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Biomedical subjects

K F Austen

Publications and source records attributed to K F Austen.

At least 73 records · Page 4Linked to original sources
PubMed1995

Interleukin 4 suppresses c-kit ligand-induced expression of cytosolic phospholipase A2 and prostaglandin endoperoxide synthase 2 and their roles in separate pathways of eicosanoid synthesis in mouse bone marrow-derived mast cells.

Mouse bone marrow-derived mast cells (BMMCs) developed with interleukin 3 (IL-3) can be stimulated by c-kit ligand (KL) and accessory cytokines over a period of hours for direct delayed prostaglandin (PG) generation or over a period of days to prime for augmented IgE-dependent PG and leukotriene (LT) production, as previously reported. We now report that IL-4 is counterregulatory for each of these distinct KL-dependent responses. BMMCs cultured for 4 days with KL + IL-3 or with KL + IL-10 produced 5- to 7-fold more PGD2 and approximately 2-fold more LTC4 in response to IgE-dependent activation than BMMCs maintained in IL-3 alone. IL-4 inhibited the priming for increased IgE-dependent PGD2 and LTC4 production to the level obtained by activation of BMMCs maintained in IL-3 alone with an IC50 of approximately 0.2 ng/ml. IL-4 inhibited the KL-induced increase in expression of cytosolic phospholipase A2 (cPLA2) but had no effect on the incremental expression of PG endoperoxide synthase 1 (PGHS-1) and hematopoietic PGD2 synthase or on the continued baseline expression of 5-lipoxygenase, 5-lipoxygenase activating protein, and LTC4 synthase. BMMCs stimulated by KL + IL-10 for 10 h exhibited a delayed phase of PGD2 generation, which was dependent on de novo induction of PGHS-2. IL-4 inhibited the induction of PGHS-2 expression and the accompanying cytokine-initiated delayed PGD2 generation with an IC50 of approximately 6 ng/ml. IL-4 had no effect on the expression of PGHS-2 and the production of PGD2 elicited by addition of IL-1 beta to the combination of KL + IL-10. IL-4 had no effect on the immediate phase of eicosanoid synthesis elicited by KL alone or by IgE and antigen in BMMCs maintained in IL-3. Thus, the counterregulatory action of IL-4 on eicosanoid generation is highly selective for the induced incremental expression of cPLA2 and the de novo expression of PGHS-2, thereby attenuating time-dependent cytokine-regulated responses to stimulation via Fc epsilon receptor I and stimulation via c-kit, respectively.

Animals↗
PubMed1995

c-kit ligand mediates increased expression of cytosolic phospholipase A2, prostaglandin endoperoxide synthase-1, and hematopoietic prostaglandin D2 synthase and increased IgE-dependent prostaglandin D2 generation in immature mouse mast cells.

We have examined the cytokine regulation of IgE-dependent prostaglandin (PG) D2 generation in mouse mast cells by assessing the changes in the levels of the transcript, translated protein, and activity of the enzymes involved in the synthesis of PGD2 from endogenous arachidonic acid. When mouse mast cells, derived by culture of bone marrow cells with WEHI-3 cell-conditioned medium as a source of interleukin (IL)-3 (BMMC), were cultured in recombinant ckit ligand (KL), sensitized with IgE, and stimulated with antigen, PGD2 generation increased 3-fold; when KL was combined with IL-3, IL-9, or IL-10, PGD2 generation increased 6-8-fold above that produced by the cells cultured in IL-3 alone. The increased IgE-dependent PGD2 generation by BMMC was apparent after 1 day of culture, reached a maximum after 2-4 days of culture, and was dose-dependent for KL and for each of the accessory cytokines. IgE-dependent generation of leukotriene C4 increased 2-fold after the cells were cultured with KL and was not increased by the addition of IL-3, IL-9, or IL-10. Assays for steady-state transcripts by RNA blotting, for protein by SDS-PAGE/immunoblotting, and for function by enzymatic activities revealed that KL alone stimulated the increased expression of cytosolic phospholipase A2 (cPLA2), prostaglandin endoperoxide synthase (PGHS)-1, and the terminal enzyme, hematopoietic PGD2 synthase, without a change in expression of 5-lipoxygenase. IL-3, IL-9, and IL-10 each enhanced the KL-induced expression of PGHS-1. In contrast, transcripts for PGHS-2, which were detected transiently after the cells had been cultured for 5 h in KL+IL-3, were not expressed during the period of subsequent increase in IgE-dependent PGD2 generation. These findings demonstrate that KL up-regulates expression of cPLA2, PGHS-1, and hematopoietic PGD2 synthase, leading to a relatively selective increase in IgE-dependent production of PGD2 from endogenously released arachidonic acid in BMMC, and they provide the first example of cytokine regulation of hematopoietic PGD2 synthase.

Animals↗
PubMed1995

The complex of FK506-binding protein 12 and FK506 inhibits calcineurin phosphatase activity and IgE activation-induced cytokine transcripts, but not exocytosis, in mouse mast cells.

FK506 and cyclosporin A (CsA) are immunosuppressive agents that inhibit IL-2 production by activated T cells, but only CsA inhibits IgE activation-induced cytokine transcripts in mouse IL-3-dependent, bone marrow-derived mast cells (BMMC). We previously associated the resistance of BMMC to FK506 with a deficiency in the expression of FK506 binding protein (FKBP) 12, a molecule that forms a complex with FK506 capable of inhibiting calcineurin phosphatase activity in vitro. In this report, we establish that FKBP12 mediates FK506 inhibition of both calcineurin phosphatase activity and IgE activation-induced cytokine transcripts in a Kirsten murine sarcoma virus-immortalized mast cell line that is FKBP12 deficient. Overexpression of FKBP12 by transfection enhanced the ability of FK506 to inhibit calcineurin phosphatase activity (IC50 = 2 nM), compared with cells transfected with the expression vector alone (IC50 > 30 nM). The IC50 value for FK506 inhibition of IgE activation-induced transcripts for TNF-alpha decreased from 40 nM in vector control cells to 10 nM in FKBP12 transfectants. Similarly, the IC50 value for inhibition of IL-6 transcripts decreased from > 1000 nM in vector control cells to 35 nM in FKBP12 transfectants. In contrast, activation-elicited release of the secretory granule mediator beta-hexosaminidase was only partially inhibited by FK506 at 1000 nM, regardless of the levels of FKBP12 expressed by the cells. Thus, FKBP12 is the dominant cytosolic protein that mediates FK506 inhibition of TNF-alpha and IL-6 transcripts.

Animals↗
PubMed1995

Tissue-regulated differentiation and maturation of a v-abl-immortalized mast cell-committed progenitor.

An immature v-abl-transformed mast cell line (V3-MC) was derived from a mouse that developed systemic mastocytosis after transplantation of v-abl-infected bone marrow cells. V3-MCs injected intravenously into adult BALB/c mice infiltrated the liver, spleen, and intestine by day 6 and underwent progressive differentiation and maturation, eventually resembling indigenous mast cells. In terms of their protease content, the V3-MCs that localized in the liver and spleen differed from those in the intestine, and both differed from the cultured V3-MCs. The acquired expression of certain proteases and the loss of expression of other proteases in these tissue V3-MCs defines particular phenotypes and indicates that the differentiation and maturation of mast cell-committed progenitor cells are primarily regulated by factors in the different tissue microenvironments.

Animals↗
PubMed1995

Purification of human lung leukotriene C4 synthase and preparation of a polyclonal antibody.

Leukotriene (LT) C4 synthase is an integral membrane protein that catalyzes the conjugation of LTA4 to reduced glutathione to form LTC4. LTC4 synthase has been cloned and characterized from transformed cell lines, but the protein has not been defined from a tissue source. LTC4 synthase was purified to homogeneity from human lung tissue, utilizing S-hexyl glutathione chromatography followed by LTC4 affinity chromatography. A greater than 100,000-fold purification with a yield of 8 to 25% (n = 4) was achieved. The purified LTC4 synthase migrated in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as an 18-kD protein, and its 19 N-terminal amino acid sequence is identical to that of purified LTC4 synthase from KG-1 myeloid cells or from expression cloning of a KG-1 library in COS cells. Using a rabbit polyclonal IgG raised against purified LTC4 synthase, SDS-PAGE immunoblotting of LTC4 synthase from human lung tissue, eosinophils, KG-1 cells, and platelets showed an 18-kD protein. Immunofluorescence staining of alveolar macrophages in human lung sections with the anti-LTC4 synthase IgG revealed LTC4 synthase to be largely perinuclear in distribution. Thus, LTC4 synthase, the biosynthetic enzyme responsible for the formation of cysteinyl LTs, is present in lung tissue in a form apparently identical to that of hematopoietic cells.

Amino Acid Sequence↗
PubMed1994

Lack of expression of the tryptase mouse mast cell protease 7 in mast cells of the C57BL/6J mouse.

Although the steady-state level of the mouse mast cell protease (mMCP) 7 transcript is below detection in the serosal and mucosal mast cells of the BALB/cJ mouse, the IL-3-dependent, bone marrow-derived mast cells (mBMMC) of this strain and four other strains contain a high steady-state level of the mMCP-7 transcript. To further analyze the expression of this mast cell tryptase, a mMCP-7-specific IgG was obtained by immunizing a rabbit with a 19-residue synthetic peptide that corresponds to its unique amino acid sequence at residues 160 to 178 (anti-mMCP-7(160-178). In a SDS-PAGE/immunoblot analysis of lysates of BALB/cJ mBMMC, anti-mMCP-7(160-178) IgG recognized a diffuse 31- to 36-kDa protein, which shifted to a sharp 27-kDa protein after treatment with N-glycanase. As assessed immunohistochemically, mMCP-7 protein is present not only in the secretory granules of BALB/cJ mBMMC, but also in the ear mast cells of this strain. In contrast, the ear mast cells of the C57BL/6J mouse do not contain detectable levels of mMCP-7 protein, although the ear mast cells of both mouse strains contain mMCP-5 protein. Because mMCP-7 mRNA and protein also were not detected in mBMMC from the C57BL/6J mouse, the failure of the ear mast cells of this strain to express mMCP-7 is most likely a consequence of an intrinsic abnormality in the mast cell-committed progenitor cells themselves, or in the bone marrow microenvironment that induces its mast cell progenitor cells to express this tryptase.

Amino Acid Sequence↗
PubMed1994

Prostaglandin endoperoxide synthase-1 and -2 couple to different transmembrane stimuli to generate prostaglandin D2 in mouse bone marrow-derived mast cells.

The view that the two isoforms of prostaglandin-endoperoxide synthase (cyclooxygenase), PGHS-1 and PGHS-2, mediate physiologic and inflammatory processes, respectively, implies separate pathways of arachidonic acid metabolism with different benefits to the host. Functional segregation of these steps in endogenous arachidonic acid metabolism in a single cell in response to different stimuli is now demonstrated. When mouse bone marrow-derived mast cells developed in interleukin-3 (IL-3)-containing medium were cultured with c-kit ligand in combination with IL-10 and IL-1 beta, transient expression of PGHS-2 mRNA and protein occurred in a dose- and time-dependent fashion, accompanied by substantial release of prostaglandin D2 (PGD2) into the culture medium from 2 to 10 h. In contrast, induction of PGHS-2 did not mediate an increase in PGD2 generation in response to stimulation with IgE and antigen. After a longer period of culture, from 24 to 48 h, the expression of PGHS-1 increased, as did the increase in IgE/antigen-dependent generation of PGD2. Dexamethasone, which inhibited the induction of PGHS-2 but not PGHS-1, and a PGHS-2-selective inhibitor suppressed cytokine-induced PGD2 generation but not IgE-dependent PGD2 generation. Thus, at a time when both PGHS-1 and PGHS-2 are present in bone marrow-derived mast cells, they function independently by coupling to different stimulus-initiated pathways to PGD2 generation from endogenously derived arachidonic acid.

Animals↗
PubMed1994

Expression cloning of a cDNA for human leukotriene C4 synthase, an integral membrane protein conjugating reduced glutathione to leukotriene A4.

Leukotriene (LT) C4 synthase, an integral microsomal membrane protein, conjugates LTA4, an epoxide intermediate, to reduced glutathione (GSH) to form a proinflammatory mediator, LTC4. A sensitive fluorescence-linked immunoassay for LTC4 was used to screen a KG-1 cDNA expression library for LTC4 synthase activity after transfection of COS cells and addition of substrate LTA4. Stepwise resolution of 240,000 colonies in 96 pools led to the identification of individual clones with maximal LTC4 synthase activity that contained a 694-bp cDNA insert. This insert was composed of a 54-bp 5' nontranslated region, an ATTAAA polyadenylylation signal, and a poly(A)+ tail. The open reading frame encodes a 16.5-kDa protein with a pI of 11.05. Hybridization with a cDNA probe demonstrated a mRNA transcript of 0.7 kbp in RNAs from human eosinophils and KG-1 cells, which contain LTC4 synthase. The nucleotide and deduced amino acid sequences of the LTC4 synthase cDNA show no significant homology to GSH S-transferases but share 31% overall amino acid identity with 5-lipoxygenase activating protein (FLAP). The identity at the N-terminal two-thirds of these two proteins is 44%, with some regions of near identity. Peptide structural analysis of the deduced LTC4 synthase predicts the presence of three transmembrane domains nearly superimposable on those of FLAP. Moreover, LTC4 synthase is inhibitable by a FLAP inhibitor, MK-886. Therefore, LTC4 synthase is distinct from the known GSH S-transferases by nucleotide and consensus amino acid sequences, and its GSH-conjugating function represents a distinct integral membrane protein belonging to a distinct gene family.

5-Lipoxygenase-Activating Proteins↗
PubMed1994

Mouse bone marrow-derived mast cells (mBMMC) obtained in vitro from mice that are mast cell-deficient in vivo express the same panel of granule proteases as mBMMC and serosal mast cells from their normal littermates.

The ear, skin, and purified serosal mast cells of WBB6F1/J-(+/+) (WB-(+/+)) and WCB6F1/J-(+/+) (WC-(+/+)) mice contain high steady-state levels of the transcripts that encode mouse mast cell protease (mMCP) 2, mMCP-4, mMCP-5, mMCP-6, and mouse mast cell carboxypeptidase A (mMC-CPA). In contrast, no mast cell protease transcripts are present in abundance in the ear and skin of WBB6F1/J-W/Wv (W/Wv) and WCB6F1/J-Sl/Sld (Sl/Sld) mice which are mast cell-deficient in vivo due to defects in their c-kit and c-kit ligand genes, respectively. We now report that the immature bone marrow-derived mast cells (mBMMC) obtained in vitro with recombinant interleukin 3 (rIL-3) or WEHI-3 cell conditioned medium from WB-(+/+), WC-(+/+), W/Wv, and Sl/Sld mice all contain high steady-state levels of the mMCP-2, mMCP-4, mMCP-5, mMCP-6, and mMC-CPA transcripts. As assessed immunohistochemically, mMCP-2 protein and mMCP-5 protein are also present in the granules of mBMMC from WB-(+/+), WC-(+/+), and W/Wv mice. That Sl/Sld and W/Wv mBMMC contain high steady-state levels of five granule protease transcripts expressed by the mature serosal, ear, and skin mast cells of their normal +/+ littermates suggests that c-kit-mediated signal transduction is not essential for inducing transcription of these protease genes. Because rIL-4 inhibits the rIL-10-induced expression of mMCP-1 and mMCP-2 in BALB/cJ mBMMC, the ability of rIL-4 to influence protease mRNA levels in WC-(+/+) mBMMC and W/Wv mBMMC was investigated. Although rIL-10 induced expression of the mMCP-1 transcript in WC-(+/+) and W/Wv mBMMC, rIL-4 was not able to suppress the steady-state levels of the mMCP-1 transcript or any other protease transcript in these cultured mast cells. Thus, not only do BALB/cJ mBMMC express fewer granule proteases than mBMMC from mast cell-deficient strains and their normal littermates but the subsequent induction of late-expressed proteases in BALB/cJ mBMMC is more tightly regulated by IL-3 and IL-4.

Animals↗
PubMed1994

Cloning of the gp49B gene of the immunoglobulin superfamily and demonstration that one of its two products is an early-expressed mast cell surface protein originally described as gp49.

gp49 was originally defined as a 49-kDa surface glycoprotein preferentially expressed on mouse interleukin-3-dependent, bone marrow-derived mast cells, which are immature progenitor cells. A previously cloned cDNA (gp49A) indicated that gp49 was a member of the immunoglobulin (Ig) superfamily, and genomic DNA analysis indicated that two genes might encode a gp49 family. We have now characterized a 5.6-kilobase pair gene, gp49B, that encodes two novel gp49 cDNAs, gp49B1 and gp49B2. The two cDNAs are identical except that gp49B2 is missing exon 6, which encodes a predicted transmembrane domain. In contrast to gp49A, gp49B1 and gp49B2 have 32 additional amino acids at their C termini containing 4 of the 6 consensus amino acids of the antigen receptor homology 1 motif found on several signal-transducing members of the Ig superfamily. When COS-7 cells were transfected with either the gp49B1 or gp49B2 cDNA, only the gp49B1 transfectants bound the B23.1 monoclonal antibody that originally defined gp49. Reverse transcriptase-polymerase chain reaction analysis of the transfectants established that both transcripts were expressed, suggesting that the product of the gp49B2 transcript was not inserted in the plasma membrane. Thus, cloning of the gp49B gene has established the organization of one of the gp49 genes and provided evidence of alternate splicing of transcripts from that gene.

Amino Acid Sequence↗
PubMed1994

Fc gamma R-mediated endocytosis and expression of cell surface Fc gamma RIIb1 and Fc gamma RIIb2 by mouse bone marrow culture-derived progenitor mast cells.

Mouse IL-3-dependent, bone marrow culture-derived mast cells (BMMC) bind IgG immune complexes through Fc receptors for IgG (Fc gamma R) but express minimal Fc gamma RIII on their surfaces. BMMC do not degranulate appreciably when their Fc gamma R are perturbed with the rat anti-mouse Fc gamma RII/III mAb 2.4G2 and F(ab')2 mouse anti-rat IgG (MAR). In contrast, after their Fc gamma R were cross-linked with mAb 2.4G2 and Na125I-labeled MAR at 37 degrees C, BMMC rapidly internalized the complex. To identify the Fc gamma R species expressed on the surface of BMMC and therefore implicated in the endocytic response, two rabbit antipeptide antisera were raised, one against a sequence common to the cytoplasmic regions of Fc gamma RIIb1 and Fc gamma RIIb2 and the other to a unique cytoplasmic region of Fc gamma RIIb1. When Fc gamma R were immunoprecipitated with mAb 2.4G2 from detergent extracts of BMMC, digested with N-glycosidase F, subjected to SDS-PAGE, and immunoblotted with the Fc gamma RIIb1- and Fc gamma RIIb1/b2-specific antibodies, BMMC were found to express Fc gamma RIIb1 and Fc gamma RIIb2. Selective immunoprecipitation of plasma membrane-localized Fc gamma RIIb1 and Fc gamma RIIb2 from [3H]leucine-labeled BMMC showed that their ratio at the cell surface was similar to their initial biosynthetic ratio. Thus, in contrast to mature serosal mast cells that degranulate on binding of IgG complexes, immature mast cells, of which BMMC are a prototype, may have a role in the clearance of complexes without concomitant release of proinflammatory mediators.

Animals↗
PubMed1994

Strain-specific and tissue-specific expression of mouse mast cell secretory granule proteases.

As assessed by RNA blot analyses with gene-specific probes, we report that the perivascular connective tissue mast cells (CTMCs) in the ear and skin of BALB/cJ mice contain abundant levels of the mouse mast cell protease (mMCP) 7 transcript, in addition to those protease transcripts present in their serosal mast cells (SMCs). High levels of the mMCP-7 transcript also were detected in the ears of WBB6F1/J(-)+/+, WCB6F1/J(-)+/+, WB/ReJ(-)+/+, and WC/ReJ(-)+/+ mice. However, the ears of these four strains and the SMCs from the WCB6F1/J(-)+/+ strain but not the BALB/cJ strain also contained high steady-state levels of the mMCP-2 transcript. The mMCP-2, mMCP-4, mMCP-5, mMCP-6, and mMCP-7 transcripts were not detected in the ears of mast-cell-deficient WBB6F1/J-W/Wv and WCB6F1/J-Sl/Sld mice, indicating that mast cells were the source of these protease transcripts in the +/+ animals. When immunohistochemical analyses of serial sections of ear and skin from WBB6F1/J(-)+/+ mice were performed with anti-mMCP-2 IgG and anti-mMCP-5 IgG, the perivascular CTMCs in these tissues were found to express both mMCP-2 and mMCP-5 in their granules. The prominent expression of mMCP-7 in constitutive perivascular CTMCs indicates that this mast cell has an extended protease phenotype relative to the SMCs of the same strains. Further, the perivascular CTMCs and SMCs of the +/+ strains differ from those in BALB/cJ mice in their prominent expression of mMCP-2.

Animals↗
PubMed1993

Induction by IL-9 and suppression by IL-3 and IL-4 of the levels of chromosome 14-derived transcripts that encode late-expressed mouse mast cell proteases.

Immature, rIL-3-dependent mouse bone marrow-derived mast cells (BMMC) contain high steady-state levels of the mouse mast cell protease (mMCP) 5 transcript but undetectable levels of the mMCP-1, mMCP-2, or mMCP-4 transcripts even though all four of their genes reside at a locus on chromosome 14. These mast cells can be induced by recombinant c-kit ligand (rKL) to obtain high steady-state levels of the mMCP-4 transcript and by rIL-10 to obtain high steady-state levels of the mMCP-1 and mMCP-2 transcripts. rIL-3 and rKL both elicit the differentiation of progenitor cells into immature BMMC and then stimulate their proliferation. We now report that although rIL-9 alone has no effect on BMMC proliferation as assessed by their incorporation of [3H]thymidine, rIL-9 in combination with rKL enhances the long term viability of BMMC. Furthermore, rIL-9 in the presence of rKL stimulates mouse BMMC to undergo a phenotypic change by inducing accumulation of high steady-state levels of the mMCP-1 and mMCP-2 transcripts. In contrast, in BMMC, the presence of rIL-4 suppresses the rIL-9-induced accumulation of the mMCP-1 and mMCP-2 transcripts, the rIL-10-induced accumulation of the mMCP-1 and mMCP-2 transcripts, and the rKL-induced accumulation of the mMCP-4 transcript, but not the rIL-3-induced accumulation of the mMCP-5 transcript. The presence of rIL-3 also suppresses the rIL-9-induced accumulation of the mMCP-1 and mMCP-2 transcripts. Because of their counter-regulatory actions on the steady-state levels of transcripts that encode three late-expressed serine proteases in BALB/cJ mice, rIL-4 and rIL-3 both inhibit the final stages of differentiation and maturation of mast cells. Because rIL-4, unlike rIL-3, is neither an inducer of early-expressed proteases nor alone a proliferative factor for BMMC, the counterregulatory actions of rIL-3 and rIL-4 on differentiation and maturation of these mouse mast cells are independent of their other functions.

Animals↗
PubMed1993

Reversible expression of mouse mast cell protease 2 mRNA and protein in cultured mast cells exposed to IL-10.

BALB/cJ mouse mast cells derived by culturing bone marrow progenitor cells in WEHI-3 cell-conditioned medium (BMMCW) do not contain mouse mast cell protease 2 (mMCP-2) mRNA, but these cells can be induced to express this transcript after exposure to rIL-10. To study the translation and granule accumulation of mMCP-2 in rIL-10-treated BMMC (BMMCW+IL-10), a rabbit antibody was developed to a synthetic peptide that corresponds to the novel amino acid sequence in mMCP-2 at residues 56 to 71. After affinity purification, this antibody, anti-mMCP-2(56-71) IgG, reacted in SDS-PAGE/immunoblots against a 28-kDa protein in BMMCW+IL-10 that had the N-terminal amino acid sequence of mMCP-2. As assessed immunohistochemically, mMCP-2 protein accumulated in the secretory granules of Kirsten sarcoma virus-immortalized mouse mast cells, BMMCW+IL-10, and the mucosal mast cells present in the jejunum of Trichinella spiralis-infected BALB/cJ mice. Time course analyses of the induction of mMCP-2 mRNA and protein in BMMCW+IL-10 revealed that these cells contain a high steady-state level of mMCP-2 mRNA 24 h after their exposure to rIL-10. Although a small amount of immunodetectable mMCP-2 protein is present in the cells treated for 24 h, large amounts of this protease are not obtained until 7 days of treatment of the cells with rIL-10. Time course analyses of the loss of mMCP-2 mRNA and protein in BMMCW+IL-10 revealed that the steady-state level of mMCP-2 mRNA decreased dramatically 24 h after rIL-10 was removed from the culture medium, but that the level of mMCP-2 protein did not decline measurably until day 5 of culture. The fact that the steady-state levels of mMCP-2 mRNA and protein in BMMC can both be reversibly altered by culturing these mast cells in the presence and absence of rIL-10 suggests that the phenotype of mast cells is not fixed. Rather, it is in a dynamic state regulated by the cytokine network to which mast cells are exposed in their different microenvironments.

Amino Acid Sequence↗