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F T Liu

Publications and source records attributed to F T Liu.

At least 91 records · Page 5Linked to original sources
PubMed1993

IgE-binding molecules (Mac-2/epsilon BP) expressed by human eosinophils. Implication in IgE-dependent eosinophil cytotoxicity.

Macrophage cell-surface protein 2 (Mac-2), a galactose specific S-type lectin identified in inflammatory macrophages, presents a high degree of homology with the rat IgE-binding protein (epsilon BP). In the present study, we show by different experimental approaches that human eosinophils can express Mac-2/epsilon BP. Flow cytometry analysis revealed that a large proportion of eosinophilic patients expressing binding sites for IgE on their eosinophil membrane, were able to bind anti-Mac-2 monoclonal antibody (mAb). Northern blot performed with eosinophil RNA hybridized with the human Mac-2 or epsilon BP cDNA probes revealed that eosinophils presented a unique transcript at 1.2 kb. Immunoprecipitation of eosinophil extracts with anti-Mac-2 mAb revealed the presence of a molecule of 29 kDa corresponding to Mac-2 protein, as well as one additional molecule of 15 kDa, absent from control alveolar macrophages. The function of these molecules was investigated in a radiolabeled IgE binding assay. Anti-Mac-2 mAb as well as galactose and lactose saccharides significantly inhibited the binding of radiolabeled human myeloma IgE protein to eosinophils. Moreover, the dose-dependent inhibition by anti-Mac-2 mAb of IgE-dependent eosinophil-mediated cytotoxicity towards parasite targets indicated the role of these IgE-binding molecules in the function of human eosinophils. These results suggest that in addition to transmembrane receptors, lectin-type molecules can participate in the IgE-dependent effector function of eosinophils.

Animals↗
PubMed1993

S-type mammalian lectins in allergic inflammation.

Our understanding of the mechanisms of allergic disease is continuously influenced by new developments in the bio-medical sciences. The studies of glycoconjugates and animal lectins have emerged as an exciting new frontier. One family of animal lectins, soluble lactose-binding lectins, has been studied extensively by a number of laboratories. Evidence is mounting that members of this family of lectins exist in the extracellular space and may be capable of affecting functions of various cells. In this article Fu-Tong Liu presents a revised view of allergic inflammation with emphasis on the modulatory effect of soluble lectins on mast-cell function.

Amino Acid Sequence↗
PubMed1992

Genes involved in tumor invasion and metastasis are differentially modulated by estradiol and progestin in human breast-cancer cells.

Invasion of basement membranes by cancer cells is a critical step in metastasis, which requires the coordinated expression of specific genes such as laminin receptors and metalloproteinases. Estradiol and progesterone modulate the clinical progression of steroid-sensitive breast cancers; however, little is known about the molecular regulation of the invasive phenotype by these hormones. We therefore examined the effects of 10 nM estradiol and/or 10 nM progestin R5020 on the expression of 2 non-integrin laminin binding proteins, the 67-kDa laminin receptor (67LR) and HLBP31 as well as the 72-kDa type-IV collagenase (MMP-2) and its inhibitor, TIMP-2, in steroid-receptor-positive (T47D and MCF-7) and -negative (MDA-MB 231) human breast-cancer cells. The relative steady-state level of 67LR mRNA was increased 2- to 3-fold by estradiol in both MCF-7 (p < 0.001) and T47D (p < 0.001) cells, also by R5020, alone or in combination with estradiol, in T47D cells (p < 0.001) and to a much less extent in MCF-7 cells. HLBP31 mRNA and protein levels were increased 2- to 3-fold (p < 0.001) by R5020 alone or in combination with estradiol, but not by estradiol alone. None of the steroid treatments affected the expression or activity of MMP-2. Interestingly, however, TIMP-2 mRNA levels and protein expression in MCF-7 and T47D cells were 50% down-regulated (p < 0.001) by treatment with R5020 or R5020 plus estradiol, but not by treatment with estradiol alone. None of these genes were modulated in steroid-independent MDA-MB231 cells. The data suggest that estradiol and progesterone might act as coordinators regulating specific genes in the steroid-sensitive breast-cancer cell, leading to the acquisition of the metastatic phenotype.

Breast Neoplasms↗
PubMed1992

Genomic cloning of the gene for an IgE-binding lectin reveals unusual utilization of 5' untranslated regions.

epsilon BP (for epsilon binding protein) is a M(r) 31,000 S-type animal lectin that binds to IgE and has been identified as the homologue of Mac-2, a macrophage cell-surface marker, as well as the lectins RL-29, CBP35, and L-34. The protein is composed of two domains with the amino-terminal portion containing tandem repeats of nine amino acids and the carboxyl-terminal half containing consensus sequences shared by S-type animal lectins. We determined the genomic map in both rat and mouse and isolated overlapping genomic clones that contain the 5' two-thirds of the murine gene. The remaining portion of the gene was obtained by polymerase chain reaction (PCR) amplification of genomic murine DNA followed by subcloning into plasmid vectors. The epsilon BP gene is composed of six exons separated by five introns. The entire amino-terminal repetitive sequence is contained in exon III, and the carboxyl-terminal domain is encoded by the three succeeding exons (IV, V, VI). The latter three exons correspond well in size and share sequence homology with three exons coding for 14-kDa S-type lectins. The sequence in exon I offers an explanation for the generation of two mRNAs differing only in their 5' untranslated sequences, previously reported in Mac-2 cDNA clones. Using cDNA synthesis and PCR amplification, we determined that two alternative splice sites are used in many different types of cells. This alternative splicing results in different 5' untranslated regions of the murine epsilon BP mRNA.

Alternative Splicing↗
PubMed1992

Inverse modulation of steady-state messenger RNA levels of two non-integrin laminin-binding proteins in human colon carcinoma.

BACKGROUND: Interactions between cells and the basement membrane glycoprotein laminin are altered during colon cancer progression. Colon carcinoma and normal mucosa cells express a variety of laminin-binding proteins, including the 67-kd laminin receptor (67 LR) and a 31-kd human laminin-binding protein (HLBP31) homologous to the 31-kd human IgE-binding protein/galactoside-binding lectin. PURPOSE: To investigate whether various laminin-binding proteins are differentially expressed in human colon carcinoma, we studied messenger RNA (mRNA) levels of the 67 LR and HLBP31 in matched tumor and adjacent normal mucosa samples from a series of 21 patients. METHODS: Total cellular RNA from tumor and normal mucosa was isolated and analyzed by Northern and slot blot hybridization. In addition, HLBP31 protein levels were assessed by the immunoblot technique. Quantitative laminin affinity chromatography was also used to measure the synthesis of HLBP31 protein in five human cancer cell lines. RESULTS: The steady-state mRNA level of HLBP31 was downregulated (i.e., decreased) in 18 of 21 human colon carcinomas compared with the level in their corresponding normal colonic mucosa. On average, the level of HLBP31 mRNA was decreased 50% +/- 30% (+/- SD) in the colon cancers. The mean ratio of colon cancer HLBP31 mRNA to adjacent normal mucosa HLBP31 mRNA was twofold lower in primary tumors of patients with metastases (0.3 +/- 0.2 SD) than in primary tumors of patients free of metastatic lesions (0.6 +/- 0.2 SD). The differences between the two groups of patients were statistically significant (P less than .05, Wilcoxon-Mann-Whitney test). We have previously shown that the ratio of colon cancer 67 LR mRNA to corresponding normal mucosa 67 LR mRNA was increased in the same patient population. When the two ratios (ratio of cancer to normal HLBP31 mRNA and ratio of cancer to normal 67 LR mRNA) were compared, HLBP31 mRNA/67 LR mRNA was significantly lower (P less than .05) in primary tumors with metastases (mean +/- SD, 0.3 +/- 0.2) than in primary cancers without metastases (mean +/- SD, 0.7 +/- 0.5). The steady-state level of HLBP31 mRNA was directly correlated with the amount of HLBP31 protein in both colon tissue samples and human cancer cell lines. CONCLUSION: HLBP31 mRNA expression in colon cancer tissues is modulated inversely to that of 67 LR mRNA expression. The down-regulation of HLBP31 appears to be associated with the metastatic capabilities of colon cancer cells. IMPLICATIONS: Prospective studies on a large cohort should determine if the systematic detection of HLBP31 and 67 LR protein and/or mRNA can be a valuable adjunct in the prognostic evaluation of primary colon cancers.

Amino Acid Sequence↗
PubMed1992

Biochemical and biophysical characterization of human recombinant IgE-binding protein, an S-type animal lectin.

IgE-binding protein (epsilon BP) was originally identified by virtue of its affinity for IgE. It is now known to be a beta-galactoside-binding lectin with the characteristic of an S-type carbohydrate recognition domain. The protein is composed of two domains: the amino-terminal domain consisting of tandem repeats and the carboxyl-terminal domain containing sequences shared by other S-type carbohydrate recognition domains. The amino-terminal domain also contains a number of potential recognition sites for collagenase cleavage. In this study, human epsilon BP was first expressed in Escherichia coli, and the carboxyl-terminal domain (epsilon BP-C) was then generated by collagenase digestion of epsilon BP. By equilibrium dialysis, the association constants of epsilon BP and epsilon BP-C for lactose were found to be similar (6.0 +/- 0.70) x 10(4) M-1 and (4.7 +/- 0.27) x 10(4) M-1, respectively. Both polypeptides contain only one lactose-binding site/molecule. By an assay involving binding of 125I-labeled epsilon BP or epsilon BP-C to solid phase IgE, and inhibition of this binding by saccharides, it was determined that epsilon BP-C retains the saccharide specificity of epsilon BP. Importantly, although unlabeled epsilon BP-C inhibited the binding of the radiolabeled epsilon BP to IgE, unlabeled epsilon BP caused increased binding to IgE, suggesting self-association among epsilon BP molecules. Oligomeric structures resulting from self-association of epsilon BP were confirmed by chemical cross-linking studies. Furthermore, epsilon BP possesses hemagglutination activity on rabbit erythrocytes, whereas epsilon BP-C lacks such activity. Based on these results, we propose a structural model for multivalency of epsilon BP: dimerization or oligomerization of epsilon BP occurs through intermolecular interaction involving the amino-terminal domain.

Animals↗
PubMed1992

An intestinal galactose-specific lectin mediates the binding of murine IgE to mouse intestinal epithelial cells.

A number of lactose-binding lectins have recently been identified in the rat and mouse intestine, one of which corresponds to the C-terminal domain of IgE-binding proteins, originally identified in rat basophilic leukemia (RBL) cells and mouse 3T3 fibroblasts. In the present report, we describe the affinity purification of a rat intestinal lactose-specific lectin which binds murine IgE antibodies. This binding most likely occurs via the immunoglobulin carbohydrate chains, as it is inhibited by lactose. This intestinal lectin molecule is also immunologically related to the previously described IgE-binding protein (epsilon BP) isolated from RBL cells, since it is recognized by antibodies raised against recombinant epsilon BP. This intestinal form of epsilon BP has a molecular mass of 17.5 kDa, which is much lower than that of its RBL cell analogue (31 kDa). The attachment of IgE to the mouse intestinal epithelium was demonstrated by immunohistochemistry, along with the presence of a corresponding mouse intestinal epsilon BP. The carbohydrate-dependent nature of this attachment was established by demonstrating that IgE binding to mouse epithelium was specifically abolished by lactose (4 mM) and by a blood-group-A-active tetrasaccharide (0.2 mM), but not by mannose (10 mM). Finally, the association of IgE with the mouse intestinal epithelium was prevented by competition with the purified IgE-binding lectin isolated from rat intestine. Although the physiological function of this intestinal protein is still unknown, the finding that IgE binds to a lectin in the intestinal epithelium pinpoints a possible novel mechanism for the regulation of IgE-mediated disorders, such as food allergy.

3T3 Cells↗
PubMed1992

Surface expression of functional IgE binding protein, an endogenous lectin, on mast cells and macrophages.

IgE-binding protein (epsilon BP) is a galactoside-specific lectin containing an S-type carbohydrate-recognition domain. It was originally identified in rat basophilic leukemia cells and is now known to be identical to a macrophage surface Ag, Mac-2, and lectins designated as CBP 35/L-34/RL-29. It has also been related to a nonintegrin laminin-binding protein isolated from mouse macrophages. In this report we have shown the following: epsilon BP is present in variable amounts in several mast cell lines, and the surface expression of epsilon BP in these cell lines is quite variable and does not correlate with the total amount of epsilon BP in the cell. epsilon BP is displayed on the cell surface in a manner that is reversible by lactose, most likely through attachment to yet unidentified glycoconjugates. The putative epsilon BP binding sites on the cell surface can be readily demonstrated by using radiolabeled epsilon BP, and the sites are present in comparable amounts in various cell lines. Expression of epsilon BP on the cell surface can be regulated; the most notable example is the upregulation of surface epsilon BP on RBL cells activated through the high-affinity IgE receptor by IgE immune complexes. Cell-surface epsilon BP is functional as measured by its ability to promote adhesion of trypsinized rabbit erythrocytes to mast cells and macrophages. On the basis of these results and reported properties of related lectins, we propose that the lectin represented by epsilon BP is a new class of cell-adhesion protein.

Animals↗
PubMed1992

The role of platelet-activating factor and peptidoleukotrienes in the vascular changes of rat passive anaphylaxis.

1. The role of platelet-activating factor (PAF) and peptidoleukotrienes as putative mediators of some of the vascular changes triggered by antigen was investigated in rats passively sensitized with monoclonal anti-DNP (2,4-dinitrophenyl) IgE. 2. Lethal anaphylaxis with respiratory distress, systemic hypotension, detachment of the intestinal mucosa, leukopenia and extravasation of protein-rich plasma was observed after antigen challenge of rats sensitized with partially purified monoclonal IgE at concentrations of 15 mg protein kg-1. 3. Analysis of the peritoneal fluid obtained after i.v. challenge with DNP-BSA (bovine serum albumin) showed the presence of significant amounts of PAF (101 +/- 8 pg/rat), whereas this mediator was undetectable in control animals. Leukotriene D4 was the predominant peptidoleukotriene that could be recovered after antigen challenge, and showed an extremely high concentration (92 +2- 15 ng/rat) as compared to PAF levels. 4. Extravasation of protein-rich plasma was observed shortly after challenge and reached a maximum at 30 min. Treatment of animals with i.v. PCA 4248 (1-2 mg kg-1) and WEB 2086 (1 mg kg-1), two chemically unrelated compounds which are antagonists of the PAF-receptor, produced a significant reduction of the extravasation of protein-rich plasma. 5. The same degree of protection could be afforded by MK-886, an inhibitor of leukotriene biosynthesis. Combined treatment with WEB 2086 and MK-886 provided greater inhibition of protein-rich plasma extravasation than either compound alone. PCA 4248 was also found to inhibit in a dose-dependent manner the systemic hypotension observed upon DNP-BSA challenge.6. These data indicate that the lipid mediators PAF and peptidoleukotrienes are major effectors of the vascular disturbances observed in rat passive IgE-mediated anaphylaxis.

Anaphylaxis↗
PubMed1991

Heterogeneous IgE glycoforms characterized by differential recognition of an endogenous lectin (IgE-binding protein).

IgE is highly glycosylated, but the function of the oligosaccharide side chains is largely unknown. The previous discovery of an animal lectin, IgE-binding protein (epsilon BP), affords an opportunity to study potential carbohydrate-dependent effector functions of IgE. epsilon BP is a beta-galactoside-specific lectin with binding affinity for IgE and is now known to be equivalent to carbohydrate-binding protein 35 and the Mac-2 Ag; thus, it may have multiple functions in addition to IgE binding. We have previously shown that rat r epsilon BP recognizes sialidase-treated human myeloma IgE to a much greater extent than the untreated IgE. In contrast, human epsilon BP binds essentially equivalently to a monoclonal murine IgE with or without sialidase pretreatment. To validate a possible role for epsilon BP in the IgE system, we investigated the pattern of recognition of epsilon BP for various polyclonal human IgE samples. We show that polyclonal IgE derived from four individuals with hyper-IgE syndrome or atopic dermatitis recognizes epsilon BP and that there is individual variation in the proportion of IgE recognized by epsilon BP, ranging from greater than 60% for one sample to almost undetectable levels in another. We conclude that epsilon BP does indeed recognize polyclonal IgE and that this recognition is modulated by sialylation of IgE oligosaccharides. Furthermore, there exist different IgE glycoforms, varying in the degree of sialylation, and these are distributed in a distinct manner in different individuals.

Antigens, Differentiation↗
PubMed1991

Complete genomic sequence of the murine low affinity Fc receptor for IgE. Demonstration of alternative transcripts and conserved sequence elements.

The complete sequence of the murine low affinity Fc receptor for IgE (Fc epsilon RII), including the 5' and 3' flanking sequences, is reported. The murine Fc epsilon RII gene spans 12.9 kb and includes 12 exons surrounding 11 introns. The composite exon sequence is virtually identical to previously reported murine Fc epsilon RII cDNA sequences. Much of the proximal promoter regions of the mouse and human homologues of Fc epsilon RII show remarkable homology to each other, including three promoter elements previously identified for MHC class II genes. The reported exon/intron structure of the human FC epsilon RII is similar to the murine homologue, except that the latter has an additional exon coding for a fourth amino acid repetitive sequence (vs three in the human gene). RNase protection studies have identified an additional transcript within intron 2 of murine Fc epsilon RIIa, similar to the human Fc epsilon RIIb form but with a different predicted sequence of the first six amino acids. This transcript is present in the mRNA of purified splenic B cells, but not in the mRNA of the Fc epsilon RII+ B lymphoma cell line M12.4.5. The murine Fc epsilon RII gene contains a large intron (4.2 kb) separating the lectin and nonlectin coding regions, and several repetitive sequences are found clustered within this intron. These results emphasize the importance of the demarcation between these domains and allude to their evolutionary and functional significance.

Amino Acid Sequence↗
PubMed1991

Pharmacological modulation of the antigen-induced expression of the low-affinity IgE receptor (Fc epsilon RII/CD23) on rat alveolar macrophages.

Brown-Norway (BN) rats were sensitized by 3 aerosol exposures to ovalbumin (OA; 10 mg/ml) at days 1, 3 and 14. At day 21, the rats were challenged with the antigen or vehicle by aerosol. Alveolar macrophages (AM) were obtained by bronchoalveolar lavage and the expression of Fc epsilon RII/CD23 was assessed by flow cytometry after staining with the BB10 monoclonal antibody. A maximum of 74% of the AM from sensitized and challenged BN rats expressed FC epsilon RII/CD23 24 h after OA exposure, compared to 12% of the cells from rats exposed to vehicle. Sprague-Dawley rats were passively sensitized by intravenous injection of 0.1 or 0.05 ml/kg mouse ascitic fluid containing dinitrophenyl (DNP)-specific monoclonal IgE (2682-1) and after 24 h exposed to an aerosol of 5 mg/ml of DNP-bovine serum albumin for 30 min. In this case also, antigen exposure induced the expression of Fc epsilon RII/CD23 on 75% AM, compared to 17% AM from saline-challenged rats. Such an induction of Fc epsilon RII/CD23 on AM was, however, not observed when the animals were challenged with either histamine, serotonin or acetylcholine by aerosol. The antigen-induced expression of Fc epsilon RII/CD23 on AM was inhibited upon treatment of the rats with ketotifen or beclomethasone. In addition, oral or aerosol administration of respectively BN 50730 or BN 52021 (two structurally unrelated platelet-activating factor antagonists), inhibited the antigen-induced Fc epsilon RII/CD23 expression on AM, indicating the participation of this lipid mediator in this process.

Animals↗
PubMed1991

mRNA variants encoding multiple forms of the high-affinity IgE receptor alpha subunit in transformed and nontransformed mast cells.

Multiple mRNA species encoding several predicted forms of the high-affinity IgE receptor alpha subunit (Fc epsilon RI-alpha) have been previously characterized from rat basophilic leukemia cells. Using the polymerase chain reaction procedure, we have extended these findings to show that one Fc epsilon RI-alpha mRNA variant, characterized by a 163-bp deletion within the coding sequence, exists in normal rat connective tissue mast cells as well as in both transformed and non transformed murine mast cell lines. In addition, a partial murine Fc epsilon RI-alpha genomic clone, spanning the internal-deletion sequence, has been identified, and from analysis of this sequence a mechanism of alternative pre-mRNA splicing is proposed. Finally, mRNA variants have been translated in a cell-free system and the protein products partially characterized.

Amino Acid Sequence↗
PubMed1990

Expression of biologically active recombinant rat IgE-binding protein in Escherichia coli.

IgE-binding protein (epsilon BP) is a protein which has affinity for IgE and was originally identified in rat basophilic leukemia (RBL) cells. Subsequently, it was found to be the rat homolog of CBP35, a murine beta-galactoside-specific lectin. This protein is also designated as L-34 and RL-29 and studied independently by several laboratories. More recently, CBP35 (epsilon BP) was found to be equivalent to Mac-2, a surface marker on activated macrophages. Using rat epsilon BP cDNA, we have succeeded in expressing recombinant epsilon BP in Escherichia coli. Milligram quantities of homogeneous epsilon BP could be obtained from bacterial lysate in a one-step affinity purification procedure utilizing lactosyl-Sepharose 4B and elution with a lactose gradient. The recombinant epsilon BP (r epsilon BP) binds mouse IgE and retains reactivity to anti-peptide antibodies specific for a sequence within rat epsilon BP. The purified r epsilon BP exhibits binding activity to various saccharides, with affinity for N-acetyllactosamine greater than thiodigalactoside greater than lactose much greater than D-galactose greater than L-arabinose, an order identical to that exhibited by native epsilon BP isolated from RBL cells. The recombinant lectin displayed hemagglutination activity when tested with rabbit erythrocytes. Although epsilon BP shares sequence homology to other lectins containing S-type (thiol-dependent) carbohydrate-recognition domains, r epsilon BP is resistant to air oxidation and does not require reducing agents for maintaining its activity. Furthermore, the single cysteine residue appears to be unexposed and can be alkylated only when the protein is denatured in 5.6 M guanidinium hydrochloride. The availability of a source for a large quantity of epsilon BP should facilitate the analysis of biological function(s) and structure-activity relationships of this lectin.

Animals↗
PubMed1990

Human IgE-binding protein: a soluble lectin exhibiting a highly conserved interspecies sequence and differential recognition of IgE glycoforms.

IgE-binding protein (epsilon BP) refers to a protein originally identified in rat basophilic leukemia cells by virtue of its affinity for IgE. It is now known to be a beta-galactoside-binding lectin equivalent to carbohydrate-binding protein 35 (CBP 35). More recently, its identity to Mac-2, a macrophage cell-surface protein, has been established. cDNA coding for human epsilon BP has been cloned from a human HeLa cell cDNA library and contains an open reading frame of 750 base pairs encoding a 250 amino acid protein. Like the rat and murine counterparts, the human epsilon BP amino acid sequence can be divided into two domains with the amino-terminal domain consisting of a highly conserved repetitive sequence (YPGXXXPGA) and the carboxyl-terminal domain containing sequences shared by other S-type lectins. The human epsilon BP sequence exhibits extensive homology to murine and rat epsilon BP with 84% and 82% identity, respectively. The homology is particularly striking in the carboxyl-terminal domain where 95% identity is found between human and murine sequences in a stretch of over 70 amino acids. A survey of epsilon BP mRNA expression from several lymphocyte cell lines revealed that the level of epsilon BP transcription may reflect a relationship between cell differentiation and epsilon BP expression. Finally, human epsilon BP was purified from several human cell lines and shown to possess lactose-binding characteristics and cross-species reactivity to murine IgE. Surprisingly, three different human myeloma IgE proteins did not show reactivity to human epsilon BP. However, after neuraminidase treatment of each human IgE, pronounced binding to epsilon BP was observed, thereby indicating that only specific IgE glycoforms can be recognized by epsilon BP.

Amino Acid Sequence↗
PubMed1990

The induction of murine B cell Ia by IgE-antigen complexes is dependent on protein synthesis and preceded by class II mRNA accumulation.

Complexes of murine monoclonal anti-DNP IgE and DNP-OVA interact with murine B cells to stimulate expression of cell surface Ia antigens. Enhanced membrane expression of class II MHC antigens was accompanied by a threefold increase of I-A and I-E transcripts, as measured by Northern blot. Peak accumulation of Ia mRNA were detected after 6 hr of incubation with IgE-antigen complexes and returned to control levels after 12 hr of incubation. Hence, induction of Ia mRNA by IgE-antigen complexes was compatible with cell surface Ia expression, both quantitatively and with regard to the time frame. The Ia-inductive effects of both IL-4 and IgE-antigen complexes were inhibited by cycloheximide and actinomycin-D. However, whereas actinomycin-D and cycloheximide blocked IL-4 induction of Fc epsilon RII expression, inhibition of transcription or protein synthesis did not abrogate the increased expression of Fc epsilon R associated with IgE-antigen complexes. These results suggest that the IgE-antigen-induction of B cell Ia expression follows from activation of transcription and de novo synthesis of Ia antigens.

Animals↗