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We have investigated the temperature variation of optical spectra comparatively for an oxygenated nonsuperconducting and a reduced superconducting crystal of Nd1.85Ce0.15CuO4+y. Anomalous gap-like structure as large as 0.3 eV has been observed in the optical conductivity spectrum of the oxygenated crystal with lowering temperature from 340 K, while little temperature-variation has been observed for the reduced crystal. Furthermore, anomalies in lattice dynamics have been observed only for the oxygenated crystal in far-infrared spectra. These spectral signatures have shown parallel temperature-dependence, signaling a possible charge ordering in the oxygenated nonsuperconducting crystal.

Rat monoclonal antibody against mouse glycosylation inhibiting factors was obtained, and radiolabeled glycosylation inhibiting factors from the mouse T-cell hybridoma, 231F1 cells, were purified by using the monoclonal antibody and antilipomodulin antibody. Analysis of the affinity-purified lymphokine by PAGE demonstrated two proteins of 14.4 kDa and 41 kDa. Both proteins migrated similarly under the reduced and unreduced conditions, indicating that each of the two species consist of a single polypeptide chain. Biologic activity of the lymphokine was recovered by extraction of the proteins from gel slices followed by renaturation. Evidence was obtained that suggested the 14.4-kDa peptide was a degradation product of the 41-kDa molecules. The 14.4-kDa peptide was also recovered by extraction of the surface-labeled 231F1 cells with Ca2+ chelator, indicating that the glycosylation inhibiting factor is associated with the cell surface.

Selective growth of human mast cells/basophils was obtained in suspension cultures of mononuclear cells from umbilical cord blood. A fraction of culture supernatant of phytohemagglutinin-stimulated T cells, which lacked interleukin 2, was required for the selective growth of mast cells. When the mononuclear cells were cultured for 2-4 wk in the presence of the fraction, 50-90% of the total cells in the cultures contained metachromatic granules. Under the optimal culture conditions, the number of mast cells/basophils recovered from the cultures was 30-60% of the number of mononuclear cells plated. Cultured mast cells/basophils bear 1.2-3.83 X 10(5) IgE receptors per cell and contained 0.48-1.6 micrograms of histamine per 10(6) cells. The average forward rate constant, k1, and dissociation constant, k-1, for the binding of human IgE to IgE receptors on the cells were 1.9 X 10(5) M-1 sec-1 and 6.9 X 10(-5) sec-1, respectively (average equilibrium constant = 2.75 X 10(9) M-1). Specific binding of human IgE with high affinity indicates that the cells recovered in the suspension culture are human mast cells/basophils. Cultured cells sensitized with human IgE released a substantial amount of histamine upon exposure to anti-IgE. The results indicate that human mast cells/basophils obtained in the culture are functionally mature.

We obtained human T-cell hybridomas that are specific for bee venom phospholipase A2 (PLA2) and constitutively secrete glycosylation inhibiting factor (GIF). Upon crosslinking of CD3, the hybridoma produced GIF having affinity for PLA2. When affinity-purified PLA2-binding GIF was used as an immunogen, monoclonal antibodies specific for the antigen-binding GIF were obtained. Monoclonal antibody 110BH3 bound the antigen-binding GIF but failed to bind the 13-kDa nonspecific GIF, as determined by both bioassay and ELISA. In contrast, 388F1, a monoclonal antibody against nonspecific GIF, gave ELISA signals with both the nonspecific GIF and the antigen-binding GIF. Gel filtration of affinity-purified antigen-binding GIF revealed the presence of a 72- to 80-kDa protein which gave ELISA signals with both 110BH3 and 388F1 and contained GIF bioactivity. Upon reduction and alkylation, the antigen-binding GIF dissociated into a 62- to 64-kDa protein which gave positive ELISA with antibody 110BH3 but no signal with antibody 388F1, and a 15-kDa protein, which gave ELISA signal with the 388F1 but not with 110BH3. Immunoblotting of a PLA2-binding GIF preparation revealed that under reducing conditions, the antigen-binding GIF dissociated a 13-kDa peptide which reacted with polyclonal antibodies against recombinant GIF. The results indicate that the 13-kDa nonspecific GIF is a subunit of antigen-binding GIF. The PLA2-binding GIF has affinity for an epitope, representing amino acid residues 19-28 in PLA2 which appears to be an external structure in the antigen.

Bridging of IgE receptors on normal rat mast cells by divalent anti-receptor antibodies induced phospholipid methylation and an increase in intracellular cyclic AMP within 15 sec after the receptor bridging. These biochemical events were followed by Ca2+ influx and histamine release. When IgE receptors on isolated plasma membranes were bridged by the antibody, both the increase in the incorporation of [3H]methyl into lipid fraction and the synthesis of cyclic AMP were demonstrated. The synthesis of cyclic AMP in this system was enhanced in the presence of GTP. The results indicated that the bridged IgE receptors are linked to both methyltransferases and adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] in the plasma membrane. An increase in cyclic AMP prior to receptor bridging suppressed phospholipid methylation in the plasma membrane, Ca2+ uptake, and subsequent histamine release. On the other hand, inhibition of phospholipid methylation by (S)-isobutyryl-3-deazaadenosine resulted in the suppression of cyclic AMP synthesis in the plasma membrane. These findings suggest that the activation of phospholipid methylation and the activation of adenylate cyclase are e, and subsequent histamine release. On the other hand, inhibition of phospholipid methylation by (S)-isobutyryl-3-deazadenosine resulted in the suppression of cyclic AMP synthesis in the plasma membrane. These findings suggest that the activation of phospholipid methylation and the activation of adenylate cyclase are e, and subsequent histamine release. On the other hand, inhibition of phospholipid methylation by (S)-isobutyryl-3-deazadenosine resulted in the suppression of cyclic AMP synthesis in the plasma membrane. These findings suggest that the activation of phospholipid methylation and the activation of adenylate cyclase are mutually regulated.

The paper presents a novel single-phase, single-way, current-source rectifier. This is based on the cascade combination of a diode bridge rectifier and a current-source Cuk power convertor. The supply current can be sinusoidally waveshaped with suppressed resonance by an appropriate switching strategy, whereas a parallel inductance-capacitance circuit of a conventional form excites the resonant frequency. Furthermore, step-up and step-down characteristics of the output current and near-unity power factor operation can be obtained. To predict steady-state and transient characteristics of the rectifier with a digital PI controller, rigorous and approximate state-space analyses are introduced. The experimental and predicted results confirm the usefulness of the rectifier presented.

Treatment of normal BALB/c splenocytes with anti-mouse IgD antibodies at 0 degrees C followed by incubation of the cells at 37 degrees C resulted in the formation of soluble factors that selectively inhibit rosette formation of lymphocytes bearing Fc delta receptors with IgD-coated erythrocytes (i.e., IgD-binding factors). Treatment of the same cells with anti-IgM antibodies failed to induce the formation of the factors. Analysis of cellular mechanisms indicated that polymerized surface IgD on B cells, as well as surface IgD-anti-IgD complexes shed from the B cells, induced T cells bearing Fc delta receptors to form IgD-binding factors. The factors formed by the anti-IgD treatment of splenic lymphocytes are composed of molecular mass species of 70 and 34 kDa, as estimated by gel filtration. Both the 70- and 34-kDa IgD-binding factors enhanced IgM and IgG1 plaque-forming cell responses of sheep erythrocyte-primed mouse spleen cells to the antigen.

Normal human T cells that proliferated in the presence of interleukin 2 (IL-2) formed IgE-binding factors when incubated with human IgE. These cells were then fused with a mutant of the human T-cell line CEM. Incubation of five hybridomas with human IgE or culture of the cells in IgE-coated wells resulted in the formation of IgE-binding factors. One hour of incubation with 10 micrograms of human IgE per ml was sufficient to induce the hybridomas to form IgE-binding factors. Polymerized IgE was much more efficient than monomeric IgE for the induction of the factor formation. As little as 10 ng of IgE dimer per ml was sufficient to induce factor formation. The IgE-binding factors produced by the hybridomas bound to human IgE-coated Sepharose and were recovered from the beads by elution at acid pH. The factors had low affinity for rat IgE but failed to bind to human IgG. The IgE-binding factors formed by four hybridomas had a Mr between 25,000 and 30,000, whereas one hybridoma formed IgE-binding factors of Mr 30,000 and Mr 15,000. The IgE-binding formed by all of the hybridomas had affinity for concanavalin A, indicating that the factors are glycoproteins.

Normal rat mast cells were stimulated by antibodies against IgE receptors (anti-RBL) or by anti-IgE, and [3H]methyl group incorporation into phospholipids, 45Ca uptake, and histamine release were examined. Anti-RBL or its F(ab')2 fragments and anti-IgE induced an increase in the incorporation of [3H]methyl into phospholipids, in 45Ca influx, and in histamine release. By contrast, Fab' monomer fragments of anti-RBL induced none of these reactions. The transient increase of [3H]methyl incorporation in lipids peaked within 15 sec after the addition of either anti-RBL or anti-IgE and fell to basal level in 30 sec. This was then followed by an influx of 45Ca that increased to a maximum in 2 min and by histamine release that reached a maximum in 3 min. Inhibition of phospholipid methylation resulted in an inhibition of 45Ca influx and histamine release. These findings demonstrate that phospholipid methylation in rat mast cells is induced by bridging of IgE receptors on the cell surface and that increased methylation of phospholipids sets the stage for an influx of Ca2+ and subsequent release of histamine.

Stimulation with glucocorticoids of mouse splenic lymphocytes and peritoneal adherent cells resulted in the formation of a soluble factor--i.e., glycosylation inhibiting factor (GIF)--that inhibits the assembly of N-linked oligosaccharide(s) to IgE-binding factors during their biosynthesis. The major cell sources of GIF are Lyt 2+ I-J+ T cells and macrophages, respectively. The molecular size of GIF from T cells was 15 kDa, while GIF from macrophages consisted of 40- and 15-kDa molecules. GIF from both cell sources bound to monoclonal antibody against lipomodulin and exerted phospholipase inhibitory activity upon dephosphorylation. In view of previous reports that glucocorticoids induce the formation of phospholipase inhibitory protein--i.e., lipomodulin/macrocortin--GIF from T cells and macrophages appear to be phosphorylated derivatives of lipomodulin. GIF released from splenic lymphocytes and macrophages of C57BL/6 mice bound to anti-I-Jb antibodies but not to either anti-I-Jk or anti-I-Js antibodies. Upon stimulation with glucocorticoids, CBA and B10.A(5R) lymphocytes released GIF that bound to anti-I-Jk antibodies but not to anti-I-Jb antibodies, while the same factor from B10.A(3R) lymphocytes bound to anti-I-Jb antibodies. The results indicate that I-J determinants are associated with lipomodulin/macrocortin from T cells and macrophages.

Nucleated cells of human umbilical cord blood were cocultured with mouse skin-derived 3T3 fibroblasts. After 7-8 weeks in culture, when the number of the other hematopoietic cells declined, metachromatic granule-containing mononuclear cells appeared in the cultures, and the number of the cells increased up to 12 weeks. After 11-14 weeks in culture, the metachromatic mononuclear cells comprised a substantial portion of the cultured cells. These cells contained 1.8-2 micrograms of histamine per 10(6) cells and bore receptors for IgE. All of the cells contained tryptase in their granules. Electron microscopic analysis showed that these cells were mature human mast cells, clearly different from the basophilic granulocytes or eosinophils that arise in a variety of circumstances in cord blood cell cultures. Most of the cultured mast cells expressed some granules with regular crystalline arrays and contained both tryptase and chymase, and thus resembled human skin mast cells.

The recombinant peptide corresponding to residues 301-376 at the junction of constant regions 2 and 3 of the human IgE epsilon chain blocked the in vivo passive sensitization of human skin mast cells and in vitro sensitization of human basophil granulocytes with human IgE antibodies. An injection of the recombinant peptide or E myeloma protein into normal skin sites 1 hr before sensitization with an allergic serum blocked passive sensitization. In this system, approximately 10-fold higher molar concentration of the recombinant peptide than E myeloma protein was required for 50% inhibition of Prausnitz-Küstner reactions. When the mononuclear cells of two normal individuals were preincubated with the recombinant peptide or E myeloma protein for 15 min before passive sensitization with the same allergic serum and the cells were challenged with an optimal concentration of an antigen, approximately 11- to 13-fold higher concentration of the recombinant peptide than E myeloma protein was required for 50% inhibition of antigen-induced histamine release. Further studies with several recombinant peptides indicated that amino acid resides 363-376 in the Fc epsilon-chain fragment are not essential for binding of the peptide to Fc epsilon-chain receptor I.

Two hybridomas that produce the mAbs 135 and 449 B4 were obtained that inhibited the binding of IgE to the Fc epsilon RL/CD23 on the EBV-transformed B cell line RPMI 8866. mAb 135 was obtained from a mouse immunized with RPMI 8866 cells, whereas mAb 449B4 was obtained from a mouse immunized with a partially purified preparation of Fc epsilon RL/CD23 obtained as the eluate of an IgE immunoabsorbent loaded with a soluble extract of RPMI 8866 cells. These two mAbs bound to Fc epsilon RL/CD23- cell lines and precipitated two polypeptides with 36,000 Mr and 28,000 Mr, which were the HLA-DR alpha and beta chains, respectively. Immunoprecipitation with mAb 135 of NP-40 lysates from dithio-bis(succinimidyl propionate) (DSP) crosslinked 125I-labeled RPMI 8866 or normal B cells incubated with rIL-4 showed three polypeptides with 42,000, 36,000, and 28,000 Mr. The 42,000 Mr polypeptide is identical to the Fc epsilon RL/CD23 since it could be precipitated by the anti-Fc epsilon RL/CD23 mAb 25 after resolubilization from the SDS-PAGE gel. Immunoprecipitations of the crosslinked cell extracts carried out with the anti-Fc epsilon RL/CD23 mAb 25 yielded the same three polypeptides. Furthermore, when RPMI 8866 or rIL-4 preincubated normal B cells were solubilized with a digitonin buffer, which prevents the dissociation of noncovalently linked polypeptide complexes, mAb 135 and mAb 25 precipitated complexes composed of three molecules with 42,000, 36,000, and 28,000 Mr. The well-characterized anti-HLA-DR mAb L243 was unable to block the binding of either IgE or mAb 135 to RPMI 8866 cells, although it could immunoprecipitate the complex (HLA-DR-Fc epsilon RL/CD23) from crosslinked cell lysates. Since mAb 135 and L243 were able to both bind the RPMI 8866 cells, it demonstrates that they bind to different epitopes of the HLA-DR complex, the mAb 135 epitope of the HLA-DR molecule being close to the IgE binding site of the Fc epsilon RL/CD23. These data demonstrated that the Fc epsilon RL/CD23 and HLA-DR antigens are spatially associated on the B cell membrane.

We have investigated expression of an IgE-binding factor (IgE-BF) cDNA in both COS-7 monkey kidney cells and Chinese hamster ovary cells. Transient expression of the IgE-BF clone in either cell type yielded IgE-BF, which potentiated an in vitro IgE response and had an affinity for lentil lectin. In contrast, when the transient expression experiments were carried out in the presence of tunicamycin, the factors no longer bound to lentil lectin. Moreover, IgE-BF expressed under these conditions suppressed an in vitro IgE response. IgE-BF lacking affinity for lentil lectin and suppressing the IgE response also resulted from transient expression of the IgE-BF gene in the presence of glycosylation inhibiting factor, a phospholipase inhibitory protein. Thus, IgE-BF that either potentiate or suppress the IgE response can be expressed from a single cloned gene; the difference in biological activities appears to be determined principally by the type of glycosylation of the common polypeptide chain. Previous work showed that IgE-BF bears an antigenic determinant recognized by the anti-Ia monoclonal antibody OX3. IgE-BF produced in the presence of tunicamycin, and IgE-BF expressed from a mutant cDNA lacking one of two carbohydrate-attachment sites, lacked the OX3 determinant. Thus, the OX3 determinant on IgE-BF appears to be associated with a site of N-linked glycosylation.

Effects of recombinant human interleukins on hematopoiesis were explored by using suspension cultures of mononuclear cells of human umbilical-cord blood and bone marrow. The results showed that interleukin 5 induced the selective differentiation and proliferation of eosinophils. After 3 weeks in culture with interleukin 5, essentially all nonadherent cells in both bone marrow and cord blood cell cultures became eosinophilic myelocytes. Culture of the same cells with interleukin 4 resulted in the selective growth of OKT3+ lymphocytes. However, OKT3+ cells did not develop if the bone marrow cells were depleted of OKT3+/OKT11+ cells prior to the culture, indicating that interleukin 4 induced the proliferation of a subpopulation of resting T cells present in cord blood and bone marrow cell preparations. In suspension cultures of bone marrow cells and cord blood cells grown in the presence of interleukin 3, basophilic, eosinophilic, and neutrophilic myelocytes and macrophages developed within 2 weeks. By 3 weeks, however, the majority of nonadherent cells became eosinophilic myelocytes. In contrast to mouse bone marrow cell cultures, neither interleukin 3 nor a combination of interleukins 3 and 4 induced the differentiation of mast cells in human bone marrow or cord blood cell cultures.

Incubation of normal mouse splenic lymphocytes with dimeric mouse IgD results in the formation of T-cell factors that selectively inhibit rosette formation of Fc delta receptor-positive lymphocytes with IgD-coated erythrocytes. The rosette-inhibiting factors bound to IgD-Sepharose and were recovered by elution at acid pH. The results indicate that the rosette-inhibiting factors are IgD-binding factors. Neither IgE-binding factors nor IgG-binding factors inhibited IgD rosettes. The IgD-binding factors induced by IgD consist of two species of molecular weight 78,000 and 37,000, respectively. The source of IgD-binding factors is Lyt-1+ T cells bearing Fc delta receptors. It appears that the binding of IgD to the receptors on the T cells induces the formation of IgD-binding factors.

A recombinant human immunoglobulin epsilon-chain gene expression product (rFc epsilon) was compared with a human E myeloma protein in the affinity for epsilon-chain Fc fragment receptors (Fc epsilon R) on cultured human basophils. The association-dissociation kinetics of the rFc epsilon-Fc epsilon R interaction are indistinguishable from that of E myeloma protein, indicating that rFc epsilon and IgE have identical affinity for the receptors. The recombinant gene product sensitizes cultured basophils for anti-IgE-induced histamine release. A dose-response curve of histamine release indicates that the gene product is equally efficient in transducing the signal for degranulation as the natural IgE. Both the rFc epsilon and IgE lost the affinity for Fc epsilon R by heating at 56 degrees C. Upon renaturation by passage through a solution of 6 M guanidine hydrochloride, rFc epsilon recovered both the affinity for Fc epsilon R and the original CD spectra. On the other hand, renaturation of heat-denatured IgE largely restored optical activity above 250 nm but restored neither the affinity for Fc epsilon R nor the CD spectrum below 220 nm. The results suggest that either the amino acid sequence or the carbohydrate present in the myeloma protein, but not the rFc epsilon, may interfere with refolding of the receptor-binding structures.

BDF1 [(C57BL/6 X DBA/2)F1] mice were primed with alum-absorbed ovalbumin, and their spleen cells were cultured with ovalbumin to activate antigen-primed T cells. The activated T cells were then propagated in interleukin 2-containing medium in the presence or absence of affinity-purified glycosylation-inhibiting factor (GIF). Upon incubation with ovalbumin-pulsed macrophages, T cells propagated in the absence of GIF produced IgE-potentiating factor and glycosylation-enhancing factor. In contrast, T cells propagated in the presence of GIF produced IgE-suppressive factor and GIF. The ovalbumin-primed T cells propagated in the presence of GIF constitutively produced the 13-kDa GIF that lacked affinity for ovalbumin. However, stimulation of the same T cells with ovalbumin-pulsed macrophages resulted in the production of 80- and 35-kDa GIF that had affinity for ovalbumin. Both the antigen-specific GIF and nonspecific GIF from the activated BDF1 T cells had I-Jb determinants. Since the ovalbumin-specific GIF is derived from Lyt-2+, I-J+ ovalbumin-specific suppressor T cells and suppresses the anti-hapten antibody response to dinitrophenyl-coupled ovalbumin, the results strongly suggest that the presence of GIF during the propagation of antigen-primed T cells facilitates the generation of antigen-specific suppressor T cells.

The paper presents a novel three-phase single-way sinusoidal rectifier to reduce supply current distortions and low power factor operations with diode bridge rectifiers. The circuit configuration is based on the cascade combination of a diode bridge and a single-ended primary inductor power convertor, in which a single power switching device provides the necessary control of the currents. If a simple pulsewidth modulation with uniform duty factor is introduced, and if the rectifier is operated in discontinuous current conduction mode, the supply currents can be sinusoidally waveshaped with a near unity power factor. Moreover, step-up and step-down characteristics of output voltage can easily be obtained. The experimental and simulated results confirm the relevance of the presented configuration as an useful rectifier with sinusoidal supply currents and step-up/down output voltage regulation.

A single-phase switch-mode rectifier employing a voltage-reversal circuit is studied. The voltage-reversal circuit is switched with a fixed frequency in order to give a supply current with a sinusoidal waveform and a near-unity power factor independent of the working conditions, and to suppress the magnetic noise caused by the low-order harmonics. The operation is macroscopically analysed by a state-space averaging method based on a DC equivalent circuit and such an operation is also simulated by a rigorous state-space method. The arrangement tested, using two insulated-gate bipolar transistors and a 16-bit microcomputer, is implemented to investigate experimentally the steady-state and transient characteristics. The experimental and simulated results confirm the relevance of a switching strategy with a fixed frequency for a single-phase switch-mode rectifier employing a voltage-reversal circuit.

Bridging of cell-bound IgE antibody molecules on colony-stimulating factor-dependent mouse mast cell line (PT-18) cells by multivalent antigen induces phospholipid methylation, a transient rise in intracellular cAMP, intracellular mobilization and uptake of Ca2+, and formation of diacylglycerol followed by histamine release. Exposure of the sensitized cells to antigen also induces a substantial increase in protein kinase C activity in the plasma membrane, which is accompanied by a slight decrease in the enzyme in cytosol. Protein kinase C activity in the membrane fraction reached maximum within 30 sec after antigen challenge and then gradually declined. The increase of the enzyme activity in the membrane could not be explained by a shift of the enzyme from cytosol, and it suggested that bridging of IgE-receptor may induce a modulation of existing enzyme to a state of higher catalytic activity. Phorbol 12-myristate 13-acetate also induced a rapid but persistent increase in protein kinase C activity in the membrane fraction of mast cells. However, the increase in the enzyme activity in the membrane was accompanied by a marked decrease in the enzyme in cytosol.

Rat mast cells, passively sensitized with monoclonal mouse IgE antibody, were stimulated with multi-valent antigen, and an increase in cytoplasmic Ca2+ was determined by using the fluorescent probe quin-2. The increase in quin-2 fluorescence reached maximum within 20 sec after the antigen challenge and then gradually declined. A substantial increase in quin-2 fluorescence was observed in the presence of EGTA, indicating that bridging of cell-bound IgE antibody molecules by antigen induced not only Ca2+ influx but also mobilization of intracellular Ca2+. Phosphatidylserine added to the medium enhanced both the antigen-induced histamine release and the increase in quin-2 fluorescence and slowed the rate at which the quin-2 signal returned to basal levels. Both the antigen-induced increase in quin-2 fluorescence and histamine release were inhibited by pretreatment of mast cells with inhibitors of methyltransferases, theophylline, or cromoglycate. It was also found that methyltransferase inhibitors and theophylline inhibited not only stimulus-dependent calcium influx but also release of bound calcium from intracellular stores. Other secretagogues, compound 48/80 (1 microgram/ml) and Ca ionophore A23187 (0.1 microM), induced a rapid increase in cytoplasmic Ca2+ in rat mast cells and subsequent histamine release. In contrast, the cocarcinogenic compound phorbol 12-myristate 13-acetate caused histamine release without increasing the quin-2 fluorescence.

Peripheral blood mononuclear cells of 10 out of 26 patients with human immunodeficiency virus type 1 (HIV-1) released IgE-binding factors, as determined by two independent assays. The formation of the factors by the mononuclear cells was enhanced by incubation of the cells with homologous IgE. In the presence of IgE, peripheral blood mononuclear cells from 15 of the 26 patients formed a detectable amount of IgE-binding factors, whereas those of normal individuals of allergic rhinitis patients failed to do so. The major source of IgE-binding factors was the T cells of the HIV-1-infected patients. The CD8+ T cells from a HIV-1-infected patient formed IgE-binding factors upon incubation with IgE, and type II receptors for Fc epsilon were detected on both CD4+ T cells and CD8+ T cells in one of five patients studied. It was also found that culture supernatants of mononuclear cells from HIV-1-infected patients released soluble factors that induce normal human T cells to form IgE-binding factors. The results suggest that lymphocytes of some HIV-1-infected patients are activated to produce lymphokines regulating formation of IgE-binding factors.

Rabbit antibody against IgE receptors or its F(ab')2 fragments induced an increase of 45Ca uptake into normal mast cells, and this process was accompanied by histamine release. Evidence was obtained that a substantial portion of 45Ca uptake was due to movement of calcium across the cell membrane. Neither 45Ca uptake nor histamine release was induced by Fab' monomer fragments of the antireceptor antibody. However, bridging of receptor-bound Fab' fragments by antirabbit IgG or bridging of receptor-bound IgE by anti-IgE induced an increase in 45Ca uptake. The results collectively indicate that crosslinking IgE receptors increases the membrane permeability of the mast cells toward calcium.

cDNA clones encoding rodent IgE-binding factors (IgE-BF) were isolated from cDNA libraries of a rat-mouse T hybridoma that secretes IgE-suppressive factor (IgE-SF) upon incubation with rat IgE. COS7 cells transfected with two of the cDNAs expressed IgE-BF, which selectively potentiate an in vitro IgE response. IgE-BF expressed in COS7 cells are glycoproteins of approximately equal to 60 and approximately equal to 11 kDa. DNA sequence analysis of an IgE-BF cDNA revealed a 556-amino acid (62 kDa) protein coding region. The results suggest that IgE-potentiating and IgE-suppressive factors share common precursor polypeptides and that the 11-kDa IgE-BF is derived from a 60-kDa precursor.

The distribution of surface IgE on human basophils was studied using fluorescence microscopy and immunoferritin electronmicroscopy. Redistribution of the IgE was dose, time and temperature dependent and required divalent anti-IgE. Cells which can release histamine in vitro were indistinguishable in these respects from cells which cannot. The redistribution was unaffected by the presence or absence of Ca++. No correlation between the conditions required for optimal histamine release and for redistribution was observed. At low doses, optimal histamine release occurred in the absence of, or before, redistribution. At higher doses redistribution occurred in the absence of histamine release. Antigen-induced histamine release was unaccompanied by gross redistribution of the surface IgE. Since both histamine release and redistribution require bridging of IgE on basophils it is concluded that only certain kinds of cross-linking of the IgE effectively stimulates these cells.

A novel single-phase rectifier for step-down AC-DC conversion is presented. This has the advantage that a single active switch can provide the necessary control over the current. The experimental results confirm that the input current can be sinusoidally waveshaped with a near-unity power factor.