Cloning of two candidate tumor suppressor genes within a 10 kb region on chromosome 13q14, frequently deleted in chronic lymphocytic leukemia.

Previous studies have indicated the presence of a putative tumor suppressor gene on chromosome 13q14, commonly deleted in patients with B-cell chronic lymphocytic leukemia (B-CLL). We have previously defined a minimally deleted region of 130 kb centromeric to the marker D13S272, and constructed a PAC and cosmid contig encompassing this area. In the present study we have made a detailed restriction and transcriptional map of the region of interest. Using these tools we have screened a panel of 206 primary CLL clones and three cell lines. In five CLL cases we found limited deletions defining the region of interest to an area of no more than 10 kb. Two adjacent genes, termed Leu1 and Leu2 (leukemia-associated gene 1 and 2), were mapped to the minimally deleted region, with several patients showing deletion borders within these genes. The Leu1 and Leu2 genes show little homology to previously published genes at the nucleotide and expected translated amino acid sequence level. Mutational analysis of the Leu1 and 2 genes in 170 CLL samples revealed no small intragenic mutations or point mutations. However, in all cases of 13q14 loss examined, the first exon of both genes, which are only 300 bp apart, were deleted. We conclude that the Leu1 and Leu2 genes are strong candidates as tumor suppressor gene(s) involved in B-CLL leukemogenesis.

Prognostic importance of p15INK4B and p16INK4 gene inactivation in childhood acute lymphocytic leukemia.

PURPOSE: The present study explores the prognostic importance of p16INK4/p15INK4B gene inactivation in childhood acute lymphocytic leukemia (ALL). MATERIALS AND METHODS: Cells from 79 pediatric ALL patients were investigated for inactivation of the p15INK4B and p16INK4 genes or loss of heterozygosity (LOH) for chromosome 9p markers by use of Southern hybridization, restriction fragment length polymorphism (RFLP) analysis, microsatellite analysis as well as single-strand conformation polymorphism (SSCP) analysis, and nucleotide sequencing of the p15INK4B and p16INK4 genes. Genetic data were correlated to clinical outcome and established prognostic factors. RESULTS: Inactivation of the p15INK4B and/or p16INK4 genes by homozygous deletion or loss of one allele and mutation of the other was detected in 24 cases (30%). Another 12 patients (15%) showed loss of one allele. A statistically significant correlation was found between inactivation of the p15INK4B/p16INK4 genes and poor prognosis (P < .01). Furthermore, inactivation proved to be an independent factor that predicted relapse, ranking second to WBC count. The trend toward overrepresentation of treatment failure was strongest in the high-risk (HR) group patients with p16INK4/p15INK4B gene inactivation. Patients with deletion of genetic material on 9p21 and normal coding sequence of the remaining p16INK4 and p15INK4B genes had a similar prognosis to that of nondeleted cases. CONCLUSION: The data suggest that analysis of p15INK4B/p16INK4 genes may contribute prognostic information in pediatric ALL.

A FISH cosmid 'cocktail' for detection of 13q deletions in chronic lymphocytic leukaemia--comparison with cytogenetics and Southern hybridization.

The most frequent structural chromosome abnormality in chronic lymphocytic leukaemia (CLL) is deletion at chromosome 13q14. Studies with Southern blot hybridisation have revealed deletions in the region located telomeric of the retinoblastoma gene in more than 40% of cases. The highest frequency of homozygous deletions has been found at the D13S319 locus and it is likely that a new tumour suppressor gene is located close to this region. We have analysed deletions in the D13S319 region in 20 selected CLL patients using conventional cytogenetic analysis, fluorescence in situ hybridisation (FISH) and Southern blot hybridisation. FISH and Southern hybridisation are equally efficient in detecting deleted clones in our study. However, FISH analysis indicate that subclones with different numbers of alleles in the D13S319 region can exist simultaneously. The cytogenetic analyses confirm that clones with different chromosomal abnormalities can occur in patients with CLL and that 13q14 deletions can be limited to one of these subclones. Furthermore, the FISH analyses show that trisomy 12 and deletion of 13q14 can occur in the same cell clone. Finally, our study confirms that mitogen stimulation of peripheral blood cells from CLL patients before FISH analysis may result in a sharp increase in normal appearing cells, which can hide leukaemic clones with deletions in the D13S319 region.

Deletion of the Ink4-locus (the p16ink4a, p14ARF and p15ink4b genes) predicts relapse in children with ALL treated according to the Nordic protocols NOPHO-86 and NOPHO-92.

Inactivation of the Ink4 gene locus locus on 9p comprising the tumour suppressor gene p16ink4a and its neighbours p14ARF and p15ink4b is common in childhood acute lymphoblastic leukaemia (ALL), but the prognostic significance is controversial. DNA from 230 patients was retrospectively analysed by Southern blotting, single strand conformation polymorphism (SSCP) and sequencing techniques. The results were correlated with clinical characteristics and outcome. One hundred and ninety-four fully analysed patients, similarly treated using the Nordic NOPHO-86 or the current NOPHO-92 protocols, were included in the outcome analysis. Deletions approached a minimally deleted region between the p16ink4a and p15ink4b genes, making the p14ARF gene the most commonly deleted coding sequence. Bi-allelic deletion was associated with high white blood cell count (WBC) (P < 0.001), T cell phenotype (P < 0.001) and mediastinal mass (P < 0.001). Patients with Ink4 locus bi-allelic deletions had an inferior pEFS (P < 0.01) and multivariate analysis indicated that bi-allelic deletion of the p16ink4a and the p14ARF genes was an independent prognostic risk factor (P < 0.05). Sub-group analysis revealed a pronounced impact of deletion status for high-risk patients, ie with high WBC. Deletion-status and clinical risk criteria (WBC) could thus be combined to further differentiate risk within the high-risk group. The analysis of the Ink4 locus adds independent prognostic information in childhood ALL treated by Nordic protocols and may help in selection of patients for alternative treatment.

A cosmid and cDNA fine physical map of a human chromosome 13q14 region frequently lost in B-cell chronic lymphocytic leukemia and identification of a new putative tumor suppressor gene, Leu5.

B-cell chronic lymphocytic leukemia (B-CLL) is a human hematological neoplastic disease often associated with the loss of a chromosome 13 region between RB1 gene and locus D13S25. A new tumor suppressor gene (TSG) may be located in the region. A cosmid contig has been constructed between the loci D13S1168 (WI9598) and D13S25 (H2-42), which corresponds to the minimal region shared by B-CLL associated deletions. The contig includes more than 200 LANL and ICRF cosmid clones covering 620 kb. Three cDNAs likely corresponding to three different genes have been found in the minimally deleted region, sequenced and mapped against the contigged cosmids. cDNA clone 10k4 as well as a chimeric clone 13g3, codes for a zinc-finger domain of the RING type and shares homology to some known genes involved in tumorigenesis (RET finger protein, BRCA1) and embryogenesis (MID1). We have termed the gene corresponding to 10k4/13g3 clones LEU5. This is the first gene with homology to known TSGs which has been found in the region of B-CLL rearrangements.

Mala s 12 is a major allergen in patients with atopic eczema and has sequence similarities to the GMC oxidoreductase family.

BACKGROUND: Atopic eczema (AE) is a chronic inflammatory skin disorder, characterized by impaired skin barrier and itch. The yeast Malassezia belongs to the normal human skin microflora and can induce IgE- and T-cell-mediated allergic reactions in AE patients. Previously, we have identified several IgE-binding components in Malassezia sympodialis extract. METHODS: Here, we report cloning, production and characterization of a M. sympodialis 67-kDa allergen. RESULTS: The sequence of the 67-kDa protein, termed Mala s 12, showed sequence similarity to the glucose-methanol-choline (GMC) oxidoreductase enzyme superfamily and was expressed as a recombinant protein in Escherichia coli. The purified protein bound flavin adenine dinucleotide with 1:1 stoichiometry per monomer of protein. The protein-bound flavin showed an extinction coefficient at 451 nm of 11.3 mM(-1)cm(-1). The recombinant 67-kDa protein did not show any enzymatic activity when tested as oxidase or dehydrogenase using choline, glucose, myo-inositol, methanol, ethanol, 1-pentanol, benzyl alcohol, 2-phenylethanol, cholesterol or lauryl alcohol as possible substrates. Recombinant Mala s 12 was recognized by serum IgE from 13 of 21 (62%) M. sympodialis-sensitized AE patients indicating that the 67-kDa component is a major allergen. CONCLUSIONS: The data show that Mala s 12 has sequence similarity to the GMC oxidoreductase family and is a major allergen in AE patients.

Higher pH level, corresponding to that on the skin of patients with atopic eczema, stimulates the release of Malassezia sympodialis allergens.

BACKGROUND: The opportunistic yeast Malassezia is a trigger factor in atopic eczema (AE). Around 30-80% of patients with AE have an IgE and/or T-cell reactivity to the yeast. Several IgE-binding components have been identified in Malassezia extracts and 11 allergens have been cloned and sequenced. The pH of the skin surface in patients with AE is higher than that of normal healthy skin. We here investigate whether different pH conditions mimicking those of AE skin and healthy skin can influence the production and release of Malassezia allergens. METHODS: Malassezia sympodialis (ATCC strain 42132) was cultured in Dixon broth at pH 6.1 to 5.0 for 1-15 days. Culture supernatants were analysed for the presence of IgE-binding components by immunoblotting. The M. sympodialis cells were analysed for allergen expression and production with immunocytochemistry and quantitative polymerase chain reaction. RESULTS: We found that M. sympodialis cells produce, express and release allergens to a greater extent when cultured at the higher pH. This was particularly true of a 67-kDa major allergen designated Mala s 12. CONCLUSIONS: The data suggest that the skin barrier in AE patients provides an environment that can enhance the release of allergens from M. sympodialis, which can contribute to the inflammation.

Rational design of hypoallergens applied to the major cat allergen Fel d 1.

BACKGROUND: Allergen-specific immunotherapy is the only treatment for allergic disease providing long-lasting symptom relief. Currently, it is mainly based on the use of crude allergen extracts. The treatment may be improved by the use of genetically engineered allergens, hypoallergens, aiming at a more effective and safer therapy. OBJECTIVE: The aim of this study was to provide a rational design of hypoallergen candidates for immunotherapy by using structural information and knowledge of B and T cell epitopes of an allergen. METHODS: The three-dimensional structure of the major cat allergen Fel d 1 was systematically altered by duplication of selected T cell epitopes and disruption of disulphide bonds. Seven Fel d 1 derivatives were generated and screened for allergenic reactivity in comparison with recombinant Fel d 1 in competition-ELISA. The allergenicity was further evaluated in basophil activation experiments and T cell reactivity was assessed in a lymphoproliferation assay. RESULTS: Three out of seven Fel d 1 derivatives, with two duplicated T cell epitopes and one or two disulphide bonds disrupted, were carefully evaluated. The three derivatives displayed a strong reduction in allergenicity with 400-900 times lower IgE-binding capacity than recombinant Fel d 1. In addition, they induced a lower degree of basophil activation and similar or stronger T cell proliferation than recombinant Fel d 1. CONCLUSION: By a rational approach, we have constructed three Fel d 1 hypoallergens with reduced IgE-binding capacities and retained T cell reactivities. This strategy may be applied to any well-characterized allergen to improve immunotherapy for allergic patients.

Intralipid decreases the bacterial lipopolysaccharide induced release of oxygen radicals and lysozyme from human neutrophils.

Human neutrophils were incubated either with purified cell envelope lipopolysaccharides (LPS) of salmonella or with different concentrations of LPS combined with Intralipid. Incubation of neutrophils with LPS alone increased their oxidative metabolism with increased release of oxygen radicals as measured by the nitroblue tetrazolium (NBT) test and chemiluminescence response. The amount of lysozyme released by the cells also increased during incubation with LPS. However, when the neutrophils were incubated with LPS together with Intralipid, the LPS induced stimulation of the neutrophil NBT reduction, chemiluminescence and lysozyme release was significantly decreased. Intralipid might substitute for plasma high density lipoproteins (HDL), which are known to inhibit the LPS effects on the neutrophils in the acute stage of an infection with Gram-negative bacteria.

Detection of Mala f and Mala s allergen sequences within the genus Malassezia.

Malassezia species are opportunistic yeasts that are involved in the pathogenesis of a number of skin diseases including atopic eczema/dermatitis syndrome. Previously, we cloned six allergens from Malassezia sympodialis isolate ATCC 42132; these allergens are designated Mala s 1, and Mala s 5-Mala s 9. Three additional allergens, Mala f 2-Mala f 4, have been isolated from M. furfur by other investigators. The objective of the present study was to investigate the presence of these Mala sequences in seven Malassezia species. Genomic DNA amplification by PCR and sequencing showed that M. globosa, M. obtusa and M. sympodialis contain DNA sequences corresponding to all the allergens except Mala f 2 and Mala f 3. M. pachydermatis contains Mala s 1, Mala f 4, and Mala s 5-Mala s 8. M. restricta and M. slooffiae possessed Mala f 4 and Mala s 6. M. furfur was seen to possess Mala f 2-Mala f 4 as well as Mala s 5-Mala s 7. Our data from reverse-transcriptase PCR showed a more species-specific pattern of amplification. M. furfur evidenced expression of Mala f 2-Mala f 4. M. globosa and M. obtusa appeared to express only Mala s 6. M. pachydermatis expressed Mala f 4, Mala s 6, and Mala s 8, while M. restricta and M. slooffiae expressed Mala f 4 and Mala s 6. M. sympodialis expressed all the allergens except Mala f 2 and Mala f 3. Different Malassezia species appear to contain both common and species-specific allergen sequences.

The role of O-antigen polysaccharide in the activation of neutrophils by lipopolysaccharides of Salmonella species.

Activation of neutrophils by lipid A, O-antigen polysaccharides (PS) and smooth lipopolysaccharides (LPS) isolated from Salmonella choleraesuis (O-6,7) and Salmonella typhimurium (O-4,5,12) was investigated. The methods used were assays for lysozyme release and for nitroblue tetrazolium (NBT) reduction which measures the level of oxidative metabolism of neutrophils. LPS from both species stimulated neutrophils to the same extent in the presence of autologous plasma. In the absence of plasma only the O-6,7 LPS activated neutrophils. Lipid A or PS isolated from both LPS either did not activate neutrophils or did so only at very high concentrations when tested in the presence of plasma; in the absence of plasma no activation occurred. The data indicate that both PS and lipid A segments of LPS are required for activation of neutrophils by LPS. We also deduce that plasma, probably complement, is required for the interaction of some LPS, e.g. O-4,5,12 with neutrophils whereas other LPS, e.g. O-6,7 can interact directly and activate neutrophils.

Effect of Brucella abortus lipopolysaccharide on oxidative metabolism and lysozyme release by human neutrophils.

Both Brucella abortus lipopolysaccharide (LPS) and lipid A were low activators of nitroblue tetrazolium reduction and lysozyme release in human neutrophils. The stimulation was dose dependent and was higher in the presence of autologous plasma than in its absence. The comparison between Brucella LPS and lipid A versus Salmonella LPS revealed that at least 100 times more LPS and 1,000 times more lipid A of the former genus were required to induce significant nitroblue tetrazolium reduction and a corresponding lysozyme release in neutrophils. Low Brucella LPS-mediated superoxide and lysozyme production might contribute to the survival of these facultative intracellular bacteria in phagocytic cells.

Effect of N-acetylcysteine(NAC) treatment on HIV-1 infection: a double-blind placebo-controlled trial.

OBJECTIVE: In a double-blind placebo-controlled trial, human immunodeficiency virus (HIV)-seropositive patients with a CD4 lymphocyte cell count of more than 200 x 10(6) . l-1 were randomised to receive either 800 mg N-acetylcysteine (NAC) or placebo for 4 months. Before treatment low plasma cysteine levels, high free radical activity in neutrophils in the presence of autologous plasma-measured by the nitroblue tetrazolium (NBT) test- and increased tumor necrosis factor (TNF)-alpha levels were found in the HIV positive patients. RESULTS: After treatment the low plasma cysteine level in the NAC group increased to normal, and the decline of the CD4+ lymphocyte count before the study start, was less steep in the NAC group than in the placebo group after treatment. There was also a reduction in TNF-alpha level. However, NAC had no effect on the radical production by neutrophils, and although it did not increase the CD4+ cell count, it may have decreased the decline in CD4+ cells. CONCLUSION: Further controlled trials with NAC are needed to determine whether it has a beneficial effect in the treatment of asymptomatic HIV-infected individuals.

Sequence variability of a prolonged tetranucleotide repeat.

A tetranucleotide repeat located in intron 20 of the RB gene consists of 16-26 CTTT(+/- T) repeats in 99% of the alleles. In the remaining 1% of alleles the segment is extended to a length of > 60 repeats. Sequence analysis revealed that the prolonged alleles either consisted of perfect CTTT(+/- T) repeats or irregular repeat sequences with variable combinations of C and T. The data provide clues to the mechanisms causing unstable expansions of repeats.

Effect of surfactant on nitroblue tetrazolium reduction of polymorphonuclear leucocytes stimulated with type Ia group B streptococci.

Activation of polymorphonuclear leucocytes (PMN) was investigated after incubation of adult human PMN and group B streptococci (GBS) type Ia with a type-specific polyclonal antiserum and a modified porcine surfactant (Curosurf). The level of oxidative metabolism of PMN was studied using a micromethod modification of the nitroblue tetrazolium (NBT) reduction test. GBS alone did not stimulate significant oxygen metabolite release from PMN, and incubation of PMN with surfactant alone resulted in decreased NBT reduction. After opsonization of GBS with a specific antibody, PMN were activated and the increased oxygen metabolite release was not suppressed when surfactant was added to the system. We conclude that the encapsulated GBS strain investigated needs opsonization with specific antibody to increase oxidative metabolism of PMN, and that incubation of PMN and opsonized GBS with surfactant does not interfere with NBT reduction.

Experimental neonatal group B streptococcal pneumonia: effect of a modified porcine surfactant on bacterial proliferation in ventilated near-term rabbits.

We studied bacterial proliferation in relation to surfactant treatment in a model of neonatal group B streptococcal (GBS) pneumonia. Surfactant (Curosurf) was isolated from pig lungs with a method preserving only polar lipids and hydrophobic proteins. Near-term rabbit fetuses were ventilated in a body plethysmograph system. At 15 min, a suspension of GBS strain 090 Ia LD (5 mL/kg, concentration approximately 10(9)/mL) was instilled intratracheally. At 30 min, surfactant (n = 12) or sterile saline (n = 13) was administered via the airways (2.5 mL/kg). A control group (n = 12) received the same volumes of saline. After 5 h the animals were killed, and samples for blood cultures and blood gases were taken from the heart. The left lung was aseptically removed, weighed, homogenized, serially diluted, and cultured on blood agar plates. The results were expressed as mean log10 colony forming units/g lung +/- SD. Compared with animals (n = 12) killed immediately after GBS instillation (8.13 +/- 0.54), there was a significant increase in bacterial numbers in both groups ventilated for 5 h, but values for surfactant-treated animals (8.96 +/- 0.38) were lower than those for animals receiving saline (9.46 +/- 0.50; p < 0.05). After 5 h, 96% of GBS-infected animals had positive blood cultures. Light microscopic examination of the right lung of GBS-infected animals revealed inflammatory changes that tended to be less prominent in surfactant-treated rabbits. We conclude that intratracheal inoculation of near-term rabbits with GBS resulted in a significant bacterial proliferation during 5 h of ventilation and that bacterial growth was mitigated by treatment with surfactant.

Macrophage reaction in rabbit lung following inhalation of iron chloride.

Groups of eight rabbits were inhalation-exposed to iron, 1.4 +/- 0.7 mg/m3 (low Fe), or 3.1 +/- 1.8 mg/m3 (high Fe) as FeCl3 or to filtered air (controls) for 2 months, 5 days/week and 6 hours/day. The alveolar macrophages were increased in number in both exposed groups. Noduli of granular macrophages were found in lungs of all the rabbits in the high-Fe group, in one from the low-Fe group, and in one control rabbit. Especially in the high-Fe group there were prominent changes in the macrophages such as enlarged lysosomes containing fibrous-looking structures, iron-rich inclusions, and densely packed, 5-nm electron-dense granules. The number of cells filled with surfactant-like inclusions as well as a smooth surface was increased in the high-Fe group and the macrophages had enhanced phagocytic capacity. There was an increase in the phospholipid concentration and in the volume density of type II cells in the high-Fe group but the level of phosphatidylcholines was not significantly changed. The fact that Fe3+ affected mainly the alveolar macrophages might be due to the relatively high concentration of iron in these cells caused by the precipitation of iron in their lysosomes.

Rabbit lung after combined exposure to soluble cobalt and trivalent chromium.

Eight rabbits were exposed to 0.7 +/- 0.4 mg/m3 Co2+ as CoCl2 and 1.2 +/- 0.7 mg/m3 Cr3+ as Cr(NO3)3 (group Co + Cr), eight to 0.6 +/- 0.5 mg/m3 Co2+ (group Co), and eight to filtered air (control group), for 4 months, 5 days/week, and 6 hr/day. All rabbits in group Co + Cr and group Co showed nodular aggregation of alveolar epithelial type II cells. Volume density of the type II cells was significantly higher in group Co + Cr than in group Co and the control group. There was intraalveolar macrophage accumulation in seven rabbits in group Co + Cr, one in group Co, and one in the control group. In lavage fluid the numbers of macrophages and the percentage of these cells with smooth surface and intracellular surfactant-like inclusions were more increased in group Co + Cr than in group Co as were oxidative metabolic and phagocytic activities of the macrophages. Total phospholipids, phosphatidylcholines, and especially 1,2-dipalmitoylphosphatidylcholine was markedly increased in group Co + Cr whereas only 1,2-dipalmitoylphosphatidylcholine was slightly increased in group Co. One mechanism behind the high amount of surfactant phospholipids in group Co + Cr seems to be an enhanced production of surfactant by the type II cells. Another mechanism is probably that Cr3+ reduces the capacity of alveolar macrophages to catabolize surfactant. The results imply that it is important to investigate effects of combinations of cobalt and chromium in the occupational environment.

p16INK4/p15INK4B gene inactivation is a frequent event in malignant T-cell lines.

The cell cycle regulators p16INK4 and p15INK4B have been mapped to the minimal region of overlap for chromosome 9p21 deletions, observed in a number of malignancies, suggesting that they could be tumor suppressor genes (TSGs). In the case of p16INK4 this has been further substantiated by the finding of small intragenic mutations. In this study we have investigated the p16INK4 and p15INK4B genes in 16 malignant T-cell lines by means of Southern blot, PCR and sequence analysis. p16INK4 allelic deletions occurred in 15 of 16 cell lines; 12 of which were homozygous and 3 hemizygous. In 1 cell line (DND 41) the remaining p16INK4 allele carried a microdeletion of 29 bp of exon 2, supporting the concept that p16INK4 is a target TSG for deletions on 9p21. Most p16INK4 deletions also included the p15INK4B gene. However, 4 of the cell lines deleted for p16INK4 showed no evidence of p15INK4B loss, indicating that p15INK4B is not the target in these cell lines.