Role of LFA-1/ICAM-1 in interleukin-2-stimulated lymphocyte proliferation

IL-2 delivery to CD8+ T cells during infection requires MRTF/SRF-dependent gene expression and cytoskeletal dynamics

Paracrine IL-2 signalling drives the CD8 + T cell expansion and differentiation that allow protection against viral infections, but the underlying molecular events are incompletely understood. Here we show that the transcription factor SRF, a master regulator of cytoskeletal gene expression, is required for effective IL-2 signalling during L. monocytogenes infection. Acting cell-autonomously with its actin-regulated cofactors MRTF-A and MRTF-B, SRF is dispensible for initial TCR-mediated CD8+ T cell proliferation, but is required for sustained IL-2 dependent CD8+ effector T cell expansion, and persistence of memory cells. Following TCR activation, Mrtfab-null CD8+ T cells produce IL-2 normally, but homotypic clustering is impaired both in vitro and in vivo. Expression of cytoskeletal structural and regulatory genes, most notably actins, is defective in Mrtfab-null CD8+ T cells. Activation-induced cell clustering in vitro requires F-actin assembly, and Mrtfab-null cell clusters are small, contain less F-actin, and defective in IL-2 retention. Clustering of Mrtfab-null cells can be partially restored by exogenous actin expression. IL-2 mediated CD8+ T cell proliferation during infection thus depends on the control of cytoskeletal dynamics and actin gene expression by MRTF-SRF signalling.

Parametrial fat tissue from high fat diet-treated SKH-1 mice stimulates transformation of mouse epidermal JB6 cells

Our previous studies indicated that decreasing visceral adipose tissue by surgical removal of the parametrial fat pads inhibited UVB-induced carcinogenesis in SKH-1 mice fed a high fat diet (HFD), but not a low fat diet (LFD) indicating that the parametrial fat tissue from mice fed a HFD played a role in skin carcinogenesis.

OBJECTIVE

In the present study, we sought to investigate how a HFD may influence the intrinsic properties of the parametrial fat tissue to influence UVB-induced skin tumor formation.

METHODS AND RESULTS

Immunohistochemical staining, adipokine array, and flow cytometry showed that parametrial fat tissue from mice fed a HFD had a higher density of macrophage-fused dead adipocytes (crown-like structures), more adipokines, and stimulated the production of more reactive oxygen species compared with parametrial fat tissue from mice fed a LFD. These differences between parametrial fat tissue from mice fed a HFD and LFD were associated with their effect on the in vitro transformation of mouse epidermal JB6 cells. Our results indicated that fat tissue filtrate (an aqueous filtrate made from the parametrial fat pad) from mice fed a HFD enhanced the conversion of JB6 cells from an epithelial-like morphology to cells with a fibroblast-like morphology to a greater extent than fat tissue filtrate from mice fed a LFD. Studies indicated that the fibroblast-like cells had decreased levels of E-cadherin, increased levels of Twist as assayed by western blot. Fat tissue filtrate made from the parametrial fat tissue of mice fed a HFD had 160% more transforming activity than that from mice fed a LFD and formed malignant mesenchymal tumors in vivo.

CONCLUSION

These studies provide the first in vitro demonstration of a parametrial fat tissue-induced transformation of an epidermal cell.

Functions of γC cytokines in immune homeostasis: current and potential clinical applications

Cytokines that signal through receptor complexes containing the common gamma (gammaC) chain receptor subunit are central regulators of lymphocyte homeostasis. In this review, we discuss the four major gammaC cytokines that have proven activity in or potential for immunotherapy: IL-2, IL-7, IL-15 and IL-21. Their shared and unique activities on specific lymphocyte populations suggest therapeutic applications such as enhancing lymphocyte reconstitution, expanding tumor and pathogen-specific lymphocytes, and optimizing vaccines. Because the responsiveness of individual lymphocyte subsets varies under different situations such as lymphopenia and active immune responses, understanding the dynamics of gammaC-containing receptor expression is important in deciding how to achieve the most desired effect. Current understanding of the biology of gammaC cytokines suggests several clinical applications, including their direct administration or use in generation of lymphocytes for adoptive transfer, increasing their endogenous production, and potentiating their activity by complex formation with specific antibodies or their specific receptor-alpha subunits. Overall, gammaC cytokines have great potential, through their targeted use alone or in combination, to be an integral part of clinical interventions with enhanced efficacy and decreased toxicity.

Activation of cerebral endothelium is required for mononuclear cell recruitment in a novel in vitro model of brain inflammation

Brain inflammation is a common event in the pathogenesis of several neurological diseases. It is unknown whether leukocyte/endothelium interactions are sufficient to promote homing of blood-borne cells into the brain compartment. The role of mononuclear cells and endothelium was analyzed in a new experimental model, the isolated guinea-pig brain maintained in vitro by arterial perfusion. This preparation allows one to investigate early steps of brain inflammation that are impracticable in vivo. We demonstrate by confocal microscopy analysis that in vitro co-perfusion of pro-inflammatory agents and pre-activated fluorescent mononuclear cells induced endothelial expression of selectins and intracellular adhesion molecule-1 in correspondence of arrested mononuclear cells, and correlates with a moderate increase in blood-brain barrier permeability. Separate perfusion of pro-inflammatory agents and mononuclear cells induced neither mononuclear cell adhesion nor adhesion molecule expression. We demonstrate that co-activation of mononuclear cells and cerebral endothelium is an essential requirement for cell arrest and adhesion in the early stages of experimental cerebral inflammation.

Selective in vivo growth of lymphocyte function- associated antigen-1-positive murine myeloma cells. Involvement of function-associated antigen-1-mediated homotypic cell-cell adhesion

OBJECTIVES

Lymphocyte function-associated antigen-1 (LFA-1) expression on multiple myeloma cells and its potential role in myeloma biology have been the subject of conflicting literature reports. In this study we used the 5T experimental mouse model to analyze the involvement of LFA-1 in myeloma cell bone marrow homing, survival, and growth.

MATERIALS AND METHODS

The 5T33MM vitro (5T33MMvt) myeloma line was used. LFA-1 and intercellular adhesion molecule-1 (ICAM-1) expression were analyzed by flow cytometry. A small molecule antagonist of LFA-1/ICAM interactions, BIRT 377, was used to block LFA-1 in vitro. Transendothelial migration was assessed by measuring migration through Transwells coated with bone marrow endothelial cells. Immediate in vivo homing was analyzed by tracing 51Cr-labeled cells. Invert microscopic cell counting was used to analyze homotypic cell adhesion. Cell cycle analysis was used to analyze apoptosis. S+G(2)/M phase analysis and 3H-thymidine incorporation were used to assess proliferation. Cells were separated into LFA-1(+) and LFA-1(-) fraction by magnetic activated cell sorting.

RESULTS

5T33MMvt cells had a heterogeneous LFA-1 expression and all cells were positive for the LFA-1 ligand ICAM-1. LFA-1 inhibition with BIRT 377 did not affect transendothelial migration of the 5T33MMvt cells; however, it did result in cell cluster scattering, indicating LFA-1 involvement in homotypic cell-cell adhesion. No effect was observed on apoptosis, but the percentage of cells in S+G(2)/M phase was decreased by 39%. 3H-thymidine incorporation confirmed this effect on 5T33MMvt cell proliferation (38% reduction). When 5T33MMvt cells were injected into animals, all myeloma cells isolated at the end stage of the disease were LFA-1(+) in contrast to the situation before injection. LFA-1(+) and LFA-1(-) MM cells had similar in vivo bone marrow homing capacities. Mice injected with LFA-1(+) 5T33MMvt cells developed myeloma (5/5) within 12 weeks after injection. In contrast, LFA-1(-) recipients did not develop the disease (0/5), even 1 year after tumor inoculation.

CONCLUSIONS

Our data suggest that LFA-1-mediated homotypic cell-cell adhesion is involved in myeloma cell proliferation and raises the possibility that this interaction may have a crucial role in in vivo myeloma cell growth. LFA-1 does not appear to play a role in the bone marrow homing of these cells.

Hemophagocytic lymphohistiocytosis is associated with deficiencies of cellular cytolysis but normal expression of transcripts relevant to killer-cell-induced apoptosis

In 65 patients with hemophagocytic lymphohistiocytosis (HLH), we found an as yet undescribed heterogeneity of defects in cellular cytotoxicity when assay conditions were modified by the incubation time, the presence of mitogen, or interleukin-2 (IL-2). The standard 4-hour natural killer (NK) test against K562 targets was negative in all patients. In patients deficient in type 1 (n = 21), type 2 (n = 5), and type 4 (n = 8) HLH, negative NK function could be reconstituted by mitogen, by IL-2, or by prolongation of the incubation time (16 hours), respectively. Most patients (n = 31) displayed the type 3 defect, defined by a lack of any cellular cytotoxicity independent of assay variations. The characteristic hypercytokinemia also concerned counterregulatory cytokines, such as proinflammatory interferon-gamma (IFN-gamma), simultaneously elevated with suppressive IL-10 in 38% of types 1-, 2-, and 4-deficient patients and in 71% of type 3-deficient patients. Elevated IFN-gamma alone correlated with high liver enzymes, but sCD95-ligand and sCD25 did not-though these markers were expected to indicate the extent of histiocytic organ infiltration. Outcome analysis revealed more deaths in patients with type 3 deficiency (P =.017). Molecular defects were associated with homozygously mutated perforin only in 4 patients, but other type 3 patients expressed normal transcripts of effector molecules for target-cell apoptosis, including perforin and granzyme family members, as demonstrated by RNase protection analysis. Thus, target-cell recognition or differentiation defects are likely to explain this severe phenotype in HLH. Hyperactive phagocytes combined with NK defects may imply defects on the level of the antigen-presenting cell.

Cybr, a cytokine-inducible protein that binds cytohesin-1 and regulates its activity

Cytokines regulate lymphocyte development and differentiation, but precisely how they control these processes is still poorly understood. By using microarray technology to detect cytokine-induced genes, we identified a cDNA encoding Cybr, which was increased markedly in cells incubated with IL-2 and IL-12. The mRNA was most abundant in hematopoietic cells and tissues. The predicted amino acid sequence is similar to that of GRP-1-associated protein (GRASP), a recently identified retinoic acid-induced cytohesin-binding protein. Physical interaction, dependent on the coiled-coil domains of Cybr and cytohesin-1, was demonstrated by coimmunoprecipitation of the overexpressed proteins from 293T cells. Cytohesin-1, in addition to its role in cell adhesion, is a guanine nucleotide-exchange protein activator of ARF GTPases. Acceleration of guanosine 5prime prime or minute-O-(thiotriphosphate) binding to ARF by cytohesin-1 in vitro was enhanced by Cybr. Because the binding protein modified activation of ADP ribosylation factor by cytohesin-1, we designate this cytokine-inducible protein Cybr (cytohesin binder and regulator).

The glucocorticoid inhibition of LFA-1 and CD2 expression by human mononuclear cells is reversed by IL-2, IL-7 and IL-15

Glucocorticoids are agents endowed with powerful immunosuppressive and anti-inflammatory properties partially related to the inhibition of adhesion-related processes. We have previously demonstrated that glucocorticoids inhibit LFA-1 and CD2 expression in human peripheral blood mononuclear cells (PBMC) by down-regulating mRNA steady-state levels. In this study, we investigated whether glucocorticoids could also act indirectly by modulating the effect/function of cytokines whose expression are known to inhibit. To test this hypothesis, we replenished the following cytokines IL-2, IL-7, IL-15, TNF-alpha, IL-1beta, IL-4 and IL-10, in an in vitro PBMC culture system. Our results indicate that only the IL-2Rgamma-chain-dependent cytokines IL-2, IL-7 and IL-15, among the cytokines of this panel, could reverse the inhibition of glucocorticoids on PBMC adhesion molecule expression and the related functions of intercellular aggregation and proliferation. Furthermore, we also demonstrated that IL-2, IL-7 and IL-15 could induce de novo the synthesis of LFA-1 and CD2. Taken together, these data suggest that glucocorticoids inhibit PBMC LFA-1 and CD2 expression not only directly by modulating transcriptional events, but also indirectly through the inhibition of IL-2Rgamma-dependent cytokines.

The immune system in the elderly: III. Innate immunity

The capability to cope with infectious agents and cancer cells resides not only in adaptive immune responses against specific antigens, mediated by T and B lymphocytes clonally distributed, but also in natural immune reactions. These innate defence mechanisms include chemotaxis, phagocytosis, natural cytotoxicity, cell interactions, and soluble mediators or cytokines. However, specific and natural immune mechanisms are always closely linked and interconnected, providing the primary defense against pathogens. The Authors discuss the main changes observed with advancing age in granulocytes and natural killer (NK) cell activity, in the expression and function of adhesion molecules, and in the pattern of cytokine production. Since phagocytic function is the primary mechanism through which the immune system eliminates most extracellular pathogenic microorganisms, analysis of this function is of clinical importance. Neutrophils from aged subjects often exhibit a diminished phagocytic capacity, as well as a depressed respiratory burst, notwithstanding an activated state. The activity of NK cells during aging has been studied extensively and different results have been reported. The most consistent data indicate an increase in cells with high NK activity with advancing age. Cells from healthy centenarians can efficiently kill target cells. This finding seems to suggest that innate immunity and in particular NK cell activity, is not heavily deteriorated with age. Conversely, a low NK activity is a predictor of impending morbidity. Immunosenescence is associated with increased expression of several cell adhesion molecules (CAM) resulting in an augmented capacity to adhere. Finally, also the cytokine network, responsible for differentiation, proliferation, and survival of lymphoid cells, undergoes complex changes with age. The main findings are a Th1 to Th2 cytokine production shift and an increased production of proinflammatory cytokines, which could explain many aspects of age-associated pathological events, such as atherosclerosis and osteoporosis.

Functional down-regulation of beta1 and beta2 integrins of lamina propria lymphocytes (LPL) and tumor-infiltrating lymphocytes (TIL) in colorectal cancer patients

Integrins play an important role in various lymphocyte functions. In this study, we isolated lamina propria lymphocytes (LPL) and tumor-infiltrating lymphocytes (TIL) from normal and malignant tissues in patients with colorectal cancer, and examined the expression of beta1 and beta2 integrins on these lymphocytes quantitatively with two-color flow cytometry. Both LPL and TIL expressed a lower level of common beta1 chain (CD29) in CD4 and CD8 subpopulations than did peripheral blood lymphocytes (PBL). Among the associated alpha chains, the expression levels of alpha1 (CD49a) and alpha2 (CD49b) were slightly higher, whereas those of alpha4 (CD49d) and alpha6 (CD49f) were markedly reduced in LPL and TIL. No significant differences were observed in expressions of any alpha1 integrin chains between these two lymphocytes populations. Similarly, both alphaL (CD11a) and beta2 (CD18) were down-regulated in TIL and LPL with CD8+ cytotoxic phenotype, but not in those with CD4+ phenotype. CD8+ TIL expressed a slightly but significantly higher level of alphaLbeta2 than did CD8+ LPL. CD8+ LPL and CD8+ TIL consistently showed significantly decreased binding to purified ICAM-1, VCAM-1 and HT29 colon cancer cells as compared with CD8+ PBL. Although CD8+ TIL showed a slightly higher level of adhesion to these substrates than did CD8+ LPL, the level was much lower than that in PBL. The expression pattern and functional down-regulation of these integrins may be one of the reasons why TIL cannot eradicate the cancer cells in colorectal cancer.

Target cell-induced apoptosis in IL-2-activated human natural killer cells

We demonstrated that tumor cells induce cell death in lymphokine-activated NK (LAK) cells, but not in non-activated NK cells. Cell death in LAK cells involves nuclear condensation and DNA cleavage, all of which are characteristic features of apoptosis. The mechanism involves signaling through integrins and requires src family tyrosine kinases and protease activities. Engagement of an apoptotic signal molecule, Fas, may also trigger LAK cell death by apoptosis. It appears that LAK cells rapidly die by apoptosis after attacking tumor cells. This phenomenon may provide a means for potential tumor target cells to escape from natural immunosurveillance during therapeutic interventions such as those using IL-2 or LAK cells.

T-cell-mediated immunity to lymphocytic choriomeningitis virus in beta2-integrin (CD18)- and ICAM-1 (CD54)-deficient mice

The T-cell response to lymphocytic choriomeningitis virus was studied in mice with deficient expression of beta2-integrins or ICAM-1. In such mice, the generation of virus-specific cytotoxic T lymphocytes was only slightly impaired and bystander activation was as extensive as that observed in wild-type mice. T-cell-mediated inflammation, assessed as primary footpad swelling and susceptibility to intracerebral infection, was slightly compromised only in beta2-integrin-deficient mice. However, adoptive immunization of mutant mice soon after local infection did reveal a reduced capacity to support the inflammatory reaction, indicating that under conditions of more limited immune activation both molecules do play a role in formation of the inflammatory exudate. Finally, virus control was found to be somewhat impaired in both mutant strains. In conclusion, our results indicate that although LFA-1-ICAM-1 interaction is important for certain aspects of the T-cell-mediated response to viruses, T-cell activation is surprisingly intact in these mutant mice, indicating extensive functional redundancy within cell interaction molecules.

Keratinocytes and cytokine/growth factors

Cytokines are polypeptide growth factors produced by most nucleated cells in the body, including epithelial cells, keratinocytes, and Langerhans cells in the skin. Cytokines can be classified into interleukins, tumor necrosis factors, chemokines, colony-stimulating factor, interferons, and growth factors. Like classic hormones, cytokines bind to specific receptors to transmit their messages to target cells. Cytokine receptors can be divided into three cytokine receptor superfamilies: the immunoglobulin superfamily, the hematopoietin family, and the tumor necrosis factor family. Following cytokine/cytokine-receptor binding (first messenger), a signal transduction pathway is initiated. Factors affecting homeostasis in the skin and oral mucosa include a delicate balance between cytokines/cytokine-receptors and their antagonists. An imbalance in these variables can influence the development of cutaneous and oral diseases-such as lichen planus, autoimmune disorders, and some neoplastic processes- and can affect wound healing. Potential uses of cytokines include cancer and antiviral therapy.

An IgG3-IL-2 fusion protein has higher affinity than hrIL-2 for the IL-2R alpha subunit: real time measurement of ligand binding

The alpha subunit of the interleukin-2 (IL-2) receptor (IL-2R alpha)3 has the highest individual affinity for IL-2 and is the only subunit not known to bind other cytokines. The interactions between IL-2 and IL-2R alpha studied in cell binding assays have revealed a number of factors which may vary significantly in different cell lines used for these assays in different laboratories. In order to avoid the problems associated with cellular assays we used an optical biosensor to examine the interaction between IL-2R alpha and hrIL-2. Real-time measurement of association and dissociation resulted in a calculated KD of 1.9 x 10(-7) M for this interaction. We then examined the IL-2R alpha binding of a potentially bivalent IgG3-IL2 fusion protein previously shown to have a higher affinity than hrIL-2 for the high affinity IL-2R but not the intermediate affinity IL-2R. Biosensor measurements of association and dissociation of IgG3-IL2 to IL-2R alpha yielded a similar association rate but a decreased dissociation rate compared to hrIL-2, resulting in a KD of 5.3 x 10(-8) M. This system is applicable to the numerous IL-2 mutants with different affinities and activities and is generalizable to other cytokine/receptor interactions.

LFA-1 subunit expression in ulcerative colitis patients

The adhesion molecule, lymphocyte function associated antigen (LFA-1) consisting of two subunits, CD11a and CD18, mediates lymphocyte migration into tissue and cell effector functions. Previous observations showed no differences in LFA-1 expression by circulating lymphocytes between inflammatory bowel disease patients and controls. The aim of the present work was to study subsets of circulating LFA-1+ lymphocytes in ulcerative colitis (UC) patients versus healthy controls. Peripheral blood mononuclear cells were obtained from 16 UC patients and 10 healthy volunteers. The percentages of CD11alo, CD11ahi, CD18lo, CD18hi T and B cells, as well as Cd25 expression on these cells were studied using double staining with monoclonal antibodies and panning procedures. The percentage of CD11hi and CD18hi T cells was significantly decreased in quiescent UC patients as compared to active disease patients and healthy controls (P < 0.05). The majority of CD25+ T cells were expressing CD11a and CD18 with low density. A detectable percentage, 2% (range 1-6%), of CD11ahiCD25+ (but not CD18hiCD25+) was found in UC patients with moderate to severe disease, but not in those with inactive UC to healthy controls. In conclusion, the percentage of CD11ahi+ and CD18hi+ T cells is decreased in peripheral blood of quiescent UC patients, which is probably associated with the effect of specific treatment. The percentage of CD11ahi+IL-2R alpha+ T cells is increased in peripheral blood of patients with active (moderate and severe) UC, which most likely reflects a sustained T-cell activation due to a persistent inflammatory process.

Interleukin-2 and human immunodeficiency virus infection: pathogenic mechanisms and potential for immunologic enhancement

A hallmark of human immunodeficiency virus (HIV) infection is the progressive loss of CD4+ T lymphocytes; however, qualitative defects in immune responses occur prior to the precipitous drop CD4+ T cell numbers. One of the first immunologic defects to be described in HIV-infected individuals is a deficiency in interleukin (IL)-2 production. The addition of IL-2 in vitro to cultures of mononuclear cells from HIV-infected individuals partially or completely restored certain defective cellular immune responses. However, production of or addition of IL-2 has also been associated with increased viral replication in infected T cells. These observations underscore the pernicious correlation between immune activation and HIV replication. However, recent in vitro and in vivo studies have provided promising preliminary results suggesting that, at least at certain stages of disease, the benefits of IL-2 mediated immune enhancement may outweigh or override the inductive effects of this cytokine on HIV production.

Role of adhesion molecules in natural killer cell-induced DNA fragmentation of cytomegalovirus-infected fibroblasts

We investigated the roles of CD11a, CD11b, CD18, and CD54 adhesion molecules in non-adherent peripheral blood mononuclear cells (NPBMC)-induced DNA fragmentation of cytomegalovirus (CMV)-infected cells. DNA fragmentation in the supernatant from CMV-infected cells and NPBMC was assayed, and cytotoxicity against CMV-infected cells was calculated. Treatment of NPBMC with monoclonal antibodies to CD11a, CD11b, CD18, and CD54 significantly reduced cytotoxicity against CMV-infected cells. A combination of anti-CD11a, anti-CD11b, and anti-CD18 antibodies further inhibited cytotoxicity against CMV-infected cells. Cytotoxicity against CMV-infected cells treated with anti-CD54 antibody was also significantly inhibited. Binding of effector cells to target cells was not affected by treatment of NPBMC or CMV-infected cells with antiadhesion molecule antibodies. These results indicate that LFA-1 (CD11a/CD18), Mac-1 (CD11b/CD18), and ICAM-1 (CD54) adhesion molecules are involved in natural killer (NK) cell-induced DNA fragmentation in CMV-infected cells.

Changes of adhesion molecule (LFA-1, ICAM-1) expression on memory T cells activated with cytomegalovirus antigen

The expression of adhesion molecules (LFA-1, ICAM-1, CD29) on T cells activated with cytomegalovirus (CMV) antigen was investigated by three-color flow cytometry analysis. Peripheral blood mononuclear cells (PBMC) from CMV-seropositive adults were cultured with CMV or control antigen for 6 days. After culture, the expression of LFA-1, ICAM-1, and CD29 on T cells in subpopulations defined as CD45RO+ or CD45RO- was analyzed. The population of cells that expressed LFA-1 at high levels (LFA-1high) among CD4+C-D45RO+ cells increased when cultured with CMV antigen compared to control antigen. The population of cells that expressed LFA-1high cells among CD8+C-D45RO+ cells was down-regulated by culture for 6 days; however, the population of LFA-1high cells among CD8+CD45RO+ cells cultured with CMV antigen was higher than when cultured with control antigen. The population of LFA-1high cells among CD4+CD45RO- and CD8+CD45RO- cells did not change after culture with CMV antigen. The intensity of CD29 and expression of ICAM-1 also increased on both CD4+CD45RO+ and CD8+CD45RO+ cells after culture with the CMV antigen. Up-regulation of adhesion molecules occurred on activated T cells by culture with the CMV antigen. This change was observed mainly on CD45RO+ T memory cells. The results suggested that these changes of adhesion molecules on activated T cells with CMV may contribute to some immune reaction or inflammatory change.

Serum cytokines, interleukin-2 receptor, and soluble intercellular adhesion molecule-1 in oral disorders

Serum levels of soluble intercellular adhesion molecule-1, soluble interleukin-2 receptor, and cytokines such as interleukin-3, interleukin-4, interleukin-6, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor were examined in patients with oral disorders with 20 healthy persons used as control subjects. Patients studied included 30 with squamous cell carcinoma, 26 with oral lichen planus, 20 with recurrent aphthous ulcer, 19 with acute odontogenic bacterial infection, 16 with pseudomembranous candidiasis, and 16 with herpetic gingivostomatitis. Compared with levels in control subjects, detectable serum levels of interleukin-3 (> or = 10 pg/ml) existed more frequently in pseudomembranous candidiasis (13/16), acute odontogenic bacterial infection (14/19), and squamous cell carcinoma (24/30) and of granulocyte-macrophage colony-stimulating factor (> or = 4 pg/ml) more frequently in recurrent aphthous ulcer (15/20) and squamous cell carcinoma (21/30). These cytokine levels were increased with T stage of squamous cell carcinoma. About 20 pg/ml of interleukin-4 was detected in serum from one third to one fourth of patients with oral lichen planus, recurrent aphthous ulcer, and squamous cell carcinoma. Tumor necrosis factor-alpha was hardly detected in most patients except those with oral lichen planus and squamous cell carcinoma in which about one third of the patients had more than 40 pg/ml of tumor necrosis factor-alpha in serum. More than 10 pg/ml of interleukin-6 was frequently detected in all disorders, especially recurrent aphthous ulcer (18/20), pseudomembranous candidiasis (12/16), and acute odontogenic bacterial infection (17/19).(ABSTRACT TRUNCATED AT 250 WORDS)

Lysis of allogeneic and autologous melanoma cells by IL-7-induced lymphokine-activated killer cells

In order to assess the potential of interleukin 7 (IL-7) as an immunotherapeutic agent in human melanoma, we have evaluated the in vitro activity of IL-7-induced lymphokine-activated killer (LAK) cells from patients with advanced melanoma against allogeneic and autologous melanoma cells. Peripheral blood lymphocytes (PBLs) from 14 patients with stage III melanoma were isolated and incubated in the presence of 1,000 U ml-1 IL-7 and 100 U ml-1 IL-2 for comparison. LAK-cell activity was determined by a 24 h cytotoxicity assay using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]. The activity of IL-7-induced LAK cells against two allogeneic melanoma cell lines was 32.7% (+/- 17.9) against SK-Mel-37 and 38.1% (+/- 12.5) against SK-Mel-23 at an effector-to-target (E/T) ratio of 20:1. The activity of IL-2-induced LAK cells was significantly higher against SK-Mel-37 (78 +/- 24.6%) and against SK-Mel-23 (73.5 +/- 19.7%). IL-7 and suboptimal doses of IL-2 (10 U ml-1) were found to have a co-stimulatory on lymphocyte proliferation as well as on LAK activity. Against autologous melanoma cells, the activity of IL-7- and IL-2-induced LAK cells did not differ significantly (55.8 +/- 25.6% versus 68.7 +/- 21.7% respectively). In two patients, IL-7-induced LAK-cell activity against autologous melanoma cells exceeded even that of IL-2 significantly (67% vs 35% and 95% vs 82%). Levels of tumour necrosis factor alpha (TNF-alpha) in the supernatants of LAK-cell cultures generated by IL-7 were lower than those of IL-2-generated LAK-cell cultures. These results suggest that IL-7 is a potential alternative to immunotherapy with IL-2 in terms of efficacy and possible side-effects and encourages pilot studies with IL-7 in melanoma patients.