Evidence for a crucial role of neutrophil-derived serine proteases in the inactivation of interleukin-6 at sites of inflammation

The bioactivity of interleukin-6 (IL-6) was found to be dramatically reduced in fluids from sites of inflammation. Here, we provide evidence that the neutrophil-derived serine proteases elastase, proteinase 3 and cathepsin G are mainly involved in its degradation and subsequent inactivation. The initially hydrolyzed peptide bonds were detected to be Val(11)-Ala(12) and Leu(19)-Thr(20) (elastase), Phe(78)-Asn(79) (cathepsin G) and Ala(145)-Ser(146) (proteinase 3). The soluble IL-6 receptor elicits a protective effect against the IL-6 inactivation by cathepsin G only. The inactivation of IL-6 by neutrophil-derived serine proteases might act as a feedback mechanism terminating the IL-6-induced activation of neutrophils.

Graft-versus-myeloma after withdrawal of immunosuppression following allogeneic peripheral stem cell transplantation

There is growing evidence for a graft-versus-myeloma effect following allogeneic stem cell transplantation. We add to this evidence by reporting complete remission achieved by withdrawal of immunosuppression in a patient with multiple myeloma progressing after HLA-identical sibling peripheral stem cell transplantation. De novo chronic graft-versus-host disease coincided with the anti-myeloma effect and responded to treatment. The patient remains in complete remission 3 years after transplant.

Establishment and characterization of four cell lines derived from human head and neck squamous cell carcinomas for an autologous tumor-fibroblast in vitro model

To study interactions between tumor cells and stromal elements, we established carcinoma cell lines as well as tumor-derived and skin fibroblast cultures from four patients with squamous cell carcinoma of the head and neck. For the characterization of the tumor cell lines we a) determined population doubling times, b) assessed morphological features by light and electron microscopy, c) investigated the expression of typical markers by immunohistochemistry, including various intermediate filaments and surface antigens, d) compared these findings with expression patterns in the respective original tumor specimens, e) evaluated p53 mutations in tumor specimens and cell lines, f) performed chromosome analysis, g) investigated the tumorigenicity in athymic mice, and h) tested the formation of both tumor and mixed tumor-fibroblast multicellular spheroids. Tumor cell cultures were considered established cell lines when maintained and passaged over a period of two years after primary explantation. The in vitro morphology of the cell lines showed well preserved characteristics of squamous cell carcinoma, and electron microscopy as well as immunohistochemistry revealed their squamous type of differentiation. All cell lines presented the same p53 genotype as the respective original tumors. Furthermore, they were successfully xenotransplanted into nude mice and formed both pure and mixed three dimensional spheroids. This experimental model allows the in vitro and in vivo investigation of various tumor-fibroblast interactions.

Inhibition of neutrophil proteinases by recombinant serpin Lex032 reduces capillary no-reflow in ischemia/reperfusion-induced acute pancreatitis

Because neutrophil proteinases such as elastase and cathepsin G are considered to play a major role in inflammatory tissue damage, the microcirculatory effect of the serine proteinase inhibitor (serpin) Lex032 after ischemia/reperfusion (I/R)-induced pancreatitis was investigated. Lex032 inhibits these proteinases by recombinant combination of alpha(1)-antitrypsin and alpha(1)-antichymotrypsin. Twenty-eight anesthetized rats received either Lex032 or NaCl 0.9% as a control solution during baseline conditions or after 1 h of complete reversible ischemia induced by microclip occlusion of the pancreatic arteries. The number of erythrocyte-perfused capillaries (functional capillary density) and the leukocyte adherence in postcapillary venules were assessed by intravital microscopy 45, 90, and 120 min after administration. In the baseline group, Lex032 increased leukocyte adherence compared with the NaCl 0.9% baseline group, without changing any other parameter. I/R without Lex-032 treatment resulted in a 50% reduction in functional capillary density, a 2-fold increase in leukocyte adherence, an increase in interleukin-6 serum concentration, and a significant fall in blood pressure during reperfusion time compared with baseline animals. Treatment with Lex032 in I/R resulted in significant preservation of capillary perfusion, an absence of interleukin-6 increase, and preservation of mean arterial pressure during reperfusion time, without changing the leukocyte adherence, compared with the NaCl 0.9% I/R group. Because of its considerable amelioration of microcirculatory perfusion, Lex032 might be useful in the treatment of pancreatic I/R tissue damage (e.g., cardiac bypass surgery, pancreas transplantation, and hemorrhagic shock) by prevention of capillary perfusion failure.

Repeated peripheral stem cell mobilization in healthy donors: time-dependent changes in mobilization efficiency

Mobilization of peripheral blood stem cells was analysed in 10 consecutive healthy donors undergoing repeated stem cell mobilization for allogeneic transplantation. Donors received recombinant G-CSF at a dose of 10 microg/kg/d for both mobilizations. Collection of stem cells was started on day 5 of G-CSF administration. To compare the efficiency of first and second mobilization, we determined the leucocyte and CD34+ cell counts in peripheral blood, and the yield of nucleated cells and CD34+ cell counts in the apheresis product. CD34+ cell numbers in peripheral blood were (median) 81.2 x 10(6)/l during the first and 50.4 x 10(6)/l during the second mobilization (P = 0.007). Likewise, CD34+ cells in the apheresis product decreased from 319.8 x 10(6) to 275.7 x 10(6) (P = 0.02). Decrease in CD34+ cell counts in peripheral blood and in the apheresis product was associated with the time interval between first and second mobilization. In a regression analysis there was a correlation between the ratios of CD34+ cell counts of first and second mobilization and the inverse of time interval between procedures (r2 = 0.51 peripheral blood; r2 = 0.74 apheresis product). Thus, stem cell yield is reduced when healthy donors receive repeated mobilization within a short time. Nevertheless, an adequate number of stem cells may repeatedly be mobilized within 2 months.

Effect of diaspirin cross-linked hemoglobin on normal and postischemic microcirculation of the rat pancreas

Microcirculatory alterations with reduced nutritive supply to the pancreas could be the cause of hyperamylasemia, which occurs in some patients receiving the vasoactive oxygen carrier diaspirin cross-linked hemoglobin (DCLHb) in clinical studies. Therefore, the effects of DCLHb on rat pancreas microcirculation were evaluated. Anesthetized Sprague-Dawley rats received one of the following treatments during baseline conditions (n = 7 rats/group): 10% hydroxyethyl starch (HAES) (0.4 ml/kg), DCLHb (400 mg/kg), or DCLHb (1,400 mg/kg). After 1 h of complete, reversible pancreatic ischemia, other animals received 10% HAES (0.4 ml/kg) or DCLHb (400 mg/kg) during the onset of reperfusion. The number of red blood cell-perfused capillaries (functional capillary density, FCD) and the level of leukocyte adherence in postcapillary venules in the pancreas were assessed by means of intravital microscopy during 2 h after treatment. In the nonischemic groups, FCD was 18% greater after DCLHb (1,400 mg/kg) than after 10% HAES treatment without any increase in leukocyte adherence. In the inschemia-reperfusion (I/R) 10% HAES group, FCD was significantly (P < 0.05) lowered, leukocyte adherence enhanced, and mean arterial pressure (MAP) reduced by 31% compared with nonischemic animals. DCLHb treatment in the I/R group resulted in a slight increase in FCD, a significant (P < 0.05) reduction of leukocyte adherence, and a complete restoration of MAP compared with the animals of the I/R control group. Thus our data provide no evidence for a detrimental effect on the pancreatic microcirculation or an enhanced risk of postischemic pancreatitis by DCLHb.

Receptors and signalling components of plant hormones

Recent advances in understanding plant hormonal signalling has resulted in the identification of a variety of signalling components including receptor kinases with homology to the bacterial two component system as well as serine/threonine kinases and protein phosphatases. In addition, the existence of MAP kinase pathways in plants indicates a similar role of these signalling cascades in the relay of exogenous signals into the nucleus as has been disclosed in animal cells. The emerging signalling pathways of the plant hormone abscisic acid and ethylene are presented.

[Optimizing plasma cell content in bone marrow aspirates]

Bone marrow samples used for flow cytometric analysis of plasma cells frequently provide a low plasma cell content. Regularly, samples used for flow cytometry are provided by second step aspiration while the first aspirate is used for cytologic examination. We investigated whether the use of secondary aspirates leads to a systematic underestimation of the bone marrow plasma cell content as a consequence of an increased blood contaminant. To test the hypothesis, plasma cell (CD38bright) percentages were established by flow cytometry in 13 pairs of primary/secondary aspirates. In all cases we found lower plasma cell contents in secondary as compared to primary aspirates (p = 0.0015). Median plasma cell counts in secondary aspirates were 57% lower compared to primary aspirates. We conclude that the use of secondary aspirates leads to systematic underestimation of the bone marrow plasma cell content.

[Establishing an umbilical cord blood bank for unrelated allogenic stem cell transplantation]

We report the establishment of a cord-blood bank in a routine hematological laboratory. Cord-blood collection was performed with placenta in utero by a trained team and immediately sent to the cord-blood bank. There, 6.8 ml cord-blood was used for analysis of nucleated cell counts, counts of CD34-positive cells, CFU's, complete HLA-typing, ABO and Rhesus blood groups, bacteriologic cultures and serology for HIV 1 and 2, HbsAg, HVC, CMV, syphilis and toxoplasmosis. The cord-blood collection was frozen and conserved at -192 degrees C. From each cord-blood vials of DNA, viable cells and plasma were cryopreserved. Between June 1997 and April 1998, 54 cord-bloods were collected. 40 of them were cryo-preserved, and 14 discarded because of low cell counts. The median volume was 109 ml with 1.4 x 10(9) nucleated cells. The in vitro capacity of proliferation of the cord-blood correlated well with the absolute counts of CD34-positive cells (r = 0.93), moderately with the relative counts of CD34 (r = 0.68) as well as the nucleated cells (r = 0.70), poorly with the volume (r = 0.44). Three of the 40 (7.5%) cord-blood products contained a bacterial contamination. This study shows that a cord-blood bank can be organised in a routine hematological laboratory, which is familiar with transplantation products. However, the procedure is time consuming, expensive and requires a highly qualified team and specialised technical equipment.

Correction of spurious blood cell counts in a patient with cryoglobulinemia reversed by the use of citrate-anticoagulated blood

Cryoglobulins may interfere with automated cell counting when proteins precipitate or blood cells aggregate. This results in spurious platelet or leukocyte counts, false values for red blood cell parameters and abnormal scattergrams. Usually it can be reversed by warming blood specimens to 37 degrees C. We describe the case of a 63-year-old woman with autoimmune disease in whom the diagnosis of cryoglobulinemia was suspected due to typical changes in blood cell counts. Artifacts were resistant to warming of the sample to 37 degrees C in both EDTA- and heparin-anticoagulated blood specimens. In contrast, the use of citrate as anticoagulant allowed correct measurements. This case underlines the role of assessment of blood counts in the detection of cryoglobulinemia. Correct measurements of automated blood counts in cryoglobulinemia may depend on the use of alternative anticoagulants.

[Immunophenotype of blast crisis in chronic myeloid leukemia]

The blast crisis in chronic myeloid leukaemia (CML) is morphologically well defined. The aim of this report was to analyze whether immunophenotyping can divide CML blast crises into subtypes as is done in acute de novo leukaemia, and whether a specific CML pattern exists. Between 1991 and 1997 we reevaluated all the immunophenotypes of patients with CML blast crises with special regard to immunological subclassification, expression of CD34, presence of aberrant markers and number of immunological clusters. Twenty-nine CML blast crises were analyzed. Seventeen were myeloid, 11 lymphoid and one biphenotypic. The blast crises were divided into subtypes as de novo acute leukaemias: of the 17 myeloid blast crises 6 were undifferentiated, 5 differentiated and 6 had monocytic differentiation. In the lymphoid blast crises there were no pro-B, 8 common-B and 3 mature-B. No T-lymphoid blast crises were observed. In 26/29 analyses (90%) CD34 was expressed in the blasts. In 17/29 analyses (59%) one or two aberrant markers were found. In summary, immunophenotyping is important in distinguishing between myeloid and lymphoid blast crises. A subclassification, as in acute leukaemias, is possible. We found no specific immunophenotypic CML pattern. A study directly comparing immunophenotyping of CML blast crises with acute de novo leukaemia is planned.

Lipomatous secretory meningioma: case report and review of the literature

Secretory meningioma is a rare entity which may be characterised by imaging features unusual for other subtypes of meningioma, such as low attenuation on CT, high (fat-tissue equivalent) signal intensity on T1-weighted MRI, marked surrounding oedema, and irregular contrast enhancement. We report a case of secretory meningioma and review the literature.

Nitrogen and oxygen regulation of Bacillus subtilis nasDEF encoding NADH-dependent nitrite reductase by TnrA and ResDE

The nitrate and nitrite reductases of Bacillus subtilis have two different physiological functions. Under conditions of nitrogen limitation, these enzymes catalyze the reduction of nitrate via nitrite to ammonia for the anabolic incorporation of nitrogen into biomolecules. They also function catabolically in anaerobic respiration, which involves the use of nitrate and nitrite as terminal electron acceptors. Two distinct nitrate reductases, encoded by narGHI and nasBC, function in anabolic and catabolic nitrogen metabolism, respectively. However, as reported herein, a single NADH-dependent, soluble nitrite reductase encoded by the nasDE genes is required for both catabolic and anabolic processes. The nasDE genes, together with nasBC (encoding assimilatory nitrate reductase) and nasF (required for nitrite reductase siroheme cofactor formation), constitute the nas operon. Data presented show that transcription of nasDEF is driven not only by the previously characterized nas operon promoter but also from an internal promoter residing between the nasC and nasD genes. Transcription from both promoters is activated by nitrogen limitation during aerobic growth by the nitrogen regulator, TnrA. However, under conditions of oxygen limitation, nasDEF expression and nitrite reductase activity were significantly induced. Anaerobic induction of nasDEF required the ResDE two-component regulatory system and the presence of nitrite, indicating partial coregulation of NasDEF with the respiratory nitrate reductase NarGHI during nitrate respiration.

Matched unrelated allogeneic bone marrow transplantation for recurrent malignant lymphoma in a patient with X-linked lymphoproliferative disease (XLP)

A 14-year-old male and a maternally related cousin were diagnosed with X-linked lymphoproliferative disease (XLP) after developing recurrent B-NHL, characterized by long disease-free intervals and absence of an increased chemoresistance of the recurrent lymphomas. The demonstration of different clonal IgH gene rearrangements in two of the lymphomas from one of the patients further supports that the lymphomas were clonally unrelated. The cousin underwent matched related BMT, whereas the proband received a deliberately delayed MUD BMT in third CR. Both are in CR 68 months and 21 months, respectively, post-BMT. Delaying BMT probably contributes to reducing treatment-related morbidity. We suggest MUD BMT as a feasible curative strategy for XLP patients with B-NHL lacking matched related donors.

Double allogeneic peripheral stem cell transplants for patients at high risk of relapse

Patients with chronic myeloid leukemia (CML) relapsing in blast crisis after HLA-identical sibling bone marrow transplantation (BMT) are difficult to treat. Infusion of donor lymphocytes or retransplantation are unlikely to result in long-term disease-free survival. Treatment intensification with allogeneic double-BMT, made possible by using repeatedly mobilized peripheral blood stem cells, offers a new treatment option. We report two patients with Philadelphia chromosome positive CML transplanted in chronic phase, relapsing with CML in myeloid blast crisis. Both received intensive induction chemotherapy (ICE) followed by a first, T cell-depleted peripheral stem cell transplant from the initial donor. Both patients engrafted rapidly (day 15). Upon hematologic recovery, a second G-CSF mobilized non-T cell-depleted peripheral stem cell transplant from the same donor was given after pretransplant conditioning with busulphan and cyclophosphamide. Again, engraftment was rapid (days 18 and 16) and both patients are alive and disease-free 18 and 21 months after allogeneic double-BMT. G-CSF mobilized peripheral stem cells allow new ways of treatment intensification with double-BMT in refractory leukemias relapsing post-transplant. This approach warrants further study.

Regulation of Pseudomonas aeruginosa hemF and hemN by the dual action of the redox response regulators Anr and Dnr

The oxidative decarboxylation of coproporphyrinogen III catalysed by an oxygen-dependent oxidase (HemF) and an oxygen-independent dehydrogenase (HemN) is one of the key regulatory points of haem biosynthesis in Pseudomonas aeruginosa. To investigate the oxygen-dependent regulation of hemF and hemN, the corresponding genes were cloned from the P. aeruginosa chromosome. Recognition sequences for the Fnr-type transcriptional regulator Anr were detected -44.5 bp from the 5' end of the hemF mRNA transcript and at an optimal distance of -41.5 bp with respect to the transcriptional start of hemN. An approximately 10-fold anaerobic induction of hemN gene expression was mediated by the dual action of Anr and a second Fnr-type regulator, Dnr. Regulation by both proteins required the Anr recognition sequence. Surprisingly, aerobic expression of hemN was dependent only on Anr. An anr mutant did not contain detectable amounts of hemN mRNA and accumulated coproporphyrin III both aerobically and anaerobically, indicating the importance of HemN for aerobic and anaerobic haem formation. Mutation of hemN and hemF did not abolish aerobic or anaerobic growth, indicating the existence of an additional HemN-type enzyme, which was termed HemZ. Expression of hemF was induced approximately 20-fold during anaerobic growth and, as was found for hemN, both Anr and Dnr were required for anaerobic induction. Paradoxically, oxygen is necessary for HemF catalysis, suggesting the existence of an additional physiological function for the P. aeruginosa HemF protein.

Increased transduction efficiency of primary hematopoietic cells by physical colocalization of retrovirus and target cells

Efficient gene transfer into hematopoietic stem cells offers a number of potential therapeutic applications. However, the relatively low titer of retroviral supernatants and the requirement for cell division to ensure integration have meant that transduction efficiency has been low. We have modified a flowthrough approach to cell transduction and have been able consistently to increase gene transfer efficiency into human hematopoietic progenitor cells. We transduced CD34 cells with retroviral vectors encoding a truncated nerve growth factor receptor (NGFR) or neo. Retroviral supernatant was pulled through 0.2-micron polycarbonated membranes, followed by placement of cells on the filter. In the absence of cytokines, the transduction efficiency of CD34 cells with a NGFR vector was increased 3-11-fold over that obtained at an identical MOI in liquid culture to produce 11%-44% transduction. Furthermore, both Thy1+ and Thy1- subsets in a total CD34 population were transduced with similar efficiency, and transduction with a neo vector, as measured by G418 resistance in clonogenic assays, increased 1.5-5-fold. The mechanism by which gene transfer is improved may reflect colocalization of cells and retrovirus. Costaining of cells transduced on the filter with an NGFR retrovirus with both an NGFR antibody and a gp70 antibody that recognizes viral coat protein revealed high-level coexpression. The levels of in vitro gene transfer we obtain are equivalent to those observed when CD34 cells are cocultured in liquid culture with cytokines. However, culture with cytokines may commit CD34 cells to differentiation and has produced disappointingly low levels of subsequent in vivo gene transfer. Gene marking studies using distinguishable retroviral vectors will provide a means of learning whether the effects of flowthrough transduction genuinely enhance the efficiency of gene transfer to human marrow-repopulating cells.

Anti-(epidermal growth factor) receptor monoclonal antibodies for the induction of antibody-dependent cell-mediated cytotoxicity against squamous cell carcinoma lines of the head and neck

Squamous cell carcinomas of the head and neck (SCCHN) frequently display high levels of the epidermal growth factor receptor (EGFR). Since EGFR is expressed on the cell surface it may form a suitable target for anticancer therapy with anti-receptor monoclonal antibodies (mAb). Besides the interference with receptor/ligand interactions, binding of mAb to EGFR leads to immunoglobulin-coated tumour cells that may induce or enhance non-specific immune effector mechanisms like antibody-dependent cell-mediated cytotoxicity (ADCC). In established cell lines of SCCHN (UM-SCC 11B, 14C, 22B, and 8029 NA) we investigated the antitumour activity of allogeneic peripheral blood mononuclear cells (PBMC) in combination with rat (ICR 62), mouse (EMD 55900), and humanized (EMD 72000) anti-EGFR mAb. In addition, autologous PBMC were available for tumour line UD-SCC 4. The EGFR protein content of the tumour cell lines ranged between 170 fmol/mg protein and 8100 fmol/mg protein, and MCF-7 cells served as receptor-negative controls. PBMC activity against SCCHN targets was determined in 96-well microtitre-plate monolayer cultures by the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay after coincubation for 4 h, 24 h and 72 h at effector target ratios of 1:1, 5:1, 10:1 and 20:1. PBMC subpopulations were obtained by macrophage depletion (plastic adherence) or natural killer (NK) cell enrichment (magnetic bead negative selection). Prolonged time of exposure and increased effector:target ratios revealed marked antitumour activity of PBMC alone. This non-specific immune destruction was enhanced considerably by humanized and rat, but not mouse anti-EGFR mAb. Increased EGFR protein in tumour cells partly correlated with an intensification of ADCC but was accompanied by decreased primary PBMC cytotoxicity. The utilization of PBMC subpopulations suggested a mainly NK-cell-mediated ADCC, which appeared to benefit directly or indirectly, e.g. via the secretion of cytokines, from other PBMC components. In conclusion, humanized (EMD 72000) and rat (ICR 62) anti-EGFR mAb were able to generate strong antitumour ADCC in target monolayers of SCCHN.

Repeated treatment with horse antilymphocyte globulin for severe aplastic anaemia

In a single-centre study the feasibility and efficacy of repeated antilymphocyte globulin (ALG) for patients with severe aplastic anaemia (SAA) not responding to an initial ALG treatment or relapsing after initial response to ALG was evaluated. 139 consecutive patients with newly diagnosed SAA were treated with ALG between 1976 and 1995. 89 patients responded to a first course; 50 patients did not become transfusion independent. Of the 89 responders, 66 remained in remission, 23 relapsed. 43 patients received a second or subsequent course of ALG for failure to respond (n = 25) or relapse (n = 18) and were given a total of 53 courses. Acute reactions in the multiply exposed patients occurred during the first ALG treatment in 11 (26%) and during subsequent exposures in 16/53 courses (30%; P > 0.2). Incidence of serum sickness was 63% (27/43) after the initial course compared to 57% (30/53) after subsequent courses (P > 0.2), but clinical signs of serum sickness occurred earlier after repeated (median 6 d) as compared to initial exposure (13d; P = 0.008). Transfusion-independent haemopoiesis was achieved in 27/43 (63%) and survival probabilities for the 43 patients receiving multiple courses of ALG was 52 +/- 8% at 10 years. The probability of developing a late clonal disorder was 53 +/- 10% after multiple, as compared to 34 +/- 7% after single exposure (P = 0.15). No difference in results was observed between patients retreated for failure to first ALG or for relapse. ALG of the same species can be repeated without increased risks of side-effects in patients with SAA. A second or subsequent course of ALG from the same source can be effective when the first course has failed.

Ammonification in Bacillus subtilis utilizing dissimilatory nitrite reductase is dependent on resDE

During anaerobic nitrate respiration Bacillus subtilis reduces nitrate via nitrite to ammonia. No denitrification products were observed. B. subtilis wild-type cells and a nitrate reductase mutant grew anaerobically with nitrite as an electron acceptor. Oxygen-sensitive dissimilatory nitrite reductase activity was demonstrated in cell extracts prepared from both strains with benzyl viologen as an electron donor and nitrite as an electron acceptor. The anaerobic expression of the discovered nitrite reductase activity was dependent on the regulatory system encoded by resDE. Mutation of the gene encoding the regulatory Fnr had no negative effect on dissimilatory nitrite reductase formation.

Immune versus natural selection: antibody aldolases with enzymic rates but broader scope

Structural and mechanistic studies show that when the selection criteria of the immune system are changed, catalytic antibodies that have the efficiency of natural enzymes evolve, but the catalytic antibodies are much more accepting of a wide range of substrates. The catalytic antibodies were prepared by reactive immunization, a process whereby the selection criteria of the immune system are changed from simple binding to chemical reactivity. This process yielded aldolase catalytic antibodies that approximated the rate acceleration of the natural enzyme used in glycolysis. Unlike the natural enzyme, however, the antibody aldolases catalyzed a variety of aldol reactions and decarboxylations. The crystal structure of one of these antibodies identified the reactive lysine residue that was selected in the immunization process. This lysine is deeply buried in a hydrophobic pocket at the base of the binding site, thereby accounting for its perturbed pKa.

The N-terminal structure of HIV-1 Tat is required for suppression of CD26-dependent T cell growth

Evidence exists that the human immunodeficiency virus-1 (HIV-1) transactivator Tat occurs extracellularly and is involved in the immunosuppression of non-HIV-1-infected T cells of acquired immunodeficiency syndrome (AIDS) patients. The mechanism of this immunosuppressive activity of Tat has been controversially discussed. Interestingly, Tat binds to the T cell activation marker CD26, which has been shown to play a key role in the regulation of growth of lymphocytes and to inhibit its dipeptidyl peptidase IV (DP IV) activity. Here we show that the N-terminal nonapeptide MDPVDPNIE of Tat is a competitive inhibitor of DP IV and suppresses DNA synthesis of tetanus toxoid-stimulated peripheral blood mononuclear cells. Amino acid exchanges at positions 5 and 6 strongly weaken these effects. 1H nuclear magnetic resonance and molecular dynamics simulations of Tat(1-9), I5-Tat(1-9), and L6-Tat(1-9) suggest a similar backbone conformation for Tat(1-9) and L6-Tat(1-9). The solution conformation of I5-Tat(1-9) considerably differs from the other two. However, Tat(1-9) fits into our previously proposed active site model of DP IV in contrast to I5-Tat(1-9) and L6-Tat(1-9). Conformational alterations with regard to the parent peptide and spatial hindrances between these both compounds and DP IV can explain the loss of inhibitory activity. Our data suggest that the N-terminal residues of HIV-1 Tat do interact directly with the active site of DP IV and that DP IV does mediate Tat's immunosuppressive effects.

Antitumor activity of anti-epidermal growth factor receptor monoclonal antibodies and cisplatin in ten human head and neck squamous cell carcinoma lines

Head and neck squamous cell carcinomas (HNSCC) frequently display increased levels of epidermal growth factor receptor (EGFR) and since the receptor is located on the cell surface, anti-EGFR antibodies appear to be suitable agents for antitumor therapy. We investigated the effect of murine EMD 55900 and rat ICR 62 monoclonal antibodies (MAb) directed against EGFR both as single agents and in combination with cisplatin. ELISA detection showed the amount of EGFR protein in HNSCC lines UM-SCC-10A, -10B, -11B, -14A, -14B, 14C, -22B and HLac 79, 8029NA, 8029DDP to range between 20 and 8100 fmol/mg protein. Compared to A431 cells, seven HNSCC lines were high and three low receptor expressors. Only low levels of TGF alpha were found in the supernatants of some untreated HNSCC lines, probably due to the consumption of TGF alpha by EGFR. Consequently, occupation of EGFR by MAb led to marked accumulation of TGF alpha in cell supernatants. Colorimetric MTT assay showed both MAbs (0.3-30nM) to have comparable dose-dependent growth inhibition which correlated with the EGFR content of the respective cell lines (p < 0.05). Using 30nM MAb, seven high receptor expressing HNSCC lines were growth inhibited by at least 20% to a maximum of 61% (mean = 38%). Combined treatment with MAb and cisplatin led to a significant decrease in cisplatin IC50 values in 5 cell lines expressing more than 1200 fmol EGFR/mg (dose modification by factor 2.1-4.1). In conclusion, anti-EGFR MAb exert direct antiproliferative activity in HNSCC lines and show additive effects in combination with cisplatin.

Myeloid leukemia and myelodysplastic syndrome relapsing as granulocytic sarcoma (chloroma) after allogeneic bone marrow transplantation

Of 229 consecutive patients receiving allogeneic blood or bone marrow stem cell transplants for acute myeloid leukemia, chronic myeloid leukemia, or myelodysplastic syndrome between 1974 and 1996, 52 patients relapsed. The original tumor recurred as granulocytic sarcoma (chloroma) in three patients (1.3%). Chloroma was found in the ovary in two patients and in the central nervous system in one patient. None of these three patients had experienced > or = grade II acute or more than limited chronic graft-versus-host disease. The intervals between transplantation and recurrence with chloroma were 2, 6, and 13 years. Two patients received a second transplant, and all three died of treatment sequelae.

Characterization of Bacillus subtilis hemN

A recently cloned Bacillus subtilis open reading frame (hemN) upstream of the dnaK operon was identified as encoding a protein involved in oxygen-independent coproporphyrinogen III decarboxylation. B. subtilis hemN functionally complemented two Salmonella typhimurium hemF hemN double mutants under aerobic and anaerobic conditions. A B. subtilis hemN mutant accumulated coproporphyrinogen III only under anaerobic conditions. Interestingly, growth experiments using the B. subtilis hemN mutant revealed normal aerobic and anaerobic growth, indicating the presence of an alternative oxygen-independent enzymatic system. Northern blot experiments identified hemN mRNA as part of an approximately 7-kb pentacistronic transcript consisting of lepA, hemN, hrcA, grpE, and dnaK. One potential start site for aerobic and anaerobic transcription was located 37 bp upstream of the translational start codon of lepA. Comparable amounts of hemN transcript were observed under aerobic and anaerobic growth conditions. No experimental evidence for the presence of hemF in B. subtilis was obtained. Moreover, B. subtilis hemY did not substitute for hemF hemN deficiency in S. typhimurium. These results indicate the absence of hemF and suggest the presence of a second hemN-like gene in B. subtilis.

Autologous peripheral blood stem cell transplantation in a patient with chronic autoimmune thrombocytopenia

Immunoablation by high-dose chemotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT) is one approach currently under discussion for the treatment and possible cure of patients with severe autoimmune diseases. Chronic immune thrombocytopenic purpura (ITP) can be refractory to current therapies and in severe cases may constitute a life-threatening condition. We performed autologous PBSCT with T-cell depletion in a patient with severe chronic ITP but observed no effect on platelet levels. This contrasts with a recent report where complete remission was induced by a similar regimen in two patients with ITP Further studies will be necessary to identify subgroups of patients who might benefit from this form of therapy.

Synthesis and NMR spectroscopy of peptides containing either phosphorylated or phosphonylated cis- or trans-4-hydroxy-L-proline

Many proteins are regulated by reversible O-glycosylation and O-phosphorylation. Whereas O-glycosylation of hydroxy-L-proline is common and well investigated, phosphorylation has not been proved so far in vivo, but this post-translational modification is entirely possible. As a first step to identify this phosphoamino acid, we describe both the syntheses of peptides phosphorylated at 4-hydroxy-L-proline and the 1H and 31P NMR parameters of these phosphopeptides. The model peptides were synthesized on solid-phase using Fmoc-strategy. Both natural isomers of 4-hydroxy-L-proline (containing the hydroxyl group in either the cis or trans position) were introduced without side-chain protection. All peptides were globally phosphorylated with O,O'-tert-butyl-N,N-diethylphosphoramidite on the solid phase and cleaved with trifluoroacetic acid. Additionally, we synthesized two classes of phosphonopeptides that mimic phosphopeptides, namely H- and methylphosphonopeptides. The NMR data were based on the model peptide Gly-Gly-Hyp-Ala, which is regarded as a typical random-coil sequence. The NMR parameters showed a significant influence of the phosphate group on the cis-trans isomerization of the Gly-Hyp bond, which may reflect a possible regulation of proteins by changing their local conformations. The 1H and 31P NMR parameters differed for each isomer, and were distinct from the parameters of phosphorylated serine, threonine and tyrosine. These known shifts can be used to identify both cis- and trans-O-phospho-4-hydroxy-L-proline in vivo.

Long-term survival and development of secondary malignancies in patients with acute myeloid leukemia treated with aclarubicin or daunorubicin plus cytosine arabinoside followed by intensive consolidation chemotherapy in a Danish national phase III trial. Danish Society of Haematology Study Group on AML

In 1991 we reported the results from a prospective randomised phase 3 trial comparing 7 days continuous infusion of cytosine arabinoside (ara-C) combined with either daunorubicin (DNR) or aclarubicin (ACR) as direct i.v. injection for 3 days as induction chemotherapy (CT) for patients with de novo acute myeloid leukemia (AML) followed by early intensive consolidation CT with two alternating cycles of high-dose ara-C and two cycles of amsacrine plus etoposide, and finally 3 days of daunomycin plus 7 days of ara-C as administered for induction of remission. A total of 174 patients with de novo AML in the age group 17-65 years were included. The patients have now been followed till death or for at least 7 years, and an evaluation of the long-term survival and the risk of developing secondary neoplasms has been made. The overall survival rate 5-years after diagnosis was 23%, and after 10 years 19%. No difference was found between the two treatment regimens in overall survival or disease-free survival (DFS). For the subgroup of 99 patients who achieved complete remission after one or two induction courses, 5- and 10-year survival rates were 35% and 31% respectively, with the highest survival rates in the age group 17-39 years (57% at 5 years) as compared with 27% in patients aged 40-60 years (P= 0.007). Seven secondary neoplasms were diagnosed simultaneously with or after the diagnosis of AML indicating a standardized incidence ratio (SIR) of 3.41, (95% CI: 1.60-7.26). In three cases the secondary neoplasms were diagnosed simultaneously with the AML diagnosis and were for that reason completely unrelated to the chemotherapy administered for AML, as the psammomatous meningeoma diagnosed after only 8 months. The remaining three neoplasms which developed subsequently did not significantly exceed the expected number, with a SIR = 1.46 (0.47-4.57). Thus, no increased risk of solid tumors causally related to the intensive chemotherapy for de novo AML was observed. However, a generally increased risk of solid tumors in patients diagnosed simultaneously with the AML diagnosis seems likely. Over 20% of the patients were alive and in complete remission 5 years after the AML diagnosis, and they have a high probability of surviving the next 5-year period.

Chemosensitivity of head and neck squamous carcinoma cell lines is not primarily correlated with glutathione level but is modified by glutathione depletion

Glutathione has a variety of important physiological functions in cellular metabolism and defense, including protection from radicals, oxidative stress, and electrophilic compounds. On the basis of this interaction with both endogenous and synthetic substances, glutathione and the key enzyme for its conjugation, glutathione S-transferase, appear to be critical determinants in tumor cell resistance to several antineoplastic drugs, e.g. platinum analogs. In ten established head and neck cancer cell lines (UM-SCC 10A, 10B, 11B, 14A, 14B, 14C, and 22B, HLac79, 8029NA, and 8029DDP4) chemosensitivity to cisplatin, carboplatin, 5-fluorouracil, and bleomycin, as well as cellular glutathione content and activity of glutathione S-transferase were determined. The results revealed no correlation between the sensitivity of tumor cells to any of the drugs tested and the level of glutathione or the activity of glutathione S-transferase. However, the cisplatin-resistant subpopulation 8029DDP4 showed the highest glutathione level and marked cross-resistance to bleomycin. Glutathione depletion with buthionine sulfoximine led to moderately increased sensitivity towards cisplatin and carboplatin in all cell lines, but did not affect their response to 5-fluorouracil or bleomycin. These results suggest that the level of glutathione or the activity of glutathione S-transferase is not a suitable parameter for the assessment of chemosensitivity in head and neck squamous-cell carcinoma lines. However, response to platinum analogs is influenced by alterations of the initial intracellular glutathione concentration.

Clinical and pathomorphological investigation of spontaneously occurring periodontal disease in dogs

Diagnostic evaluation of, and treatment planning for, different periodontal diseases of dogs are a common problem in veterinary dentistry. Therefore the aim of the present study was to propose a classification for inflammatory periodontal disease. One hundred and twenty-three male and female poodles (from two to over 12 years) were used for the clinical investigations; 120 periodontitis teeth were analysed for pathomorphological signs of inflammation. The recorded data made it possible to differentiate five forms of gingivitis (gingivitis simplex, hyperplastica, ulcerosa, granulomatosa and desquamativa) and three forms of periodontitis (juvenile, rapidly progressive adult and chronic adult periodontitis). The pathomorphological investigations allowed a differentiation between acute progressive inflammation, chronic nonprogressive inflammation, chronic proliferative inflammation and chronic resorptive inflammation. It is concluded that standardised diagnoses as well as the pathomorphological background may be helpful tools for providing effective treatment-strategies.

Epidemiology of periodontal disease in poodles

The periodontal condition of 123 poodles was assessed using the parameters of depth of gum pocket, attachment level, bleeding on probing, and plaque and calculus accumulation. No dogs were free of periodontal disease. The number of deep pockets and dramatic loss of attachment ranged from 0.1 teeth in young dogs to 4.2 teeth in old animals. A sixfold increase in deep pocketing took place in dogs between the ages of six and seven, followed by a twofold increase in the number of teeth missing in dogs within the 10 to 11 year age group. First premolars, incisors and second molars were at highest risk. No correlation between dietary conditions and disease incidence could be detected. It is concluded that, by concentrating their diagnostic efforts on those age groups and types of teeth at highest risk, clinicians could improve the effectiveness of their treatment interventions.

Correction of the platelet adhesion defect in delta-storage pool deficiency at elevated hematocrit--possible role of adenosine diphosphate

Previous studies on patients with storage pool deficiency (SPD) who are specifically deficient in platelet dense granules (delta-SPD) have suggested a role for dense granule substances, in all likelihood adenosine diphosphate (ADP), in mediating thrombus formation on subendothelium at high shear rates. The role of dense granule substances in mediating platelet adhesion appears to be more complicated Previous studies in delta-SPD suggested an adhesion defect that was strongly influenced by the patient's hematocrit (Hct) value. To explore further the possibility that red blood cells (RBCs) may influence the role that platelet storage granules play in mediating adhesion at high shear rates, we have measured adhesion (and thrombus formation) throughout a preselected range of Hct values (30% to 60%) in normal subjects and in patients with delta-SPD. The present studies confirm the defect in platelet adhesion in patients with delta-SPD, most significantly at Hct values of 30% to 40%. This defect (but not that of thrombus formation) can be completely corrected by the addition of RBCs. The correction of the platelet adhesion defect by RBCs was specific for delta-SPD; it was not observed in either von Willebrand's disease or thrombasthenia. Studies performed on normal blood under conditions that could be expected to block any effect of ADP on adhesion and an analysis of the type of adhesion defect in delta-SPD suggest that ADP may be involved in the process required for platelet spreading on the subendothelium. The corrective effect of RBCs on platelet adhesion in delta-SPD appears to be chemical rather than physical in nature, possibly due to shear-induced release of RBC ADP or to other recently described properties of RBCs that enhance collagen-induced platelet interactions.

Solid-phase synthesis of H- and methylphosphonopeptides

We introduce solid-phase syntheses of H- and methylphosphonopeptides, giving access for the first time to a new class of mimics for o-phosphoamino acids. The model peptides H-GlyGlyXaaAla-OH (Xaa = Ser, Thr) were synthesized on a solid-phase using Fmoc/tBu strategy and HBTU/HOBt activation by incorporation of hydroxyl-protected serine and threonine. As selectively cleavable hydroxyl-protecting groups we used triphenylmethyl and tert-butyldimethylsilyl for both amino acids, as described in the literature. All peptides were phosphitilated with O, O-di-tert-butyl-N,N-diethylphosphoramidite and yielded H-phosphonopeptides after trifluoroacetic acid cleavage. Alternatively we phosphonylated the peptides with O-tert-butyl-N,N-diethyl-P-methylphosphonamidite, which was synthesized by a two-step one-pot procedure starting from commercially available chemicals. All H- and methylphosphonopeptides were obtained in high purities and yields, as shown by reversed-phase high-performance liquid chromatography and anion-exchange chromatography. The phosphonopeptides were characterized by 1H and 31P NMR. We confirmed their molecular masses by electrospray mass spectrometry and analyzed their fragmentation schemes, which seemed to be characteristic for each class of analogues. The H-phosphonopeptides lost phosphonic acid (H3PO3, 82 mass units) and the methylphosphonopeptides lost methylphosphonic acid (MeH2PO3, 96 mass units). Both H- and methylphosphonopeptides represent a new and simply accessible class of mimics for phosphopeptides. Compared with the corresponding phosphopeptides all phosphonopeptides were synthesized in higher yields and purities (> 80%).

The N-terminal X-X-Pro sequence of the HIV-1 Tat protein is important for the inhibition of dipeptidyl peptidase IV (DP IV/CD26) and the suppression of mitogen-induced proliferation of human T cells

Recent data in the literature suggest that the HIV-1 Tat(1-86) protein exhibits immunosuppressive effects. Moreover, Tat was found to interact with dipeptidyl peptidase IV (DP IV), which is identical to the T cell activation marker CD26. Here we show that the N-terminal amino acid sequence of Tat is essential for the inhibition of DP IV-catalyzed IL-2(1-12) degradation. N-terminal modification of Tat with rhodamine prevented inhibition of enzymatic activity of DP IV as well as suppression of DNA synthesis of mitogen-stimulated human T cells. Moreover, natural peptides containing the X-X-Pro N-terminal motif of Tat also inhibited DP IV activity. These data suggest the existence of endogenous immunomodulatory oligopeptides which influence immune cell proliferation and differentiation via DP IV as does HIV-1 Tat.

CD26 mediates the action of HIV-1 Tat protein on DNA synthesis and cytokine production in U937 cells

The human immunodeficiency virus 1 (HIV-1) Tat protein is known to be capable of suppressing antigen- and CD3-induced activation of human T cells. Previously, it was shown that Tat can bind to the dipeptidyl peptidase IV (DP IV, CD26) and inhibit the degradation of the chromogenic substrate Gly-Pro-p-nitroanilide. Using the method of free zone capillary electrophoresis, here we have shown that the DP IV-catalyzed hydrolysis of the NH2-X-Pro-containing cytokine peptides IL-2(1-12), IL-1 beta(1-6), and IL-6(1-12) was also significantly inhibited by the Tat protein. Moreover, HIV-1 Tat at a concentration of 10 micrograms/ml was found to have a strong suppressive effect on DNA synthesis and IL-1 beta production, but stimulates secretion of IL-1 receptor antagonist (IL-1RA) and TNF-alpha of CD26-expressing U937-H cells. It did not impair neither DNA synthesis nor cytokine production of low CD26-expressing U937-L cells. Similar results have been found with synthetic DP IV/CD26 inhibitors (Immunobiol., 1994, vol. 192, pp. 121-136). These data strongly suggest that Tat protein is a potent "natural" inhibitor of DP IV/CD26, and they support the hypothesis that DPIV plays a role in Tat's immunosuppressive activity.

Biodegradation of cyclic and substituted linear oligomers of poly(3-hydroxybutyrate)

Cyclic oligo(3-hydroxybutyrate), oligo(3-HB), was synthesized and purified, resulting in oligolides that contained three to seven (R)-3-hydroxybutyrate units (triolides up to heptolides). In addition, linear 3-HB octamers obtained as either tert-butyl or methyl esters were substituted with different end groups at the hydroxy end. The hydroxy terminus was replaced by either a benzyloxy, trifluoroacetoxy, crotonyloxy (S)-3-hydroxybutyryloxy, or fluorenylmethylcarbonyloxy (FMOC) group. P(3-HB) hairpin loops occurred on the surface of certain regions of the polymer, especially of lamellar crystallites. Cyclic 3-HB oligomers provide a model system for these loops. It is assumed that they provide attachment points for the depolymerizing enzymes. All of the (R)-oligolides tested were degraded except the (R)-triolide. Triolides were not degraded, suggesting that enzymatic attack was prevented presumably by steric hindrance on the rigid ring system. Unsubstituted linear octamers were degraded. Biodegradation was prevented when the hydroxy terminus was protected by the FMOC group, but was not dependent on a free hydroxy terminal group; all other protecting groups did not prevent degradation. Substitution of the carboxy end of a methyl or tert-butyl ester group did not influence biodegradation.

Inhibition of dipeptidyl peptidase IV (DP IV) by anti-DP IV antibodies and non-substrate X-X-Pro- oligopeptides ascertained by capillary electrophoresis

Dipeptidyl peptidase IV (DP IV)-catalyzed hydrolysis of the NH2-X-Pro-containing N-terminal dodecapeptide of IL-2 was studied using free zone capillary electrophoresis as an alternative peptidase assay. In contrast to the conventional DP IV substrate glycyl-prolyl-p-nitroanilide (Gly-Pro-pNA), the hydrolysis of this peptide by DP IV was found to be significantly inhibited by anti-DP IV antibodies. Inhibition of DP IV was also observed with a number of non-substrate oligopeptides containing an N-terminal X-X-Pro- structure, including the HIV Tat protein. For Met-IL-2(1-6), we determined a competitive inhibition with an inhibition constant of ca. 100 microM.

The anaerobic life of Bacillus subtilis: cloning of the genes encoding the respiratory nitrate reductase system

The Gram-positive soil bacterium Bacillus subtilis, generally regarded as an aerobe, grows under strict anaerobic conditions using nitrate as an electron acceptor and should be designated as a facultative anaerobe. Growth experiments demonstrated a lag phase of 24 to 36 hours after the shift from aerobic, to the onset of anaerobic respiratory growth. Anaerobically adapted cells grew without further lag phase after their transfer to fresh anaerobic growth medium. The cells change their morphology from rods to longer filament-like structures when moved from aerobic to anaerobic respiratory growth conditions. Surprisingly, anaerobically grown B. subtilis lost the capacity for sporulation. An investigation of the molecular basis of the switch between aerobic and anaerobic growth was initiated by the cloning of the genes encoding the respiratory nitrate reductase from B. subtilis. Oligonucleotides deduced from conserved amino acid sequence regions of eubacterial respiratory nitrate reductases and related enzymes were used for the isolation of the genes. Four open reading frames with significant homology to the E. coli respiratory nitrate reductase operons (narGHIJ, narZYWV) were isolated and termed narGHJI. A chromosomal knock-out mutation of the B. subtilis nar operon totally abolished nitrate respiration.

Irradiation of bone metastases in breast cancer patients: a randomized study with 1 year follow-up

The results from a prospective randomized trial comparing two different radiation schedules for treatment of painful bone metastases in women with recurrent breast cancer are presented. A total of 217 patients with painful bone metastases were randomized to either 30 Grey (Gy) in ten fractions, five fractions a week (5F/W) or 15 Gy in three fractions 2F/W. The effect of treatment was evaluated by pain assessment, the radiological response and the degree of side-effects. The patients were rated at start of treatment and after 1, 3, 6 and 12 months. No difference between the two radiation regimes was found, neither in achieved pain relief, improvement in level of activity and medication, nor was there any difference in radiological response and side-effects from treatment. Both regimes resulted in a significant improvement in both pain score and level of activity 1 month after treatment, an improvement which persisted during the follow-up period. We conclude that 15 Gy given in three fractions 2F/W is as effective as 30 Gy in ten fractions 5F/W, but more convenient to the patient and of less cost to society.

Foreign DNA sequences are received by a wild-type strain of Aspergillus niger after co-culture with transgenic higher plants

Different transgenic plants of Brassica napus, Brassica nigra, Datura innoxia and Vicia narbonensis expressing the hph gene under the control of the 35s promoter were co-cultivated with mycelial material of Aspergillus niger in microcosms under sterile conditions. A significantly higher number of hygromycin B-resistant colonies of re-isolated fungi was obtained if compared with co-cultures with non-transgenic plants. The hph gene and other foreign sequences could be detected in some of the resistant strains only for a short time after selection, indicating a rapid loss of foreign DNA. A more stable transgenic strain was obtained after co-culture with transgenic plants of D. innoxia including a high number of hph copies in their genome. DNA with detected pUC sequences was prepared to transform E. coli DH5 alpha. One of the recovered plasmids is shown to include pieces of the plant-transforming vector and a foreign sequence. The 35s-regulated expression of genes is studied in A. niger.

Further studies on the presence of functional tissue factor activity on the subendothelium of normal human and rabbit arteries

Although tissue factor (TF) activity has been observed on the subendothelial surface of rabbit aorta and human umbilical cord, immunofluorescent and in situ hybridization methods have failed repeatedly to demonstrate TF in the intima of human blood vessels. In the present study, TF activity on everted, de-endothelialized arteries was studied by two methods. One utilized a flow system and measured fibrin deposition and fibrinopeptide A formation. The other utilized a newly developed rotating probe system and measured the conversion of factor X to factor Xa in the presence of factor VIIa and Ca+2. The study attempted to control, or assess, the possibility that functional TF could have been exposed on the vessel surface by the procedures used to prepare the arterial segments. By both methods, TF activity was detected on the subendothelium of rabbit aortae and human umbilical arteries, and was unaffected by the length of storage or by inclusion of actinomycin D in the storage buffer. TF activity was also observed in the subendothelium of adult human ileo-colic, internal mammary, and renal arteries, studied by the rotating probe method. The latter may underestimate TF activity, as some of the factor Xa formed appears to bind to the subendothelial surface. TF activity (Xa formation) was detected on the luminal surface (subendothelium) of non-everted arteries, but increased activity was observed after eversion of the vessel. The source of the subendothelial TF, and its presence in normal subendothelium in vivo, requires further study. In addition, if any of the TF activity observed in this study was derived from injured endothelial or myointimal cells during preparation of the everted vessel segments, the techniques described could serve as a useful model for studying TF-induced thrombosis and factor Xa formation on injured blood vessels, and for evaluating the anti-thrombotic properties of TF-inhibitors.

Dipeptidyl peptidase IV (CD 26) and aminopeptidase N (CD 13) catalyzed hydrolysis of cytokines and peptides with N-terminal cytokine sequences

A number of natural cytokines are characterized as having dipeptidyl peptidase (DP) IV susceptible N-terminal peptide sequences. Here we demonstrate that oligopeptides with sequences analogous to the N-terminal part of human IL-1 beta, IL-2, TNF-beta and murine IL-6 were hydrolyzed by purified DP IV and aminopeptidase N (AP-N). The rate of DP IV-catalyzed hydrolysis of these peptides was negatively correlated with their chain length. In contrast to these results, no degradation was found under our conditions for the intact recombinant cytokines, IL-1 alpha, IL-1 beta, IL-2, G-CSF and for natural IL-2, independent of whether DP IV and AP-N were used separately or in combination.

Glycosylation of human prolactin regulates hormone bioactivity and metabolic clearance

To analyze the role of individual glycosylation pattern on PRL biopotency, monomeric prolactin (PRL), secreted by human prolactinoma cells in culture, was isolated by gel filtration and separated by affinity chromatography on Concanavalin A-Sepharose or Lentil-Agarose. These lectins allowed the isolation of PRL glycoforms containing either biantennary, mannose-rich or fucosylated complex carbohydrate structures, respectively. Endoglycosidase treatment and carbohydrate content of PRL was found to be consistent with N-linked oligosaccharides of mannose-rich structure and complex units terminated in sialic acid. Mannose-rich PRL and PRL with biantennary oligosaccharides promoted cell growth of rat lymphoma cells to a diminished extent compared to non-glycosylated PRL (NG-PRL), indicating that the two major types of carbohydrate structure are able to decrease the intrinsic bioactivity of PRL. Metabolic clearance of the various forms of PRL in rats was also found to be highly dependent upon hormone glycosylation. The various glycosylated forms (G-PRLs) proved to be totally eliminated from the circulation within 60 min, faster than NG-PRL 10% of which was still present at that time. Mannose-rich or biantennary G-PRLs were differently cleared in a biphasial fashion with a similar rapid phase of about 2 min followed by distinct slow phases of 12 and 27 min, respectively. The presence of fucose did not alter this distribution. In contrast, NG-PRL was eliminated with a half-time of approximately 5 min, followed by a very slow disappearance over several h. It thus appeared that glycosylation increased the metabolic clearance rate of PRL from 0.13 +/- 0.07 ml/min for NG-PRL to 0.47 +/- 0.12 ml/min for PRL with biantennary carbohydrate chains and 0.8 +/- 0.2 ml/min for the hormone with mannose-rich oligosaccharides. The distribution of PRL to target and elimination organs was also found to be different according to the carbohydrate structure present in the hormone. NG-PRL and mannose-rich G-PRL showed higher incorporation in liver than biantennary G-PRL which was preferentially eliminated by the kidney. Altogether, the current data show that addition of oligosaccharides to PRL as well as carbohydrate structure contribute to modulate both the duration of the hormone in the blood and its distribution to different organs. It is proposed that glycosylation may selectively down-regulate PRL action at individual target tissues.