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D H Katz

Publications and source records attributed to D H Katz.

At least 55 records · Page 3Linked to original sources
PubMed1988

Antigenic differences between natural and recombinant murine IL-1.

Natural (n) interleukin 1 (IL-1) and recombinant (r) IL-1 alpha of murine P388D1 cell line origin were investigated for their antigenicity in rabbits. Both nIL-1 and rIL-1 alpha evoked an antibody response. By solid-phase radioimmunoassay, anti-nIL-1 antibodies bound nIL-1 and rIL-1 alpha equally well; in contrast, the anti-rIL-1 alpha antibodies bound homologous rIL-1 alpha significantly more than nIL-1 suggesting either a lack of antibodies directed against certain epitope(s) on nIL-1 or presence of low affinity antibodies. Moreover, unlike anti-nIL-1 antibodies, anti-rIL-1 antibodies failed to inhibit augmentation of thymocyte proliferation by either IL-1. Thus, antigenic differences between nIL-1 and rIL-1 alpha appear to elicit an overlapping but different antibody response in rabbits.

Animals↗
PubMed1987

Inhibitory activity of interleukin B on the suppressor T cell hybrid T2D4.

Interleukin B (IL-B), a product of unstimulated B cells, is defined by its ability to selectively prevent the differentiation of suppressor T lymphocytes from precursors into effectors. The present study was undertaken to determine whether IL-B could also be active in modulating the activity of the T cell hybrid T2D4, which produces immunoglobulin-binding suppressor factors. T2D4 cells can be selectively induced by incubation with various isotypes of antibody to express isotype-specific Fc receptors and to release soluble factors that suppress production of the corresponding isotype. The data presented here demonstrate that IL-B is greatly effective in inhibiting T2D4 activities. Either pretreatment with IL-B or continuous exposure to IL-B prevents isotype activation of T2D4. As a result, T2D4 cells do not express isotype receptors and do not produce detectable amounts of isotype-specific suppressor factors. This IL-B regulatory activity on T2D4 is temperature dependent and is inhibited by cytochalasin B. These findings provide new insights on the mechanism by which IL-B enhances antibody responses, and they offer a conceptual framework for analyzing IL-B activity on suppressor T cells.

Animals↗
PubMed1986

FcR epsilon+ lymphocytes and regulation of the IgE antibody system. V. Preliminary physicochemical characterization of the T cell-selective IgE-induced regulant EIRT.

We previously showed that murine lymphoid cells exposed to elevated levels of IgE exhibit the de novo expression of Fc receptors for IgE (FcR epsilon), and the production of soluble mediators, which we have termed IgE-induced regulants (EIR). Described herein is the preliminary physicochemical characterization of one such regulant, that being the EIR responsible for the Lyt-2+ T cell-dependent expression of FcR epsilon and secretion of an IgE-binding factor (IgE-BF) which can potentiate IgE synthesis; the former activity has been denoted EIRT for its selectivity of action on T cells, and the latter activity has been termed enhancing effector molecule (EEM) for its presumed potentiating influence on IgE antibody synthesis. Characterized in parallel was the conventional lymphoid cell-derived cEIRT and a murine monoclonal T cell hybridoma-(MBI-2)-derived mcEIRT. EIRT from either source was shown to exhibit the characteristics of a protein with a molecular mass of 45 to 60 kd. Once enriched by gel filtration, neither cEIRT nor mcEIRT preparations displayed any other EIR-like activity except that of EIRT, as evidenced by the ability of these preparations to act selectively to induce the Lyt-2 T cell-dependent expression of FcR epsilon and the production of EEM, the lack of detectable SFA activity that could induce Lyt-1+ T cells to produce the IgE-BF denoted suppressive effector molecule (SEM), and the lack of detectable levels of the B cell-selective EIRB, as indicated by the incapacity of either preparation to induce B cell FcR epsilon expression. Neither cEIRT nor mcEIRT displayed IgE-binding affinity, in contrast to the EEM produced in response to stimulation with these regulants. The only EIR-like activity detected in the unfractionated supernatant fluid from cultures of the monoclonal T cell hybridoma MBI-2 was that of EIRT. Careful in vitro analysis established that such preparations did not contain enhancing factor of allergy (EFA), SFA, EIRB, or IgE-BF. Thus, the enhancement of IgE synthesis observed in animals given this mcEIRT preparation was most likely due to the activity of EIRT known to be present. During the course of these studies, clues as to the physicochemical nature of other EIR activities was obtained. Thus, upon molecular sieve analysis, two distinct molecular mass species of EIRB (one 15 to 20 kd and the other 30 to 35 kd) were demonstrated to be present in conventional lymphocyte-derived cEIR.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

B-lymphocyte regulation of the immune system. III. Preparation and characterization of rabbit antibodies that inhibit the biological activity of the lymphokine, B-cell-derived enhancing factor (BEF).

Antibodies that inhibit the biological activity of B-cell-derived enhancing factor (BEF) were produced in a rabbit immunized with BEF obtained from a non-immunoglobulin-producing B-cell line. Immunoglobulin G (IgG) fractions purified from the preimmune or the immune rabbit serum were compared by testing for their capacity to inhibit regulatory activities of BEF. It was found that the enhancing activity exerted by BEF on the in vitro antibody response to sheep red blood cells was inhibited when anti-BEF IgG was incorporated in the cultures. Moreover, anti-BEF IgG abolished the inhibitory activity exerted by BEF on the expression of Fc receptor by lymphoid cells. Comparable concentrations of preimmune IgG were ineffective in inhibiting BEF activity. The passage of supernatant fluid containing BEF activity through an anti-BEF IgG-coupled Sepharose column yielded an 84-fold purified product that exhibit BEF immunoregulatory properties. These results will accelerate further studies aimed at better characterization of the BEF molecule(s).

Animals↗
PubMed1986

Use of a portable ribosome-binding site for maximizing expression of a eukaryotic gene in Escherichia coli.

To maximize expression of a eukaryotic gene in Escherichia coli, a series of plasmids were constructed containing various synthetic ribosome-binding sites (RBS). These sites consist of a Shine-Dalgarno (SD) region (with translation stop codons in all three reading frames) positioned at distances 5-9 nucleotides (nt) from the AUG initiator codon of the gene coding for human T-cell growth factor (TCGF or IL-2). The region encompassing the RBS through the TCGF structural gene from each of these plasmids was inserted as a 'cassette' into seven different E. coli expression vectors, and TCGF production was measured. Our results demonstrate a greater than 2000-fold range of TCGF synthesis dependent upon the promoter and the synthetic RBS used. The translational efficiency of the TCGF gene was found to be influenced by the quality of the RBS, which is in part determined by the external sequence context of this site. The synthetic RBS, containing the necessary information for the translation initiation process, readily accessible by restriction sites, should be of general usefulness in obtaining maximum expression of eukaryotic genes in E. coli.

Base Sequence↗
PubMed1986

B-cell-derived lymphokines: regulatory effects on the immune system.

While both regulatory and effector functions within the T cell lineage have been extensively studied, B lymphocytes have been considered merely a source of humoral antibodies until recently. With the exception of antibody feedback, only a limited number of investigations have been designed to explore the possibility that B cells may exert regulatory activity. The purpose of this review is to analyze how B cells can modulate themselves by generating signals (lymphokines), which under certain circumstances may initiate a chain of regulatory events. Only factors exclusively produced by B cells are considered. While, for the most part, this review is dedicated to recent studies on nonimmunoglobulin B cell factors, the role played by Ig molecules as immunoregulatory linker molecules, independently of their antigenic specificity, will be briefly examined. Furthermore, some basic questions regarding the biological significance of these regulatory mechanisms will be raised.

Animals↗
PubMed1985

The IgE antibody system is coordinately regulated by FcR epsilon-positive lymphoid cells and IgE-selective soluble factors.

Recent studies in mice have demonstrated that exposure of lymphocytes to appropriate levels of IgE initiates a cascade of cellular and molecular interactions which function as a network to control IgE synthesis. A key manifestation of these events is the expression of Fc receptors for IgE (FcR epsilon) on both B and T lymphocytes, and the fact that such expression of FcR epsilon can be selectively modulated by the isotype-specific regulatory mediators, suppressive factor of allergy (SFA) and enhancing factor of allergy (EFA). In humans, we have previously shown that the in vitro induction by pokeweed mitogen (PWM) of IgE biosynthesis by peripheral blood lymphocytes (PBL) can also be selectively suppressed by SFA. Herein we show that PWM also induces expression of FcR epsilon+ and FcR gamma+ cells among human PBL by day 2 or 3 in culture, and this early development of FcR epsilon+ lymphocytes appears to be a coordinate event with the ultimate de novo synthesis of IgE in this system. Moreover, as previously documented for IgE synthesis, the presence of SFA causes a 50% reduction of FcR epsilon+ cells induced by PWM. This inhibition is selective, since FcR+ cells for IgG are not affected by exposure to human SFA derived from a recently constructed human T cell hybridoma line which constitutively secretes large quantities of biologically active human SFA. These findings further support the regulatory role that FcR epsilon+ lymphocytes must play in the development of IgE responses by human cells in vitro, and suggest a mechanism by which SFA can selectively inhibit IgE synthesis in PWM-stimulated cultures of human PBL.

Animals↗
PubMed1985

B lymphocyte regulation of the immune system. II. Inhibition of Fc receptor expression of lymphocytes by BEF, a lymphokine of B cell origin.

Recently, we described a new lymphokine of B cell origin, capable of selectively preventing the differentiation of T suppressor cells from the precursor into the effector stage. As a result, antibody production against various antigens is markedly increased. We termed this lymphokine B cell-derived enhancing factor (BEF). To discern the mechanism(s) by which BEF interferes with the activation of T suppressor cells, experiments were undertaken to explore the effect of BEF on the induction of Fc receptors (FcR). The induction of FcR on T cells has been implicated in the down-regulation of antibody synthesis, and it has been suggested that the expression of FcR for a given immunoglobulin precedes the release of factors with regulatory functions for the corresponding isotype. In the experiments reported here, murine spleen cells were incubated for 24 hr in the presence of IgG1 or IgA monoclonal antibodies, were washed, and the number of FcR gamma 1+ and FcR alpha+ cells were calculated by a rosette assay. The effect of BEF was studied either during the inductive phase or before, i.e., by pretreating the cells with BEF for 18 hr at 37 degrees C before the inductive phase. Our results show that BEF abolishes, in a dose-dependent manner, the expression of isotype-specific FcR in spleen cells when present during the inductive phase, as well as when cells are pretreated with it. In successive experiments, we tested the effect of BEF on the induction of FcR on T cell-enriched or B cell-enriched spleen cells. The results show that BEF is effective in selectively inhibiting FcR expression on T lymphocytes, but not on B lymphocytes, once isolated from the total spleen cell population. These findings provide further insight into the mechanism by which BEF modulates the immune response, and suggest that different mechanisms may be involved in the induction of FcR on T and B lymphocytes, respectively.

Animals↗
PubMed1985

B lymphocyte regulation of the immune system. I. In vivo biologic activity of the novel lymphokine, B cell-derived enhancing factor (BEF).

B cell-derived enhancing factor (BEF) is a lymphokine of B cell origin which was originally identified and characterized by its ability to enhance in vitro antibody responses, an effect shown to be due to the ability of BEF to reduce the activation of suppressor T cells. The present study was undertaken to determine whether BEF could also be active in modulating antibody responses in vivo. The data presented here demonstrate that BEF is biologically active in vivo, as manifested by significantly enhanced primary IgM and IgG antibody responses in mice that were either injected with BEF prepared exogenously or implanted with growing BEF-secreting cells of a B cell line. Moreover, BEF was shown to enhance subsequent development of immunologic memory in mice pretreated with BEF at the time of primary immunization; these mice then displayed enhanced secondary responses when challenged with the same antigen some weeks later. The mechanism by which BEF exerts biologic activities to positively modulate in vivo antibody responses and immunologic memory reflects the ability of BEF to modulate one or more T cell functions, as evidenced by the following findings. 1) Transient in vitro exposure to BEF of T cells, but not of B cells, endowed such cells with the capacity to adoptively transfer enhanced primary antibody responses to irradiated recipients. 2) Utilizing adoptive in vivo antibody responses, in which fractionated B cell or T cell populations were obtained from BEF-pretreated mice, revealed that one effect of BEF which results in enhanced immunologic memory is related to its activity on T cells during the priming phase of the immune response. Finally, the existence of this B cell-derived lymphokine and the demonstration of its in vivo regulatory effects on the immune system provide yet another example of the emerging biologic importance of B lymphocytes in the overall regulation of the immune system.

Animals↗
PubMed1985

Heavy and light chains of a mouse monoclonal autoantibody express the same idiotype.

We report on the detection of the same idiotype (Id62) on the heavy and light chains of a mouse monoclonal autoantibody to thyroglobulin. This result was obtained by a simple, sensitive, and reproducible technique, namely immunoblot on nitrocellulose paper of electrophoretically separated heavy and light chains by using a panel of 125I-labeled anti-idiotype probes. These included polyclonal heterologous and syngeneic affinity-purified antibodies and a syngeneic monoclonal antibody. The immunoblot findings were confirmed through the solid-phase radioimmunoassay binding of the anti-idiotype probes to isolated H and L polypeptide chains prepared by conventional chromatography methods. Because anti-idiotype probes define a putative regulatory idiotype of the BALB/c autoimmune response to thyroglobulin, it is suggested that the simultaneous presence of the same idiotype on H and L chains may confer to antibody regulatory properties within the idiotypic network. The significance of the existence of the same idiotype on H and L chains and the implication of this finding for the regulation of the immune response to self antigens are discussed.

Animals↗
PubMed1984

IgE class-restricted tolerance induced by neonatal administration of soluble or cell-bound IgE. Cellular mechanisms.

Certain aspects of the phenomenon of IgE class-restricted tolerance induced in mice by neonatal treatment with monoclonal IgE, either in soluble form or coupled to syngeneic spleen cells, were examined. The present studies document that this tolerance results from exposure to IgE molecules, irrespective of their antigen specificity, and the resulting effects are polyclonal in nature since IgE responses directed against antigenic determinants unrelated to the tolerance-inducing IgE molecules are affected. Moreover, such findings indicate that the molecular subregion(s) responsible for inducing IgE class-restricted tolerance resides in the epsilon heavy chain constant region domain(s) of IgE. When soluble IgE is employed, tolerance induction results from neonatal treatment with doses as low as 2.5 micrograms per injection per mouse; cell-bound IgE is considerably more potent, in terms of total dose required, since tolerance results from treatment with as few as 1 X 10(6) cells per injection (per mouse), equivalent to an absolute quantity of 0.2 ng of IgE per injection. This long-term class-specific tolerance appears to be a unique feature of the IgE antibody system, since treatment of mice with monoclonal antibodies of the IgA, IgG1, or IgG2b isotypes, either in soluble or cell-bound form, does not perturb antibody responses of their corresponding isotypes or in the IgE class. By analyzing the lymphoid cells of IgE-tolerant mice after they reached adulthood, the following observations were made: (a) lymphoid cells from such tolerant mice fail to develop FcR epsilon + cells upon in vitro stimulation with IgE, as is characteristically observed with lymphoid cells from nontolerant mice; and (b) mice rendered tolerant by neonatal treatment with soluble IgE possess IgE class-restricted suppressor T cells, demonstrable in adoptive transfer experiments, whereas no such suppressor cells are evident in mice in which cell-bound IgE was used for neonatal treatment. The latter observations could mean that two different mechanisms underlie the IgE class-restricted tolerance, or both mechanisms operate coordinately to varying degrees depending upon which regimen is used for tolerance induction, as discussed herein.

Animals↗
PubMed1984

Spontaneous proliferation in unfractionated spleen cell cultures: autologous mixed-lymphocyte reactions (AMLR) which can be differentially regulated by prostaglandins and lymphokines.

The present studies were undertaken to define the contribution of the autologous or syngeneic mixed-leukocyte reactions (AMLR/SMLR) to the cellular proliferation observed in unfractionated spleen cell cultures. Proliferation was studied in whole, untreated 6-day murine spleen cell cultures supplemented with syngeneic serum. These cultures exhibited relatively low but significant levels of cellular proliferation as measured by uptake of radioactive thymidine ([3H]TdR). Treatment of spleen cells with monoclonal anti-Thy 1.2 antibody and complement before culture, the addition of specific anti-I-A monoclonal antibodies to the cultures or removal of Ia+ adherent cells before initiation of culture all inhibited the proliferative response significantly. Thus, the autologous proliferation of untreated and unfractionated spleen cells manifests the main characteristics of the AMLR/SMLR, namely, its dependence on T (responder) and Ia+ (stimulator) cells and specific inhibition by anti-I-A antibodies. A marked augmentation in cellular proliferation was observed in unfractionated spleen cell cultures treated for the initial 24 hr of culture with 5 X 10(-6) M indomethacin, an inhibitor of prostaglandin synthesis. Conversely, the addition of 7 X 10(-9) M prostaglandin E1 (PGE1) to these cultures depressed cellular proliferation. This suppression of autologous splenic cell proliferation induced by PGE1 could be partially reversed by the addition of concanavalin A-induced lymphokine (LK) preparations early in the culture. These findings indicate that (a) the proliferation of unfractionated spleen cell cultures occurring in the absence of exogenous stimulatory signals is due largely to an ongoing AMLR, and (b) biologically active mediators with opposing influences, namely, prostaglandins and immunostimulatory LK, participate in the regulation of the AMLR.

Alprostadil↗
PubMed1984

Mouse monoclonal IgE antibodies specific for ragweed pollen antigens.

In order to obtain monoclonal IgE antibody specific for the major allergens in ragweed pollen extracts, hybridomas were constructed from spleens of mice immunized with ragweed antigen E (AgE). Two hybridomas were selected for thorough study, both secreting antibodies of the IgE class. Large quantities of IgE antibodies were isolated by affinity purification using Sepharose 4B conjugated with ragweed pollen proteins (Fraction A). Both MAbs were found to bind to a high molecular weight and heterogeneous population of proteins, but not to monomeric AgE as demonstrated by protein blot analysis. It is suspected that both MAbs react with low affinity with AgE determinants and binding could be demonstrated only with aggregated forms of AgE. Although the specific antigens with which they react are unknown, these monoclonal IgE antibodies should be useful reagents, complementing the previously obtained monoclonal anti-dinitrophenyl IgE antibody, for studying various aspects of the mouse and human IgE antibody systems.

Animals↗