Inhibition of JAK2 Suppresses Myelopoiesis and Atherosclerosis in Apoe-/- Mice.

OBJECTIVE: Increased myelopoiesis has been linked to risk of atherosclerotic cardiovascular disease (ACD). Excessive myelopoiesis can be driven by dyslipidemia and cholesterol accumulation in hematopoietic stem and progenitor cells (HSPC) and may involve increased signaling via Janus kinase 2 (JAK2). Constitutively activating JAK2 mutants drive biased myelopoiesis and promote development of myeloproliferative neoplasms (MPN) or clonal hematopoiesis, conditions associated with increased risk of ACD. JAK2 inhibitors have been developed as a therapy for MPNs. The potential for JAK2 inhibitors to protect against atherosclerosis has not been tested. We therefore assessed the impact of JAK2 inhibition on atherogenesis. METHODS: A selective JAK2 inhibitor TG101348 (fedratinib) or vehicle was given to high-fat high-cholesterol Western diet (WD)-fed wild-type (WT) or Apoe-/- mice. Hematopoietic cell profiles, cell proliferation, and atherosclerosis in WT or Apoe-/- mice were assessed. RESULTS: TG101348 selectively reversed neutrophilia, monocytosis, HSPC, and granulocyte-macrophage progenitor (GMP) expansion in Apoe-/- mice with decreased cellular phosphorylated STAT5 and ERK1/2 and reduced cell cycling and BrdU incorporation in HSPCs, indicating inhibition of JAK/STAT signaling and cell proliferation. Ten-week WD feeding allowed the development of marked aortic atherosclerosis in Apoe-/- mice which was substantially reduced by TG101348. CONCLUSIONS: Selective JAK2 inhibition reduces atherogenesis by suppressing excessive myelopoiesis in hypercholesterolemic Apoe-/- mice. These findings suggest selective JAK2 inhibition as a potential therapeutic approach to decrease ACD risk in patients with increased myelopoiesis and leukocytosis.

The prognostic relevance of serum lactate dehydrogenase and mild bone marrow reticulin fibrosis in essential thrombocythemia.

The 2016 World Health Organization (WHO) diagnostic criteria for myeloproliferative neoplasms (MPN) underscore the prognostically-relevant distinction between essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (pre-PMF). In addition, leukocytosis has been identified as an important prognostic marker in otherwise WHO-defined ET. However, controversy remains regarding the objectivity of morphologic criteria in distinguishing ET from pre-PMF and the precise prognostic cutoff values for leukocytosis. Serum lactate dehydrogenase (LDH) level might be a biologically more accurate measure of leukocyte turnover and a more sensitive marker of pre-PMF, in otherwise WHO-defined ET. In the current study of 183 consecutive patients with WHO-defined ET, the presence of grade 1 bone marrow (BM) fibrosis did not affect presenting clinical or laboratory features; in contrast, increased serum LDH at diagnosis was associated with leukocytosis (p = .002), thrombocytosis (p < .001), palpable splenomegaly (p = .03) and higher international prognostic score (IPSET) (p = .002); serum LDH did not correlate with BM fibrosis, JAK2/CALR/MPL or TET2/ASXL1 mutations. In univariate analysis, risk factors for survival included age ≥60 years (p = .002; HR 10.2, 95% CI 2.3-44.6), male sex (p = .02; HR 3.2, 95% CI 1.2-8.2), leukocyte count ≥15 × 109 /L (p = .007; HR 4.7, 95% CI 1.5-14.6), and increased serum LDH (p = .002; HR 3.7, 95% CI 1.5-9.1), but not BM fibrosis (p = .17). In multivariable analysis, age, sex and serum LDH remained significant; serum LDH also remained significant, in the context of IPSET (p = .003) and in patients with leukocytosis (p = .003). We conclude that serum LDH level carries an independent prognostic value for survival in ET and might represent a biologically more accurate surrogate for leukocytosis.

Hematopoietic arginase 1 deficiency results in decreased leukocytosis and increased foam cell formation but does not affect atherosclerosis.

BACKGROUND AND AIMS: Arginase1 (Arg1), an M2 macrophage marker, plays a critical role in a number of immunological functions in macrophages, which are the main cell type facilitating atherosclerotic lesion development. Arg1 uses the substrate l-arginine to create l-ornithine, a precursor molecule required for collagen formation and vascular smooth muscle cell differentiation. By reducing l-arginine availability, Arg1 limits the production of nitric oxide (NO), a pro-atherogenic factor in macrophages. In endothelial cells, conversely, NO is strongly anti-atherogenic. However, until now, the role of Arg1 in atherosclerosis is largely unknown. The aim of this study is to specifically investigate the effect of Arg1 deletion in hematopoietic cells on atherosclerosis susceptibility. METHODS: Ldlr KO mice were transplanted with Arg1flox/flox;Tie2-Cre (Arg1 KO) bone marrow (BM) or wildtype (WT) BM. After 8 weeks of recovery on chow diet, recipients mice were fed a Western-Type Diet (WTD) for 10 weeks to induce atherosclerosis. RESULTS: After 10-week WTD challenge, blood leukocyte counts were decreased by 25% (p < 0.001), and spleen leukocytes were decreased by 35% (p = 0.05) in Ldlr KO mice transplanted with Arg1 KO BM compared to mice transplanted with WT BM. The decrease in leukocytes was due to lower B lymphocyte counts. However, oxLDL-specific antibodies were increased in plasma of Ldlr KO mice transplanted with Arg1 KO BM compared to WT BM transplanted controls, whereas oxLDL-specific IgM was not affected. On the other hand, peritoneal foam cells in Arg1 KO BM recipients were increased 3-fold (p < 0.001) compared to WT BM recipients. No change in blood cholesterol was found. Despite changes in leukocyte counts and macrophage foam cell formation, we did not observe differences in atherosclerotic plaque size or plaque macrophage content in the aortic root. Surprisingly, there was also no difference in plaque collagen content, indicating that absence of macrophage Arg1 function does not reduce plaque stability. CONCLUSIONS: Deletion of Arg1 in hematopoietic cells adversely affects blood leukocyte counts and increases foam cell formation. However, no effects on atherosclerosis could be demonstrated, indicating that hematopoietic Arg1 function is not a decisive factor in atherosclerotic plaque formation.

Acat1 gene ablation in mice increases hematopoietic progenitor cell proliferation in bone marrow and causes leukocytosis.

OBJECTIVE: To investigate the role of acyl-CoA:cholesterol acyltransferase 1 (ACAT1) in hematopoiesis. APPROACH AND RESULTS: ACAT1 converts cellular cholesterol to cholesteryl esters for storage in multiple cell types and is a potential drug target for human diseases. In mouse models for atherosclerosis, global Acat1 knockout causes increased lesion size; bone marrow transplantation experiments suggest that the increased lesion size might be caused by ACAT1 deficiency in macrophages. However, bone marrow contains hematopoietic stem cells that give rise to cells in myeloid and lymphoid lineages; these cell types affect atherosclerosis at various stages. Here, we test the hypothesis that global Acat1(-/-) may affect hematopoiesis, rather than affecting macrophage function only, and show that Acat1(-/-) mice contain significantly higher numbers of myeloid cells and other cells than wild-type mice. Detailed analysis of bone marrow cells demonstrated that Acat1(-/-) causes a higher proportion of the stem cell-enriched Lin(-)Sca-1(+)c-Kit(+) population to proliferate, resulting in higher numbers of myeloid progenitor cells. In addition, we show that Acat1(-/-) causes higher monocytosis in Apoe(-/-) mouse during atherosclerosis development. CONCLUSIONS: ACAT1 plays important roles in hematopoiesis in normal mouse and in Apoe(-/-) mouse during atherosclerosis development.

Factors affecting matrix metalloproteinase-8 levels in the vaginal and cervical fluids in the first and second trimester of pregnancy.

BACKGROUND: Cervical ripening during pregnancy resembles an inflammatory process. Matrix metalloproteinases (MMPs), particularly MMP-8, have been linked to inflammatory processes. We studied the concentrations of, and factors associated with, MMP-8 in the lower genital tract fluids in the first and second trimesters. METHODS: In a prospective population-based cohort study, vaginal and cervical swab samples were obtained from 2130 unselected pregnant women undergoing their first and second trimester ultrasound screening. MMP-8 was determined by immunofluorometric assay. Use of antibiotics, history of vaginal bleeding, and history of sexual intercourse were recorded on both occasions. Vaginal smears were obtained for Gram-staining and leukocyte counting. Cervical length was measured by ultrasonography. The main outcome measures were MMP-8 concentrations in the vagina and cervix. RESULTS: The median (range) MMP-8 concentrations in vaginal and cervical samples were 107.4 microg/l (undetectable-2406.6 microg/l) and 318.3 microg/l (0.1-2074.6 microg/l), respectively, in the first trimester, and 112.5 microg/l (undetectable-2093.4 microg/l) and 344.8 microg/l (0.4-1783.5 microg/l), respectively, in the second trimester. Multiparity and vaginal leukocytosis were both associated with increased MMP-8 concentrations in vaginal and cervical samples in both trimesters. Bacterial vaginosis (BV) was associated with increased vaginal and cervical MMP-8 in the first trimester, but only with increased vaginal MMP-8 in the second trimester. A history of sexual intercourse (in the previous 48 h) was associated with lower MMP-8 concentrations in cervical samples in both trimesters. CONCLUSIONS: MMP-8 concentrations were lower in vaginal samples than in cervical samples, and no difference was found between the first and second trimesters. Multiparity, BV and an elevated leukocyte count in the vagina were associated with increased MMP-8 concentrations. Sexual intercourse had an opposite effect. The study suggests that MMP-8 is a physiologic constituent in lower genital tract fluids, where it may be involved in host response to inflammatory and infectious processes.

Multiple expression of matrix metalloproteinases in murine neurocysticercosis: Implications for leukocyte migration through multiple central nervous system barriers.

During the course of murine neurocysticercosis (NCC), disruption of the unique protective barriers in the central nervous system (CNS) is evidenced by extravasation of leukocytes. This process varies according to the anatomical sites and diverse vascular beds analyzed. To examine mechanisms involved in the observed differences, the expression and activity of eight matrix metalloproteinases (MMPs) were analyzed in a murine model of NCC. The mRNA expression of the MMPs studied was upregulated as a result of infection, and active MMPs were mainly detected in leukocytes migrating into the brain. Polarized expression and gelatinolytic activity of several MMPs were identified in immune cells extravasating pial vessels as early as 1 day post infection. In contrast, leukocytes expressing active MMPs and extravasating parenchymal vessels were not observed until 5 weeks post infection. In ventricular areas, most of the MMP activity was detected in leukocytes traversing the ependyma from leptomeningeal infiltrates. In addition, immune cells continued to express active MMPs after exiting vessels suggesting that enzymatic activity of MMPs is not just required for diapedesis. These results correlate with our previous studies showing differential kinetics in the disruption of the CNS barriers upon infection and help document the important role of MMPs during leukocyte infiltration and inflammation.

Leukocytosis and risk stratification assessment in essential thrombocythemia.

PURPOSE: Established risk factors for thrombosis in essential thrombocythemia (ET) include age and previous vascular events. We aimed to refine this risk stratification by adding baseline leukocytosis. PATIENTS AND METHODS: We enrolled 657 patients with ET followed for a median of 4.5 years who developed 72 major thrombosis. Cox proportional hazard model was performed to analyze the thrombotic risk and to discriminate ET patients with or without thrombosis, multivariable C statistic index was used. We searched for leukocytes cutoff with the best sensitivity and specificity by a receiver operating characteristic curve. RESULTS: Results confirmed that age and prior events are independent risk factors for thrombosis and showed a gradient between baseline leukocytosis and thrombosis. On the contrary, no significant association was found either for JAK2(V617F) allele burden and for other laboratory parameters, including platelet number. In the model with conventional risk factors alone, C statistic ratio for total thrombosis was 0.63 and when leukocytosis was added, the change was small (C = 0.67). In contrast, in younger and asymptomatic patients (low-risk category), C statistic value indicated an high risk for thrombosis in patients with leukocytosis, similar to that calculated in conventionally defined high-risk group (C = 0.65). The best leukocyte cutoff values for predicting the events was found to be 9.4 (x 10(9)/L). CONCLUSION: We suggest to include baseline leukocytosis in the risk stratification of ET patients enrolled in clinical trials.

Leukocytosis, JAK2V617F mutation, and hemostasis in myeloproliferative disorders.

Thrombosis is a leading cause of morbidity and mortality in patients with essential thrombocythemia (ET) and polycythemia vera (PV). Several mechanisms have been proposed to cause or to contribute to the acquired thrombophilic state of these patients, including platelet and red blood cell abnormalities. The increase in white blood cell count, found in most subjects with these disorders, raises the possibility that circulating leukocytes may represent another prothrombotic factor, as demonstrated for other conditions, including sickle cell, coronary heart, and peripheral arterial diseases. Published data demonstrate that neutrophil activation occurs in ET and PV patients in parallel with the appearance of laboratory signs of hemostatic system activation, suggesting an involvement of these cells in the pathogenesis of the thrombotic predisposition of these subjects. In 2005, an acquired point mutation in the pseudokinase domain of Janus kinase 2 (JAK2(V617F)) has been described in these disorders, and has attracted an enormous interest both as a diagnostic and prognostic tool, and as a potential therapeutic target. Retrospective data have identified JAK2(V617F) as a risk factor for thrombosis in ET, and have also shown a close association with abdominal vein thrombosis. JAK2(V617F) is variably associated with thrombosis and, more consistently, with elevations in blood cell counts. A clear link appears to exist between leukocytosis, JAK2(V617F), and the hemostatic system activation in patients with Bcl-negative myeloproliferative disorders.

beta-Glucuronidase activity in cerebrospinal fluid pleocytosis due to urinary tract infection.

AIM: This study examines the beta-glucuronidase activity in the cerebrospinal fluid (CSF) of patients with urinary tract infection (UTI) and sterile CSF pleocytosis and the feasibility of using these measurements for diagnostic purposes. METHODS: beta-Glucuronidase activity was measured in the CSF from 22 in each group neonates and infants with UTI and sterile CSF pleocytosis, bacterial meningitis, aseptic meningitis of apparently viral etiology and controls without CSF pleocytosis. RESULTS: The median (range) beta-glucuronidase activity in UTI with sterile CSF pleocytosis was 44.1 (33.2-57.1), whereas in the controls without CSF pleocytosis it was 19.1 (7.0-22.7), in aseptic meningitis of apparently viral etiology it was 26.5 (21.0-30.0) and in bacterial meningitis it was 168 (70.0-1152). The difference between the enzyme activity in the CSF of the patients with UTI and those in the other groups of neonates and infants is significant (p < 0.0001), with no overlapping between UTI and the other groups of children studied. Both the sensitivity and specificity of the activity was 100%. Conversely, there was a broad overlapping of the classic CSF laboratory parameters among the groups of subjects studied. CONCLUSION: beta-Glucuronidase activity in cell-free CSF discerns, with much greater accuracy than the classic CSF laboratory parameters, sterile CSF pleocytosis due to UTI from that of bacterial and viral meningitis and from control subjects without CSF pleocytosis.

Golgi GDP-fucose transporter-deficient mice mimic congenital disorder of glycosylation IIc/leukocyte adhesion deficiency II.

Modification of glycoproteins by the attachment of fucose residues is widely distributed in nature. The importance of fucosylation has recently been underlined by identification of the monogenetic inherited human disease "congenital disorder of glycosylation IIc," also termed "leukocyte adhesion deficiency II." Due to defective Golgi GDP-fucose transporter (SLC35C1) activity, patients show a hypofucosylation of glycoproteins and present clinically with mental and growth retardation, persistent leukocytosis, and severe infections. To investigate effects induced by the loss of fucosylated structures in different organs, we generated a mouse model for the disease by inactivating the Golgi GDP-transporter gene (Slc35c1). Lectin binding studies revealed a tremendous reduction of fucosylated glycoconjugates in tissues and isolated cells from Slc35c1(-/-) mice. Fucose treatment of cells from different organs led to partial normalization of the fucosylation state of glycoproteins, thereby indicating an alternative GDP-fucose transport mechanism. Slc35c1-deficient mice presented with severe growth retardation, elevated postnatal mortality rate, dilatation of lung alveoles, and hypocellular lymph nodes. In vitro and in vivo leukocyte adhesion and rolling assays revealed a severe impairment of P-, E-, and L-selectin ligand function. The diversity of these phenotypic aspects demonstrates the broad general impact of fucosylation in the mammalian organism.

Paradoxical neutrophil elastase release in endovascular abdominal aortic aneurysm repair.

Endovascular repair of abdominal aortic aneurysm potentially avoids problems associated with prolonged aortic cross-clamping that occurs with open repair, but it appears to have its own biologic consequences, which may relate to neutrophil elastase release. Blood samples of consecutive patients undergoing open or endovascular abdominal aneurysm repair were analyzed for neutrophil elastase/alpha(1)-antitrypsin complex and free elastase. Free elastase rose from baseline and fell quickly in open repair patients, returning to baseline by 144 hours. In the endovascular repair group, it continued to increase for up to 144 hours. Bound elastase increased to 24 hours, returning to baseline in endovascular repair patients by 72 hours, but remaining elevated in open repair patients at 144 hours. Open repair patients showed raised elastase/alpha(1)-antitrypsin complex and initial raised free elastase levels. High free elastase levels in endovascular repair patients may reflect less bound elastase and may paradoxically lead to a prolonged inflammatory postoperative response.

Leukocytosis is a risk factor for thrombosis in essential thrombocythemia: interaction with treatment, standard risk factors, and Jak2 mutation status.

Leukocytes contribute to the pathogenesis of thrombosis in essential thrombocythemia (ET) through recently discovered mechanisms of activation and interaction with platelets and endothelial cells. To evaluate whether an increased leukocyte count was associated with thrombosis and whether this effect can be modulated by therapy, we analyzed the clinical course of 439 patients with ET followed at the Ospedali Riuniti di Bergamo. The strength of the association was measured at diagnosis or before thrombotic events by multivariable analyses carried out using data at baseline as well as time-varying covariates. The results showed that (1) an increased leukocyte count at diagnosis was associated with thrombosis during follow-up ("baseline analysis," relative risk [RR] 2.3, 95% confidence interval [CI] 1.4-3.9, P = .001); (2) hydroxyurea (HU) lowered leukocytosis and reduced the strength of the association between leukocytosis and thrombosis ("time-dependent analysis," RR 1.6, 95% CI 0.9-2.0, not significant [NS]); (3) the association of leukocytosis and thrombosis was more evident in untreated low-risk patients (RR 2.7, 95% CI 1.2-6.4, P = .01) compared with HU-treated high-risk patients (RR 1.6, 95% CI 0.8-3.2, NS); and (4) the presence of JAK2 V617F was not identified as a risk factor for thrombosis during follow-up despite a significant association between the mutation and leukocytosis. We suggest validation of these findings in prospective clinical studies.

Biology, clinical relevance, and molecularly targeted therapy in acute leukemia with FLT3 mutation.

Overexpression and activating mutations of receptor tyrosine kinases (RTKs) are known to be involved in the pathophysiology of several kinds of cancer cells. FMS-like receptor tyrosine kinase 3 (FLT3), together with KIT, FMS, and platelet-derived growth factor receptor, is a class III RTK. FLT3 mutations were first reported as internal tandem duplication (FLT3/ITD) of the juxtamembrane domain-coding sequence; subsequently, a missense point mutation at the D835 residue and point mutations, deletions, and insertions in the codons surrounding D835 within a FLT3 tyrosine kinase domain (FLT3/KDMs) have been found. FLT3 mutations are the most frequent genetic alterations so far reported in acute myeloid leukemia and are involved in the signaling pathway of autonomous proliferation and differentiation block in leukemia cells. Several large-scale studies have confirmed that FLT3/ITD is strongly associated with leukocytosis and a poor prognosis. Therefore, routine screening for FLT3 mutations is recommended to stratify patients into distinct risk groups. However, because high-dose chemotherapy and stem cell transplantation cannot overcome the adverse effects of FLT3 mutations, the development of FLT3 kinase inhibitors is expected to produce a more efficacious therapeutic strategy for leukemia therapy.

Changes in plasma level of human leukocyte elastase during leukocytosis from physical effort.

Physical exercise is known to induce immunological changes, mainly leukocytosis and neutrophil activation. However, it is not known to what extent the leukocytosis, observed after exertion, is associated with an increase in plasma neutrophil elastase, an early marker of inflammatory response and neutrophil degranulation. In the present study changes in circulating leukocyte and neutrophil counts and human neutrophil elastase plasma levels were evaluated in volley-ball players before and after 2 h and 12 h prolonged training, during a competition season. For comparison, the same parameters were evaluated in untrained subjects before and after a jogging session. Basal white blood cell WBC, polymorpho nuclear PMN, and human polymorpho nuclear-elastase PMN-ELA values were within the normal healthy reference range and no significant differences were found between the two groups studied. Venous blood samples of nine volley-ball players showed a statistically significant increase in blood WBCs after 2 h exercise. This effect was paralleled by a statistically significant increase in PMN-ELA concentration compared to the values observed in the same individuals at rest. The exercise did not significantly change the basal correlation parameters between PMN level and PMN-ELA concentration. More pronounced WBC, PMN, and PMN-ELA increases were observed in the seven inactive subjects after 2 h jogging. There was no linear correlation between increased PMN counts and increased PMN-ELA concentrations in untrained subjects after exercise. The results show that not only the leukocyte count but also PMN-ELA plasma levels can be higher after physical effort. This has a practical significance as regards differential diagnosis demonstrating that determination of these two laboratory parameters can give abnormally high values even in the absence of an existing inflammatory process. Besides, lack of correlation between PMN count and PMN-ELA plasma levels in the untrained group suggest a state in which activation of the neutrophils is not connected with their number in peripheral blood.

Clinical significance of low protein phosphatase-1 activity of blasts in acute myelogenous leukemia with high white cell counts.

We have previously shown that protein phosphatase-1 (PP1) is the most abundant Ser/Thr phosphatase in human adult primary leukemic cells. To determine the clinical importance of PP1 expression, we compared PP1 activity of leukemic blasts with other putative prognostic factors in 46 patients with acute myelogenous leukemia (AML) who were treated with remission induction chemotherapy. PP1 was ubiquitously but differently expressed in various FAB subtypes (M1-M5), although PP1 activity was significantly higher in blasts of AML-M4 than in AML-M2. PP1 activity was significantly lower in elderly patients > or =55 years (P=0.005), and in those with high white cell counts > or =100,000/microl (P=0.039) at initial diagnosis. Correlation was observed between PP1 activity (<0.15 vs > or =0.15 nmol/min/10(8) cells) and prognosis of AML patients. Eleven of 46 patients with less than 0.15 nmol/min/10(8) cells (low PP1 activity group) had significantly lower overall survival than those with > or =0.15 nmol/min/10(8) cells (high PP1 activity group). The median overall survival was 8 months for patients with low PP1 activity compared to 27 months for those with high PP1 activity in their AML cells. Multivariate analysis using Cox's proportional hazard model showed that low PP1 activity significantly contributed to prognosis. This preliminary study suggests that low PP1 activity may be associated with shortened survival time for AML patients with high white cell counts.

Selective inhibition of inducible nitric oxide synthase exacerbates erosive joint disease.

NO is an essential cytotoxic agent in host defense, yet can be autotoxic if overproduced, as evidenced in inflammatory lesions and tissue destruction in experimental arthritis models. Treatment of streptococcal cell wal1-induced arthritis in rats with N:(G)-monomethyl-L-arginine (L-NMMA), a competitive nonspecific inhibitor of both constitutive and inducible isoforms of NO synthase (NOS), prevents intraarticular accumulation of leukocytes, joint swelling, and bone erosion. Because increased inducible NOS (iNOS) expression and NO generation are associated with pathogenesis of chronic inflammation, we investigated whether a selective inhibitor of iNOS, N:-iminoethyl-L-lysine (L-NIL), would have more directed anti-arthritic properties. Whereas both L-NMMA and L-NIL inhibited nitrite production by streptococcal cell wall-stimulated rat mononuclear cells in vitro and systemic treatment of arthritic rats with L-NMMA ablated synovitis, surprisingly L-NIL did not mediate resolution of inflammatory joint lesions. On the contrary, daily administration of L-NIL failed to reduce the acute response and exacerbated the chronic inflammatory response, as reflected by profound tissue destruction and loss of bone and cartilage. Although the number of iNOS-positive cells within the synovium decreased after treatment with L-NIL, immunohistochemical analyses revealed a distinct pattern of endothelial and neuronal NOS expression in the arthritic synovium that was unaffected by the isoform-specific L-NIL treatment. These studies uncover a contribution of the constitutive isoforms of NOS to the evolution of acute and chronic inflammation pathology which may be important in the design of therapeutic agents.

Nasal neutrophilia and release of myeloperoxidase induced by nasal challenge with platelet activating factor: different degrees of responsiveness in atopic and nonatopic subjects.

BACKGROUND: Nasal challenge with platelet activating factor (PAF) is able to induce local neutrophilia, with a different degree of responsiveness in atopic subjects and in nonatopic subjects. We investigated whether nasal accumulation of neutrophils induced by PAF is accompanied by the release of neutrophil-derived mediators. METHODS: Nasal lavages were performed before and after challenge with PAF (500 nmol), lyso-PAF (500 nmol), and saline solution in 10 patients with allergic rhinitis and 10 normal subjects to evaluate changes in neutrophil counts and the release of myeloperoxidase (MPO) and immunoreactive leukotriene B4. RESULTS: PAF caused neutrophilia, which appeared after 30 minutes in atopic subjects and after 3 hours in nonatopic subjects. Furthermore, when compared with saline insufflation, PAF caused a significant release of MPO in the nasal lavage fluids collected 30 minutes, 3 hours, and 24 hours after challenge in atopic subjects and 3 hours after challenge in nonatopic subjects, with higher values in the former than in the latter. Neutrophil counts correlated with MPO levels in the nasal lavages collected after PAF challenge. A lower degree of neutrophilia was found 3 hours after stimulation with lyso-PAF in both groups of subjects, with a marginal release of MPO in atopic subjects only. No significant increase of immunoreactive leukotriene B4 levels in nasal lavages was found after challenge with either PAF or lyso-PAF. CONCLUSION: These results indicate that PAF-induced neutrophilia in the nose is accompanied by the release of MPO, which appears earlier and is more marked in atopic subjects than in nonatopic subjects.

[The interrelation of serum lysozyme level and cytoplasmic lysozyme level].

By means of the immunocytochemical method, the level of cytoplasmic lysozyme in leukocytes from healthy volunteers (n = 50) and from patients with uremia (n = 50), leukocytosis (n = 50), various forms of leukemia (n = 36) and myelodysplastic syndrome (MDS) (n = 7) were analysed, and compared with that of simultaneously assayed serum lysozyme. Both the cytoplasmic and serum levels of lysozyme in uremia and leukocytosis were significantly higher than normal subjects (p < 0.001). No correlation, however, was found between their cytoplasmic and serum levels of lysozyme. Morphological analysis for various kinds of leukemia and MDS indicated that myelocytic and monocytic cells became highly positive for lysozyme staining with maturation, and that lymphocytes, leukemic myeloblasts and monoblasts were negative. The cytoplasmic and serum lysozyme levels of leukemias or MDS having a number of lysozyme-positive cells were elevated as compared with those of normal individuals. Among them acute myelocytic leukemia (FAB M4) revealed an excellent correlation between the lysozyme levels in cytoplasm and in serum. The rest whose serum lysozyme level tend to be lower than the cytoplasmic one gave poor correlation. Thus, serum lysozyme level is not fully reflected by the cytoplasmic level. The dual determination of cytoplasmic and serum lysozyme is suggested to be helpful on estimating leukemia types, the degree of cellular maturation and total cell mass, and might also provide a valuable tool for prediction of prognosis for these disorders.