bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of events mediating B cell proliferation and Ig production by using T cell membranes and lymphokines.
Authors: Hodgkin P D , Yamashita L C , Coffman R L , Kehry M R
Published: December 2022

The initiation by Th cells of B cell proliferation and differentiation to produce Ig involves both cell contact- and lymphokine-mediated signals. Plasma membrane-enriched fractions from stimulated, but not unstimulated, Th cells induced Ag nonspecific and MHC unrestricted proliferation of 60 to 70% of small dense B cells. Induction of stimulatory membrane activity was inhibited by cycloheximide, and the activity was eliminated by both protease and heat treatment of membranes. Membrane-stimulated B cells did not differentiate to secrete Ig; however, addition of a lymphokine-containing supernatant from activated Th cells or the combination of IL-4 and IL-5 resulted in substantial Ig production, predominantly of the IgM, IgG1, IgA, and IgE isotypes. The quantity and isotype distribution of the antibodies secreted were similar to those produced after B cell activation by the intact Th cells and Ag. Therefore, membranes from activated Th cells in combination with lymphokines normally secreted by such cells can replace intact Th cells and provide a defined system to identify molecular events important for B cell activation.
Internalization of Ia molecules by antigen-presenting B cells is limited.
Authors: Mehringer J H , Cullen S E
Published: December 2022

Our data demonstrate that the uptake of surface Ia into an intracellular compartment of B lymphoma or normal spleen cells is limited to about 20% after 2 to 3 h. The extent of internalization does not vary with several types of stimulation, including LPS, phorbol esters, anti-Ig-plus phorbol ester-stimulated EL-4 T cell supernatant, and Con A supernatant. Resting and activated B cells had similar rates of internalization. The rate and extent of uptake of surface Ia molecules into an intracellular compartment was monitored quantitatively through the use of a mAb radiolabeled with 125I. The internalization of Ia molecules was compared to that of transferrin receptor, a receptor that undergoes rapid internalization and recycling and accumulates in a intracellular pool that can be trapped by monensin. The internalization of Ia was not affected by monensin, although its synthetic pathway is disturbed by this drug. The potential use of internalized Ia for formation of T cell-triggering complexes of Ia and Ag fragments is not ruled out by these data, but it appears unlikely that internalization provides the major mechanism permitting Ia interaction with Ag.
Induction of graft versus host-associated immunodeficiency by CD4+ T cell clones.
Authors: Tary-Lehmann M , Rolink A G , Lehmann P V , Nagy Z A , Hurtenbach U
Published: December 2022

Previous studies have shown that the injection of parental T cells into MHC class II mismatched F1 recipient mice can lead to graft-vs-host (GvH) reaction that manifests itself by multiple symptoms. The objective of our study was to analyze GvH reactivity induced by a single T cell clone specific for host I-A or I-E alloantigen. The T cell clones tested for GvH potential were CD4+, with or without cytolytic activity in vitro and with a lymphokine pattern that classifies them as Th1 cells. The inoculation of a single T cell clone induced a severe, but transient immunodeficiency in the host that was independent of its cytolytic activity, as demonstrated by the failure to generate a CTL response to third party allogeneic cells in vitro. Induction of immunodeficiency in the recipients required preactivation of the clones in vitro by rIl-2 and the presence of the stimulator class II alloantigen in the host. Spleen cells from these mice lacked suppressor cells, they were deficient in Il-2 secretion and exhibited a decrease in the number of CD4+ T cells. In addition, I-E expression was reduced, however, without any changes in the macrophage population and an increase in surface Ig and the B cell marker B220. Simultaneous to the immunodeficiency, the clone-injected mice produced elevated antibody titers to ssDNA.
Obligatory action of polypeptide growth factors for the IL-1-mediated prostaglandin E2 production in fibroblasts. Potential role of growth factors in modulation of tissue response to IL-1.
Authors: Chiou W J , Bonin P D , Singh J P
Published: December 2022

Our studies show that in connective tissue cells, induction of PGE2 synthesis in response to IL-1 requires costimulation with platelet-derived growth factor (PDGF) or fibroblast growth factor (FGF). In cells incubated in medium containing fresh serum, IL-1 induced a dose-dependent synthesis of PGE2. However, when the cells were incubated in medium containing low serum or platelet poor plasma (lacking PDGF), IL-1 alone failed to induce PGE2 synthesis. PGE2 synthesis was restored when platelet poor plasma was supplemented with PDGF. Addition of PDGF or FGF together with IL-1 resulted in a 14- and 66-fold stimulation of PGE2 synthesis, respectively. Stimulation was dependent on the concentration of both IL-1 and the growth factor. PGE2 synthesis was also dependent on the synthesis of new proteins. In cells simultaneously treated with IL-1 and PDGF, PGE2 synthesis was initiated after a lag of 2 to 3 h, proceeded first with a rapid rate for 6 h, and then with a slower rate through 24 h. PGE2 synthesis during the latter, slower phase was greatly enhanced by pretreatment with PDGF, but not by pretreatment with IL-1. PDGF pretreatment also resulted in maintenance of 10- to 12-fold higher cell surface IL-1-binding during this phase. These data provide evidence for potentially novel interactions between PDGF and IL-1 activities, one of which is the modulation of IL-1 receptors by PDGF. Furthermore, these studies suggest that by virtue of their effect on IL-1 activities, PDGF and FGF may play additional roles in connective tissues, including an indirect role in inflammatory processes.
Frequency analysis of lymphokine-secreting CD4+ and CD8+ T cells activated in a graft-versus-host reaction.
Authors: Kelso A
Published: December 2022

Lymphokine secretion by in vivo-activated T cells was analyzed at the population and single-cell levels in lymphocytes from mice undergoing an acute allogeneic graft-vs-host reaction (GVHR). Three observations were made. First, constitutive lymphokine production by these cells was very low but could be dramatically up-regulated by TCR ligation. Thus, even when harvested at the peak of the GVHR, fewer than 0.1% of lymphocytes secreted detectable granulocyte-macrophage (GM)-CSF, IFN-gamma, or IL-3 in the first 24 h in vitro, and average production of these lymphokines in bulk cultures was less than 10(-5) U/cell. However, when cultured for 24 h with anti-CD3 antibody under conditions which activated less than 0.1% of normal cells, about 30% of GVHR T cells secreted GM-CSF, IFN-gamma, and/or IL-3, and average production levels were increased by 10(3)- to 10(4)-fold. Together with evidence that host alloantigen-induced lymphokine secretion was 10 to 100 times lower than the anti-CD3 response, these data suggest that physiologic lymphokine synthesis by most T cells is low (less than 10(-18) mol of IL-3 per cell) but can be raised above the threshold of detection by TCR cross-linking. Second, individual GVHR lymphocytes varied markedly in their total and relative production of different lymphokines in response to anti-CD3 stimulation, with some cells secreting IL-3 alone, some secreting IL-3 accompanied by other lymphokines (GM-CSF and/or IFN-gamma), and some secreting other lymphokines without detectable IL-3. Finally, both CD4+ and CD8+ T cells from GVHR mice responded to anti-CD3 antibody by secreting IL-3 and other lymphokines: purified CD4+ cells contained an average of 16% and CD8+ cells an average of 10% anti-CD3-inducible lymphokine-secreting cells. By contrast, only 2 to 3% of cells of either subset formed clones in cultures with host allogeneic cells and IL-2, suggesting that clonogenic alloreactive cells were a minority of the T cells activated in the GVHR.
Molecular signals for phosphatidylinositol modification of the Qa-2 antigen.
Authors: Ulker N , Hood L E , Stroynowski I
Published: December 2022

Most cell surface proteins are anchored to the cell bilayer by hydrophobic membrane-spanning domains. Recently it has been shown that a small class of molecules are attached to cell surfaces via a phosphatidylinositol moiety covalently linked to the C-terminus of the mature processed polypeptide. The molecular signals that identify a polypeptide for phosphatidylinositol (PI) attachment have not been well defined in any system, but are thought to reside in the C-terminus of the primary translation product. We report that all the signals responsible for PI anchoring of Qa-2 Ag are confined to the 36 C-terminal residues of the precursor proteins. To investigate further the features that signal cleavage and PI addition, we have studied mutants of two closely related murine class I MHC molecules: the PI-linked Ag, Q9b, from the Qa-2 Ag family, and the integral membrane transplantation antigen, H-2Ld. The addition of 15 amino acids to the three residue long cytoplasmic domain of Q9b or the mutation of Asp295 found in its C-terminal hydrophobic domain to Val converts this molecule into an integral membrane protein. However, the introduction of a short three residue cytoplasmic tail and Asp295 into the transmembrane domain of H-2Ld does not convert this molecule to a PI-linked one. The results of these analyses suggest that the PI-processing signals may depend on overall conformation, hydrophobicity, and length of the C-terminal domain of the precursor protein. In addition these data indicate that PI anchoring of class I Ag requires more than two mutational steps and may have been selected during the evolution.
Alloantigen-induced activation of rat splenocytes is regulated by the oxidative metabolism of L-arginine.
Authors: Hoffman R A , Langrehr J M , Billiar T R , Curran R D , Simmons R L
Published: December 2022

Activated macrophages have been demonstrated to metabolize the amino acid L-arginine by the oxidative pathway to produce nitric oxide, citrulline, and NO2-/NO3-. Nitric oxide has been shown to be cytostatic for tumor targets and to inhibit the mitochondrial respiration and other functions of the macrophages that produce it. Addition of NG monomethyl-L-arginine (NMA), a competitive inhibitor of oxidative L-arginine metabolism, to rat splenocyte (SPL) MLC results in allospecific lymphocyte proliferation and CTL induction. In the absence of NMA, neither proliferation nor CTL induction is observed. Citrulline and NO2-/NO3- levels in the supernatants of rat SPL MLC are decreased in the presence of NMA compared with cultures without NMA. NMA also augments the proliferation and CTL induction in mouse SPL MLC. Detectable levels of cytokines able to induce T cell proliferation were present in supernatants of rat SPL MLC without NMA on days 1 to 5 of culture. Supernatants of cultures with NMA contained detectable levels of cytokines on days 1 to 3 and undetectable levels by days 4 and 5 of culture, concomitant with the observed lymphocyte proliferation and presumed depletion of cytokines. Thus, inhibition of rat SPL proliferation to alloantigen seems not to be caused by the lack of production of cytokines able to induce T cell proliferation. The inhibition of proliferation and CTL induction in rat SPL cultures may be caused by a direct effect of the cytostatic products of oxidative L-arginine metabolism on lymphocyte proliferation, or by an indirect deleterious effect on the mitochondrial respiration and viability of macrophages that oxidatively metabolize L-arginine. Alternatively, diversion of L-arginine to the oxidative pathway may affect production of polyamines that are necessary for cell growth and proliferation.
Protective efficacy of a cloned Brugia malayi antigen in a mouse model of microfilaremia.
Authors: Kazura J W , Maroney P A , Pearlman E , Nilsen T W
Published: December 2022

Immunization of mice with irradiated Brugia larvae or parasite extracts has been shown to induce partial resistance to microfilaremia and enhance clearance of infective larvae. We recently reported the cloning of a 548 amino acid 62-kDa Brugia malayi Ag identified on the basis of reactivity with antisera to a subset of protective microfilarial Ag. Our study describes the protective efficacy against microfilaremia in mice, immunogenicity, and parasite stage-specificity of this candidate vaccine molecule. Immunization of Swiss or BALB/c mice with 1 to 3 micrograms of a 92-kDa trpE fusion protein encoding amino acids 1-479 reduced the intensity of microfilaremia by 40 to 60% compared to control animals given buffer or bacterial trpE (p less than 0.01 to 0.001). Mice immunized with the 92-kDa fusion protein developed delayed-type hypersensitivity reactivity to B. malayi as assessed by enhanced footpad swelling 24 and 48 h after intradermal injection of adult worm extract and in vitro lymph node mononuclear cell proliferation (3H-thymidine uptake) in response to the fusion protein (mean +/- SD stimulation index 4.7 +/- 0.8 vs 2.0 +/- 1.4 for trpE, p less than 0.05). Proliferative responses of lymph node cells coincubated with three other fusion proteins corresponding to the filarial protein truncated from its carboxyl-terminus suggest that dominant T cell epitopes of the 62-kDa Ag are encompassed by amino acids 437-479. Rabbit antibody to the 92-kDa trpE fusion protein immunoprecipitated a 62-kDa polypeptide from [35S] methionine biosynthetically labeled B. malayi microfilariae, adult female, and adult male worms. These data indicate that a recombinant Ag expressed in several developmental stages of B. malayi is capable of inducing partial resistance against microfilariae and Ag-specific T cell responses in mice.
The BALB/c secondary response to the Sb site of influenza virus hemagglutinin. Nonrandom silent mutation and unequal numbers of VH and Vk mutations.
Authors: Clarke S , Rickert R , Wloch M K , Staudt L , Gerhard W , Weigert M
Published: December 2022

We have determined the nucleotide sequences of the expressed VH and Vk genes from 13 secondary (2 degrees) hemagglutinin (HA) (Sb) specific hybridomas derived from a single mouse. These antibodies share an Id, H37-68 (68Id) that dominates the 2 degrees HA(Sb) response in this mouse, but is rare or absent from 2 degrees responses of other mice. We find that these antibodies derive from five clones. The H chains of these antibodies are encoded by a single VH gene joined to a variety of DH and JH genes. The length of complementarity-determining region (CDR) 3 and sequence of the D-J junction are restricted, suggesting selection on CDR3 of the H chain. The L chains are more diverse. In the presented examples, they are encoded by the Vk21C and Vk21E genes and a Vk9 gene, and are joined to Jk1, 2, or 4. Each antibody is extensively mutated. The nature and distribution of the mutations suggests that 68Id-producing cells have been selected by Ag, although there are differences regarding the domain (VH, Vk, or both) in which mutations were selected. The implications of these findings on the idiosyncratic nature of the 68Id antibody response to HA(Sb) are discussed. There are two unusual characteristics regarding somatic mutation in these hybridomas. Whereas the expressed VH and Vk21 genes appear to have accumulated mutations at a high rate (1 to 1.5 x 10(-3)/base pairs/division, the expressed Vk9 genes appear to have accumulated mutations at a 5 to 15-fold lower rate than the expressed VH genes in the same cells. There is also a surprisingly high number of parallel silent somatic mutations in the VH genes, of which all but one are clustered to a 28-bp region in framework region 2 and CDR 2-encoding segments. The probability that this could have occurred by a random mutational process is essentially zero.
A set of closely related antibodies dominates the primary antibody response to the antigenic site CB of the A/PR/8/34 influenza virus hemagglutinin.
Authors: Kavaler J , Caton A J , Staudt L M , Schwartz D , Gerhard W
Published: December 2022

Approximately 50% of the primary antibody response of BALB/c mice to the A/PR/8/34 influenza virus hemagglutinin is directed to the Cb site, one of the four major antigenic regions of the molecule. To determine the structural basis of the anti-Cb site response, we have examined the paratypic and genetic diversity exhibited by a panel of 24 primary and 4 secondary response mAb specific for this antigenic region. Reactivity pattern analysis demonstrated 20 distinct fine specificities among these antibodies, and V region gene sequence analysis showed that they are encoded by 17 different VH gene segments from 6 VH gene families and 14 different VK gene segments from 6 VK gene groups. Despite this overall diversity, many of the antibodies can be placed in a limited number of sets based on the shared expression of VH and/or VK genes. One set contains antibodies encoded by a single gene of the VK4/5 group in combination with one of two closely related genes from the J558 VH family. This set accounts for half of the Cb site-specific primary response hybridomas, indicating that the representation of the various anti-Cb site B cell specificities during the primary response to A/PR/8/34 influenza virus is not uniform. The preferential participation of B cells expressing this VH/VK combination is largely responsible for the dominance of anti-Cb site antibodies in the primary anti-hemagglutinin response.
Interclonal and intraclonal diversity among anti-DNA antibodies from an (NZB x NZW)F1 mouse.
Authors: Marion T N , Tillman D M , Jou N T
Published: December 2022

The immunologic basis for the generation of autoantibodies that are characteristic of systemic autoimmunity in mice and humans remains obscure. Experiments directed toward the analysis of serum antibody and the cell populations that combine to generate antibody in autoimmune mice have led to the proposition that autoantibody production, including anti-DNA, results from the nonselective, polyclonal activation of B cells. The present results from the molecular analyses of anti-DNA autoantibodies from an individual (NZB x NZW)F1 autoimmune mouse, however, are inconsistent with a clonally nonselective model for autoantibody production and are most consistent with a clonally selective, Ag-driven model for anti-DNA autoantibody production. These results demonstrate that Ig V region structures contributed by germ-line V region genes; recombinational diversity, including unusual DH gene usage and DH-DH recombination; and somatic mutation during B cell clonal expansion are all important for generating antibody and presumably B cell Ig receptor specificity for nucleic acids including native, duplex DNA.
Clustered H chain somatic mutations shared by anti-p-azophenylarsonate antibodies confer enhanced affinity and ablate the cross-reactive idiotype.
Authors: Parhami-Seren B , Wysocki L J , Margolies M N , Sharon J
Published: December 2022

A cluster of four consecutive CDR2 somatic mutations are shared by the VH regions of two independently isolated hybridoma antibodies with specificity for p-azophenylarsonate (Ars). The mutations appear to be derived by a series of independent events. To assess the influence of these shared somatic mutations on antibody affinity for Ars and on idiotypy, we introduced them, via site-directed mutagenesis, into the V region of an anti-Ars antibody that was otherwise unmutated and we eliminated them from the mutated context of one of the two antibodies in which they were originally found. Results of affinity measurements by fluorescence quenching and of idiotypic binding assays performed on these engineered mutants demonstrated that the shared mutations increased affinity for Ars and eliminated the predominant Id associated with strain A anti-Ars antibodies and four of five idiotypes defined by anti-idiotypic mAb. These results support the interpretation that a strong affinity-based selection pressure has favored the clonal expansion of B cells with receptors containing these mutations despite the loss of a predominant Id. Thus, in producing antibodies containing V regions conferring high affinity for Ag, the combined processes of somatic mutation and clonal selection have generated a common structural solution through parallel repeats.
Chromosomal location of the Ly-49 (A1, YE1/48) multigene family. Genetic association with the NK 1.1 antigen.
Authors: Yokoyama W M , Kehn P J , Cohen D I , Shevach E M
Published: December 2022

The Ly-49 (A1, YE1/48) Ag is a disulfide-linked dimer with 44-kDa subunits, and is expressed on the cell surface of rare T cell tumors of C57BL/6 origin. Although this Ag is undetectable by flow microfluorimetry analysis, normal cells have been shown to express the A1 Ag by immunoprecipitation experiments performed on surface radioiodinated spleen and thymus cells. We (J. Immunol. 143:1379, 1989) and others (J. Immunol. 142:1727, 1989) have recently isolated cDNA encoding the Ly-49 Ag. Southern blots with an Ly-49 cDNA probe revealed multiple bands, consistent with cross-hybridization to other members of a multigene family, and significant RFLP between the C57BL/6 and BALB/c strains. When the RFLP patterns displayed by other common laboratory strains as well as informative recombinant inbred strains were examined, the Ly-49 gene family displayed five RFLP patterns and the entire family was found to reside on a contiguous stretch of the distal portion of mouse chromosome 6, the same region to which the NK1.1 Ag has been mapped. Although tissue distribution studies and transfection analysis ruled out the possibility that Ly-49 was identical to NK1.1 Ag, approximately 20% of NK1.1 cells isolated from normal spleen coexpressed Ly-49 and all Ly-49+ cells were CD3-. Although spleen cells cultured in high doses of rIL-2 demonstrated similar coexpression of NK1.1 and Ly-49, approximately 10% of CD3+ cells coexpressed Ly-49. The chromosomal mapping data and the expression of the Ly-49 and NK1.1 Ag suggest that the NK1.1 Ag may be a member of the Ly-49 multigene family.
Effects of cholera toxin on human B cells. Cholera toxin induces B cell surface DR expression while it inhibits anti-mu antibody-induced cell proliferation.
Authors: Anastassiou E D , Yamada H , Francis M L , Mond J J , Tsokos G C
Published: December 2022

Experiments were performed to investigate the effect of cholera toxin (CT) on human B cell function. Highly purified (greater than 98% CD20+) human peripheral blood B cells were exposed to CT in the presence or absence of anti-mu antibody. Treatment of highly purified B cells with CT stimulated enhanced expression of surface DR molecules, whereas it did not enhance expression of other B cell surface activation markers including transferrin or IL-2R. Neither the A nor the B subunits of CT by themselves enhanced the expression of surface DR Ag. In addition, 8-bromo-cAMP alone or in combination with the B subunit did not increase the expression of human B cell surface DR Ag. These findings suggest that neither elevation of cAMP nor binding to GM1 ganglioside are sufficient to stimulate this activation parameter in B cells. Associated with CT-mediated enhanced expression of MHC class II molecules we found that CT-treated B cells also served as stronger stimulators, compared with control cells, of both autologous and allogeneic MLR responses in peripheral blood T cells. Although CT stimulated early events in B cell activation, it inhibited anti-mu antibody-induced B cell thymidine incorporation by 55 to 75%. Inhibitory effects of CT were observed even when CT was added to cultures as late as 36 h after the addition of the anti-mu antibody. These results suggest that CT has both a stimulatory and inhibitory effect on human B cells and that the stimulatory effect may be mediated via a cAMP-independent mechanism.
Polyclonal activation of rat B cells. II. Dextran sulfate as a cofactor in mitogen-induced and antigen-induced differentiation of rat B lymphocytes.
Authors: Minchin S A , Leitenberg D , Stunz L L , Feldbush T L
Published: December 2022

Salmonella typhimurium mitogen (STM) is a polyclonal activator of rat B lymphocytes, triggering them to proliferate, but not differentiate, to antibody-secreting cells. When lymphokines in the form of a supernatant from Con A-stimulated splenocytes (CAS) are added to B cell cultures activated by STM, only a small number of cells are driven to differentiate. Only with the addition of a third signal provided by the polyanionic polysaccharide dextran sulfate (DXS) is significant rat B cell differentiation observed. In this study, we have shown that this requirement for DXS is not unique to the STM mitogen. LPS, Staphylococcus aureus Cowan I-fixed cells, and anti-Ig antibody all induced rat B cell proliferation with little differentiation, even in the presence of CAS. DXS was necessary to induce differentiation in all cultures costimulated with mitogen and CAS. The requirement for DXS for optimal B cell differentiation is also observed with other lymphokine preparations such as the supernatants from PMA-stimulated EL-4 cells and PHA-stimulated human T cells. Furthermore, this augmentative effect of DXS in rat B cell differentiation was not confined to polyclonal activation systems. Ag-specific IgG secretion was also increased when DXS was added to Ag and CAS costimulated cultures of B cells harvested from the draining lymph nodes of rats immunized with DNP-keyhole limpet hemocyanin. Within the polyclonal activation system, a method of staged additions of STM, DXS, and CAS to B cell cultures was used to investigate the role of DXS during B cell differentiation. Optimal differentiation occurred only when DXS was present in the B cell cultures in conjunction with CAS. The augmentation in differentiation seen with DXS did not appear to be due to the recruitment of an additional CAS-responsive B cell subset, because cycling, low density B cell blasts showed large increases in IgM secretion with subsequent exposure to DXS and CAS. These studies suggest tha DXS acts as a cofactor to various differentiation factors, augmenting polyclonal and Ag-specific rat B cell differentiation. The relevance of DXS to in vivo immune responses is discussed.
Augmentation of monocyte chemotaxis by 1 alpha,25-dihydroxyvitamin D3. Stimulation of defective migration of AIDS patients.
Authors: Girasole G , Wang J M , Pedrazzoni M , Pioli G , Balotta C , Passeri M , Lazzarin A , Ridolfo A , Mantovani A
Published: December 2022

Preincubation for 20 h with 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) markedly augmented the chemotactic responsiveness of human blood monocytes to the classical chemoattractant, FMLP. A modest enhancement of monocyte spontaneous locomotion in the absence of chemoattractants was also observed. Maximal increase of monocyte migration was observed after pretreatment with 10(-9) M 1,25(OH)2D3 and was detectable at FMLP concentrations ranging from 10(-10) to 10(-7) M. Pretreatment with 1,25(OH)2D3 augmented the number of monocyte high affinity FMLP receptors (1500 +/- 220 and 3800 +/- 300 sites per cell for untreated and 1,25(OH)2D3-pretreated cells, respectively) with no significant changes in Kd values (2 +/- 0.5 nM and 4 +/- 1 nM, for untreated and 1,25(OH)2D3-pretreated monocytes). Enhanced chemotaxis was not restricted to FMLP, because 1,25(OH)2D3-treated monocytes showed enhanced migration also in response to activated C components and chemotactic cytokines. In agreement with previous observations, monocytes from AIDS patients showed defective migration capacity. In vitro exposure to 1,25(OH)2D3 stimulated monocyte migration in all 10 patients examined with considerable quantitative differences among individuals. Regulating the responsiveness of mature monocytes to chemo-attractants, 1,25(OH)2D3, produced systemically or in situ by immunocompetent cells, could play a role in the regulation of the recruitment of monocytes at sites of inflammation, cell-mediated immunity, or bone resorption. The potential of 1,25(OH)2D3 as a restorative agent under conditions of defective phagocyte recruitment deserves further exploration.
In vivo effects of anti-IL-4 monoclonal antibody on neonatal induction of tolerance and on an associated autoimmune syndrome.
Authors: Schurmans S , Heusser C H , Qin H Y , Merino J , Brighouse G , Lambert P H
Published: December 2022

The role of IL-4 in the cellular interactions leading to the induction of CTL tolerance to H-2b alloantigens and to the development of a lupus-like autoimmune disease in BALB/c mice after neonatal injection with (C57BL/6 x BALB/c)F1 cells was investigated in vivo by using an anti-IL-4 mAb. Treatment of F1 cell-injected BALB/c mice with 15 mg of anti-IL-4 mAb was shown to interfere with tolerance induction, as assessed by the high percentages of H-2b target cell lysis and the very low or undetectable levels of B cell chimerism markers observed in these mice. Treatment with 4.5 mg of anti-IL-4 mAb interfered with tolerance induction only in one-third of F1 cell-injected BALB/c mice, but that dose induces specific modulations of the autoimmune manifestations in all mice, leading to the nearly complete prevention of the disease. In particular, the production of anti-ssDNA IgG1 and of total IgG1 and IgE antibodies was seriously affected by the treatment, as well as the proliferation and membrane Ia and K expression of F1 donor splenic cells and thymic APC. Treatment of F1 cell-injected BALB/c mice between 24 and 48 h of life with 0.5 mg of anti-IL-4 mAb did not interfere with tolerance induction, but had similar effects on the autoimmune syndrome as treatment with 4.5 mg. These results suggest that, after F1 cell injection of newborn mice, IL-4 plays an important role in the cellular interactions leading to the induction of tolerance to the corresponding alloantigens and to the development of the associated autoimmune syndrome.
Regulation of cytokine-induced human C-reactive protein production by transforming growth factor-beta.
Authors: Taylor A W , Ku N O , Mortensen R F
Published: December 2022

Transforming growth factor-beta (TGF-beta) modified production of the major human acute phase reactant, C-reactive protein (CRP), induced by the inflammatory cytokines, IL-1 beta or IL-6. CRP mRNA accumulation in the hepatoma PLC/PRF/5 cell line was slightly more rapid, but of smaller magnitude in response to IL-1 beta (fourfold increase) than to IL-6 (10-fold increase); however, the amount of CRP protein accumulating in the culture medium was similar for both cytokines. TGF-beta at concentrations greater than or equal to 0.1 pg/ml inhibited the induced IL-1 or IL-6 CRP production; whereas concentrations less than 0.1 pg/ml slightly enhanced CRP synthesis. Addition of TGF-beta to the cultures up to 16 h after the PLC/PRF/5 cells were already exposed to IL-1 or IL-6 resulted in the cessation of CRP production. CRP mRNA accumulated in hepatoma cells treated with both TGF-beta and IL-6, although CRP protein synthesis was inhibited. A similar pattern of inhibition of CRP production by TGF-beta occurred when Hep 3B.2 cells were treated with a mixture of IL-1 and IL-6. Enhanced production of CRP was observed only when TGF-beta was added to the cells before the cytokine. This enhanced CRP response was sensitive to cycloheximide. TGF-beta added along with IL-6 inhibited the metabolic labeling of CRP with [35S]methionine; however, enhanced incorporation of [35S]methionine into CRP was observed when the cells were exposed to TGF-beta before IL-6 addition. Therefore, TGF-beta is potentially a potent regulator of CRP synthesis by hepatocytes at the post-transcriptional level.
Participation of C1q and its receptor in adherence of human diploid fibroblast.
Authors: Bordin S , Ghebrehiwet B , Page R C
Published: December 2022

C1q binds through its collagen-like domain to specific surface receptors of fibroblasts and to adhesive elements of extracellular matrix including fibronectin, collagens, proteoglycans, and laminin. To determine whether C1q participates in fibroblast adhesion, cells in serum-free medium were plated on surfaces coated with purified C1q at physiologic ionic strength and pH. Surfaces coated with fibronectin or collagen type I served as positive controls, and those coated with BSA were negative controls. Substratum-adsorbed C1q promoted fibroblast adhesion to a maximum of 73% of available cells within 90 min at 37 degrees C. Adhesion was C1q concentration dependent, saturable, specific, and dependent on the collagen-like domain of the molecule. De novo protein synthesis plays a role in adhesion: pretreatment of fibroblasts with cycloheximide reduced adherence about 50% of controls. Addition of exogenous fibronectin, collagen type I, or C1q as soluble mediators did not affect adhesion of the cycloheximide-treated cells to C1q substrate. Adhesion could be accounted for primarily, although not completely, by the C1q receptors. Antibodies raised against the Raji cell C1q receptors (alpha C1qR Ab) specifically inhibited fibroblast adhesion to C1q substrates about 60% of controls. The binding of fibroblasts to C1q substrates could be inhibited about 24% of controls with the GRGDTP cell recognition peptide. GRGDTP and alpha C1q Ab had an additive effect on adhesion that was inhibited 77 to 80% of controls. We conclude from these data that aggregated rather than monomeric C1q may be the natural ligand of the fibroblast C1q receptor, and the biologic function of the receptor in cells of the connective tissue may be cell adhesion.
Monoclonal antibodies against an HLA-B27-derived peptide react with an epitope present on bacterial proteins.
Authors: Raybourne R B , Williams K M
Published: December 2022

The role of molecular mimicry in the spondyloarthropathies was investigated with respect to the epitopes involved. mAb were produced against a synthetic peptide whose sequence was derived from a polymorphic region of the HLA-B27 molecule (amino acids 63-83). Two antibodies (J7F2 and H2B6) were selected for study on the basis of their ability to react with bacterial envelope proteins (ELISA) and B27-positive cells (immunofluorescence). J7F2 reacted preferentially with B27-positive cells and neither antibody reacted with MHC class I negative cells. Based on SDS-PAGE blot analysis of bacterial envelope proteins, the pattern of reactivity for both antibodies (against 36- and 19-kDa proteins) was the same as that for a third monoclonal produced against bacterial envelope and reactive with B27-positive cells. This apparent epitope similarity was investigated by using synthetic peptides to inhibit binding of the monoclonals. The B27 synthetic peptide and a smaller peptide derived from it were efficient inhibitors of antipeptide and antibacterial antibody binding to bacterial Ag and B27-positive cells. These studies provide insight into the molecular basis of cross-reactivity between bacterial proteins and MHC class I molecules.
Degree of platelet activating factor-induced neutrophil migration is dependent upon the molecular species.
Authors: Carolan E J , Casale T B
Published: December 2022

Multiple molecular species of platelet activating factor (PAF) are produced as a result of inflammatory processes. PAF-induced neutrophil migration across endothelium is intrinsic to inflammatory responses. We therefore compared the ability of three naturally occurring PAF species (C16:0, C18:0, and C18:1), which only varied at carbon 1, to induce 51Cr-labeled human neutrophil migration across a naked 3-microns pore filter and human umbilical vein endothelial (HUVE) monolayers cultured on these filters. Time-course experiments indicated that all species of PAF tested induced significant neutrophil migration between 15 and 45 min. PAF-induced neutrophil migration through both filters alone and HUVE monolayers occurred at lower doses with C16:0 PAF. The rank order of chemotactic potency for the PAF species was C16:0 greater than C18:0 greater than C18:1 with both filters and endothelium coated filters as barriers. Intrinsic differences in the potency of these PAF molecular species to induce neutrophil chemotaxis were greater when HUVE cells were the barriers vs when filters alone were the barriers. Regardless of the molecular species used, at optimal PAF doses the degree of neutrophil migration through HUVE cells was often greater than that through filters alone. The specific PAF antagonist WEB 2086 inhibited neutrophil migration induced by all three PAF species equally. WEB 2086 pretreatment of the neutrophil or WEB 2086 coincubation with PAF, but not WEB 2086 pretreatment of the HUVE cell monolayers, significantly inhibited (65 to 80%) neutrophil migration. We conclude that the degree of PAF-induced neutrophil migration is dependent upon the molecular species of PAF. Moreover, the barrier through which the neutrophil must migrate appears to be important in influencing the overall chemotactic response to the various PAF species.
Induction of the respiratory burst in HL-60 cells. Correlation of function and protein expression.
Authors: Levy R , Rotrosen D , Nagauker O , Leto T L , Malech H L
Published: December 2022

Differentiation of myeloid cells is associated with the gradual acquisition of functional capacity to produce a respiratory burst. In our study HL-60 cells were differentiated to the monocyte phenotype with IFN-gamma or 1,25-dihydroxyvitamin D3, or to the neutrophil phenotype with retinoic acid or DMSO to compare the time-course of expression of membrane and cytosolic oxidase components, and to correlate this with the appearance of a functional oxidase. Over a 6-day period of induction the rank order of the ability of these agents to induce expression of PMA-stimulated superoxide production was: IFN-gamma greater than 1,25(OH)2D3 greater than retinoic acid greater than DMSO. Immunoblot analysis of HL-60 membranes and cytosol was used to assess the amount of specific phagocyte oxidase factors (91 and 22 kDa subunits of membrane cytochrome b558 (gp91 and p22), and 47 and 67 kDa cytosol oxidase factors (p47 and p67)). HL-60 cell membranes or cytosol were tested in a cell-free assay of superoxide production by mixing with normal neutrophil cytosol or membranes, respectively. p47 was first detected at 16 h of differentiation, increasing similarly thereafter with all induction regimens and reaching a maximum by 3 to 4 days. The earliest detection of p67 varied from 2 to 6 days depending on the inducing agent and appeared to be the limiting cytosol component. Small amounts of both subunits of cytochrome b558 were detected in uninduced HL-60 membranes, but were sufficient to support substantial superoxide production when combined with normal neutrophil cytosol. Both cytochrome b558 subunit proteins and membrane oxidase activity increased during differentiation in parallel. We conclude that membrane and cytosol components of the NADPH oxidase complex appear at different times and increase differently during HL-60 differentiation. The production of p67 is the major factor limiting the respiratory burst during HL-60 differentiation.
A soluble factor produced by inoculation of human monocytes with Leishmania donovani promastigotes suppresses IFN-gamma-dependent monocyte activation.
Authors: Engelhorn S , Bruckner A , Remold H G
Published: December 2022

Whereas human cultured monocytes preactivated with IFN-gamma increase their antileishmanial capacity, monocytes inoculated with Leishmania donovani before IFN-gamma treatment fail to respond with an increase of antileishmanial capacity. Cell surface expression of class II MHC products also fails to be increased by IFN-gamma in the infected monocytes, although the accumulation of HLA-DR alpha-chain mRNA is increased to the same extent in infected and noninfected activated monocytes. This inhibition of monocyte activation is caused in a dose-dependent manner by a soluble substance elaborated into the cell supernatant after inoculation of monocytes with L. donovani and is referred to as activation suppressing factor (ASF). ASF activity can be abrogated by dialysis and by treatment with a proteinase, indicating that ASF is a small peptide.
Induction of T helper cell unresponsiveness to antigen by macrophages from schistosomal egg granulomas. A basis for immunomodulation in schistosomiasis?
Authors: Stadecker M J , Kamisato J K , Chikunguwo S M
Published: December 2022

The present studies were undertaken in an effort to understand the role of mononuclear phagocytes in the regulation of the T cell-mediated granulomatous inflammatory response in experimental murine schistosomiasis mansoni. We report that macrophages from schistosomal egg granulomas did not efficiently stimulate, but rather induced marked proliferative unresponsiveness to Ag in an IL-2-producing, I-Ek-restricted, CD4+ Th cell clone specific for pigeon cytochrome c. The unresponsive state of the T cells was achieved after incubation with granuloma macrophages in the presence of the specific Ag fragment 81-104, but not with either of them independently, and was, similarly, restricted by the I-Ek molecule. Equivalent amounts of peritoneal macrophages from schistosome-infected, but not from normal mice, were also effective in inducing T cell unresponsiveness. We postulate that granuloma macrophages, and potentially other accessory cells in schistosome-infected individuals, are similarly capable of inducing anergy in egg Ag-specific Th cells, and that the resulting inhibited T cell reactivity, which translates into failure of lymphokine secretion and of clonal expansion, represents a major basis of the immunologic down-regulation (immunomodulation) of granulomatous hypersensitivity, characteristically seen in this disease.
Characterization of new mouse V kappa groups.
Authors: D'Hoostelaere L A , Klinman D
Published: December 2022

A lambda gt10 BXSB spleen cDNA library was screened with a DNA probe for the C kappa region. Forty individual C kappa+ phages were tested for hybridization with DNA probes representing 11 V kappa region groups. Of the phage inserts large enough to contain V kappa region sequences, 3 were negative for hybridization with all 11 V kappa region probes. The inserts from those three were subcloned, sequenced, and compared with V kappa region sequences in the gene bank. One was identical to 87.92.6 for the region sequenced (a member of V kappa RF). The second showed 93.8% sequence similarity with AN04 and called V kappa 32. The third called V kappa 33 showed 76% sequence similarity with the human sequence V52 and 73.2% sequence similarity with the mouse sequence L6. An insert from V kappa 32 containing the 5' untranslated regions through the codon for Cys 88 of the V kappa region was used as a probe in Southern blot analysis of genomic DNA from inbred and congenic strains of mice. V kappa 32 is a four to eight member group and some of the members are retained in the B6.PL-Ly2a congenic and missing from the B6.PL (85NS) congenic consistent with a map location near V kappa 28. The same filters were hybridized with the insert from V kappa 33 containing 5' untranslated region through the codon for Ser 93 of the V kappa region. V kappa 33 is a one to three member group and using the B6.PL congenics maps with the polymorphic fragments of V kappa 32 and V kappa 28.
Identification of rabbit genomic Ig-VH pseudogenes that could serve as donor sequences for latent allotype expression.
Authors: Fitts M G , Metzger D W
Published: December 2022

Synthetic DNA oligomers specific for the VHa allotypes of rabbit Ig genes have been used to identify latent allotypic sequences in homozygous a1 and a2 rabbits. Two Ig VH pseudogenes containing latent a3 regions have been cloned from the genome of a homozygous a2 rabbit. Analysis of the regions associated with allotype expression indicates that these two pseudogenes contain VHa- sequences in framework region 1 (FR1) and VHa3 sequences in FR3. One gene has undergone an unusual rearrangement with a third VH gene, deleting their intervening sequences and recombining in FR3 with sequences 5' to the leader exon. Our results demonstrate the presence of latent VH sequences in the genomic DNA of normal rabbits and suggest that a mechanism such as gene conversion is responsible for expression of genetically-unexpected Ig VH genes.
A V kappa-J kappa junctional change in an antidigoxin recombinant antibody destroys digoxin-binding activity.
Authors: Hudson N W , Bruccoleri R E , Steinrauf L K , Hamilton J A , Mudgett-Hunter M , Margolies M N
Published: December 2022

A set of high affinity antidigoxin antibodies were previously identified with high homologous V kappa 1A L chain sequences but were associated with two entirely different VH regions and two dramatically different specificities for digoxin analogs. Antibodies 40-20, 40-60, 40-90, and 40-100 displayed similar binding specificities but differed from that of antibody 26-10. In a previous study using somatic cell fusion for Ig chain recombination we demonstrated that a recombinant antibody consisting of the H chain of antibody 26-10 and the L chain of antibody 40-20 retained digoxin binding and the 26-10 Id, but displayed a binding specificity pattern dominated by the 26-10 H chain donor. In the present study we produced three additional chain recombinant antibodies that contain the 26-10 H chain recombined with each of the L chains of antibodies 40-60, 40-90, and 40-100. All four recombinants expressed the 26-10 Id indistinguishably from the 26-10 antibody. Two of the recombinants (using the 40-60 and 40-90 L chains) bind digoxin; however, the recombinant using the 40-100 L chain failed to bind digoxin. Complete sequence analyses of the 40-20, 40-60, 40-90, and 40-100 VH and VL regions were performed. Antibodies 40-90 and 40-100 have identical VH region sequences but differed only in their L chains at position 96 (proline/leucine). This single difference at the VK-JK junction abolished digoxin binding in the context of one H chain (26-10), but does not cause a significant change in binding in association with the "normal" parental chains 40-90 and 40-100. Thus, structurally closely related VL regions can recombine with different VH regions to form digoxin binding sites of different specificity; in one binding site the identity of a L chain junctional residue is critical whereas in the second binding site that residue is unimportant. Molecular modeling studies revealed major differences between calculated binding site structures for 26-10 when leucine is substituted for proline at position 96 in the 26-10 VL region.
IL-2-PE40 prevents the development of tumors in mice injected with IL-2 receptor expressing EL4 transfectant tumor cells.
Authors: Kozak R W , Lorberboum-Galski H , Jones L , Puri R K , Willingham M C , Malek T , Fitzgerald D J , Waldmann T A , Pastan I
Published: December 2022

A number of different immunotherapeutic reagents are currently being developed to target IL-2R for the treatment of leukemia, graft rejection, and certain autoimmune diseases. Previously, we have shown that IL-2-PE40, a chimeric protein composed of human IL-2 linked to the N-terminus of a truncated form of Pseudomonas exotoxin (PE), could effectively kill a variety of cell lines in vitro expressing either low, intermediate, or high affinity IL-2R. Here, we demonstrate that IL-2-PE40 can successfully retard or prevent the growth of a lethal ascites tumor or a solid tumor composed of EL4J murine thymoma cells transfected with the p55 murine IL-2R. The transfected line, EL4J-3.4, expresses 1,000 to 3,000 high affinity IL-2R. Survival extension in the ascites model was achieved by initiating treatment either after 4 to 6 h or within 5 days post-tumor injection in both athymic nude and C57BL/6 mice. Similarly, the growth of an aggressive s.c. solid tumor could also be inhibited. Extension of survival was not achieved either by using the truncated toxin alone not attached to IL-2 or by using an IL-2-PE40Asp553 mutant lacking a functional toxin. Survival extension was not caused by IL-2 activated NK or other host effector mechanisms as IL-2-PE40 was unable to prevent the receptor-negative EL4J parental line from forming a lethal ascites or a solid tumor. Thus, IL-2-PE40 is a potent, specific cytolytic reagent that may prove useful in the arsenal of anti-IL-2R immunotherapeutics.