Lymphokine-activated killer (LAK) cell activity in tumor-infiltrating lymphocytes from non-small cell lung cancer

Tumor-infiltrating lymphocytes (TILs) are often seen in non-small cell lung cancers (NSCCs). Their functional role in the pathogenesis of lung cancer is unknown. The authors studied TILs in 27 patients with NSCC and determined the following: (1) the immunologic phenotype as defined by monoclonal antibodies against various surface markers, (2) activation state as indicated by interleukin-2 (IL-2) receptor expression and the kinetics of proliferation response to IL-2, and (3) the ability to develop lymphokine-activated killer (LAK) type cytotoxicity against both natural killer (NK)-resistant tumor cell targets (M14) and fresh autologous tumor cells. The authors' results show TILs from NSCCs to be a heterogeneous population composed of T-cells, B-cells, monocytes, and NK cells in frequencies similar to those found in peripheral blood lymphocytes (PBLs). TILs demonstrated increased IL-2 receptor expression and a more rapid proliferative response to IL-2 than PBLs, implying activation of TILs by the tumor milieu. Finally, TILs generated cytotoxicity against NK-sensitive (K562) and NK-resistant (M14) cell line targets consistently after in vitro treatment with IL-2 but were less consistent in their ability to lyse fresh autologous tumor cells and less effective than PBL LAK cells in lysing all targets. Comparison with LAK cells generated from normal volunteers suggests that decreased killing of autologous tumor cells only partially results from an inherent resistance to lysis by fresh NSCC targets. It appears, therefore, that tumor cells taken from NSCCs are not readily killed by the immune cells that infiltrate the tumor stroma and that this failure does not result from nonspecific immune deficiency in TILs.     

Phenotype analysis of tumour-infiltrating lymphocytes and lymphocytes in peripheral blood in patients with renal carcinoma

INTRODUCTION: When checking tumour growth, a number of observations indicate that the immune system plays a significant role in patients with renal cell carcinoma (RCC). Infiltration by lymphocytes (tumour infiltrating lymphocytes, TILs) is more prevalent in RCC than any other tumours. T lymphocytes are the dominant population of TIL cells. Views concerning the role of T lymphocytic subpopulations, B lymphocytes and NK cells in an anti-tumour response are not established. AIM: The aim is to determine the phenotype and activation of T and B lymphocytic subpopulations and NK cells and to compare their representation in tumour stroma and peripheral blood lymphocytes (PBL) in patients with RCC. MATERIAL AND METHODS: Samples of peripheral blood taken from the cubital and renal veins and tumour stroma cells were obtained from 44 patients in the course of their surgeries carried out due to primary RCC. TILs were isolated from mechanically disintegrated tumour tissue. Immunophenotype multiparametric analysis of PBL and TILs was carried out. Their surface and activation characteristics were determined by means of flow cytometer. RESULTS: CD3+ T lymphocytes (69.7%) were the main population of TILs. The number of CD3+/CD8+ T lymphocytes was significantly higher in TILs, 42.6% (p < 0.01), while CD4+ T lymphocytes were the majority population in peripheral blood, 41.35% (p < 0.001). The representation of CD3+/69+ T lymphocytes was significantly higher in TILs, 32.9%, compared to PBL (p < 0.001). On the contrary, the numbers of CD3+/CD25+, CD8+/57+ and CD4+/RA+ (naive CD4+ T lymphocytes) were higher in PBL (p < 0.001). The differences in representation of (CD3-/16+56+) NK cells and CD3+/DR+ T cells in TILs and PBL were not significant. CONCLUSION: The above-mentioned results prove that the characteristics and intensity of anti-tumour responses are different in compared compartments (tumour/PBL). CD3+/CD8+ T lymphocytes are the dominant lymphocytic population of TILs. The knowledge of the phenotype and functions of effector cells, which are responsible for anti-tumour response, are the basic precondition for understanding the anti-tumour immune response and the cause of its failure.     

Mistletoe Lectin I-Induced Effects on Human Cytotoxic Lymphocytes. I. Synergism with Il-2 in the Induction of Enhanced Lak Cytotoxicity

This report demonstrates that in vitro activation of human cells with the β-galactoside-specific lectin from mistletoe (ML-I) or interleukin-2 (IL-2) results in different patterns of activation and function of cytotoxic cells. It is now well established that natural killer (NK) and lymphokine-activated killer (LAK) cytotoxicity is mainly mediated by resting (NK) and IL-2-activated (LAK) CD56-positive (+) cells respectively. Culture of peripheral blood lymphocytes (PBL) for 3 days with ML-I led to expansion and activation of T cells which demonstrated NK-and LAK-like cytotoxicity. T lymphocyte subset analysis revealed that in total PBL, ML-I preferentially stimulated and expanded CD8+ T cells which mediated the cytotoxic effect. Incubation of highly purified CD8+ T cells alone with ML-I did not lead to induction of cytotoxicity, which required the presence of both CD4+ and CD 14+ (monocytes) cells, suggesting that ML-I does not exert a direct effect on CD8+ T cells. Activation of PBL with both ML-I and IL-2 resulted in simultaneous induction of T and CD56+ cell-mediated NK and LAK cytotoxicity. These data suggest that treatment with ML-I and DL-2 might provide an approach to induce maximum cytotoxicity against tumors and to recruit both T and NK cells for tumor therapy.     

Tumour-infiltrating lymphocytes in primary melanoma: functional consequences of differential IL-2 receptor expression

Tumour-infiltrating lymphocytes (TIL) have been isolated from early primary melanoma (Clark level III) and expanded in vitro using culture conditions with low concentrations of IL-2 (50 U/ml). Immediately after isolation TIL consisted of mainly CD3⁺ T cells, and the portion of CD56⁺ natural killer (NK) cells was below 20%. Fresh TIL cultures could be distinguished by CD25 expression since some contained up to 33%, others less than 5% CD25⁺ cells. These showed differences in subsequent development during in vitro expansion. CD25-cxprcssing cultures remained stable in their phenotype, whereas the second TIL type showed major changes: CD3 (ca 70–30%) expression decrease. CD25 (ca 5–35%) and CD56(ca 15–55%) expression increase. The TIL type, which remained dominated by CD3⁺ T cells, killed autologous tumour cells efficiently (⁵¹Cr-rclcase greater than 30% at a E/T ratio of 20:1). which could be blocked by MoAbs against MHC class I molecules. In contrast, the other TIL type exhibited weak cytotoxicity (less than 17%⁵¹Cr-release at an E/T ratio of 20:1) against the autologous tumour. Therefore, the expression of CD25 on freshly isolated TIL is a good marker for tumour specificity of in vitro expanded TIL.     

Later development of Fas ligand-mediated cytotoxicity as compared with granule-mediated cytotoxicity during the maturation of natural killer cells.

We classified CD56+ CD3- natural killer (NK) cells into CD2- CD56dim (CD2- NK), CD2+ CD56dim (CD2+ NK) and CD2+ CD56bright populations, and investigated mainly functional differences between the former two populations. CD2- and CD2+ NK cells were the same in their morphology and several surface molecules except for CD2. The percentages of CD2- NK cells in total NK cells were higher in the cord blood and marrow than in the peripheral blood of adults or children. Freshly isolated CD2- NK cells had CD2 in the cytoplasm, and gradually expressed it on the surface upon incubation with interleukin-2 (IL-2). These results demonstrated that CD2 is an antigen which appears on the surface during the maturation of NK cells. The granule-mediated cytotoxicities, which are mainly performed by the perforin molecule, of CD2+ NK cells against K562 and Daudi cells were higher than those of CD2- NK cells, and they were inhibited to the levels of CD2- NK cells by the addition of a blocking anti-CD2 monoclonal antibody (mAb). Fas ligand (FasL) mRNA was expressed in freshly isolated CD2+ NK cells but not in the CD2- NK cells. Neither freshly isolated NK populations showed FasL-mediated cytotoxicity, and only CD2+ NK cells lysed Fas-transfected targets after the 24-hr incubation with IL-2. Based on these results, CD2- NK cells have already developed granule-mediated cytotoxicity equal to that of CD2+ NK cells except for the CD2-associated activity, but they, unlike CD2+ NK cells, totally lack FasL-mediated cytotoxicity. These findings suggest that FasL-mediated cytotoxicity may be acquired at more mature stages of NK-cell maturation than granule-mediated cytotoxicity.     

Limiting dilution analysis (LDA) of cells responding to recombinant interleukin-2 without previous stimulation: evidence that all responding cells are lymphokine-activated potent effectors

The relationship between peripheral blood mononucleated cells spontaneously bearing the IL-2 receptor (IL-2R) and cell cytotoxicity for the natural killer (NK)-sensitive K562 target cell line was investigated. For this purpose, three types of experiments were performed. (i) Positive selection of cells spontaneously bearing the IL-2R was carried out by culturing peripheral blood lymphocytes (PBL) in the sole presence of recombinant IL-2 (rIL-2). Cytotoxicity was assessed at Day 6 of the culture in a 4 hr cytotoxic assay. (ii) Negative selection was performed by complement mediated lysis using the B1.49.9 monoclonal antibody which is specific for the IL-2R. (iii) Limiting dilution analysis of non-adherent PBL was carried out in the presence of rIL-2 alone. The colonies obtained were divided and daughter colonies assayed for anti-K562 cytotoxicity in a 6 hr cytotoxic assay and for proliferation. The results show that: (i) a 6-day culture of human non-adherent PBL in the presence of rIL-2 alone leads to a sharp increase in anti-K562 cytotoxicity; (ii) depletion of B1.49.9 positive PBL strongly decreases cytotoxicity against K562 targets; (iii) limiting dilution analysis indicates that all colonies grown without activation in the presence of autologous serum and rIL-2 can mediate cytotoxicity against K562 targets, which is not the case when the starting population is activated. Thus, our data taken together strongly suggest that lymphocytes spontaneously bearing the IL-2R are directly involved in K562 lysis by fresh PBL (classical NK activity). Moreover, we demonstrate that all colonies able to proliferate without any activation, in the sole presence of rIL-2, are potent K562 killers (in this case, these cells correspond to the so-called lymphokine activated killers, LAK).     

Human recombinant IL-4 decreases the emergence of non-specific cytolytic cells and favours the appearance of memory cells (CD4+CD45RO+) in the IL-2-driven development of cytotoxic T lymphocytes against autologous ovarian tumour cells.

As IL-4 and IL-6 have also been reported to promote the development of T lymphocytes such as IL-2, we investigated their role in the development of specific cytotoxic T lymphocytes (CTL) against autologous ovarian tumours in mixed lymphocyte tumour cultures (MLTC). Peripheral blood lymphocytes (PBL) from five ovarian carcinoma (OC) patients were incubated with autologous OC cells at a PBL:OC cell ratio of 20:1 in IL-2 alone (50 U/ml for the first week and 200 U/ml thereafter) or with IL-4 (100 U/ml) and/or IL-6 (5 U/ml). Neither IL-4 nor IL-6 improved lymphocyte proliferation consistently. In contrast, IL-4 reduced significantly the development of LAK activity as assayed against Daudi cell line, and decreased modestly the emergence of natural killer (NK) activity as assayed against K562. This property was not shared by IL-6. The prevention of the development of non-specific cytolytic activity (LAK and NK activities) was much stronger when the MLTC was started with IL-4 in the absence of IL-2 during the first week in culture. A concomitant drop in NKH-1 expression (CD56) was observed. By inhibiting the emergence of non-specific cytotoxicity, IL-4 provided better evidence of the specific cytolytic activity directed at ovarian cells. In parallel, a significant increase in the generation of memory cells (CD4+CD45RO+) was observed with IL-4. In conclusion, in this model, IL-4 added before IL-2 decreases significantly the emergence of non-specific cytotoxic cells, and promotes the generation of memory cells. These properties may be of interest in the design of strategies aimed at obtaining tumour-specific cells for investigational and immunotherapeutic purposes.     

Accumulation of CD16-CD56+ natural killer cells with high affinity interleukin 2 receptors in human early pregnancy decidua.

Most human peripheral blood natural killer (NK) cells express the phenotype CD16+CD56+. However, a very minor subset of NK cells express CD16-CD56+, and these NK cells bear both interleukin 2 receptor (IL-2R)alpha (p55) and IL-2R beta (p75) (high affinity IL-2 receptors). In this report, we demonstrate that in human early pregnancy decidua--an interface between maternal immunocompetent cells and fetus (placenta)--abundant (approximately 83%) CD16-CD56+ NK cells with high affinity IL-2 receptors were present, and these cells responded to low amounts of IL-2 (4.5 pM). These CD16-CD56+ NK cells significantly expressed an early activation antigen, CD69, in vivo, whereas peripheral CD16-CD56+ NK cells did not express CD69. These findings suggest that CD16-CD56+ NK cells in early pregnancy decidua may be activated in vivo, and may play an important role in immunoregulation during early pregnancy. Also, decidual lymphocytes may be useful materials to study the mechanism of MHC-unrestricted cytotoxicity of this type of NK cells.     

Heterogeneity amongst natural killer cells revealed by limiting dilution culture; selectivity against virus-infected and tumour cell targets.

Previous studies have suggested that natural killer (NK) cells exhibit heterogeneous cytotoxicity towards different tumour cell targets. No studies have set out to determine whether different NK populations have relative selectivity for virus-infected cells. The aims of this study were to determine if this was the case for short-term clones, and whether there were differences in relative selectivity for particular target cells between clones with NK activity but with different surface phenotypes. Cells from different starting populations [whole peripheral blood lymphocytes (PBL), E-rosette positive or negative, CD16+ or CD3- cells] were grown in limiting dilution culture (LDC) with interleukin-2 (IL-2). The precursor frequency (NK-p) of cells proliferating and exhibiting NK activity towards various virus-infected or uninfected fibroblasts or tumour cell targets was determined by split-well analysis of the LDC. The relative NK-p were similar for different individuals, but were much lower for virus-infected fibroblasts than a tumour cell target. The pattern of cytotoxicity of 757 short-term clones, identified from the LDC, against four to five tumour and virus-infected target cells were analysed. We conclude that there was selective lysis of virus-infected cells by a proportion of NK clones which were predominantly PBL-derived (mainly CD3+). Twenty-six per cent of E(+)-derived clones lysed Molt4 cells only in the absence of phytohaemagglutinin (PHA), and a proportion of PBL- or E(+)-derived clones (up to 44%) lysed uninfected or virus-infected fibroblasts but not Molt4+PHA. Thus, under hese conditions lectin-induced cytotoxicity does not detect total potential cytotoxicity.     

Phenotype, cytokine production and cytolytic capacity of fresh (uncultured) tumour-infiltrating T lymphocytes in human renal cell carcinoma

We investigated the phenotype and functional capacities of tumour-infiltrating lymphocytes (TIL), freshly isolated from primary renal cell carcinoma (RCC) specimens (n = 20). Three-colour flow cytometry immunophenotyping revealed that RCC TIL consist mainly of CD3⁺ T cells, with a clear predominance of CD4⁻CD8⁺ over CD4⁺ CD8⁻ T cells, and a marked population of CD4⁺ CD8⁺ T cells. Natural killer (NK) cells were also strongly represented (> 25% in 15 of 20 tumour samples), while B cells constituted a minor TIL subset (< 5% in 18 of 20 tumour samples). More importantly, the T and NK cells within the tumour displayed a significantly higher expression of the early activation marker CD69 than their counterparts in adjacent normal renal tissue and in peripheral blood. Expression of CD54 and of HLA-DR was also elevated on CD3⁺ TIL, and HLA-DR expression was further vigorously up-regulated following ex vivo stimulation with anti-CD3, all suggesting enhanced immune activity within the tumour microenvironment. CD3⁺ CD4⁺ TIL displayed a normal capacity to up-regulate CD25 expression and to secrete both Th1-type (IL-2, tumour necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ)) and Th2-type (IL-4, IL-5 and IL-10) cytokines upon triggering with anti-CD3. Furthermore, cytokine production was susceptible to modulation by CD28 costimulation. CD3⁺ CD8⁺ TIL, on the other hand, consistently demonstrated a poor up-regulation of CD25 upon triggering with anti-CD3, and displayed poor ex vivo cytolytic activity in an anti-CD3-redirected 4-h cytotoxicity assay against murine P815 cells. Collectively, our findings indicate that the CD3⁺ CD4⁺ TIL in RCC have normal functional capacities, whereas the proportionally major CD3⁺ CD8⁺ TIL are functionally impaired. The relevance of these findings to the in vivo local immune response in RCC is discussed.     

In vitro activation of lymphocytes from nonsmall cell cancer patients by interleukin 2 and anti-CD3 antibody

The current interest in adoptive immunotherapy of cancer has stimulated research into novel approaches of activating lymphocytes in vitro. We have studied the effect of anti-CD3 antibody on the in vitro activation of peripheral blood lymphocytes and tumor infiltrating lymphocytes (TIL) taken from patients with nonsmall cell cancer of the lung (NSCC). We demonstrate that anti-CD3 substantially enhances the proliferative response and bulk culture growth of interleukin 2 (IL-2)-activated killer cells. The addition of anti-CD3 to IL-2-treated TIL enhances their cytotoxicity against fresh autologous NSCC tumor targets, but not against the cancer cell lines K562 and M14. The effectors generated by culture in IL-2 and anti-CD3 have greatly increased IL-2 receptor expression and are predominantly CD4+ cells. These results establish anti-CD3 as a potentially powerful agent in the in vitro activation of lymphocytes from cancer patients.     

Activation of human NK cells by plasmacytoid dendritic cells and its modulation by CD4+ T helper cells and CD4+ CD25hi T regulatory cells

Plasmacytoid dendritic cells (pDC) represent a specialized cell population that produce type I interferon (IFN) in response to virus. Although type I IFN is a natural killer (NK) cell modulator, a direct role for pDC in coordinating NK cell functions has not yet been elucidated in detail, especially in humans. Here we report that human pDC, following engagement of Toll-like receptor (TLR) 9, not only activate autologous NK cells, as indicated by the induction of CD69 expression, but also enhance their effector functions, especially cytotoxicity. Moreover, they can induce selective proliferation of CD56bright CD16- NK cells. This activity can be strongly augmented by the addition of autologous CD4+ CD25- T helper cells in an IL-2-dependent fashion. Strikingly, CD4+ CD25hi T regulatory (Treg) cells completely abrogate this IL-2-dependent proliferation of NK cells, while they are not able to influence NK cell activation or proliferation solely induced by pDC. Our data show that TLR9-engaged pDC represent a critical stimulus for human NK cells and that CD4+ Th cells and CD4+ CD25hi Treg cells play an important role in modulating human NK cell responses.     

Long-term cultures of human peripheral blood lymphocytes with recombinant human interleukin-2 generate a population of virtually pure CD3+ CD16- CD56- large granular lymphocyte LAK cells.

It has been reported that lymphocytes from peripheral blood (PBL) cultured with interleukin-2 (IL-2) produce predominantly CD16+ lymphokine-activated killer (LAK) cells. We developed a two-step method to generate LAK cells from human PBL in long-term cultures (10-12 days) with recombinant human IL-2 (rhIL-2) and characterized the evolving LAK cell population by testing its phenotype and cytotoxic activity as a function of time. The starting PBL displayed some natural killer (NK) cytotoxicity but no LAK activity. At day 6, the cells were a mixed population of about 80% CD3+ and 6% CD16+ cells. Little proliferation was evident but strong LAK activity was detected. After 10-12 days, major cell expansion had occurred and they were essentially a pure (greater than 90%) CD3+ CD16- CD56- cell population large granular lymphocyte (LGL) by morphology that displayed strong non-MHC-restricted killing activity (greater than 200 lytic units). Over the same period of time, the CD16+ cells had almost completely regressed in these cultures. This preferential induction of CD+ LAK cells was not an effect of IL-2 concentration as 10 U/ml was as effective as 500 U/ml. Further characterization revealed a major population of CD4+ (60%) and CD8+ (30%) with a smaller fraction (less than 9%) of gamma delta + cells. These results indicate that a virtually pure CD3+ LAK cells population was produced with long-term cultures of lymphocytes from peripheral blood in rhIL-2, in which active proliferation of the CD3+ but not CD16+ cells occurred.     

Suppression of natural killer cells in the presence of CD34+ blood progenitor cells and peripheral blood lymphocytes.

Abstract Mobilization of CD34 + peripheral blood progenitor cells (PBPCs) with granulocyte-colony stimulating factor (G-CSF) may induce functional alterations in peripheral blood lymphocyte (PBL) subsets. We and others have shown that natural killer (NK) cells from PBPC collections are less expandable in vitro than those obtained during steady-state hematopoiesis. We show here that the extent of this proliferation deficit is related to the number of circulating CD34 + cells in vivo at the time of PBPC apheresis. Likewise, addition of autologous CD34 + cells to unseparated PBL reduced the expansion of the NK-cell subset by 22.2% +/- 6.0% (n = 10; P <.005). In contrast, when using purified NK cells, their proliferation remained unimpaired by autologous CD34 + cells. Supernatants from CD34 + cells cultured with autologous PBLs had an inhibitory effect on proliferation of purified NK cells (n = 16; P =.03), indicating that an interaction between CD34 + cells and lymphocytes is essential for the suppressive effect on NK cells. To investigate the role of T cells in this interaction, intracellular cytokines were determined in T cells cultured for 7 days with or without autologous CD34 + cells. When cultured with CD34 + cells, the frequency of IL-2-producing CD4 + and CD8 + T cells was reduced by 19% and 24%, respectively, compared with T cells cultured alone (n = 7; P =.016). Interferon-gamma-producing T cells were slightly reduced ( P = not statistically significant [ns]). Finally, the influence of T cells and NK cells on the recovery of myeloid colony-forming cells (CFU-GMs) from purified CD34 + cells was examined. In the presence of T cells, 16% +/- 6% of the input CFU-GM recovered after 7 days, compared with 5% +/- 4% in the presence of NK cells (n = 5; P = ns). Our findings point to an inhibition of NK-cell proliferation mediated by an interaction of CD34 + cells and T cells occurring during PBPC mobilization with G-CSF.     

Characterization of Human CD4+ T-Cell Clones that Secrete Helper Factor(s) for B-Cell Proliferation and Maturation

Human peripheral blood lymphocytes (PBL) were activated with K46M, a m mitogenic monoclonal antibody against La-reactive T lymphocyte surface structures. The cultures were expanded in the presence of interleukin 2 (IL-2). After 1 month of culture, the activated T cells were cloned by limiting dilution at 0.5 cells/well. Five clones with the CD3+CD4+ phenotype and one clone with the CD3+CD8+ phenotype were obtained. The CD3+CD8+ clone (K99) displayed a strong major histocompatibility complex (MHC)-unrestricted cytolytic activity against MOLT-4 and a weaker reactivity against the bladder tumour cell lines T24 and RT4. The natural killer (NK)-susceptible K562 cells were not lysed. Two of the CD3+CD4+ clones (K91 and K914) showed a helper activity in pokeweed mitogen (PWM)-induced IgG production by B cells. These cells differed in the expression of CD45R and CDw29 antigens, as defined by the monoclonal antibodies 2H4 or D10D11 and 4B4. When stimulated with PWM for 48 or 72 h, clone K91 and an additional CD4-positive clone (K913) secreted a factor into the supernatants which helped B cells to produce IgG. The K913 supernatant also induced some IgM production. The supernatant obtained after similar stimulation of K914 cells was inactive. None of these supernatants induced B cells to proliferate when tested together with phorbol myristate acetate (PMA). However, when K91 and K914 cells were activated with phytohaemagglutinin (PHA) for 48 or 72 h, the supernatant from K91 was strongly helpful in B-cell proliferation, whereas the supernatant from K914 cultures was only moderately active. In conclusion, we have established human T helper clones that release different factors supporting either B-cell proliferation or maturation when stimulated with PWM or PHA.     

Functionally different HTLV I-infected T cell lines with the same phenotype derived from a patient with melanoma

Two autologous T cell lines infected with HTLV I are described. T cells from a patient with malignant melanoma were infected with HTLV I by co-culture with a HTLV I-producing T cell line, SLB I. Both T cell lines express identical phenotype (CD3+, CD4+, 4B4+, 2H4-) but they demonstrate marked differences in growth characteristics and function. One of these two lines, referred to as TFTx, established from the autologous tumor activated peripheral blood lymphocytes (PBL), grows in culture without any exogenous interleukin-2 (IL-2), secretes no detectable amount of IL-2 or gamma interferon (IFN) or tumor necrosis factor (TNF) alpha or beta. The other line (TFATx), established from a co-culture between the autologous PBL, lethally irradiated TFTx and the autologous melanoma cells TF-M, is IL-2-dependent for growth, secretes IFN gamma and TNF alpha and beta. TFTx exerts profound suppression of generation of cytotoxicity in the autologous PBL in co-culture with the autologous melanoma cells TF-M. In contrast, the TFATx enhances the cytotoxic response in similar co-culture. In addition to suppression of cytotoxic response, supernatant from TFTx suppresses the lectin-activated proliferation of PBL. In 4-h chromium release microcytotoxicity assays, neither line exhibits conventional characteristics of cytotoxic cells. Thus, phenotypically identical HTLV I-infected CD4+ T cell lines derived from the same individual exhibit opposite regulatory functions.     

Immunologic effects of intermediate-dose IL-2 i.v. after autologous hematopoietic cell transplantation in pediatric solid tumors.

Adoptive immunotherapy with interleukin-2 (IL-2) may control minimal residual disease (MRD) and prevent relapse after autologous hematopoietic cell transplantation (AHCT). The objective of this study was to determine the immunologic effects of intermediate doses of intravenous (i.v.) IL-2 after AHCT in children with poor-prognosis solid tumors. Eleven patients received a median five cycles consisting of escalating doses of IL-2 i.v. for 5 days after a median time interval of 94 days post-AHCT. The phenotype of lymphocyte subsets was investigated before and after each cycle, and parallel determination of natural killer (NK) cell activity was performed. Immunotherapy induced a significant increase in total lymphocyte count (TLC), T, NK, and, to some extent, B cells. Among NK cells, CD56+ bright cells expanded more than CD56+ dim cells. High expansion of CD56+ cells with CD94 inhibitory receptor was observed, whereas no difference was recorded in the number of CD3+ CD56+ and CD8+ CD57+ cells. NK activity stabilized after the first cycle of IL-2 and remained elevated during the study period. Cycles of IL-2 immunotherapy induced repeated significant expansion of T cells and NK cells, mostly of the immature CD56+ bright phenotype. Despite enhanced NK activity, relapses occurred frequently, which might have been due to increased CD94 activation and a poor response from the cytotoxic NK T cells and CD8+ CD57+ T cells.     

Effect of IL-21 on NK cells derived from different umbilical cord blood populations

IL-21 plays a role in the proliferation and maturation of NK cells developed from hematopoietic stem cells. In this study, we found that IL-21, in the presence of physiological concentration of hydrocortisone (HC), has a significant impact on the functions of NK cells derived from umbilical cord blood (CB) populations. We demonstrate that IL-21, in combination with Flt3-ligand, IL-15 and HC, induces high proliferative responses and, apart from enhancing NK-mediated cytotoxicity, it also induces a significant increase in lymphokine-activated killer activity of CB/CD34+-derived CD56+ cells. In addition, IL-21 induced changes in the CD56+ cell cytokine secretion profile. Thus, we observed increased levels of IL-10 and granulocyte macrophage colony-stimulating factor, whereas tumor necrosis factor-alpha levels decreased. IFN-gamma production was also modified by IL-21, depending on the presence or absence of IL-18. CB/CD34+ cells did not express the IL-21R ex vivo, but receptor expression was induced during their commitment to differentiation into CD56+ cells. Our data ascribe to IL-21 an essential role on NK cell development and function under conditions similar to the in vivo CB microenvironment.     

The emergence of non-cytolytic NK1.1+ T cells in the long-term culture of murine tumour-infiltrating lymphocytes: a possible role of transforming growth factor-beta.

The mechanism by which murine tumour-infiltrating lymphocytes (TIL) decreased their anti-tumour activity during an in vitro culture with interleukin-2 (IL-2) was investigated. A phenotype analysis revealed that the TIL cultured for 7 days (TIL-d7) were exclusively NKI.1- CD4- CD8+ CD3+ cells and that this population was replaced by natural killer (NK)1.1+ CD4- CD8 CD3+ cells by day 27 (TIL-d27) during the culture of TIL. The TIL-d7 cells showed a cytolytic activity against B16 melanoma, whereas the TIL-d27 cells had lost this activity, suggesting that the decrease in the anti tumour effect of TIL during the culture with IL-2 was due to their populational change. Analysis on the characteristics of the TIL-d27 cells revealed that they expressed skewed T-cell receptor (TCR) V beta 5 and increased mRNA expression of V alpha 14. In addition, they expressed transforming growth factor beta (TGF-beta) mRNA. Interestingly, TGF-beta augmented the proliferation of TIL-d27 cells under the presence of IL-2, but suppressed that of TIL-d7 cells. Moreover, the proliferation of TIL-d27 cells was suppressed by anti-TGF-beta monoclonal antibody. Collectively, these results suggest that, in contrast to its suppressive effect on anti-tumour effector T cells. TGF-beta could be an autocrine growth factor for NKL1.1+ T cells and thereby induce non-cytolytic NK1.1+ T cells in the long-term culture of TIL.     

Expansion and immunological study of human tumor infiltrating gamma/delta T lymphocytes in vitro.

Goffa/delta T cells have stimulated a lot of interest because of their unique features in antigen recognition and cytotoxicities to many autologous and/or allogeneic tumor cells. We have developed a novel method to selectively expand larger amounts of human tumor-infiltrating gamma/delta T lymphocytes (gamma/delta TILs) ex vivo by immobilized pan- anti-TCRgamma/delta monoclonal antibody in the presence of exogenous IL-2. The expanded gamma/delta TILs mainly expressed CD45RO and HLA-DR molecules and did not express CD4. CD8+ gamma/delta TILs accounted for 19% of gamma/delta TILs. The expression of CD25 molecule on expanded gamma/delta T cells was inducible and downregulated following a time course. The Vdelta1 and Vdelta2 subsets amount to 37 and 58%, respectively. The expanded gamma/delta TILs show an IL-2-dependent proliferation, MHC class I-unrestricted and TCRgamma/delta-related cytotoxicities to two MHC class I+ and two MHC class I+ allogeneic tumor cell lines in vitro.