Nephrin in human lymphoid tissues

When nephrin, the protein product of NPHS1, was cloned, it was proposed to be specific for the kidney glomerular podocytes. Recently, however, new reports have emerged verifying additional nephrin expression sites, particularly the insulin-producing beta cells of the pancreas, as well as the central nervous system. In this study, we demonstrate nephrin expression in lymphoid tissues, specifically the tonsil, adenoid and lymph node. Nephrin mRNA expression levels were 4-fold higher in tonsils and adenoids than in thymus or B lymphocytes, and 20-fold higher than in T lymphocytes or monocytes, as shown by quantitative RT-PCR analysis. Anti-nephrin antibodies recognised a specific 165-kDa band in lysates of tonsil and adenoid. In immunofluorescence and immunohistochemichal stainings of adenoid and lymph node sections, nephrin-positive cells were detected in the germinal centres of the lymphoid follicles in a staining pattern typical for interdigitating cells. These results indicate a definite and additional presence of nephrin in lymphoid tissue.

Oral treatment of acute myeloid leukaemia with etoposide, thioguanine, and idarubicin (ETI) in elderly patients: a prospective randomised comparison with intravenous cytarabine, idarubicin, and thioguanine in the second and third treatment cycle

A randomised multicentre study was conducted among patients over 65 yr of age with newly diagnosed acute myeloid leukaemia (AML) to compare oral treatment with etoposide 80 mg/m(2) and thioguanine 100 mg/m(2) twice daily on 5 d and idarubicin 15 mg/m(2) on 3 d (ETI) to a mainly i.v. combination of cytarabine 100 mg/m(2) twice daily on 5 d, idarubicin 12 mg/m(2) x 1, and thioguanine (TAI). Ninety-two patients were enrolled. Their median age was 72 yr, range 65-84 yr. Sixty-five patients had de novo AML, 21 AML subsequent to myelodysplastic syndrome, and six treatment-related AML. They received at first a 6-d i.v. treatment with cytarabine and idarubicin. After the first treatment, 68 patients were randomised to receive two cycles of ETI (n = 36) or TAI (n = 32) and thereafter maintenance with mercaptopurine and methotrexate. Of the 92 patients, 52 (57%) achieved remission at some stage. The median survival was 10 months. There were no significant differences between the patients randomised to ETI or TAI in the remission rate (67% vs. 72%), survival (12 months from randomisation in both arms), event-free survival or relapse rate. The patients randomised to receive ETI spent significantly fewer days at hospital during the two randomised cycles (20 vs. 41 d, P = 0.010), and they had fewer days with infusions, shorter neutropenias and thrombocytopenias and fewer and less severe infections. In conclusion, treatment with oral ETI resulted in a similar antileukaemic effect as obtained with mainly i.v. TAI, with less toxicity and reduced need for hospitalisation.

Mapping the binding domain of the F18 fimbrial adhesin

F18 fimbrial Esherichia coli strains are associated with porcine postweaning diarrhea and pig edema disease. Recently, the FedF subunit was identified as the adhesin of the F18 fimbriae. In this study, adhesion domains of FedF were further studied by constructing deletions within the fedF gene and expressing FedF proteins with deletions either together with the other F18 fimbrial subunits or as fusion proteins tagged with maltose binding protein. The region essential for adhesion to porcine intestinal epithelial cells was mapped between amino acid residues 60 and 109 of FedF. To map the binding domain even more closely, all eight charged amino acid residues within this region were independently replaced by alanine. Three of these single point mutants expressing F18 fimbriae exhibited significantly diminished capabilities to adhere to porcine epithelial cells in vitro. In addition, a triple point mutation and a double point mutation completely abolished receptor adhesiveness. The result further confirmed that the region between amino acid residues 60 and 109 is essential for the binding of F18 fimbriae to their receptor. In addition, the adhesion capability of the binding domain was eliminated after treatment with iodoacetamide, suggesting the formation of a disulfide bridge between Cys-63 and Cys-83, whereas Cys-111 and Cys-116 could be deleted without affecting the binding ability of FedF.

Mapping the binding domain of the F18 fimbrial adhesin

F18 fimbrial Esherichia coli strains are associated with porcine postweaning diarrhea and pig edema disease. Recently, the FedF subunit was identified as the adhesin of the F18 fimbriae. In this study, adhesion domains of FedF were further studied by constructing deletions within the fedF gene and expressing FedF proteins with deletions either together with the other F18 fimbrial subunits or as fusion proteins tagged with maltose binding protein. The region essential for adhesion to porcine intestinal epithelial cells was mapped between amino acid residues 60 and 109 of FedF. To map the binding domain even more closely, all eight charged amino acid residues within this region were independently replaced by alanine. Three of these single point mutants expressing F18 fimbriae exhibited significantly diminished capabilities to adhere to porcine epithelial cells in vitro. In addition, a triple point mutation and a double point mutation completely abolished receptor adhesiveness. The result further confirmed that the region between amino acid residues 60 and 109 is essential for the binding of F18 fimbriae to their receptor. In addition, the adhesion capability of the binding domain was eliminated after treatment with iodoacetamide, suggesting the formation of a disulfide bridge between Cys-63 and Cys-83, whereas Cys-111 and Cys-116 could be deleted without affecting the binding ability of FedF.

Inhibition of human natural killer cell activity by cereulide, an emetic toxin from Bacillus cereus

The lipophilic toxin, cereulide, emitted by emetic food poisoning causing strains of Bacillus cereus, is a powerful mitochondria toxin. It is highly lipophilic and rapidly absorbed from the gut into the bloodstream. We tested how this toxin influences natural killer (NK) cells, which are important effectors in defence against infections and malignancy. Cereulide inhibited cytotoxicity and cytokine production of natural killer cells, caused swelling of natural killer cell mitochondria, and eventually induced natural killer cell apoptosis. The suppressive effect on cytotoxicity was fast and toxic concentration low, 20-30 microg/l. As the emesis causing concentration of cereulide is around 10 microg/kg of total body mass, our results suggest that emesis causing or even lower doses of cereulide may also have a systemic natural killer cell suppressive effect.

Complement C4 deficiency and HLA homozygosity in patients with frequent intraoral herpes simplex virus type 1 infections

Three consecutive patients with no apparent immunodeficiency who had frequent intraoral herpes simplex type 1 recurrences, a rare complication of herpes simplex virus infection, were found to have a total deficiency of either the A or B isotype of the complement component C4 and to be homozygous for the studied HLA antigens. A combination of HLA homozygosity, which may lead to impaired T cell recognition of viral peptides, and deficiency in the classical complement pathway, which can compromise virus neutralization, may predispose to severe and frequent herpes simplex virus infections.

In vivo glucose-stimulated amylin secretion is increased in nondiabetic patients with pancreatic cancer

The incidence of diabetes is increased in patients with pancreatic cancer, but the mechanisms underlying this association are not clear. Alterations in beta-cell function, such as formation of amyloid from excessive production of amylin and reduced expression of GLUT2, have been suggested to be possible mechanisms. We compared in vivo secretory responses of amylin and insulin (n = 37) and expression of GLUT2 in pancreata (n = 10) obtained at surgery between diabetic and nondiabetic patients with and without pancreatic tumors. Fourteen had pancreatic adenocarcinoma, 7 had diabetes (duration 6 +/- 3 years) and a pancreatic tumor, 8 had type 2 diabetes (duration 6 +/- 2 years), and 8 were normal subjects. First (0 to 10 minutes) and second (10 to 120 minutes) phase insulin and amylin secretion were characterized using the hyperglycemic clamp technique. Both amylin and insulin concentrations followed a biphasic pattern in nondiabetic subjects. In nondiabetic patients with pancreatic cancer, total, as well as nonglycosylated amylin concentrations, were increased compared with nondiabetic subjects without pancreatic cancer. Both first- and second-phase plasma amylin and serum immunoreactive insulin concentrations were low in all patients with diabetes, ie, both in type 2 diabetes and in those patients with diabetes and pancreatic tumors. At surgery, specimens were obtained for characterization of GLUT2 expression in beta cells, which was unaltered in nondiabetic (n = 7) and diabetic (n = 3) patients. Amyloid staining was similarly negative in diabetic and nondiabetic pancreata independent of pancreatic carcinoma. In conclusion, plasma amylin, but not insulin concentrations, are increased in nondiabetic patients with pancreatic cancer, but low in all patients with diabetes. These data support the potential of using an increase in the ratio of circulating amylin to insulin as a marker for pancreatic cancer in nondiabetic patients.

IFN-alpha and IL-18 synergistically enhance IFN-gamma production in human NK cells: differential regulation of Stat4 activation and IFN-gamma gene expression by IFN-alpha and IL-12

IFN-gamma, a product of NK and T cells, is a key cytokine contributing innate and adaptive immunity. IFN-gamma production is induced via direct cell-cell contacts with APC and IFN-gamma -producing cells or by cytokines. During microbial infections macrophage-derived IFN-alpha, IL-12, and IL-18 enhance IFN-gamma production and Th1 response. Here we show that IFN-alpha in combination with IL-18 very efficiently induces IFN-gamma expression also in primary, nonactivated NK cells and in NK-92 cell line. Comparison of the kinetics of IFN-gamma mRNA expression in nonactivated NK cells, NK-92 cells and activated T cells stimulated with IFN-alpha or IL-12 revealed that, although both of these cytokines directly up-regulate IFN-gamma mRNA expression, its levels remain elevated much longer with IL-12 stimulation. In both NK cells and T cells, Stat4 is known to be critical in IL-12 and IFN-alpha signaling. We show that Stat4 activation is transient in cells stimulated with IFN-alpha, whereas IL-12 induces more long-lasting activation of the transcription factor. This prolonged activation of IFN-gamma gene by IL-12 may result in more efficient IFN-gamma production compared to that of IFN-alpha. Our results demonstrate that IFN-alpha and IL-18 are important innate cytokines in inducing NK cell IFN-gamma production.

Loss-of-function mutations in TYROBP (DAP12) result in a presenile dementia with bone cysts

Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL; MIM 221770), also known as Nasu-Hakola disease, is a recessively inherited disease characterized by a combination of psychotic symptoms rapidly progressing to presenile dementia and bone cysts restricted to wrists and ankles. PLOSL has a global distribution, although most of the patients have been diagnosed in Finland and Japan, with an estimated population prevalence of 2x10-6 (ref. 2) in the Finns. We have previously identified a shared 153-kb ancestor haplotype in all Finnish disease alleles between markers D19S1175 and D19S608 on chromosome 19q13.1 (refs 5,6). Here we characterize the molecular defect in PLOSL by identifying one large deletion in all Finnish PLOSL alleles and another mutation in a Japanese patient, both representing loss-of-function mutations, in the gene encoding TYRO protein tyrosine kinase binding protein (TYROBP; formerly DAP12). TYROBP is a transmembrane protein that has been recognized as a key activating signal transduction element in natural killer (NK) cells. On the plasma membrane of NK cells, TYROBP associates with activating receptors recognizing major histocompatibility complex (MHC) class I molecules. No abnormalities in NK cell function were detected in PLOSL patients homozygous for a null allele of TYROBP.

Inhibition of human NK cell function by valinomycin, a toxin from Streptomyces griseus in indoor air

Streptomyces griseus strains isolated from indoor dust have been shown to synthesize valinomycin. In this report, we show that human peripheral blood lymphocytes treated with small doses (30 ng ml(-1)) of pure valinomycin or high-pressure liquid chromatography-pure valinomycin from S. griseus quickly show mitochondrial swelling and reduced NK cell activity. Larger doses (>100 ng/ml(-1)) induced NK cell apoptosis within 2 days. Within 2 h, the toxin at 100 ng ml(-1) dramatically inhibited interleukin-15 (IL-15)- and IL-18-induced granulocyte-macrophage colony-stimulating factor and gamma interferon (IFN-gamma) production by NK cells. However, IFN-gamma production induced by a combination of IL-15 and IL-18 was somewhat less sensitive to valinomycin, suggesting a protective effect of the cytokine combination against valinomycin. Thus, valinomycin in very small doses may profoundly alter the immune response by reducing NK cell cytotoxicity and cytokine production.

c-Myc and E1A induced cellular sensitivity to activated NK cells involves cytotoxic granules as death effectors

The contact of natural killer (NK) cells with foreign cells and with certain virus-infected or tumor cells triggers the cytolytic machinery of NK cells. This triggering leads to exocytosis of the cytotoxic NK cell granules. The oncoproteins c-Myc and E1A render cells vulnerable to NK cell mediated cytolysis yet the mechanisms of sensitization are not well understood. In a model where foreign cells (rat fibroblasts) were cocultured with human IL-2 activated NK cells, we observed that NK cells were capable of efficiently killing their targets only if the cells overexpressed the oncogene c-Myc or E1A. Both the parental and the oncogene expressing fibroblasts similarly triggered phosphoinositide hydrolysis in the bound NK cells, demonstrating that NK cells were cytolytically activated in contact with both resistant parental and oncogene expressing sensitive target fibroblasts. The cell death was independent of wild-type p53 and was not inhibited by an anti-apoptotic protein EIB19K. These results provided evidence that c-Myc and E1A activated the NK cell induced cytolysis at a post-triggering stage of NK cell-target cell interaction. In consistence, the c-Myc and E1A overexpressing fibroblasts were more sensitive to the cytolytic effects of isolated NK cell-derived granules than parental cells. The data indicate that oncogenes activate the cytotoxicity of NK cell granules. This mechanism can have a role in directing the cytolytic action of NK cells towards the virus-infected and cancer cells.

Comparison between four and eight cycles of intensive chemotherapy in adult acute myeloid leukemia: a randomized trial of the Finnish Leukemia Group

In acute myelogenous leukemia (AML) intensive postremission treatment is needed for an optimal result. However, it is not known how long the treatment should last and how many courses are necessary. The object of this prospective study was to compare four and eight intensive chemotherapy cycles in the treatment of adult de novo AML. In a multicenter study, 248 consecutive patients, aged from 16 to 65 years, were treated with intensive induction treatment. The patients in remission after two courses were randomized to receive either two (short arm) or six (long arm) additional intensive cycles of chemotherapy. The median follow-up time of the living patients is 68 months. Of the patients, 77% achieved complete remission, and 36% of all patients survived for 5 years. Seventy-three patients were randomized to the short arm and 66 to the long arm. There was no significant difference in the relapse-free survival (median 21 months vs 17 months) or overall survival (43 months vs 39 months) between the short and long arms, respectively. Treatment-related deaths occurred in 31 patients (13%), 11 of them in first remission. More than one-third of the patients survived for 5 years. It seems probable that the first few months after diagnosis are decisive for the prognosis if the chemotherapy is intensive, and further treatment cannot markedly influence the outcome.

Long-term supplementation with alpha-tocopherol and beta-carotene and prevalence of oral mucosal lesions in smokers

OBJECTIVE

To assess the effect of alpha-tocopherol and beta-carotene supplementation on the prevalence of oral mucosal lesions in smokers.

DESIGN

An end-point examination of a random sample of participants in a controlled trial for 5-7 years (Alpha-Tocopherol Beta-Carotene Cancer Prevention Study) in Helsinki, Finland.

SUBJECTS

A total of 409 white male cigarette smokers, aged 55-74 years who received either alpha-tocopherol (50 mg per day) or beta-carotene (20 mg per day) supplementation, both of these or placebo capsules.

METHODS

Clinical examination of oral mucosae, histological examination of lesions showing leukoplakia and cytological examination of buccal epithelium. Statistical analysis using Fisher's exact test.

RESULTS

No statistically significant differences were found between the study groups either in the prevalence of oral mucosal lesions or in the cells of unkeratinized epithelium. Leukoplakia was present in 24 (5.9%) of the subjects. Seven lesions showed dysplasia.

CONCLUSION

The present study on oral health does not support the hypothesis that alpha-tocopherol or beta-carotene supplementation plays an essential role in preventing oral mucosal changes in smokers.

Successful treatment of platelet transfusion refractoriness: the use of platelet transfusions matched for both human leucocyte antigens (HLA) and human platelet alloantigens (HPA) in alloimmunized patients with leukaemia

Six patients, 4 with acute myeloid leukaemia and 2 with a myelodysplastic syndrome who were refractory to random donor platelet transfusions and alloimmunized to human leucocyte antigens (HLA) and human platelet alloantigens (HPA), were treated with HLA- and HPA-matched platelet transfusions. In all the patients refractoriness and alloantibodies to HLA as well as HPA-1b or HPA-5b were detected simultaneously. Sixty-seven transfusions (445 units) of HLA- and HPA-matched platelets were given and responses to them were, in general, satisfactory in all the patients. No major spontaneous bleeding occurred. Four patients underwent bone marrow transplantation despite alloimmunization. The percentages of platelet transfusion days with a platelet nadir below 20x10(9)/l were 88% for the last 3 random donor platelet transfusions and 39% for the first 3 HLA- and HPA-matched platelet transfusions, respectively (p=0.009, Fisher's exact test). Four patients received also HLA-matched platelets, but responses to them were poor. The small number of transfusions with HLA-matched platelets precluded comparisons to either the random donor or HLA- and HPA-matched platelet transfusions. It seems that HLA- and HPA-alloimmunized patients can be successfully supported with HLA- and HPA-matched platelet concentrates.

Natural killer cells: endothelial interactions, migration, and target cell recognition

Natural killer (NK) cells form a unique third group of lymphocytes that differs from T and B cells in surface phenotype, target recognition, and function. By producing cytokines and exerting cytotoxicity, NK cells participate in the resistance against microbial infections and malignant disease. The research on the molecular mechanisms of migration and target cell recognition by NK cells has recently developed rapidly. NK cells express a number of adhesion molecules common to hematopoietic lineage, bind to endothelium, extravasate, and respond to chemotactic stimuli, much resembling T cells in those respects. However, NK cells are probably capable of transmigration and infiltration merely through activation by cytokines and chemokines, as opposed to the requirement of antigen presentation in the initial activation of T cells. Target cell recognition and ensuing cytotoxicity of NK cells is a sum effect of a delicate balance between the effects of inhibitory and activating NK cell receptors. NK cells express several well-defined MHC I-recognizing receptors that inactivate their functions. In pathological alterations of MHC I expression, the inhibitory receptors do not engage and thus permit the lysis of the target cell. The receptors that trigger the cytolytic machinery of NK cells are less well known. Some candidate triggering receptors have been identified and it seems that NK cell triggering is mediated by multiple receptors, as is the inhibition of cytotoxicity. For example, NK cells clearly detect target cell-bound antibodies and thus mediate antibody-dependent cytotoxicity. They may also detect carbohydrate moieties, normal but pathologically distributed adhesion molecules, as well as ligands for a number of co-stimulatory receptors.

The ezrin protein family: membrane-cytoskeleton interactions and disease associations

Ezrin, radixin, moesin and merlin form a subfamily of conserved proteins in the band 4.1 superfamily. Ezrin protein subfamily members act as linkers between the plasma membrane and the cytoskeleton. Members of the subfamily have been shown to interact with each other, with cell adhesion molecules such as CD44 and with F-actin. Recent data indicate that intercellular adhesion molecules 1 and 2 also interact with ezrin. The proteins are also involved in the redistribution of intercellular adhesion molecules and the organization of cell membrane structures. Merlin is a tumor suppressor that is involved in tumorigenesis of schwannomas and meningiomas. Merlin has the same overall protein structure as the other proteins in the subfamily but may have partially distinct functions.

Natural killer cell-target cell interactions

Research into the molecular mechanisms of target cell recognition by natural killer (NK) cells has recently progressed rapidly. NK cells express several MHC I recognizing receptors that inactivate the NK cells' functions. In pathological alterations of MHC I expression, the NK cell inhibitory receptors do not engage and thus permit the lysis of the target cell. The receptors that trigger the cytolytic machinery of NK cells, after the permission of lysis from the inhibitory receptors, are poorly characterized. Some candidate triggering receptors have been identified and it seems that triggering of NK cell killing is mediated by multiple receptors, as is the inhibition of cytotoxicity.

Lymphocyte adhesion molecule ligands and extracellular matrix proteins in gliomas and normal brain: expression of VCAM-1 in gliomas

To identify antigenic differences between gliomas and normal brain, we have immunohistochemically studied the expression of lymphocyte adhesion molecules (ICAM-1, ICAM-2, ICAM-3, VCAM-1, E-selectin and CD58), epidermal growth factor receptor (EGFR) and extracellular matrix proteins (collagen IV, fibronectin, laminin, merosin, tenascin and vitronectin) in these tissues. Gliomas expressed high levels of ICAM-1, CD58 (LFA-3), EGFR, tenascin and vitronectin, whereas only very low levels were detected in normal brain. VCAM-1 expression was detected in 15 out of 25 gliomas but not in normal brain. The presence of VCAM-1 in gliomas was verified by immunoblotting and RNase protection assay, and in glioma cell lines by Northern blotting. Expression of VCAM-1 in gliomas may partially explain lymphocytic infiltration, and anti-VCAM-1 antibodies may be of potential in antibody mixtures for targeted therapy of gliomas.

Intensive chemotherapy of poor prognosis myelodysplastic syndromes (MDS) and acute myeloid leukemia following MDS with idarubicin and cytarabine

Forty patients with high risk myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) preceded by MDS were treated with intensive induction and consolidation chemotherapy in a prospective multicenter pilot study. They were given two cycles of cytarabine 100 mg/m with 12-h intervals on days 1-7 and idarubicin 12 mg/m2 on days 5-7, both intravenously. Patients who were in remission after these two cycles were given two further cycles of cytarabine on days 1-5 and idarubicin on day 5. No maintenance treatment was given. Eleven out of 19 MDS patients (58%) and 10 out of 21 AML patients (48%), in total 21 out of 40 patients (53%), entered remission. Eight patients underwent allogeneic bone marrow transplantation. The follow-up time was 13-48 (median 33) months. At the time of the analysis, seven patients survived, four patients with MDS all of whom had been treated with bone marrow transplantation (three in continuous remission), and three patients with AML treated with chemotherapy only (two in continuous remission). The median survival of the patients treated with chemotherapy only was 12 months, with the median progression-free survival being 8 months. In view of the poor prognostic factors of the patients, the remission rate was satisfactory, but the responses as well as the survival were short. The post-remission treatment needs to be improved.

Different expression of adhesion molecules on stromal cells and endothelial cells of capillary hemangioblastoma

Cell-cell and cell-matrix interactions are essential for many basic functions, including differentiation and development. In pathological conditions such as inflammation and tumorigenesis adhesive events also play a major role. Cellular adhesion is mediated by specific molecules expressed by both normal and neoplastic tissues. Capillary hemangioblastoma is a tumor of controversial origin, characterized by two major components, vacuolated stromal cells and a capillary network. In order to shed light on the differentiation of the stromal cells and the interactions between the two major components of hemangioblastoma we studied the expression of several adhesion molecules by immunocytochemistry. The endothelium-associated adhesion molecules (ICAM-1, ICAM-2, VCAM-1, PECAM-1 and ELAM-1) were expressed by endothelial cells within the tumors, but not by stromal cells. In contrast, the stromal cells showed strong neuronal cell adhesion molecule (NCAM/CD56) expression, further distinguishing them from endothelial cells. In addition, the stromal cells expressed CD44, which is of interest, as this membrane protein is linked to ezrin, a cytoskeleton-associated protein also expressed by stromal cells. We conclude that the stromal cells and endothelial cells of capillary hemangioblastoma exhibit quite divergent expression patterns of adhesion molecules. The NCAM expression in stromal cells suggests neuroectodermal or mesenchymal differentiation of this tumor. In addition, the NCAM expression could contribute to the sometimes problematic differential diagnosis between capillary hemangioblastoma and metastatic renal cell carcinoma of the central nervous system.

ICAM-2 redistributed by ezrin as a target for killer cells

Very little is known about the receptors and target molecules involved in natural killer (NK) cell activity. Here we present a model system in which interleukin-2-activated killing by NK cells depends on the intercellular adhesion molecule ICAM-2 and is regulated by the distribution of ICAM-2. The level of ICAM-2 expression in NK-sensitive and resistant cells is similar, but in sensitive cells ICAM-2 is concentrated into bud-like cellular projections known as uropods, whereas in resistant cells it is evenly distributed. The cytoskeletal-membrane linker protein ezrin is also localized in uropods. Transfection of human ezrin into NK-resistant cells induces uropods formation, redistribution of ICAM-2 and ezrin, and sensitizes target cells to interleukin-2-activated killing. These results reveal a new mechanism of target-cell recognition: cytotoxic cells recognize adhesion molecules that are already present on normal cells, but in diseased cells are concentrated into a biologically active cell-surface region by cytoskeletal reorganization. The results also highlight the importance of cytoskeletal interactions in the regulation of ICAM-2-mediated adhesive phenomena.

Expression of complement membrane regulators membrane cofactor protein (CD46), decay accelerating factor (CD55), and protectin (CD59) in human malignant gliomas

Gliomas are malignant brain tumors, which, despite recent progress in surgical and radiological treatment, still have a poor prognosis. Since gliomas apparently resist immunological clearance mechanisms, we became interested in examining bow gliomas resist killing by the human complement system. The resistance of human cells to complement-mediated damage is, in large part, mediated by specific inhibitors of complement:membrane cofactor protein (CD46), decay-accelerating factor (CD55), and protectin (CD59). In the present study we examined the expression of complement regulators in 14 human glioma tumors and in 7 glioma cell lines (U251, U87, HS683, U373, U138, U118, and H2). Protectin was found to be strongly expressed by all glioma tumors and cell lines. Northern blotting analysis demonstrated the typical pattern of four to five protectin mRNAs in the glioma cells. Except for blood vessels, the expression of decay-accelerating factor was weak or absent in the tumors in situ, whereas in the cell lines its expression varied, ranging from negative to intermediate. Membrane cofactor protein was moderately expressed by all the cell lines but only weakly in the tumors. Cell-killing experiments demonstrated that the glioma cell lines were exceptionally resistant to C-mediated lysis. Five of the seven cell lines (U373, HS683, U118, U138, and H2) resisted complement lysis under conditions where most other cell lines were sensitive to killing. Neutralization experiments using specific monoclonal antibodies indicated that protectin was functionally the most important complement regulator in the glioma cells. The killing of the U87 and U251 cells could be significantly increased by a blocking anti-protectin monoclonal antibody, whereas for the other cell lines only moderate or no response was observed. The H2 cell line resisted killing by all antibodies and by complement. These results show that protectin is the most important complement regulator on human glioma cells. The exceptional complement resistance of some glioma cell lines suggests that they may utilize other, hitherto less well characterized, mechanisms to resist complement killing.

Activation of natural killer cell migration by leukocyte integrin-binding peptide from intracellular adhesion molecule-2 (ICAM-2)

Intracellular adhesion molecule-2 (ICAM-2), one of the ligands of CD11a/CD18 (LFA-1), is mainly expressed on endothelial and hematopoietic cells. The biological significance of ICAM-2 has remained unclear. Previous findings have shown that a peptide from ICAM-2, spanning residues 21-42 from the first immunoglobulin domain, enhances natural killer (NK) cell cytotoxicity and induces T cell aggregation. We have now studied the effect of the same ICAM-2 peptide on NK cell migration in the Boyden chamber assay. The peptide significantly increased NK cell migration up to 215 +/- 21%, as compared to migration of control cells (100%), and the induction was inhibited by anti-CD11a monoclonal antibodies. The ICAM-2 peptide also induced polymerization of F-actin at the leading edge of migratory NK cells. Cross-linking of CD11a/CD18 receptors with anti-CD11a or anti-CD18 monoclonal antibodies and secondary antibodies resulted in receptor recycling, increased migration, and actin polymerization, but led to slight inhibition of cytotoxicity. The ICAM-2 peptide did not induce such a receptor recycling. Phosphotyrosine immunoblotting experiments showed that the ICAM-2 peptide increased the phosphorylation of 150- and 35-kDa proteins. During cross-linking with antibodies, only the 150-kDa protein showed increased phosphorylation. The results show that depending on the type of CD11a/CD18 receptor ligation different kinds of signals are transduced in NK cells. These signals may either trigger only locomotion, or both locomotion and cytotoxicity. Based on these findings, a major function for ICAM-2 on endothelium may be triggering of migration of adhering leukocytes.

Expression and characterization of a B cell growth promoting polypeptide derived from the 12 kDa B cell growth factor gene (BCGF 1)

The expression and partial purification of recombinant 12 kDa B cell growth factor are reported. The polypeptide was derived from the genomic sequence of the gene (BCGF 1) which is here shown to be a single copy gene that localizes to human chromosome 16. When expressed as a glutathione S-transferase fusion protein in E. coli, the protein appears as a 38 kDa polypeptide in Western blot analysis using a peptide antibody. The purified fusion protein stimulates the proliferation of activated human B cells in a dose-dependent manner, and the active site resides within the 104 carboxy-terminal amino acids. The availability of biologically active recombinant 12 kDa B cell growth factor will enable its evaluation in B cell growth regulation, and provides a new means of in vitro culturing of human B lymphocytes.

Requirement of CD4+ lymphocytes in IL-2-stimulated NK cell proliferation

Growth requirements of human natural killer cells in IL-2-supplemented cultures were studied. NK cell proliferation was monitored by the MAC (morphology antibody chromosomes) technique and subset specific cell cycle analysis, which both enable direct determination of cell growth in specific lymphocyte subsets among heterogeneous lymphocyte populations. Our results show that even in the presence of saturating concentrations of IL-2, the proliferative capacity of purified CD16+ cells is quite low, but can be stimulated in a dose dependent manner by CD4+ cells. CD4+ cells could partially be replaced by IL-4 but not by various other commercially available cytokines. These results provide further evidence of the requirement of accessory stimuli in NK cell proliferation, and support the interpretation that NK cells have a direct regulatory role in specific T cell responses.

Cell lineage involvement of recurrent chromosomal abnormalities in hematologic neoplasms

Analysis of most hematologic neoplasms indicates the involvement of one or more cell lineages in the bone marrow and/or the blood but rules out the involvement of all lineages in any one neoplasm. It is important to detect lineage involvement in order to clarify which stem cells are involved in leukemia, to predict prognosis, and to select appropriate treatment. Our aim was to study the cell lineage involvement of some of the recurrent chromosomal abnormalities seen in hematological neoplasms. The direct morphology-antibody-chromosomes (MAC) method was used. The deletion 20q in myeloproliferative diseases (MPD), the deletion of 5q and t(1;7) in myelodysplastic syndromes (MDS), and t(3;3) in acute myeloid leukemia subtype M7 (AML-M7) were seen in all or at least in two myeloid lineages. These were interpreted as stem cell abnormalities. Deletion 13q in MPD, t(8;21) in AML-M2 and t(15;17) in AML-M3 were seen in granulocytic lineages only; t(14;18) in non-Hodgkin's lymphoma and trisomy 12 as the sole abnormality in chronic lymphocytic leukemia (B-CLL) were seen only in immunoglobulin light chain clonal B cells; inversion 14 in T-CLL was seen only in T cells, whereas t(15;14) in acute lymphocytic leukemia with eosinophilia (ALL-EO) was seen in lymphoid stem cells but not in mature granulocytes or lymphocytes. Additional abnormalities (in addition to the Philadelphia chromosome) in chronic myeloid leukemia (CML) were seen in all myeloid cell lineages and also in mature granulocytes, B cells, and large granular lymphocytes. Abnormalities in Hodgkin's disease were restricted to CD30-positive Reed-Sternberg cells. Trisomy 8 and monosomy 7 are abnormalities that may be present in either stem cells or any of the single cell lineages.

Promotion of natural killer cell growth in vitro by bispecific (anti-CD3 x anti-CD16) antibodies

Bispecific heteroconjugated F(ab')2 fragments were prepared from pepsin-digested monoclonal OKT3 (anti-CD3) and 3G8 (anti-CD16) antibodies with 5,5'-dithiobis- (2-nitrobenzoic acid). When these bispecific antibodies (BsA) were added to peripheral blood lymphocyte (PBL) cultures with 100 U/ml human recombinant interleukin-2 (rIL-2), preferable growth of natural killer cells occurred. After 3 weeks the frequencies of CD56+ and CD56+3- cells in cultures with BsA were 74 +/- 7% and 65 +/- 7%, respectively, compared with 48 +/- 6% and 29 +/- 7% in control cultures. The frequencies of CD3+ lymphocytes in the presence of BsA, cells from 1-day cultures were labelled with fluorescein isothiocyanate (FITC)-conjugated anti-CD3, CD4 and CD8 monoclonal antibodies (mAb) and propidium iodide which stains dead cells. Flow cytometry revealed that more than 95% of the dead cells in cultures with BsA were CD3+. Thirty-seven per cent of CD3+, 43% of CD4+ and 17% of CD8+ cells were dead on day 1, and after 3 days the CD4+/CD8+ ratio among viable lymphocytes was 1.6 in the control and 0.5 in BsA cultures. Taken together, these results show that bispecific (anti-CD3 x anti-CD16) F(ab')2 fragments are strongly immunomodulatory by inducing the killing of T cells by CD16+ cells.

Cancer incidence among 78,000 asthmatic patients

The risk of cancer was evaluated among 77,952 asthma patients with bronchial asthma. The series was obtained through linkage of two registers: the Finnish Social Insurance Institution's file of asthma patients and the Finnish Cancer Registry. There was a significant excess risk of lung cancer in both sexes, the standardized incidence ratio (SIR) being 1.32 among men and 1.66 among women. In women, the risk of cancer of the rectum was significantly increased (SIR 1.42), whereas the risks of cancer of the corpus uteri and multiple myeloma were lower than expected (SIR 0.76 and 0.53, respectively). In men, the incidence of cancer of the larynx was significantly reduced (SIR 0.63) and that of the bladder increased (SIR 1.25). When both sexes were combined, cancers of the colon (SIR 1.17) and rectum (SIR 1.28) also showed a significantly elevated risk. A reduction in risk was seen in stomach cancer (SIR 0.88) and lymphatic leukaemia (SIR 0.55). The increased lung cancer risk may be due to local inflammatory changes. It is possible that differences in the immune system, e.g. natural killer cell activity, explain some of the reduced cancer risks.

A leukocyte integrin binding peptide from intercellular adhesion molecule-2 stimulates T cell adhesion and natural killer cell activity

Adhesion is of pivotal importance for a number of leukocyte functions. Little is known about the binding between leukocyte integrins and the intercellular adhesion molecules (ICAMs). Normally integrins are nonadhesive, and require a stimulus to become active. We have now identified a peptide from ICAM-2, which binds to leukocyte integrins and activates adhesion. Furthermore, the peptide strongly increased the binding and cytotoxicity of natural killer cells. These findings show that adhesion-dependent leukocyte functions can be activated by ligand-derived peptides, and therefore provide evidence that the avidity of leukocyte integrins is up-regulated by integrin-ligand interactions.

Non-major histocompatibility complex-restricted killer cells in human cord blood: generation and cytotoxic activity in recombinant interleukin-2-supplemented cultures

Interleukin-2 (IL-2)-induced generation of non-major histocompatibility complex (MHC)-restricted killer cells among human cord blood lymphocytes (CBL) was investigated. After 1 week in culture with recombinant (r)IL-2 and human serum (HuSer), the cytotoxicity of CBL against K562 and COLO cells greatly exceeded the cytotoxicity of cultured adult peripheral blood lymphocytes. Culturing of CBL with rIL-2 and HuSer led to preferable generation of CD56+ cells. After 1 month in culture, the number and frequency of CD56+ cells had increased by more than 50 and nine times, respectively. The generation of CD56+ cells in CBL cultures may at least partially be explained by their comparatively strong expression of the IL-2 receptor (IL-2R) beta-chain (p75).

Effects of recombinant alpha-2b-interferon therapy in patients with progressive MS

The effects of systemic recombinant interferon-alpha-2b were studied in 6 carefully selected patients with progressive multiple sclerosis. 3.0 million IU were given as daily subcutaneous injections for 6 months, 5 patients showed worsening disability, and in 4 of them new or enlarged lesions were detected in MRI. In one patient no change in disability was found; his MRI showed regressed changes. The mean progression index during the treatment was significantly higher (p < 0.02) than during the previous 2 to 3 years' period of continuous progression. The frequency of peripheral blood natural killer (CD16+) cells declined significantly 3 months during the treatment, but returned to the pretreatment values after termination the treatment. An increase of intrathecal IgG synthesis and oligoclonal bands was demonstrated in 4 and 3 patients, respectively. Our experience suggests that long-term recombinant IFN-alpha-2b treatment may activate the immunological process of MS.

Expression of integrins and other adhesion molecules on NK cells; impact of IL-2 on short- and long-term cultures

We have investigated, using flow cytometry, the expression of 19 adhesion molecules on fresh and IL-2-activated NK cells. The study included beta 1, beta 2 and beta 3 integrins, CD2, CD54 and CD58 (belonging to the immunoglobulin superfamily), and CD44 and L-selectin (homing receptors). alpha 1 and alpha 2 of the beta 1 integrins were non-existent and alpha 3 was weak on freshly isolated NK cells, but their expression increased after 4 weeks in culture with IL-2. On the other hand, some down-regulation of alpha 4 and alpha 5 and disappearance of alpha 6 was detected. CD 11a/CD18 was upregulated by IL-2, whereas CD11b-c/CD18 were down-regulated. As a novel finding we detected beta 3 on IL-2-activated T and NK cells. CD2, CD44, CD54 and CD58 were increased by IL-2 but L-selectin was strongly down-regulated on the long-term-activated NK cells. Although IL-2-activated lymphocytes are potent tumor-lysing killer cells in vitro and therefore a potential modality in cancer treatment, the IL-2 induced changes in lymphocyte adhesion molecule expression may also lead to undesired effects, such as altered untargeted distribution and compromised migratory capacity.

Survival rates in lung cancer patients with and without bronchial asthma

Bronchial asthma itself or the treatment of asthma may modify the immunological response to cancer. The survival of lung cancer patients with a preceding diagnosis of bronchial asthma was compared with that of non-asthmatic lung cancer patients in Finland during 1970-1989. This was accomplished by linking two nation-wide data registers, the medication reimbursement register and the cancer registry. For 921 out of the 926 asthmatic patients with lung cancer diagnosed after the diagnosis of bronchial asthma, a non-asthmatic referent patient, matching with respect to sex, anatomical site, and histological type of tumour, as well as to age and year of lung cancer diagnosis, was successfully found in the files of the Cancer Registry. Another referent group was formed by using the stage of lung cancer at diagnosis as an extra matching criterion; this search was successful for 895 asthmatic lung cancer patients. The corrected 5-year survival rate of asthmatic lung cancer patients was 8.4% and that of the referent patients, not matched for stage, 9.6%. When stage was included as matching criterion the corresponding rates were 8.5% and 8.1% respectively. None of these differences were significant. The prognosis of asthmatic and non-asthmatic lung cancer patients thus seemed to be similar.

Regulation of natural killer cell activity by transforming growth factor-beta and prostaglandin E2

The separate and combined effects of transforming growth factor-beta 1 (TGF-beta 1) and prostaglandin E2 on human natural killer (NK) activity were studied. Peripheral blood lymphocytes (PBL) and large granular lymphocytes (LGL, 70-90% purity) were used as effector cells and K562 as targets. Overnight incubation of the effector cells with TGF-beta 1 resulted in a significant inhibition of NK activity. TGF-beta 1 did not influence the expression of CD3, CD16, CD18 or CD56 antigens on PBL. Combination of TGF-beta 1 with indomethacin gave the same NK-suppressive effect as TGF-beta 1 alone, showing that the inhibition of NK activity by TGF-beta 1 is not due to an increase in PGE2 levels. TGF-beta did not influence cAMP level in PBL whereas PGE2 significantly increased it. On the other hand, TGF-beta 1 and PGE2 showed an additive inhibitory effect on NK activity. TGF-beta 1 did not reduce the binding of PBL and LGL to K562. PGE2 suppressed the binding and TGF-beta 1 did not influence this suppression. TGF-beta 1 also suppressed IL-2-induced activation of NK activity and increase of expression of the granule proteins granzyme A and perforin. PGE2 did not appear to affect granzyme A and perforin contents. The results indicate that TGF-beta 1 and PGE2 suppress NK activity by different mechanisms.

Prognostic value of non-MHC-restricted killer cell activity in lung cancer

The prognostic value of peripheral blood non-MHC-restricted cytotoxicity against the myeloid leukaemic line K562 in lung cancer patients was studied. At the time of diagnosis and before operation, 57 patients with lung cancer were tested for cytotoxicity and subsequently followed for up to 4 years. In addition, 145 lung cancer patients, 30 patients with non-neoplastic lung diseases and 76 healthy donors were tested for cytotoxicity without the follow-up, in order to correlate the stage of lung cancer and the growth rate of tumours to the level of non-MHC-restricted cytotoxicity. On average, lung cancer patients had similar non-MHC-restricted cytotoxicity to the controls. However, patients with stage II-IV diseases showed an impaired activity, stages III and IV differing significantly from the controls. This result shows that the decline in natural killer (NK) activity is associated with tumour burden. Patients with slowly growing neoplasms had stronger cytotoxic activity than patients with fast or moderately progressing disease. In the follow-up study, the whole material of 57 patients showed only a slight correlation between cytotoxicity and survival: 42% of the patients with strong activity survived for more than 2.5 years, whereas 6% of the patients with weak activity did so. In stage I patients there was no correlation between cytotoxicity and survival, nor was there a correlation in patients with stages II-IV of the disease. Hence, in our group of patients the determination of cytotoxicity preoperatively yielded no prognostic information beyond that already available from staging. However, those stage II-IV patients that survived for 1 year or more after the diagnosis and cytotoxicity tests, showed a significant correlation between cytotoxicity and survival.

Migration of recombinant IL-2-activated T and natural killer cells in the intercellular space of human H-2 glioma spheroids in vitro. A study on adhesion molecules involved

The migration of rIL-2-activated T and NK cells into the intercellular space of glioma tissue was studied using multicellular spheroids grown from the human H-2 glioblastoma cell line as targets. Lymphocytes of all analyzed subtypes migrated into the spheroids, but CD56+ cells were particularly migratory. Lymphocytes and the H-2 tissue expressed adhesion molecule subunits for the following potential cell-cell or cell-matrix interactions: alpha 3 beta 1 (VLA-3) to fibronectin, laminin, and collagen; alpha 4 beta 1 (VLA-4) and alpha 5 beta 1 (VLA-5) to fibronectin; alpha 6 beta 1 (VLA-6) to laminin; alpha 4 beta 1 to VCAM-1; alpha L beta 2 (Leu-CAMa/LFA-1) to CD54 (ICAM-1); CD44 to fibronectin, collagen, laminin, hyaluronate; CD2 to CD58 (LFA-3); and CD56 (N-CAM) to CD56. In the H-2 tissue, CD54 and VCAM-1 were expressed as a gradient. The expression of CD54 was weak in the peripheral zone and the expression was stronger in the quiescent deeper zone, whereas the distribution of VCAM-1 showed an inversed pattern. The low expression of CD54 was up-regulated along the frontier of migrating lymphocytes. The migration was almost totally prevented by the anti-CD18 (beta 2) mAb IB4 and TS1/18, and also strongly inhibited by the anti-CD54 mAb LB-2. Instead, mAb known to inhibit the binding of beta 1 integrins to fibronectin were not significantly inhibitory. However, a combination of the GPEILDVPST and GRGDS peptides, which compete for the binding of alpha 4 beta 1 and alpha 5 beta 1 to fibronectin and may also affect other adhesion systems, partially prevented migration.

Migration of recombinant IL-2-activated T and natural killer cells in the intercellular space of human H-2 glioma spheroids in vitro. A study on adhesion molecules involved

The migration of rIL-2-activated T and NK cells into the intercellular space of glioma tissue was studied using multicellular spheroids grown from the human H-2 glioblastoma cell line as targets. Lymphocytes of all analyzed subtypes migrated into the spheroids, but CD56+ cells were particularly migratory. Lymphocytes and the H-2 tissue expressed adhesion molecule subunits for the following potential cell-cell or cell-matrix interactions: alpha 3 beta 1 (VLA-3) to fibronectin, laminin, and collagen; alpha 4 beta 1 (VLA-4) and alpha 5 beta 1 (VLA-5) to fibronectin; alpha 6 beta 1 (VLA-6) to laminin; alpha 4 beta 1 to VCAM-1; alpha L beta 2 (Leu-CAMa/LFA-1) to CD54 (ICAM-1); CD44 to fibronectin, collagen, laminin, hyaluronate; CD2 to CD58 (LFA-3); and CD56 (N-CAM) to CD56. In the H-2 tissue, CD54 and VCAM-1 were expressed as a gradient. The expression of CD54 was weak in the peripheral zone and the expression was stronger in the quiescent deeper zone, whereas the distribution of VCAM-1 showed an inversed pattern. The low expression of CD54 was up-regulated along the frontier of migrating lymphocytes. The migration was almost totally prevented by the anti-CD18 (beta 2) mAb IB4 and TS1/18, and also strongly inhibited by the anti-CD54 mAb LB-2. Instead, mAb known to inhibit the binding of beta 1 integrins to fibronectin were not significantly inhibitory. However, a combination of the GPEILDVPST and GRGDS peptides, which compete for the binding of alpha 4 beta 1 and alpha 5 beta 1 to fibronectin and may also affect other adhesion systems, partially prevented migration.

The expression of human intercellular adhesion molecule-2 is refractory to inflammatory cytokines

The beta 2-integrin CD11a/CD18 binds to the intercellular adhesion molecules (ICAM)-1 (CD54) and ICAM-2. ICAM-1 has a wide distribution, and its expression is up-regulated by various cytokines. In contrast, ICAM-2 has a more restricted distribution, and is mainly expressed on endothelial cells. In the present study we show that it is not induced by inflammatory cytokines or other treatments on any of several cells studied. Moreover, antibodies to the intercellular adhesion ligands were not able to block all CD11a/CD18-dependent adhesion, indicating the presence of additional CD11a/CD18 ligands.

Recognition of chromosome 6-associated target structures by human lymphokine-activated killer cells

Different populations of unstimulated and IL-2-activated PBL were used in binding and killing assays against somatic mouse/human lymphocyte cell hybrids containing different human chromosomes. Unstimulated PBL effector cells showed low binding and killing activity to both cell hybrids and mouse parental cell lines. However, IL-2-activated killer (LAK) cells bound strongly to, and effectively killed, cell hybrids carrying human chromosome 6, but were inefficient in both assays to mouse parental cells and to cell hybrids not carrying human chromosome 6. These results show that human LAK cells but not endogenous NK cells bind and kill mouse/human lymphocyte hybrids containing human chromosome 6. We thus suggest that LAK cells recognize ligands encoded by genes on chromosome 6.

Recognition of chromosome 6-associated target structures by human lymphokine-activated killer cells

Different populations of unstimulated and IL-2-activated PBL were used in binding and killing assays against somatic mouse/human lymphocyte cell hybrids containing different human chromosomes. Unstimulated PBL effector cells showed low binding and killing activity to both cell hybrids and mouse parental cell lines. However, IL-2-activated killer (LAK) cells bound strongly to, and effectively killed, cell hybrids carrying human chromosome 6, but were inefficient in both assays to mouse parental cells and to cell hybrids not carrying human chromosome 6. These results show that human LAK cells but not endogenous NK cells bind and kill mouse/human lymphocyte hybrids containing human chromosome 6. We thus suggest that LAK cells recognize ligands encoded by genes on chromosome 6.

A monoclonal antibody to the human leukocyte adhesion molecule intercellular adhesion molecule-2. Cellular distribution and molecular characterization of the antigen

The DNA of the human leukocyte adhesion molecule intercellular adhesion molecule-2 (ICAM-2) was synthesized by the polymerase chain reaction, and a protein A-ICAM-2 fusion protein was expressed in Escherichia coli. The fusion protein was used as immunogen to obtain mAb to ICAM-2. The 6D5 antibody was selected by its reactivity in immunofluorescence with the endothelial cell line Eahy926. The antibody precipitated a 55,000 m.w. glycoprotein from radioactivity surface labeled cells and also reacted in Western blotting. As measured by immunofluorescence flow cytometry, the antibody reacted with lymphoblastoid B cells of normal origin, some Burkitt lymphoma cell lines, vascular endothelial cells, the endothelial cell line Eahy926, 4 and a subpopulation of Con A-stimulated blood mononuclear cells. The two Ig-like domains of ICAM-2 were separately expressed in E. coli, and the antibody was shown to react with the NH2-terminal domain. The antibody inhibited the CD11/CD18-dependent binding of HL-60 promyelocytic leukemia cells to transfected COS-1 cells.