAK activity against autologous cultured tumor cells in 6 patients, but there was no significant correlation between in vitro autologous tumor cell lysis by LAK cells and the clinical response to immunotherapy. In conclusion, although a complete response could not be obtained, it can be said that this immunotherapy may be effective against RCC, in particular lung metastases, since a partial response was achieved in 3 of 14 patients. However, it should be taken into consideration that this immunotherapeutic approach may have a risk of increasing the frequency of brain metastases.

[Immunotherapy and urological malignancy]

Immunotherapy gained popularity as a treatment modality for malignant diseases in the 1960s. A number of trials, using tumor vaccines, immunopotentiators, interferons, cytokines and others, demonstrated antitumor effects in several urological malignancies, and, to date, immunotherapy plays a major role in treatment of advanced renal cell carcinoma and superficial bladder carcinoma. Interferon or interleukin-2, which became available for large scale clinical trial with the development of bioengineering, however, were shown to be not effective as initially expected, by single agent. Rational design of new strategies with multiple agents in combination based on basic and clinical research, should provide progress in treatment of urological malignancies.

Lymphokine-activated killer traffic assay and our preliminary clinical results of regional arterial infusion of lymphokine-activated killer cells for renal cell carcinoma

In vivo distribution of radiolabeled lymphokine-activated killer (LAK) cells that were administered either through the caudal vein or the abdominal aorta of Lewis rats was studied. The LAK traffic study showed remarkable increase in radioactivity in several organs peripheral to the arterial injection site. We began treating the patients with metastatic renal cancer by means of regional arterial administration of LAK cells. This treatment was supported by the results of the traffic assay. Our regional LAK therapy, which involves a weekly leukapheresis in combination with daily systemic low dose interleukin-2 administration, has been in practice for over 2.5 years. Seven out of 12 metastatic lesions in the 7 patients treated showed regression. Two responding cases have been alive for over 2 years. Responding lesions were bone, muscle, para-aortic lymph node, and/or retroperitoneum. The regional arterial administration of LAK cells is local therapy. However, this mode of therapy could be useful for those patients with extrapulmonary nonresectable metastasis and at least one injectable feeding artery. This study shows our laboratory data concerning the localization of LAK cells transferred via arterial route and our clinical cases treated with regional arterial administration of LAK cells.

Current status of hemapheresis in the United States

The face of automated hemapheresis in the United States is changing. No longer is it appropriate to view hemapheresis primarily in terms of therapeutic plasma exchange. For many centers, the bulk of day-to-day activities revolves around donor cytapheresis to satisfy the ever-increasing need for units of platelet concentrates. Indications of therapeutic plasma exchange are becoming better focused, with neurological patients being among those most frequently managed. New and innovative applications of automated hemapheresis technology will continue to be developed. Current examples include the production of lymphocyte-activated leukocytes for cancer therapy, use of extracorporeal photoactivation of leukocytes for immune modulation, and the collection of hematopoietic progenitors from peripheral blood for autologous transplantation. As we enter the 1990s, it is important to be aware of new technology and applications and to have the vision to apply them in innovative ways. However, it is also critical to demand rigorous scientific review before broadly adopting any new idea as a standard of practice.

The immunotherapy of human cancer with interleukin 2: present status and future directions

Interleukin-2 (IL-2) is the principal soluble factor responsible for the proliferation of activated T cells. In animal models and humans, administration of IL-2 can induce regressions of established cancers. These antitumor effects may be partially mediated by cytotoxic effector cells activated by IL-2, including lymphokine-activated killer (LAK) cells and cytotoxic T lymphocytes. IL-2 has additional effects on other components of the cellular immune system, including B cells and macrophages, and induces secretion of other soluble mediators, including tumor necrosis factors (TNF) alpha and beta, and interferon-gamma. These effects may contribute to the antitumor activity of IL-2 as well as its dose-related toxicity. Multiple Phase I and II trials have been completed or are ongoing evaluating the clinical and biological effects of IL-2 given by diverse routes and schedules, both alone and in combination with infusions of ex vivo IL-2-activated autologous LAK cells. Other studies have begun to explore the potential for antitumor synergy when IL-2 is combined with the different interferons, TNF, monoclonal antibodies, and cytotoxic drugs. The biology, toxicity, and clinical activity documented in IL-2 clinical trials to date are reviewed, and prospects for future directions outlined.

Interstitial nephritis in a patient receiving adoptive immunotherapy with recombinant interleukin-2 and lymphokine-activated killer cells

A patient receiving adoptive immunotherapy with recombinant interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells for metastatic melanoma developed acute renal insufficiency out of proportion to the decrease in her renal perfusion after 4 days of receiving IL-2. On the 8th day of IL-2 and the 3rd day of LAK cell infusion she expired suddenly from an acute intra-abdominal hemorrhage due to rupture of a metastasis. Postmortem examination of the kidneys showed an interstitial infiltrate consisting largely of lymphocytes and concomitant tubulitis. Immunoperoxidase staining of the infiltrating cells with a panel of lymphocyte-specific monoclonal antibodies showed the majority of cells to be T lymphocytes (70-75%), with a more focal infiltrate of B lymphocytes (25-30%) and rare monocytes, granulocytes and natural killer cells. This patient represents the first reported case of acute interstitial nephritis associated with IL-2 immunotherapy. Our finding is consistent with the hypothesis that the acute renal failure that accompanies this therapy may sometimes be due to intrinsic renal disease as well as the usual pre-renal failure. Nephritis may be caused by IL-2-mediated effects on lymphocytes, resulting in renal parenchymal infiltration.

Highly oncolytic adherent lymphocytes: therapeutic relevance for leukemia

We have generated and characterized a highly oncolytic adherent lymphocyte subset (A-LAK) from eight leukemic patients with non-lymphocytic leukemia (NLL) in remission and one NLL patient in relapse. Our studies demonstrated that A-LAK was superior in its oncolytic activity (tested in a 3-h 51Cr release assay) to conventionally prepared (LAK) and non-adherent (NA) IL-2 cultures. No activity was observed by this highly oncolytic subset against normal bone marrow (BM). A-LAK also displayed highest proliferative activity in 7-11 day cultures (5- to 58-fold expansion) in comparison to LAK (0.7- to 2.7-fold) or NA (1.0- to 2.6-fold) cultures. Analysis of phenotype of unseparated, NA and adherent (A-LAK) lymphocytes 24 h after IL-2 activation showed that the A-LAK was composed predominantly of high intensity (bright) CD11a+ (LFA-1) lymphocytes (75 +/- 4.8%) when compared to the other two populations (12 +/- 2.1%). Similarly, A-LAK contained higher proportion of CD11b (CR3 receptor)-positive lymphocytes (39 +/- 2.1%) than unseparated and NA lymphocytes (11 +/- 1.4%). Double marker phenotypic studies showed that A-LAK cultures were heterogeneous and distribution of individual lymphocyte subsets differed among NLL patients. While in A-LAK culture of some patients the CD56+, CD3- natural killer (NK) cell subset was predominant, CD3+, CD56- lymphocyte subset was prevalent in others. Highest A-LAK lytic activity was always correlated with highest NK cell content. Characterization studies (using the complement-depletion technique) showed that independently of the distribution of lymphocytes in A-LAK cultures, CD16+, CD56+, CD3- NK cell subset displayed highest oncolytic effect. CD5+ subset also participated in cytotoxic function. These observations indicated that A-LAK may represent a new therapeutic approach to treatment of leukemia.

Imaging pattern of radiolabelled lymphokine-activated killer cells in patients with metastatic malignant melanoma

In patients with metastatic malignant melanoma the distribution patterns of radiolabelled lymphokine-activated killer (LAK) cells were investigated. Peripheral mononuclear cells (PMC) were isolated from six patients. LAK cells were generated by culturing PMC in complete medium containing 1000 U interleukin (IL)-2/ml and labelled with indium 111 before retransfer. We obtained scans at 2.5, 24, 48 or 96 h after injection with a high resolution gamma-camera. Intravenously injected LAK cells distributed to the lungs, liver, spleen and bone marrow. External tumour detection of known lymph node and bone metastases was successful in four. It failed in one patient with a solitary lung metastasis and in another patient with subcutaneous metastases. Our results suggest that LAK cells show tumour homing, providing a direct interaction between tumour and cytotoxic cells. We conclude that PMC seem to retain their ability to migrate after IL-2 stimulation and 111In-labeling. This technique may be helpful for kinetics studies or external detection of metastases in patients with malignant melanoma.