Induction Of Lymphokine-activated Killer Cells Research Articles

Interleukin 7 enhances cytolytic T lymphocyte generation and induces lymphokine-activated killer cells from human peripheral blood.

The effects of purified recombinant interleukin 7 (IL-7) on the generation of cytolytic T lymphocytes (CTL) in mixed lymphocyte culture (MLC) and on the induction of lymphokine-activated killer (LAK) cells in autologous cultures of human peripheral blood mononuclear cells were investigated. IL-7 was found to induce the generation of both CTL and LAK cells in bulk cultures. The appearance of peak CTL activity in MLC established with exogenous IL-7 was delayed in comparison with replicate cultures containing exogenous IL-2, but both cytokines stimulated quantitatively similar levels of antigen-specific lytic activity. An IL-2-neutralizing antiserum inhibited substantially, but not completely, the effect of IL-7 on CTL generation, implying the existence of both an indirect component of IL-7 activity via IL-2 utilization, as well as an IL-2-independent component. Cell surface phenotypic analysis of IL-2- or IL-7-generated CTL effector cells revealed that CD8+ cells were responsible for the vast majority of lytic activity. Limiting dilution analysis (LDA) revealed that essentially identical frequencies of CTL precursors (CTL-P) were capable of clonal expansion and/or differentiation in the presence of exogenous IL-2, IL-4, or IL-7, supporting the concept that all three of these cytokines are capable of exerting a major influence on T cell growth and differentiation. Approximately half of the CTL-P that responded in IL-7-supplemented LDA cultures did so in an IL-2-independent manner. IL-7 stimulated the development of LAK cells in autologous bulk cultures, but only weakly in comparison with IL-2. In contrast to its effects on CTL generation, the induction of LAK cells by IL-7 was virtually independent of IL-2. LAK cells induced by IL-7, like those induced by IL-2, were phenotypically heterogeneous and included CD8+, CD56+, and gamma/delta+ cells. Limiting dilution analysis indicated that IL-2 stimulated fivefold more LAK-P than IL-7 and 220-fold more than IL-4. Collectively, these data suggest that IL-7 has potent regulatory effects on human cytolytic cell populations and, either alone or in combination with other cytokines, could be important for the in vitro expansion of cells for adoptive immunotherapy.

腎細胞癌患者の養子免疫療法に関する研究

The immune responses in patients with renal cell carcinoma were evaluated from the production of interleukin-2 (IL-2), the expression of IL-2 receptors and the activity of lymphokine activated killer (LAK) cells. In addition, the effect of the patient's serum on the expression of IL-2 receptors and LAK activity were investigated. The production of IL-2 by peripheral blood mononuclear cells (PBM) from patients with renal cell carcinoma was not suppressed, when compared with that in controls. However, the expression of IL-2 receptors tended to decrease with the progression of clinical stage. The LAK cells generated by PBM of patients with renal cell carcinoma had significant cytotoxic activity against Daudi cells, ACHN cells and autologous tumor cells, while autologous serum suppressed the expression of IL-2 receptors and the induction of LAK cells in patients with renal cell carcinoma. Furthermore, serum from patients with renal cell carcinoma suppressed the cytotoxic activity of LAK cells generated by PBM from a normal volunteer. These results indicated the presence of immunosuppressive factors in the serum of patients with renal cell carcinoma which impaired the clinical effect of treatment using IL-2 or LAK cells.

Induction of human lymphokine-activated killer cells by IFN-alpha and IFN-gamma.

By traditional definitions, NK cells can be activated by cytokines to exhibit two functionally distinct levels of cytotoxicity. Whereas IL-2-mediated activation of NK cells leads to the development of lymphokine-activated killer (LAK) cytotoxicity, characterized by the acquisition of cytolytic activity against NK-resistant targets, IFN-treated NK cells become activated without the acquisition of novel cytolytic specificities. In this study we show that NK cells activated by 18 to 24 h of stimulation with either IFN-alpha or IFN-gamma do acquire LAK cytolytic activity, demonstrated by the ability of IFN-treated PBMC to lyse NK-resistant COLO 205 cells as well as fresh tumor targets. The level of IFN-alpha-induced LAK activity was significantly greater than that induced by IFN-gamma, although IL-2-induced LAK activity was considerably greater than IFN-alpha-induced LAK cytotoxicity. Maximal IFN-induced LAK cytotoxicity occurred after 24 h of culture, and occurred with the use of IFN-alpha at 500 U/ml and IFN-gamma at 1000 U/ml. Whereas neutralizing antibody experiments demonstrated that IFN-alpha-induced LAK activation did not involve the participation of endogenously produced IL-2, the partial inhibition (63%) of IFN-gamma-induced LAK cytotoxicity by anti-IL-2 and of IL-2-induced LAK by anti-IFN-gamma (33.3%) indicates that the induction of LAK cytotoxicity by either of these individual cytokines involves the endogenous production and participation of the other cytokine. Similar to IL-2-induced LAK cells, phenotypic analysis revealed that IFN-alpha/gamma LAK cells were Leu-19+, although the Leu 19"dim"+ subset exhibited greater IFN-induced LAK activity than the Leu-19"bright"+ subset. The results of this study clearly demonstrate that IFN-alpha and IFN-gamma induce classic LAK activity and IFN-gamma plays a participatory role in the optimal induction of LAK cells by IL-2.

Lymphokine-activated killer cell induction in tumor-infiltrating leukocytes from colon cancer patients.

Lymphokine-activated killer (LAK) cell induction was evaluated in the peripheral blood mononuclear cells (PBMC) from 28 colon cancer patients and in the tumor-infiltrating leukocytes (TIL) from 20 of the patients' colon cancer specimens. Modulation of LAK cell induction in TIL and PBMC by inhibitors of arachidonic acid metabolism also was examined. LAK cells were induced in vitro in isolated TIL and PBMC by culturing with 500 U/ml of recombinant interleukin-2 (IL-2) for 3 to 5 days, and this was followed by the assessment of cytolytic activity against natural killer (NK)-resistant Chang hepatoma cells. LAK cell induction in the TIL was depressed significantly, compared with LAK cell induction in the PBMC of colon cancer patients (P less than 0.01). In the majority of cases, indomethacin augmented LAK cell induction in the TIL (P = 0.073 for the entire group, compared with cultures not treated with indomethacin) and nordihydroguaiaretic acid (NDGA) depressed LAK cell induction (P less than 0.05 for the entire group, compared with cultures not treated with NDGA). Further characterization of the mechanisms responsible for modulating LAK cell induction in the TIL of cancer patients may identify ways to optimize their use in adoptive cellular immunotherapy.

Lymphokine‐activated Killer Induction and Its Regulation by Macrophages in Malignant Pleural Effusions

Mononuclear cells (MNC) from pleural effusions and peripheral blood of 18 patients with primary lung cancer with malignant pleural effusion were studied. Pleural and blood MNC generated lymphokine‐activated killer (LAK) activity similarly when cultured for 4 days with an optimal concentration of interleukin 2 (IL‐2). Highly purified lymphocytes (>98%) and monocyte‐macrophages (>90%) were isolated by discontinuous Percoll gradient centrifugation from pleural and blood MNC. Pleural macrophages, as well as blood monocytes, showed significant augmenting effects on in vitro LAK cell induction from pleural and blood lymphocytes by IL‐2. During daily intrapleural administration of IL‐2, significant induction of LAK activity in vivo was observed after 3 days, but then this LAK activity in pleural MNC decreased almost to zero by day 15. Daily injections of IL‐2 resulted in reduction in the up‐regulation of LAK induction by pleural macrophages and also in increase in the levels of soluble IL‐2 receptors in pleural effusions. These findings indicate that in vivo LAK induction of lymphocytes in malignant effusions by IL‐2 may be regulated by macrophages in the effusions.

Augmentation of Murine Lymphokine‐activated Killer Cell Induction by a Factor Produced by Nocardia rubra Cell Wall Skeleton‐stimulated T Cells

Four‐hour exposure of C3H/HeN mouse spleen cells to Nocardia rubra cell wall skeleton (N‐CWS) before 4‐day culture with a suboptimal dose of human recombinant interleukin 2 (rIL 2) augmented the induction of lymphokine‐activated killer (LAK) cell activity, whereas the treatment with N‐CWS alone induced no cytotoxicity. In accordance with this, the IL 2 binding activity of spleen cells was augmented by combined stimulation with N‐CWS and rIL 2. The augmented cytotoxicity was mediated by Thy‐1.2+, Lyt‐1.1−, Lyt‐2.1− and asialo GM1+ cells. Cell cultures in diffusion chambers revealed that N‐CWS‐treated spleen cells produced a LAK cell induction‐helper factor (LAK‐helper factor, LHF) when cultured with rIL 2. The LHF production required Thy‐1.2+, Lyt‐1.1+, Lyt‐2.1+ and asialo GM1− cells, and the coexistence of unstimulated accessory cells was also essential for the LHF production. Cells responding to both LHF and rIL 2 to generate LAK activity were Thy‐1.2−, Lyt‐1.1−, Lyt‐2.1− and asialo GM1+. The culture fluid of spleen cells stimulated with both N‐CWS and rIL 2 contained no tumor necrosis factor (TNF) activity, and the additional stimulation with N‐CWS caused no production of either IL 2 or interferon (IFN). Murine recombinant interleukin la (Mu‐rIL 1α) could not replace the augmentative effect of N‐CWS on LAK cell induction. These results suggest that in the presence of rIL 2, N‐CWS stimulates murine T cells to produce LHF that is probably distinct from IL 1, IL 2, TNF and IFN.

The augmentation of lymphokine-activated killer cells induced by partial hepatectomy in mice.

Spleen cells that are cultured with interleukin 2 for as short a time as 4 days develop the ability to lyse syngeneic natural killer-resistant tumor cells but not to lyse syngeneic lymphoblasts. When mice were subjected to partial hepatectomy (HEP), the spleen cells exhibited not only an augmentation of natural killer activity, but also an augmentation of in vitro induction of lymphokine activated killer (LAK) cells. Furthermore, the LAK cells exhibited lytic activities against syngeneic lectin-induced lymphoblasts and regenerating liver cells. The sensitivity of regenerating liver cells to lysis by LAK cells was detected as early as one day after HEP, and continued until day 14. Analysis by cell depletion techniques using monoclonal antibodies and complement, as well as discontinuous gradient sedimentation, indicated that the LAK cells activated by HEP were Thy-1+, Lyt-2+, asialo GM1+ and Lyt-1-, lymphocytes with a low density. After the intravenous (i.v.) administration of anti-asialo GM1 before HEP, the in vitro induction of LAK cells was remarkably inhibited.

Up-regulation by granulocyte-macrophage colony-stimulating factor (GM-CSF) of induction of lymphokine (IL-2)-activated killer (LAK) cells by human blood monocytes.

The role of recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) in monocyte-mediated up-regulation of lymphokine-activated killer (LAK) cell induction by IL-2 was examined. Treatment of blood mononuclear cells (MNC) of healthy donors with GM-CSF for 4 days in the presence of IL-2 resulted in a significant increase in LAK activity against natural killer (NK)-resistant Daudi cells, as assessed by the 4 hr 51Cr-release assay. For determination of the role of GM-CSF in LAK induction, highly purified lymphocytes (greater than 99%) and monocytes (greater than 90%) were isolated from MNC by counter-flow centrifugal elutriation (CCE). Pre-treatment of monocytes for 4 days with GM-CSF before addition of lymphocytes plus IL-2 resulted in a significant dose-dependent increase in monocyte-mediated up-regulation of LAK induction, but in the absence of monocytes GM-CSF had no effect on LAK cell induction. Similarly, GM-CSF augmented the proliferative response of lymphocytes to IL-2 in the presence of monocytes as assessed by 3H-TdR uptake. Treatment with anti-GM-CSF antibody completely abolished up-regulation of LAK induction by GM-CSF-treated monocytes. When blood monocytes were separated into 5 fractions by CCE, GM-CSF-responding monocytes were found to be responsible for up-regulation of LAK induction. These results suggest that GM-CSF may be important in monocyte-mediated up-regulation of LAK cell induction in vivo.

Induction of lymphokine-activated killer cells against human leukemia cells in vitro

The induction of lymphokine-activated killer (LAK) cells against fresh human leukemia cells was investigated. Two thirds of the 62 leukemias examined were susceptible to the lytic effect of allogeneic IL-2 induced LAK cells in vitro. No substantial differences could be detected between myeloid or lymphoid leukemias or with regard to the FAB subtype or the immunophenotype. Culturing mononuclear cells from peripheral blood or bone marrow of leukemia patients with IL-2 resulted in an expansion of residual large granular lymphocytes and development of cytotoxic activity. The combination of IL-2 with IFN-gamma or the presence of tumor cells during the activation process led to an enhancement of LAK cell cytotoxicity. These results suggest that LAK cells may be useful in the treatment of leukemia.

Augmentative effect of Nocardia rubra cell-wall skeleton on the induction of human lymphokine-activated killer (LAK) cells by the production of LAK cell helper factor(s).

Nocardia rubra cell wall skeleton (N-CWS) was found to synergistically augment lymphokine-activated killer (LAK) cell generation from human peripheral blood mononuclear cells (PBMC) in the presence of a suboptimal dose of recombinant interleukin-2 (rIL-2). N-CWS increased the number of PBMC expressing IL-2 receptor on their surfaces, and the presence of N-CWS at the early stage of the culture period was essential for the exertion of its augmentative activity on the LAK induction. The predominant phenotype of LAK precursor cells responding to N-CWS and rIL-2 was CD3- CD16+. Culture supernatant from N-CWS-stimulated PBMC was found to act as a substitute for N-CWS in the induction of LAK generation in the presence of rIL-2, suggesting that these cells produced a factor capable of augmenting LAK cell induction (LAK helper factor, LHF). LHF was found to have a molecular mass of 29 kDa by gel filtration, and could also function as a killer helper factor to augment allo-antigen-specific cytotoxic T lymphocyte generation from human peripheral blood T cells as well as murine thymocytes. LHF showed no species specificity, indicating that it is different from IL-4. The enhancing activity of LHF was not neutralized with anti-TNF alpha, anti-IL-1 alpha, or anti-IL-1 beta antibodies. Furthermore, no tumor necrosis factor-alpha (TNF alpha), TNF beta, IL-1 alpha, beta, IL-2, IL-5, IL-6 or interferon activity was detected in semi-purified LHF during enzyme-linked immunosorbant assay and biological assays. The present findings indicate that LHF produced from N-CWS-stimulated PBMC is a molecule distinct from TNF alpha, TNF beta, interferon, IL-1, -2, -4, -5, and -6, and suggest that LHF might be a novel lymphokine involved in LAK generation.

Partial correction of defective generation of lymphokine-activated killer cells in patients with chronic myelogenous leukaemia after in vivo treatment with interferon-alpha (Wellferon).

Patients with chronic myelogenous leukaemia (CML) in untreated chronic phase are deficient in their ability to generate lymphokine-activated killer (LAK) cells from peripheral blood mononuclear cells although they possess essentially normal levels of CD16+ and Leu19+ lymphocytes, which do not seem to be actively suppressed by tumour cells. Attempts to enhance LAK cell generation in these patients are reported here. Combining the lymphokines interleukins-2, with -4 and -5 (IL-2, IL-4, IL-5), was not successful; in fact, IL-4 depressed LAK cell induction in both normal donors and CML patients. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate also failed to enhance cytotoxicity of normal donors or patients, and indomethacin was similarly without effect. The only agent found to enhance LAK cell induction by IL-2 in normal donors was interferon-gamma (but not IFN-alpha) and even this modest effect was not seen with the cells of CML patients. Increasing concentrations of IL-2 and/or culture duration also failed to improve LAK cell generation by patients. The only improvement in LAK cell generation was observed in CML patients treated for one or more months with IFN-alpha, where a steady increase of LAK activity with time after initiation of therapy was noted. These results show that the blockade of LAK cell induction in chronic-phase myelogenous leukemia patients is difficult to lift pharmacologically in vitro but possibly susceptible to biological response modifiers in vivo.

Monocyte-dependent, serum-borne suppressor of induction of lymphokine-activated killer cells in lymphocytes from melanoma patients.

Both phytohemagglutinin-induced cytotoxicity and recombinant-interleukin-2 (rIL-2)-induced lymphokine-activated killer (LAK) activity against noncultured melanoma cells were significantly reduced when peripheral blood mononuclear cells (PBMC) from patients with metastatic melanoma were incubated in RPMI medium 1640 and 10% autologous human serum instead of 10% fetal calf serum, while serum from either healthy donors or patients with primary melanoma did not affect the level of cytotoxicity. The serum-mediated suppression was not restricted by major histocompatibility complex and was time-dependent. Addition of 10% human serum from the patients with metastatic melanoma [HS-Pt(m)] to the culture of PBMC with rIL-2 at the same time or 1 day after incubation significantly inhibited LAK activity. However, addition of 10% HS-Pt(m) 2 or 3 days after incubation did not inhibit LAK activity. Incubation of PBMC for 2 h with a high dose (10(4) U/ml) of rIL-2 in the presence of 10% HS-Pt(m), followed by incubation in the absence of either rIL-2 or HS-Pt(m), did not affect LAK cell activity. These results suggest that HS-Pt(m) inhibits the early stage of LAK cell differentiation, rather than the binding of rIL-2 to PBMC or a later stage in the differentiation. In contrast to PBMC, monocyte-depleted peripheral blood lymphocytes exhibited comparable levels of LAK activity when cultured with rIL-2 either in 10% fetal calf serum, 10% human serum from healthy donors or 10% HS-Pt(m). Addition of purified autologous monocytes to the culture of monocyte-depleted peripheral blood lymphocytes with rIL-2 suppressed LAK cell induction when 10% HS-Pt(m) was present. Thus serum-mediated suppression of LAK cell induction is largely dependent on the presence of monocytes, which may produce a secondary inhibitor that acts on lymphocytes. Addition of indomethacin to the culture did not reverse this monocyte-dependent serum-mediated suppression in a majority of cases, suggesting that prostaglandin E2 does not have a major role in the suppression.

Expansion of lymphokine-activated killer cells for clinical use utilizing a novel culture device

The major problems encountered in the application of lymphokine-activated killer (LAK) cell therapy in man are the massive culture volumes required for LAK cell induction and the paucity of LAK cells available for administration (human doses are ⩽ 10% of effective murine LAK cell doses). We have, therefore, developed and tested a plastic porous culture device, Sclair plastic bags (E.I. DuPont De Nemours Co.), that can be utilized at virtually any volume and does not require rotation for optimal use. Normal or patient lymphocytes were cultured in the device or in plastic 16 mm wells at 1–20 × 10 6/ml RPMI 10% human sera with 1500 pM interleukin-2 for 4 days: LAK cell activity did not decline despite high cell densities. The device was equal to the 16 mm wells in induction of normal donor and patient LAK cell activity when either autologous fresh tumor or Raji targets were used. In a non-therapeutic clinical evaluation we isolated and stored in liquid nitrogen autologous tumor cells from 11 patients with cancer. 2–6 weeks post-operatively lymphocytes and mononuclear cells from these patients and paired normal donors were obtained and LAK cells were induced in Sclair bags or standard culture wells. Autologous patient LAK cell activity and normal donor LAK cell activity against patient's tumor cells were equivalent in the Sclair culture device and culture well system. Lymphocyte recovery and [ 3H]thymidine incorporation were also similar. Subsequently, we developed an expansion scheme utilizing the device in which cell density was maintained at optimal levels by changing media and reducing cell concentration after 6, 10 and 14 days of culture. We were able to expand LAK cell number 5–10-fold with no loss of LAK cell activity in this time frame utilizing both normal and patient cells. In this system plasma and sera were equivalent in their capacity to support LAK cell expansion but < 10% plasma or sera supported suboptimal activation. Thus, we have developed a practical system to augment the number of LAK cells available for human LAK cell therapy and simultaneously reduce the complexity and volume of the induction system.

Accessory cells, dendritic cells, or monocytes, are required for the lymphokine-activated killer cell induction from resting T cell but not from natural killer cell precursors.

In this study we have investigated the role of accessory cells in the development of lymphokine-activated killer cells (LAK) from highly purified human NK and small resting T cell progenitors. As accessory cells we used autologous, as well as allogeneic, monocytes, and dendritic cell enriched cells. Both NK and T cells were able to generate LAK activity, but their activation requirements were different. NK cells were activated merely by IL-2, and accessory cells did not enhance their lytic activity in the presence or absence of IL-2. Conversely, T cells were practically unresponsive to even high concentrations of IL-2 having a strict requirement for accessory cells for the development of lytic activity and proliferation. Accessory cells differed in their ability to activate T cells presumably depending on their ability to induce IL-2 synthesis, allogeneic dendritic cells being the most effective accessory cells and IL-2 synthesis stimulators. Allogeneic accessory cells could induce lytic activity in T cells even in the absence of exogenous IL-2. Thus, accessory cells play a central role in expanding the LAK effector cell population.

Induction of lymphokine-activated killer cells from rat thymocytes using recombinant human interleukin-2.

Using a 4-h 51Cr release assay, we observed that thymocytes from Fischer strain rats incubated with recombinant human interleukin-2 (rhIL-2) developed cytotoxicity to YAC-1 lymphoma, 9L-glioma, and B-16 melanoma cells (effector/target ratio = 25/1). Induction of the lymphokine-activated killer (LAK) cells was as follows: (1) when 5 x 10(6)/ml thymocytes were cultured with various concentrations of rhIL-2 (50, 125, 250, 500, or 1,000 units/ml) for 4 days, no cell proliferation was observed at any concentration. However, the LAK cells showed significant cytotoxicity toward all tumor cells at more than 50 units/ml. (2) When 5 x 10(6)/ml thymocytes were cultured for 1 to 6 days with 250 units/ml of rhIL-2, the harvested cell count decreased markedly after the 2nd day. The cytotoxicity of all the tumor cells became significant after the 2nd day, with peak activity on the 4th day. In rat splenocytes, on the other hand, the LAK cells could not be identified because rat splenocytes developed nonspecific cytotoxicity in medium containing fetal calf serum without adding rhIL-2.

Prerequisite for the induction of lymphokine-activated killer cells from T lymphocytes.

Human blood mononuclear cells were separated into Leu-11+7-NK, Leu-11-7+, and Leu-11-7-T cells by means of a combination of the Percoll gradient method and C-mediated cytolysis using mAb. When purified Leu-11+7-NK, Leu-11-7+, and Leu-11-7-T cells were cultured with rIL 2 (500 U/ml) for 6 days in a medium supplemented with 10% FCS, Leu-11+7-NK cells responded at the maximum level and Leu-11-7+ cells responded moderately as shown by both cell-proliferation response and cytotoxic activity generated. On the other hand, Leu-11-7-T cells did not respond at all to rIL-2. However, when Leu-11-7-T cells were cultured with rIL-2 in a medium supplemented with 10% autologous serum, they showed considerable responsiveness to rIL-2. In addition, much greater response to Leu-11-7-T cells were produced by the addition of monocytes. Monocyte cytokines, neither IL 1, IFN-gamma, TNF, nor their combination were able to substitute for monocytes in the induction culture. In contrast, the response level of Leu-11+7- NK cells remained unchanged irrespective of supplementation with autologous serum to medium or the addition of monocytes to the culture. These results indicated that culture conditions in the experiments significantly affected the results as to determination of lymphokine-activated killer cell precursors, especially the result pertaining to the conversion of T lymphocytes to lymphokine-activated killer cells. Under appropriate conditions, not only NK cells but also T cells are important precursors of lymphokine-activated killer cells.

The effect of adherent cells on induction of lymphokine-activated killer cells: Study in patients with hepatocellular carcinoma and liver cirrhosis.

The effect of adherent cells on induction of lymphokine-activated killer cells: Study in patients with hepatocellular carcinoma and liver cirrhosis.

The regulatory effect of adherent cells on lymphokine activated killer cells

We analyzed the effect of adherent cells on the induction of lymphokine-activated killer (LAK) cell activity by depleting adherent cells from peripheral blood lymphocytes (PBL) or by adding adherent cells to PBL before culture with interleukin-2. We found that adherent cells clearly down-regulate LAK cell induction. These inhibitory effects are dependent on the number of adherent cells added. Inhibitory effects of adherent cells are abolished by the addition of indomethacin to the LAK culture. Soluble factors derived from adherent cells, such as interferons and interleukin-1, have a slight enhancing effect on LAK induction. In contrast, adherent cells appear to inhibit LAK induction primarily by producing prostaglandin E2(PGE2). PGE2 in turn inhibits the induction of LAK effector cells by inhibiting the expression of the transferrin receptor on LAK cells. These effects are manifested most strikingly in the early phases of LAK induction.

Frequent T4-positive cells with cytolytic activity in spleens of patients with Hodgkin's disease (a clonal analysis).

Purified T lymphocytes isolated from spleens of untreated patients with Hodgkin's disease (HD) were cloned by using a microculture system previously shown to allow clonal expansion of virtually all peripheral blood T lymphocytes. Cells were plated under limiting conditions with irradiated feeder cells and PHA. Interleukin 2 (IL 2)-containing supernatants were added 48 hr later. The phenotypic and functional characteristics of a total number of 221 clones derived from six different HD spleens were investigated and compared with those of 133 clones obtained from three spleens of otherwise healthy individuals who underwent posttraumatic splenectomy. The majority of T cell clones derived from HD spleens expressed the T4+ (helper/inducer) phenotype. However, further functional characterization showed that as much as 50% of these T4+ clones displayed cytolytic activity in a lectin-dependent lytic assay allowing detection of cytolytic cells of any specificity. In contrast, less than 10% T4+ clones derived from control spleens were cytolytic, as assessed by the same lectin-dependent lytic assay. The cytolytic potential of T4+ and T8+ clones established from spleens of patients with HD did not reflect the induction of lymphokine-activated killer cells, because only a minority of them displayed natural killer (NK) activity against NK-sensitive K562 and MOLT-4 cell lines. These findings indicate that T lymphocytes found in the spleens of patients with HD may represent, at least in part, the expansion of a subset present in small percentages among normal peripheral blood or spleen T lymphocytes, which is involved in a cytotoxic reaction.

Induction of lymphokine activated killer cells in serum-free medium

Lymphokine activated killer (LAK) cells may play a role in immunosurveillance against spontaneous neoplasms. To date, LAK cells have been grown in medium supplemented with human serum (HS). Formulation of a defined medium that supports LAK cell generation would be useful to delineate the mechanisms that regulate LAK cell induction. When compared to HS medium, optimal induction of LAK cells required medium containing transferrin, insulin, bovine serum albumin, fatty acids (linoleic, oleic, palmitic), pyruvate and indomethacin. In addition, when 5% autologous monocytes were added to PBMC cultured in serum-free medium without indomethacin, marked suppression of LAK cell induction occurred. Addition of indomethacin abrogated suppression and resulted in enhanced cytotoxicity compared to non-adherent PBMC cultured in HS medium.