Search PubMed⌕ Search

Biomedical subjects

R Alam

Publications and source records attributed to R Alam.

At least 55 records · Page 3Linked to original sources
PubMed1996

Characterization of histamine releasing factors in diisocyanate-induced occupational asthma.

Immunologic mechanisms contributing to diisocyanate-induced occupational asthma (OA) are poorly defined. There is a relatively low incidence of diisocyanate-specific IgE antibody responses. The frequent occurrence of delayed onset asthmatic responses in workers with diisocyanate asthma suggests a role for cellular immune mechanisms. We have shown in vitro production of antigen-specific mononuclear cell-derived histamine releasing factors (HRF) by peripheral blood mononuclear cells (PBMCs) of workers with OA. Monocyte chemoattractant protein-1 (MCP-1) and RANTES (acronym for "regulated on activation normal T expressed and secreted") are chemokines found in PBMC supernatants that express HRF activity. Diisocyanate-exposed workers were tested for diisocyanate antigen-stimulated enhancement of HRF, MCP-1, and RANTES production in supernatants of PBMCs and for serum specific IgE and IgG antibody levels to diisocyanate antigens bound to human serum albumin (HSA). PBMCs of workers with diisocyanate OA showed significantly increased production of antigen-specific HRF activity and MCP-1 ( > 300 ng/ml) compared to diisocyanate-exposed asymptomatic workers (P < 0.05). Antigen-stimulated enhancement of MCP-1 mRNA was demonstrated by reverse-transcription PCR. RANTES mRNA and chemokine secretion ( < 1 ng/ml) was also demonstrated in PBMCs, but did not show antigen enhancement in OA workers. Hapten specificity for the diisocyanate chemical to which a patient had been exposed was demonstrated for HRF enhancement and for IgG antibody reactions, but not for IgE reactions. HRF production was demonstrated in PBMC subpopulations, including lymphocytes and purified T cells. OA subjects showed increased CD8+ cells by immunofluorescence (mean CD4+: CD8+ = 1.2 +/- 0.2). The results suggest that diisocyanate antigen enhancement of HRF and MCP-1 production are stimulated by hapten-specific T cell reactions. Since a weak association has been found between IgE antibody synthesis and induction of diisocyanate OA, the role of T cell cytokines and chemokines in the pathogenesis of OA requires further investigation.

Asthma↗
PubMed1996

IL-13 released by and localized in human basophils.

We and others have shown that human basophils can synthesize and release IL-4. However, IL-13, a cytokine that closely resembles IL-4, has not hitherto been described as a basophil product. The production of IL-13 by basophils was demonstrated by immunocytochemistry. Approximately 70% of basophils stimulated with anti-FcepsilonRIalpha (antibody to the alpha subunit of IgE receptor type I) stained for IL-13. Under similar experimental conditions, mononuclear cells failed to stain for IL-13. The cytokine was localized to basophilic granules by electron microscopic examination of immunogold staining. The secretion of IL-13 into the culture supernatant was assayed by ELISA. Kinetic studies showed detectable IL-13 release at 3 h, which steadily increased up to 24 h. This is significantly different from the kinetics of basophil histamine and IL-4 release. IL-13 production was also observed upon stimulation with anti-IgE, anti-FcepsilonRIalpha, IL-3, and A23187 in a dose-dependent manner. PBMC, neutrophils, and eosinophils isolated from the same donors did not release IL-13 after anti-IgE stimulation. The anti-IgE-induced basophil IL-13 synthesis could be enhanced by IL-3 preincubation (with and without IL-3 preincubation, anti-IgE-induced IL-13 production was 227 +/- 99 and 42 +/- 13 pg/10(6) basophils, respectively). PBMC produced a significant amount of IL-1 3 upon stimulation with PHA, but a low level of IL-13 in response to A23187 and/or PMA. Eosinophils and neutrophils did not produce IL-13 when cultured with A23187, IL-5, and anti-FcepsilonRIalpha. This is the first demonstration of IL-1 3 production by basophils. Our data suggest that basophils, in addition to secreting mediators, can represent an important source of proallergic cytokines.

Basophils↗
PubMed1996

Intranasal fluticasone propionate inhibits recovery of chemokines and other cytokines in nasal secretions in allergen-induced rhinitis.

BACKGROUND: Allergen-induced nasal responses are associated with the recovery of proinflammatory mediators and cytokines. In recent years, a distinct group of chemotactic cytokines, chemokines, has been the focus of intense investigation as to their possible role in the pathogenesis of allergic diseases. Although corticosteroids have been known to be effective in the treatment of allergic diseases, their mechanism(s) of action has not been fully elucidated. OBJECTIVES: To study the effect of topical fluticasone on the recovery of chemokines (IL-8, MIP-1 alpha, and RANTES) and other cytokines (IL-1 beta, IL-6, and GM-CSF) from nasal mucosa following allergen challenge. To correlate the improvement of rhinitis symptoms with cytokine levels during early-phase and late-phase allergic responses. METHODS: A randomized, double-blind, placebo-controlled crossover study of fluticasone propionate, 200 micrograms q d, was performed in ten subjects with allergic rhinitis. Allergen challenge was administered after 1 week of treatment. Nasal secretions were collected immediately after challenge and during the late-phase reactions; symptom scores were recorded simultaneously. Nasal cytokines were assayed by specific ELISA. RESULTS: The allergen challenge caused early-phase and late-phase allergic reactions and increased recovery of IL-1 beta, IL-6, IL-8, RANTES, MIP-1 alpha, and GM-CSF from the nasal mucosa. Intranasal fluticasone inhibited the allergen-induced increase in nasal symptoms. This was associated with decreases in cytokine recovery. A significant correlation was observed between decreases in cytokine levels and in symptom scores after treatment. CONCLUSION: Our results suggest that treatment with topical fluticasone propionate inhibits allergen-induced nasal responses and the associated increase in the production/secretion of chemokines and other proinflammatory cytokines.

Administration, Topical↗
PubMed1996

Increased MCP-1, RANTES, and MIP-1alpha in bronchoalveolar lavage fluid of allergic asthmatic patients.

Chemokines are cytokines that induce chemotaxis of inflammatory cells. We studied the presence of chemokines in bronchoalveolar lavage fluid (BALF) obtained from nine allergic asthmatic patients and six nonsmoking normal individuals. The cells were pelleted, and ribonucleic acid (RNA) was extracted by using RNAzol B. BALF was assayed for monocyte chemoattractant protein-1 (MCP-1), regulated upon activation in normal T cells, expressed, probably secreted (RANTES), macrophage inflammatory protein-1alpha (MIP-1alpha) and interleukin-8 (IL-8) by enzyme-linked immunosorbent assay (ELISA). The levels of MCP-1, RANTES, and MIP-1alpha were significantly higher in the asthma patients than in the control subjects (p<0.04). The concentrations of RANTES and MCP-1 correlated with the lymphocyte count in the BAL specimens (r = 0.61 and 0.68, respectively). BALF showed eosinophil chemotactic activity in vitro that was blocked by anti-RANTES and anti-MCP-3 antibodies. The total cellular RNA was reverse-transcribed and the complementary deoxyribonucleic acid (cDNA) was amplified with the polymerase chain reaction (PCR) for MCP-1, MCP-3, RANTES, MIP-1alpha, IL-8, and beta-actin. We found that messenger ribonucleic acids (mRNAs) for MCP-1, MCP-3, RANTES, MIP-1alpha, and IL-8 were produced by BAL cells from most asthmatic and normal subjects. We conclude that chemokines are produced in the airways, and that an increased recovery of MCP-1, RANTES, and MIP-1alpha is observed in allergic asthmatic patients.

Adolescent↗
PubMed1995

Mechanism of inhibition of eosinophil activation by transforming growth factor-beta. Inhibition of Lyn, MAP, Jak2 kinases and STAT1 nuclear factor.

The activation of eosinophils by IL-5 plays a crucial role in the pathogenesis of allergic and parasitic disorders. IL-5 has recently been shown to activate Lyn and Jak2 tyrosine kinases, MAP kinases, and STAT1 nuclear factor. We have previously reported that TGF-beta blocks the IL-5-induced activation of eosinophils. In this study, we investigated the effect of TGF-beta on the IL-5-induced signaling molecules in eosinophils. Purified eosinophils from mildly allergic patients were preincubated with TGF-beta and then stimulated with IL-5. The cell lysates were then immunoprecipitated and blotted with antiphosphotyrosine Abs. The activity of the kinases was further studied in the immune-complex kinase assay. We found that TGF-beta inhibited the tyrosine phosphorylation of multiple proteins in eosinophils. The identity of some of the proteins was established by immunoprecipitation. We found that TGF-beta inhibited tyrosine phosphorylation of Lyn, Jak2, and a 44-kDa MAP kinase. In further experiments, it blocked the activation of the above kinases as determined by immune-complex kinase assay. TGF-beta also inhibited phosphorylation of the STAT1 (p91) nuclear protein in eosinophils. We believe that the inhibition of Lyn, Jak2, MAP kinase, and the STAT1 nuclear protein may underlie the inhibitory activity of TGF-beta on eosinophils.

Animals↗
PubMed1995

The activation of the Jak-STAT 1 signaling pathway by IL-5 in eosinophils.

The intracellular signal transduction of IL-5 in eosinophils is unknown. The objective of this study was to investigate the involvement of the newly discovered Jak-STAT pathway in the IL-5 signal transduction mechanism. Eosinophils were purified from peripheral blood by discontinuous Percoll gradients and stimulated with IL-5. The involvement of Jak 2 was investigated by immunoprecipitation followed by immunoblotting for tyrosine phosphorylation. The activation of Jak 2 was studied by autophosphorylation of the immunoprecipitated kinase. Jak 2 was tyrosine phosphorylated within 1 to 3 min after stimulation of eosinophils with IL-5. Further, the immunoprecipitated Jak 2 obtained from IL-5-stimulated cells underwent autophosphorylation. Jak 2 coprecipitated with the beta-subunit of the IL-5 receptor, suggesting a physical association of the kinase with the receptor. The nuclear factor STAT-1 (p91) was investigated by immunoprecipitation followed by immunoblotting for tyrosine phosphorylation. STAT-1 was tyrosine phosphorylated within 15 min of IL-5 stimulation. The presence of STAT-1 in the nuclear extract was studied by electrophoretic mobility shift assay. IL-5 induced two proteins that bound to the gamma-activating sequence. In the presence of an anti-STAT-1 Ab, the band was supershifted. Thus, we demonstrated that IL-5 activated the Jak 2-STAT 1 signaling pathway in eosinophils. We speculate that the Jak 2-STAT 1 pathway may be involved in the activation of IL-5-inducible genes in eosinophils.

Base Sequence↗
PubMed1995

The intracellular signal transduction mechanism of interleukin 5 in eosinophils: the involvement of lyn tyrosine kinase and the Ras-Raf-1-MEK-microtubule-associated protein kinase pathway.

Interleukin 5 (IL-5) regulates the growth and function of eosinophils. The objective of this study was to investigate the intracellular signal transduction mechanism of IL-5 in eosinophils. Purified eosinophils were stimulated with IL-5, and the involvement of various kinases was investigated by immunoblotting, immune complex kinase assay, and in situ denatured/renatured kinase assay. We found that IL-5 induced tyrosine phosphorylation and activation of a number of kinases. Two species of lyn kinases (53 and 56 kD) were present in eosinophils. Both forms were Tyr-phosphorylated and activated rapidly within 1 min. Further, lyn kinase was physically associated with the IL-5 beta receptor in eosinophils. Ras was studied by immunoprecipitation followed by thin-layer chromatography. Ras bound higher quantities of [alpha-32P]guanosine 5'triphosphate upon stimulation with IL-5. Raf-1 kinase showed increased Tyr phosphorylation on immunoblotting and increased activity in the immune complex kinase assay. Two species of MEK (MAP or Erk kinase) (41 and 45 kD) were identified in eosinophils, which underwent autophosphorylation upon stimulation. Microtubule-associated protein (MAP) kinase (p44) was Tyr-phosphorylated on immunoblotting and had increased activity in the immune-complex kinase assay. MAP kinases were also studied after metabolic radiolabeling of the cells with [32P]orthophosphates. IL-5 stimulated phosphorylation of MAP kinases in situ. Thus, we have delineated major components of an important signaling pathway in eosinophils. We believe that one of the signals generated by IL-5 receptor activation is propagated through the lyn-Ras-Raf-1-MEK-MAP kinase pathway.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1995

Secretion of chemokines and other cytokines in allergen-induced nasal responses: inhibition by topical steroid treatment.

We have demonstrated the detection of proallergic cytokines in the nasal secretions after antigen challenges. Our aim was to determine the secretion kinetics of chemokines (interleukin [IL]-8, macrophage inflammatory protein-1 alpha [MIP-1 alpha], and RANTES) and other cytokines (IL-1 beta and granulocyte/macrophage colony-stimulating factor [GM-CSF] after allergen challenges and their inhibition by steroid therapy. Ten allergic patients were given either beclomethasone dipropionate (BDP) or placebo in a double-blind, randomized, crossover manner. Allergen challenges were performed after 1 wk of treatment. Nasal secretions were collected serially for 11 h after allergen challenge by a matrix method. Subjects maintained symptom scores at each time point of nasal secretion recovery. Cytokines were measured by specific enzyme-linked immunosorbent assays. The mean peak values for each cytokine and total symptom scores during the early (ER) and/or late-phase reactions (LPR) were significantly reduced during the BDP treatment period (p < 0.05). The levels of cytokine correlated (p < 0.05) with corresponding total symptom scores during ER (IL-1 beta and MIP-1 alpha) and LPR (all cytokines). Our findings document local elevations of IL-1 beta, GM-CSF, and chemokines in the nasal secretions after allergen challenges and their inhibition by steroids. We speculate that the inhibition of cytokine production and secretion in the nasal mucosa may contribute to the clinical efficacy of topical steroids.

Beclomethasone↗
PubMed1994

MSF, a novel cytoplasmic chaperone which functions in precursor targeting to mitochondria.

Mitochondrial import stimulation factor (MSF) unfolds wheat germ lysate synthesized aggregated mitochondrial precursor proteins and stimulates their mitochondrial import in an ATP dependent manner. Here we analysed the function of MSF mainly by utilizing chemically pure adrenodoxin precursor (pAd). MSF bound to the unfolded pAd and prevented it from losing import competence and also restored the import competence of the aggregated pAd dependent on ATP hydrolysis. The import incompetent aggregated mitochondrial precursors induced the ATPase activity of MSF and the activity was strongly inhibited by isolated mitochondrial outer membrane (OM) but not by trypsin treated outer membrane (tOM). The precursor induced ATPase activity of N-ethylmaleimide (NEM)-treated MSF was not inhibited by OM. In this context, the MSF-precursor complex specifically bound to OM and binding was abolished both by the treatment of OM with trypsin and by the treatment of MSF with NEM. These results show that MSF is a novel cytoplasmic chaperone protein with a mitochondrial precursor-targeting function.

Adenosine Triphosphatases↗
PubMed1994

Monocyte chemotactic protein-2, monocyte chemotactic protein-3, and fibroblast-induced cytokine. Three new chemokines induce chemotaxis and activation of basophils.

Cytokine-dependent mediator release from basophils and mast cells may play an important role in the pathogenesis of allergic and inflammatory conditions. Many C-C chemokines have been found to activate basophils and mast cells. We investigated the effect of three newly identified C-C chemokines, monocyte chemotactic protein-2 and -3 (MCP-2, MCP-3) and fibroblast-induced cytokine (FIC) on basophils and mast cells. We found that all three cytokines induced histamine secretion from basophils in a dose-dependent manner. The secretion of histamine was a Ca(2+)-dependent process. MCP-3 was the most potent activator of basophils. MCP-3 and FIC activated basophils from all study subjects, whereas the histamine release by MCP-2 was donor-dependent. The histamine-releasing activity of MCP-2, MCP-3, and FIC was compared with that of MCP-1, RANTES, and macrophage inflammatory protein-1 alpha using basophils from 10 donors. MCP-1 was the most potent among all the C-C chemokines. However, MCP-3 was nearly as potent. MCP-2, MCP-3, and FIC induced significant chemotaxis of basophils. None of the cytokines activated mouse peritoneal mast cells. The synthesis of mRNA for MCP-3 was investigated by reverse-transcription PCR using allergen-stimulated PBMC and bronchoalveolar lavage cells. Both MNC and bronchoalveolar lavage cells expressed mRNA for MCP-3. The results of this study indicate that MCP-2, MCP-3, and FIC are novel histamine-releasing factors.

Allergens↗
PubMed1994

Transforming growth factor beta abrogates the effects of hematopoietins on eosinophils and induces their apoptosis.

Hematopoietins, interleukin (IL)-3, IL-5, and granulocyte/macrophage colony-stimulating factor (GM-CSF) have previously been shown to prolong eosinophil survival and abrogate apoptosis. The objective of this study was to investigate the effect of transforming growth factor beta (TGF-beta) on eosinophil survival and apoptosis. Eosinophils from peripheral blood of mildly eosinophilic donors were isolated to > 97% purity using discontinuous Percoll density gradient. Eosinophils were cultured with hematopoietins with or without TGF-beta for 4 d and their viability was assessed. We confirmed previous observations that hematopoietins prolonged eosinophil survival and inhibited apoptosis. TGF-beta at concentrations > or = 10(-12) M abrogated the survival-prolonging effects of hematopoietins in a dose-dependent manner and induced apoptosis as determined by DNA fragmentation in agarose gels. The effect of TGF-beta was blocked by an anti-TGF-beta antibody. The anti-TGF-beta antibody also prolonged eosinophil survival on its own. The culture of eosinophils with IL-3 and GM-CSF stimulated the synthesis of GM-CSF and IL-5, respectively, suggesting an autocrine mechanism of growth factor production. TGF-beta inhibited the synthesis of GM-CSF and IL-5 by eosinophils. TGF-beta did not have any effect on the expression of GM-CSF receptors on eosinophils. We also studied the effect of TGF-beta on eosinophil function and found that TGF-beta inhibited the release of eosinophil peroxidase. Thus, TGF-beta seems to inhibit eosinophil survival and function. The inhibition of endogenous synthesis of hematopoietins may be one mechanism by which TGF-beta blocks eosinophil survival and induces apoptosis.

Antibodies, Monoclonal↗
PubMed1994

Macrophage inflammatory protein-1 alpha and monocyte chemoattractant peptide-1 elicit immediate and late cutaneous reactions and activate murine mast cells in vivo.

We have previously reported that monocyte chemoattractant protein-1 (MCP-1) is the most potent histamine-releasing factor (HRF) for basophils. Macrophage inflammatory protein-1 alpha (MIP-1 alpha) has modest histamine-releasing activity. The objective of this study was to investigate whether MCP-1 and MIP-1 alpha would activate mast cells in vivo and induce a cutaneous inflammatory reaction in mice. To this goal, mouse hind footpads were separately injected with 20 microliters of human recombinant MCP-1 or MIP-1 alpha (10(-7) M). Diluent was used as a control in the second footpad. The footpad-swelling response was measured at 30 min, 1 h, and then hourly for 6 h. Both MCP-1 (2.72 +/- 0.2 vs 2.1 +/- 0.03 mm for diluent, n = 8, p < 0.02) and MIP-1 alpha (3.0 +/- 0.1 vs 2.1 +/- 0.03 mm for diluent, n = 8, p < 0.02) induced an immediate swelling reaction. The immediate reaction was followed by a sustained late reaction that peaked within 1 h and lasted for more than 6 h. Histologic examination of the footpads, obtained at hour 2, revealed that MCP-1 caused mild mononuclear cell infiltrates, moderate degranulation of mast cells, and soft tissue swelling. In contrast, MIP-1 alpha induced a severe inflammatory reaction that consisted of neutrophils, mononuclear cells, and degranulated mast cells. Electron microscope examination of the tissue revealed features of extensive mast cell degranulation by MIP-1 alpha and to a lesser extent by MCP-1. Thus, we conclude that mast cells are activated on injection of MCP-1, whereas degranulation of mast cells and recruitment of leukocytes contribute to the footpad reaction induced with MIP-1 alpha.

Animals↗
PubMed1994

cDNA cloning and characterization of mitochondrial import stimulation factor (MSF) purified from rat liver cytosol.

We identified a liver cytosolic protein factor that stimulated the import of wheat germ lysate-synthesized precursor proteins into mitochondria. It was termed mitochondrial import stimulation factor or MSF [Hachiya, N. et al. (1993) EMBO J. 12, 1579-1586]. It consisted of 32-kDa (MSFL) and 30-kDa (MSFS) polypeptides as assessed by SDS-PAGE. MSF recognized the presequence portion of mitochondrial precursor proteins and catalyzed the depolymerization and unfolding of in vitro synthesized mitochondrial precursor proteins in an ATP-dependent manner. We report here the cDNA cloning and characterization of MSF. Microsequencing of MSFL and MSFS showed that they belonged to a highly conserved, widely distributed eukaryotic protein family, collectively designated as 14-3-3 proteins. We cloned the cDNA of MSFL and that of one component of MSFS (MSFS1) from a rat liver cDNA library. The cloned cDNAs were separately expressed in Escherichia coli and the expressed proteins were purified to homogeneity. The purified recombinant MSFL and MSFS1 stimulated mitochondrial import of adrenodoxin precursor (pAd) synthesized in vitro with wheat germ lysate translation system. Recombinant MSFL or MSFS1 had the ability to bind with denatured pAd and they kept the precursor in an import-competent state. Rabbit polyclonal antibodies raised against the recombinant proteins inhibited the import-stimulation activity of rat liver cytosol as well as that of authentic purified MSF. Identification of MSF as 14-3-3 proteins establishes a novel function for this family of proteins and indicates their role as cytosolic chaperones to aid many important cellular events.

14-3-3 Proteins↗
PubMed1994

Proinflammatory cytokines in nasal secretions of allergic subjects after antigen challenge.

To study the role of cytokines in allergic late-phase reactions (LPR), we measured cytokines (interleukins [IL]-1 beta, IL-2, IL-4, IL-5, IL-6, and granulocyte-macrophage colony-stimulating factor [GM-CSF]) in nasal secretions (NS) of eight allergic subjects following antigen or saline provocation. NS were collected hourly for 10 h after challenge by a newly developed matrix method. All subjects recorded hourly symptom scores. Cytokines were measured using specific enzyme-linked immunosorbent assays (ELISA). Compared with prechallenge values, significant levels of IL-1 beta were detected in all subjects during the immediate reaction (peak, 51.0 +/- 22.4 pg/ml) and LPR (peak, 78.5 +/- 22.6 pg/ml) after antigen challenges (p < 0.01) but not saline challenges. In contrast, GM-CSF and IL-6 showed a delayed rise (peak, 26.4 +/- 1.3 pg/ml and 33.8 +/- 10.0 pg/ml, respectively) at hour 4 in the antigen-challenge period (p < 0.01 versus saline). NS from 4 donors also showed detectable IL-5 (7.6 to 155 pg/ml) during the immediate reaction and LPR after allergen challenges (versus saline, p < 0.01). The levels of cytokine correlated (p < 0.05) with corresponding total symptom scores during the immediate reaction (IL-1 beta) and LPR (IL-1 beta, GM-CSF, and IL-6). IL-2 and IL-4 were not detected in any sample. Thus, IL-1 beta, IL-5, IL-6, and GM-CSF are present in the LPR of allergic rhinitis, and their correlation with clinical responses may suggest their role in allergic inflammation.

Enzyme-Linked Immunosorbent Assay↗
PubMed1994

Interleukin-1 receptor antagonist protein inhibits the synthesis of IgE and proinflammatory cytokines by allergen-stimulated mononuclear cells.

The ability of interleukin-1 (IL-1) to activate diverse cell populations supports its role as a preeminent cytokine in the pathogenesis of chronic inflammation. In this study, we investigated the role of Il-1 and IL-1 receptor antagonist protein (IRAP) in the regulation of allergen-induced synthesis of IgE and proinflammatory cytokines. The temporal expression of IL-1 beta and IRAP during 5-day allergen-activated peripheral mononuclear cell (PMNC) cultures suggested differential production of the two cytokines. To determine the influence of IRAP on IL-1-mediated cellular responses, we cultured PMNC from allergic donors with specific allergens in the presence or absence of IRAP pretreatment. Culture supernatants were assayed for IgE and cytokines using specific enzyme-linked immunosorbent assay. IRAP at concentrations 0.01, 0.1, and 1 microgram/ml decreased the allergen-stimulated IgE synthesis by 33 +/- 7%, 50 +/- 7%, and 66 +/- 5%, respectively (P < 0.05). Increasing the concentration of allergen did not affect the reduction in IgE synthesis observed in the presence of IRAP. Lipopolysaccharide-stimulated IgE synthesis was also significantly inhibited by IRAP (P < 0.05). In parallel experiments, anti-IL-1 beta monoclonal antibody showed a comparable inhibitory pattern on IgE synthesis (P < 0.05). IRAP inhibited the synthesis of interleukin-6, tumor necrosis factor-alpha, and granulocyte/macrophage colony-stimulating factor in a dose-dependent manner (P < 0.05); the mean inhibition was 31 +/- 4%, 75 +/- 5%, and 88 +/- 2%, respectively, at 1 microgram/ml of IRAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1993

RANTES is a chemotactic and activating factor for human eosinophils.

RANTES is a member of the 8-kDa cytokine family that has been shown to possess chemotactic activity for monocytes and CD4 T cells. In this study, we investigated whether RANTES could affect eosinophil chemotaxis and function. Peripheral blood eosinophils from blood donors were isolated on Percoll gradients to > 98% purity and then used for chemotaxis, flow cytometry, eosinophil cationic protein release assay, and survival assay. We found that RANTES is chemotactic for eosinophils at 10(-9) to 10(-8) M concentrations. RANTES elicited 65% of the chemotactic response to 10(-7) M platelet-activating factor in all experiments. The mechanism of chemotaxis was investigated by studying the expression of adhesion molecules on eosinophils by flow cytometry. We found that RANTES up-regulated the expression of CD11b/CD18 on eosinophils in a dose-dependent manner. In another set of experiments, purified eosinophils incubated with various concentrations of RANTES released eosinophil cationic protein as measured by a RIA. We also investigated the effect of RANTES on eosinophil density. Leukocytes were incubated in the presence or absence of RANTES, and the distribution of eosinophils on discontinuous Percoll gradients was then examined. We found that eosinophils became hypodense (< 1.085) when incubated in RANTES. However, unlike IL-3, RANTES did not affect the survival of eosinophils in a 4-day culture system. Thus, we established that RANTES is a chemotactic and activating factor for eosinophils.

Chemokine CCL5↗
PubMed1993

A mitochondrial import factor purified from rat liver cytosol is an ATP-dependent conformational modulator for precursor proteins.

Rat liver cytosol contained an activity that stimulated the import of wheat germ lysate-synthesized precursor proteins into mitochondria. The activity was purified 10,000-fold from the cytosol as a homogeneous heterodimeric protein. This protein (termed mitochondrial import stimulation factor or MSF) stimulated the binding and import of mitochondrial precursor proteins. MSF was also found to recognize the presequence portion of mitochondrial precursors and catalyze the depolymerization and unfolding of in vitro synthesized mitochondrial precursor proteins in an ATP-dependent manner; in this connection, MSF exhibited ATPase activity depending on the important-incompetent mitochondrial precursor protein. The mitochondrial binding and import-stimulating activities were strongly inhibited by the pretreatment of MSF with NEM, whereas the ATP-dependent depolymerization activity was insensitive to the NEM treatment, suggesting that the process subsequent to the unfolding was inhibited with the NEM treatment. We conclude that MSF is a multifunctional cytoplasmic chaperone specific for mitochondrial protein import.

Adenosine Triphosphatases↗