Function of the Msx2 gene in the morphogenesis of the skull.
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Aging↗
Biomedical subjects
L Wu
Publications and source records attributed to L Wu.
Molecular cloning and characterization of a human eotaxin receptor expressed selectively on eosinophils.
The chemokine eotaxin is unusual in that it appears to be a highly specific chemoattractant for eosinophils. Ligand-binding studies with radiolabeled eotaxin demonstrated a receptor on eosinophils distinct from the known chemokine receptors CKR-1 and -2. The distinct eotaxin binding site on human eosinophils also bound RANTES (regulated on activation T expressed and secreted) and monocyte chemotactic protein (MCP)3. We have now isolated a cDNA from eosinophils, termed CKR-3, with significant sequence similarity to other well characterized chemokine receptors. Cells transfected with CKR-3 cDNA bound radiolabeled eotaxin specifically and with high affinity, comparable to the binding affinity observed with eosinophils. This receptor also bound RANTES and MCP-3 with high affinity, but not other CC or CXC chemokines. Furthermore, receptor transfectants generated in a murine B cell lymphoma cell line migrated in transwell chemotaxis assays to eotaxin, RANTES, and MCP-3, but not to any other chemokines. A monoclonal antibody recognizing CKR-3 was used to show that eosinophils, but not other leukocyte types, expressed this receptor. This pattern of expression was confirmed by Northern blot with RNA from highly purified leukocyte subsets. The restricted expression of CKR-3 on eosinophils and the fidelity of eotaxin binding to CKR-3, provides a potential mechanism for the selective recruitment and migration of eosinophils within tissues.
Amino Acid Sequence↗
Probing the function of Asp128 in the lower molecular weight protein-tyrosine phosphatase-catalyzed reaction. A pre-steady-state and steady-state kinetic investigation.
The role of Asp128 in the catalytic mechanism of the low Mr protein-tyrosine phosphatase (PTPase) from the fission yeast Schizosaccharomyces pombe has been investigated by a combination of site-directed mutagenesis and pre-steady-state and steady-state kinetic analysis. The corresponding aspartic acid in the bovine enzyme is located on a loop adjacent to the phosphate-binding loop and forms a hydrogen bond with the oxygen atom of the bound sulfate or phosphate that is structurally homologous to the ester oxygen in substrates [Su et al. (1994) Nature 370, 575-578; Zhang, M., et al. (1994) Biochemistry 33, 11097-11105]. Asp128 has been replaced by a Glu, an Asn, and an Ala. The kcat for the hydrolysis of p-nitrophenyl phosphate (pNPP) decreases by factors of 6.7, 400, and 650 for the mutants D128E, D128N, and D128A, respectively. Compared to the wild type, the binding affinity for phosphate is decreased 2 and 4.3-fold, respectively, for the D128A and D128N mutants, whereas no change in affinity is observed for the D128E mutant. An evaluation of the burst kinetics demonstrates that Asp128 plays a role in both the phosphoenzyme intermediate formation (k2) and breakdown (k3). Thus, substitution at Asp128 by a Glu, an Asn, or an Ala reduces k2 by 17, 7480, and 11900 and reduces k3 by 6.2, 380, and 40. The greater effect on k2 and k3 is consistent with a dissociative transition-state for the low M(r)PTPase-catalyzed reaction. Results from the rapid kinetics, partition experiments, and leaving group dependence experiments suggest that for the wild type and D128E mutant, the rate-limiting step is k3, whereas k2 has become rate-limiting for the D128N mutant. With the exception of pNPP, k2 may also be rate-limiting for D128A. Taken together, these results are consistent with Asp128 or Glu128 acting as a general acid to donate a proton to the phenolate leaving group in the phosphorylation step, and the carboxylate side chain plays a role as a general base to activate a nucleophilic water molecule in the dephosphorylation step. The presence of the general acid ensures productive partitioning toward phosphoenzyme formation. In the absence of the general acid, the nature of the transition-state for the phosphorylation step is sensitive to the pKa of the attacking active site thiol group and changes with the structure of the leaving group.
Aspartic Acid↗
Immunohistochemical analysis of steroid 5 alpha-reductase type 1 in human scalp and prostate.
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3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
Specificity of coupling of muscarinic receptor isoforms to a novel chick inward-rectifying acetylcholine-sensitive K+ channel.
The G-protein-gated inward-rectifying K+ channel GIRK1 has been demonstrated in heart and brain. These tissues also both express the M2, M3, and M4, muscarinic acetylcholine receptors (mAChR) (Gadbut, A.P., and Galper, J.B. (1994),J. Biol. Chem. 269,25823-25829). Only the M2 mAChR has been demonstrated to couple to GIRK1 (Kubo, Y., Reuveny, E., Slesinger, P. A., Jan, Y. N., and Jan, L. Y. (1993) Nature 264, 802-806). In this study we determined the specificity of coupling of the M3 and M4 mAChR to a new GIRK1 cloned from a chick brain cDNA library. This clone codes for a 492-amino acid protein that is 93% identical to rat GIRK1 and is expressed in brain, atrium, and ventricle, but not skeletal muscle. In Xenopus laetis oocytes co-expression of GIRK1 with either the chick M2 or M4 mAChR gave carbamylcholine (10 microm)-stimulated K+ currents of 308 +/-26 nA and 298 +/-29 nA, respectively, which were both Ba2+- and pertussis toxin-sensitive. Activation of the M3 receptor produced 2382 +/-478 nA of current which was insensitive to Ba2+ and pertussis toxin, but was 85% inhabitable by the Cl channel blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid (10-20 microm) consistent with coupling to an endogenous Ca2+-activated Cl- channel via a phosphatidylinositol-dependent mechanism. Co-expression of the cardiac inward rectifier CIR with chick M2 or M4 mAChR and GIRK1 increased currents more than 10-fold, but had no effect on specificity of coupling. These data demonstrate a new function for the M4 mAChR and a high degree of specificity for coupling of each receptor subtype to GIRK1.
Acetylcholine↗
Determinants of substrate recognition in the protein-tyrosine phosphatase, PTP1.
Photoaffinity labeling has been used to identify amino acids involved in recognition of protein substrates by the protein-tyrosine phosphatase PTP1. The photoactive amino acid p-benzoylphenylalanine (Bpa) was incorporated into a phosphotyrosine-containing peptide derived from epidermal growth factor autophosphorylation site Tyr992 (EGFR988 998). This peptide photoinactivated PTP1 in a time- and concentration-dependent manner. Three lines of evidence indicate that the interaction between PTP1 and the photoaffinity label was specific: 1) photoinactivation was inhibited in the presence of a non-Bpa-containing peptide from EGFR Tyr992 in molar excess. 2) The photoaffinity label-containing phosphopeptide was rapidly dephosphorylated by PTP1 with kinetic constants similar to those of the non-Bpa-containing peptide under identical conditions. 3) After complete photoinactivation, the level of incorporation of radioactive photoaffinity label into PTP1 was approximately 0.9 mol of label/mol of enzyme, consistent with a 1:1 stoichiometry of photolabeling. Radiolabeled peptide was used to identify sites of cross-linking to PTP1. Bpa peptide-PTP1 was digested with trypsin, and radioactive fragments were purified by high performance liquid chromatography (HPLC) and analyzed by Edman sequencing. In two parallel experiments which were analyzed using different HPLC columns, a site in the alpha2 region of PTP1, most likely Ile23, was labeled by the Tyr992-derived peptide. The results are discussed in light of the crystal structure of human PTP1B and suggest that an additional mode of substrate recognition must exist for PTP1 catalysis.
Affinity Labels↗
Modulation of K+ channel currents by serum amineoxidase in neurons.
The influence of bovine serum amineoxidase (SAO), a circulating copper-enzyme, on neuronal K+ channels is described. Bovine SAO enhanced K+ channel currents in N1E-115 neuroblastoma cells in a time-dependent manner. Unlike ceruloplasmin (another copper-protein, shown as depolarizing factor in neurons), SAO had no effect on resting potential of neurons. However, pretreatment of cells with SAO inhibited ceruloplasmin-induced membrane depolarization. Although ceruloplasmin alone inhibited K+ channel currents, it further enhanced K+ channel currents in the presence of SAO. Therefore, SAO may be another endogenous modulator of neuronal K+ channels with effect and mechanisms different from those of ceruloplasmin.
Amine Oxidase (Copper-Containing)↗
Overlapping phenotypes of multidrug resistance among panels of human cancer-cell lines.
In addition to P-glycoprotein (Pgp), 2 proteins related to multidrug resistance (MDR) have recently been described. The Multidrug-Resistance-associated protein (MRP) is one of the ATP-binding-cassette (ABC) transporters. The Lung-Resistance Protein (LRP) is the major component of human vaults, which are newly described cellular organelles and thought to mediate intracellular transport processes. Using immunocytochemical methods, we have examined the expression of MRP and LRP among panels of human cancer-cell lines not selected for drug resistance which have been previously characterized for expression of Pgp, and in vitro response to a variety of anti-cancer drugs. Expression of MRP and LRP was observed in 47/55 (87%) and 46/59 (78%) cell lines, respectively. Statistically significant correlations were observed between expression of each of these 3 proteins and in vitro sensitivity to at least one drug classically associated with MDR. LRP showed the greatest individual predictive value, which also applied to several non-classical MDR drugs. Co-expression of 2-3 MDR-related proteins was observed in 64% of the lines and was, in general, associated with high relative levels of drug resistance. Previously identified "classic" MDR lines as well as "pan-resistant" lines concurrently expressed all 3 MDR-related proteins. Some highly drug-resistant cell lines without detectable MDRI/Pgp were found to express relatively high levels of MRP and LRP. The high prevalence of MRP and LRP expression observed in this large set of cell lines, which have not been subjected to laboratory drug selection, suggests that MDR mechanisms associated with these proteins may be widespread in human malignancies. Moreover, the overlapping of these more recently recognized MDR phenotypes with Pgp-type MDR results in a complex phenotype, the understanding of which may be of importance in the development of new drugs and design of clinical treatment protocols, particularly those seeking to employ strategies to reverse the MDR phenotype.
ATP-Binding Cassette Transporters↗
Biochemical characterization of the human cyclin-dependent protein kinase activating kinase. Identification of p35 as a novel regulatory subunit.
The activation of cyclin-dependent protein kinases (Cdks) is dependent upon site-specific phosphorylation and dephosphorylation reactions, as well as positive and negative regulatory subunits. The human Cdk-activating protein kinase (Cak1) is itself a Cdc2-related cyclin-dependent protein kinase that associates with cyclin H. The present study utilized specific anti-Cak1 antibodies and immunoaffinity chromatography to identify additional Cak1-associated proteins and potential target substrates. Immunoprecipitation of metabolically labeled human osteosarcoma cells revealed a number of Cak1-associated proteins, including p95, p37 (cyclin H), and a 35-kDa protein that was further characterized herein. Microsequence analysis obtained after limited proteolysis revealed peptide fragments that are similar, but not identical to, human and yeast cyclins, thus identifying p35 as a cyclin-like regulatory subunit. The greatest sequence similarity of human p35 is with Mcs2, a yeast cyclin that is essential for cell cycle progression. Immunoaffinity chromatography performed under nondenaturing conditions afforded the isolation of enzymatically active Cak1 from cell lysates, enabling studies of kinase autophosphorylation and comparative substrate utilization. Immunoaffinity-purified Cak1 phosphorylated monomeric Cdc2 and Cdk2, but not Cdk4; the phosphorylation of both Cdc2 and Cdk2 were increased in the presence of recombinant cyclin A. These studies indicate that the Cak1 catalytic subunit, like Cdc2 and Cdk2, associates with multiple regulatory partners and suggests that subunit composition may be an important determinant of this multifunctional enzyme.
Amino Acid Sequence↗
Keratinocyte growth factor induces granulation tissue in ischemic dermal wounds. Importance of epithelial-mesenchymal cell interactions.
BACKGROUND: Keratinocyte growth factor acts specifically on epithelial cells and is presumed to play an important role in tissue repair. OBJECTIVE: To examine the wound-healing effects of keratinocyte growth factor under hypoxic conditions in vivo and in vitro. DESIGN AND INTERVENTIONS: Dermal ulcers were created in the ischemic ears of 40 anesthetized young female rabbits. Either recombinant keratinocyte growth factor (rKGF) or buffer was applied to each wound. Wounds were bisected and analyzed histologically at days 7 and 10 after wounds were created. For the in vitro study, normal keratinocytes were treated with rKGF (20 ng/mL) and cultured under hypoxic (3.5% oxygen) conditions. The conditioned media were collected at 48 and 72 hours. MAIN OUTCOME MEASUREMENTS: The amount of epithelial growth and deposition of granulation tissue were measured in all wounds. The amount of transforming growth factor alpha in keratinocyte-conditioned media was measured by using a sensitive radioimmunoassay. A proliferation assay of dermal fibroblasts, treated with conditioned media, was also performed under 3.5% oxygen culture conditions. RESULTS: The rKGF (range, 5-40 micrograms per wound) that was applied significantly increased new epithelium by greater than 70% (P = .03) at days 7 and 10 after wounds were created. A significant increase in new granulation tissue formation (170%) was also observed in rKGF-treated wounds at day 10, at a dose of 40 micrograms per wound (P < .002). The amount of transforming growth factor alpha protein in the conditioned media that were treated with rKGF (20 ng/mL) increased by 26.8% and 171% at 48 and 72 hours, respectively, over that of controls. The conditioned media from rKGF-treated keratinocytes, grown for 72 hours, resulted in a 51% increase in the proliferation of primary rabbit dermal fibroblasts. CONCLUSION: Keratinocyte growth factor enhances the wound-healing process of ischemic ulcers, indicating that epithelial-mesenchymal cell interactions are critical for the healing of wounds under ischemic conditions and possibly under normal conditions as well.
Animals↗
CD4 and CD8 expression and T cell antigen receptor gene rearrangement in early intrathymic precursor cells.
The earliest T precursor population in the adult mouse thymus, considered to have the surface phenotype CD4lo8-3-44+25-Thy-1lo c-kit+ (termed the low CD4 precursor), has been shown to have the capacity to produce B cells and dendritic cells, as well as T cells, and to have the T cell antigen receptor (TCR) C beta gene region in germ-line configuration. Because of evidence that this precursor population may have low levels of CD8 as well as CD4 on the cell surface, it was isolated, stained for surface CD4 and CD8 and assayed for the expression of messenger RNA (mRNA) for CD4 and CD8 by the reverse transcriptase polymerase chain reaction (RT-PCR). The low CD4 precursors gave definite, moderate levels of staining for both CD8 and CD4, in contrast to downstream precursors which showed only marginal staining and so could be considered as genuine CD4-8-3- triple negatives. The low CD4 precursor expressed a significant level of mRNA for CD4, indicating that the surface CD4 was produced by these cells. However, the low CD4 precursor did not express a detectable level of mRNA for CD8, suggesting that the surface CD8 was acquired from other cells. Since the low CD4 precursor population was found already to express mRNA for enzymes involved in TCR gene rearrangement, including in this study terminal deoxynucleotidyl transferase (TdT), a PCR procedure was used to assay early precursors for D-J rearrangements at the TCR beta gene locus. However, the low CD4 precursor had the TCR beta D-J genes in germ-line configuration, D-J gene rearrangements being first detected several stages downstream in the CD3-4-8-44-25-+ precursor population. We conclude that a transient synthesis of CD4, but not of CD8, characterize these early thymus precursors. Although they have initiated synthesis of some recombination-associated enzymes, full commitment to the T lineage and TCR gene rearrangement is a later event.
Animals↗
High-performance field inversion capillary electrophoresis of 0.1-23 kbp DNA fragments with low-gelling, replaceable agarose gels.
Field inversion capillary gel electrophoresis (FICGE) has been used for the separation of 0.1-23 kbp DNA fragments in a low-melting, low-gelling agarose gel. The influence of the amplitude of the voltage pulses, the pulse times and gel concentrations on the separation factor has been studied and found to be similar to that of polyacrylamide gels. Very high resolution can be obtained by altering continuously the pulse times and/or voltage according to a program tailor-made for the size of the DNA molecules to be separated (programmed FICGE). The advantage of these agarose gels in comparison with polyacrylamide gels is that they are nontoxic, easy to prepare and they have high UV transmission. They give a resolution that is equivalent to or better than that of polyacrylamide gels, and the risk of bubble formation in the gel is small. In addition, they are replaceable and, therefore, very convenient for automated analyses.
Automation↗
Plant mitosis promoting factor disassembles the microtubule preprophase band and accelerates prophase progression in Tradescantia.
The regulation of mitosis in higher plant cells has been investigated by microinjecting protein kinase from the metaphase-arresting (met1) mutant of Chlamydomonas. Biochemical characterization of this enzyme complex confirms the presence of a p34cdc2/cyclin B-like kinase. The enzyme was injected into living stamen hair cells of Tradescantia virginiana in which microtubules (MTs) were visualized using fluorescent analogue cytochemistry and confocal laser scanning microscopy. Microinjection of this p34cdc2/cyclin B-like kinase caused rapid disassembly of the preprophase band of MTs but not of interphase-cortical, spindle or phragmoplast MTs. Effects of the enzyme on the cytomorphology of live prophase cells were also monitored using video microscopy. We found that injection of this enzyme accelerated chromatin condensation and nuclear envelope breakdown. This indicates the presence and function in plants of an enzyme that can initiate nuclear division similar to the maturation or mitosis promoting factor (MPF) of animal cells. These studies provide the first direct evidence that the mitotically-active form of plant MPF can drive disassembly of preprophase band MTs, chromosome condensation and initiation of mitosis in plant cells.
Animals↗
Bioextraction of selenium by forage and selected field legume species in selenium-laden soils under minimal field management conditions.
A forage plant, tall fescue (Festuca arundinacea), and a selected field legume species, sour clover (Melilotus indica), were examined for their selenium (Se) bioextraction abilities in Se-laden soils under minimal management conditions. Natural vegetations in a 2-acre plot adjacent to the forage plots were also studied for Se accumulation comparisons. During the dry season, in the fall of 1994, the field plots were either irrigated weekly or without irrigation. No fertilization and weed control were applied. The plants were harvested in May 1995. There were considerable differences in the ability of Se uptake between the forage and the legume species and among the naturally established plant species; the amount of Se accumulated per land area was largely dependent on their respective biomass production. Comparing Se concentration between preplant and postharvest, there was a detectable reduction in the soil selenate, selenite, and water-extractable organic Se in the tall fescue and melilotus plots. The field irrigation provided more favorable conditions for bioextractions and dissipation of Se by the plants. However, the available soil Se only accounts for less than 10% of the total soil Se and no detectable reduction of total soil Se was found. This may be due to the large inventory and variation of Se concentrations in the field soils and therefore obscured the detectable differences. For practical considerations, the forage plants can be repeatedly harvested and used for rangelands of Se deficiency currently seen in some northern California counties.
Analysis of Variance↗
Sequence and transcription of Qa-2-encoding genes in mouse lymphocytes and blastocysts.
The protein product of the mouse preimplantation embryo development (Ped) gene, which controls the rate of preimplantation embryonic cleavage division and subsequent embryo survival, is the Qa-2 antigen. This major histocompatibility complex (MHC) class I b protein is encoded by four genes, Q6, Q7, Q8, and Q9. The present study was undertaken to begin to elucidate which of the four Qa-2-encoding genes are responsible for the Ped gene phenotype in the C57BL/6 mouse (H2(b)). First, restriction maps of the four genes, using 25 restriction enzymes, were created. The RE maps confirmed that Q6 is similar to Q8 and Q7 is similar to Q9, but that the Q6/Q8 gene pair differs from the Q7/Q9 gene pair. The genomic DNA sequences of Q6 and Q8 were determined, as well as the DNA sequences of exons 4 - 8 of Q9, and the 5' regulatory regions of Q6, Q8, and Q9. This DNA sequence information, combined with the published DNA sequence information for the entire Q7 gene and exons 1 - 3 of Q9, allowed us to design primers for reverse transcription-polymerase chain reaction that could distinguish which of the four genes were transcribed in mouse lymphocytes and embryos. It was found that all four genes are transcribed in lymphocytes, but only Q7 and Q9 are transcribed in mouse embryos. Thus, both Q7 and Q9 are candidates for the genes responsible for the Ped gene phenotype.
Amino Acid Sequence↗
Viral IL-10 gene therapy inhibits TNF-alpha and IL-1 beta, not IL-6, in the newborn endotoxemic mouse.
INTRODUCTION: Modulation of the inflammatory cascade within the liver of critically ill infants may improve the chance of survival. Using gene therapy, the authors hypothesized that augmented local production of the counter-regulatory cytokine viral interleukin-10 (IL-10) in vivo will modulate the critical cytokines in the inflammatory response. The purpose of the present study was to determine whether replication-defective adenovirus-mediated viral IL-10 (vIL-10) gene transfer and expression within the liver can achieve this goal in newborn mice. MATERIALS AND METHODS: Four-week-old Balb/c mice were administered (intraperitoneally) 1 x 10(9) plaque-forming units (pfu) per milliliter of an adenovirus vector (E1a/b-deleted) than encodes the sv40 promoter and the BCRF1 cDNA, or of control vector dl434 that expresses no foreign gene. Forty-eight hours later the mice were challenged with 50 micrograms/kg of lipopolysaccharide (LPS) they were killed 1, 2, 6, or 24 hours later (six at each time point). Southern blot analysis was performed on genomic DNA isolated from the liver, lung, and kidney to assess gene transfer of BCRF1. Homogenized liver protein was analyzed for tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, IL-6, and recombinant vIL-10. RESULTS: Southern blot analysis confirmed successful gene transfer to the liver but not to the lung, kidney, or dl434-transduced liver in mice that received adenovectors. Viral IL-10 levels within the liver ranged from 14 to 18 ng/mL. In controls, TNF-alpha production was elevated at early time points, to 18,000 pg/mL, but decreased rapidly by 24 hours after LPS challenge. The TNF-alpha levels of animals treated with Ad5svBCRF1 were significantly lower than those of controls throughout the course of study (P < .0001). After the LPS challenge, hepatic IL-1 beta decreased, from a maximum of 800 pg/mL (2 hours) to 411 pg/mL (24 hours). Inhibition of IL-1 beta by vIL-10 occurred at 1 hour (P > .016) and 2 hours (P < .001) only. Hepatic production of IL-6 after LPS challenge ranged from 7 to 8,000 pg/mL in all groups and was not altered by vIL-10 gene therapy. CONCLUSION: In vivo administration of adenovectors encoding BCRF1 to newborn mice results in efficient hepatic transduction and expression of recombinant vIL-10. The Kupffer cell response to LPS is suppressed with respect to TNF-alpha and IL-1 beta, but not IL-6. In vivo modulation of hepatic cytokine responses is achievable using gene products that mimic cellular cytokines. This is an effective model for the selective evaluation of therapeutic gene products for gene therapy of sepsis.
Animals↗
Impact of neonatal vitamin A supplementation on infant morbidity and mortality.
OBJECTIVE: To determine whether vitamin A supplementation at birth could reduce infant morbidity and mortality. STUDY DESIGN: We conducted a placebo-controlled trial among 2067 Indonesian neonates who received either 52 micromol (50,000 IU) orally administered vitamin A or placebo on the first day of life. Infants were followed up at 1 year to determine the impact of this intervention on infant mortality. A subgroup (n = 470) was also examined at 4 and 6 months of age to examine the impact on morbidity. RESULTS: Vital status was confirmed in 89% of infants in both groups at 1 year. There were 19 deaths in the control group and 7 in the vitamin A group (relative risk = 0.36; 95% confidence interval = 0.16, 0.87). The impact was stronger among boys, infants of normal compared with low birth weight, and those of greater ponderal index. Among infants examined at 4 months of age, the 1-week period prevalence of common morbidities was similar for vitamin A and control infants. However, during this same 4-month period, 73% and 51% more control infants were brought for medical treatment for cough (p = 0.008) and fever (p = 0.063), respectively. CONCLUSIONS: Neonatal vitamin A supplementation may reduce the infant mortality rate and the prevalence of severe respiratory infection among young infants.
Birth Weight↗
Depletion of CD8+ T cells enhances pulmonary inflammation but not airway responsiveness after antigen challenge in rats.
BACKGROUND: CD8+ (OX-8+) T cells may suppress airway inflammation and airway responsiveness after allergen challenge. OBJECTIVE: We studied the effects of depletion of OX-8+ T cells on allergen-induced lung eosinophilia and airway responsiveness in the Sprague-Dawley rat. METHODS: Sprague-Dawley rats were sensitized to ovalbumin and challenged by aerosol 14 days later. Test animals received either low-dose (2 mg, n = 9) or high-dose (3 mg, n = 7) OX-8 monoclonal antibody (mAb), whereas controls (n = 8) received BALB/c ascites fluid. A fourth group of animals (n = 10) was not sensitized to ovalbumin and also received ascites fluid. Twenty-four hours after ovalbumin challenge, responsiveness to methacholine was measured, and lung inflammation was assessed in the large airways and small airways and parenchyma. RESULTS: Circulating and airway CD8+ T cells were decreased by OX-8 mAb administration with greatest changes in animals treated with high-dose OX-8 mAb compared with controls (blood: 1.0% +/- 3.6% vs 18.7% +/- 3.9%, p < 0.05); (large airways: 2.5% +/- 1.2% vs 13.8% +/- 1.2%, p < 0.05). Ovalbumin challenge resulted in increases in macrophages and neutrophils in the small airways and parenchyma of sensitized compared with unsensitized rats (p < 0.05). High-dose OX-8 mAb further increased total leukocytes, attributable to increases in neutrophils and eosinophils, retrieved from the large airways and small airways and parenchyma compared with other groups (p < 0.05). Airway responsiveness to methacholine was not significantly different between control and ovalbumin-challenged animals and was not augmented by OX-8 pretreatment. CONCLUSION: CD8+ T cells modulate the extent of allergen-induced airway inflammation. However, the enhancement of inflammation was not sufficient to affect airway responsiveness.
Animals↗