bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple regions of HLA-DR beta 1 chains determine polymorphic epitopes recognized by monoclonal antibodies.
Authors: Alber C A , Watts R , Klohe E P , Drover S , Marshall W H , Radka S F , Karr R W
Published: December 2022

To investigate the locations of antibody binding epitopes on HLA class II molecules, four DR4/7 beta 1 hybrid cDNA were constructed by exchanging the DNA encoding the NH2-terminal portions (amino acids 1 to 40) or the COOH-terminal portions (amino acids 41 to 94) of the first domains of DR4 beta 1- and DR7 beta 1-chains, in association with DNA encoding either the DR4 beta 1 or DR7 beta 1 second domains. Transfectants expressing a DR alpha cDNA and a wild-type DR4 beta 1 or DR7 beta 1 cDNA or one of four hybrid DR4/7 beta 1 cDNA were produced, and the binding to the transfectants of anticlass II mAb, which detect polymorphic epitopes on either DR4 or DR7 molecules, was analyzed. Four different patterns of mAb binding to the transfectants were observed, indicating that multiple regions of DR beta 1-chains play the predominant roles in the contributions of these chains to polymorphic epitopes recognized by mAb on intact molecules. The relevant regions of these chains and the number of mAb that recognize the associated polymorphic epitopes are: 1) the COOH-terminal portion of the first domain of DR4 beta 1; a DR4-specific mAb, 2) the NH2-terminal portion of the first domain of DR7 beta 1; two mAb, including a DR7-specific mAb, 3) the NH2-terminal portion of the first domain of DR4 beta 1; seven mAb, and 4) the second domain of DR4 beta 1; one mAb.
The beta-chain of the IL-2 receptor (p70) is tyrosine-phosphorylated on YT and HUT-102B2 cells.
Authors: Sharon M , Gnarra J R , Leonard W J
Published: December 2022

IL-2 has previously been shown to rapidly induce activity of a tyrosine kinase. High-affinity IL-2 receptors that mediate the major mitogenic signals of IL-2 contain both p70 and p55 chains. p55 has no potential tyrosine phosphorylation sites and lacks consensus sequences found in protein tyrosine kinases. Inasmuch as the phosphorylation of hormone receptors is generally an important mechanism for regulating receptor function, we have now investigated the phosphorylation status of p70. By using anti-phosphotyrosine antibodies to immunoprecipitate affinity-labeled IL-2 receptors and to probe Western blots, we provide data suggesting that p70, but not p55, is constitutively tyrosine-phosphorylated on the leukemic cell lines studied.
Identification of a unique IgG Fc binding site in human intestinal epithelium.
Authors: Kobayashi K , Blaser M J , Brown W R
Published: December 2022

In experiments to determine whether serum antibodies in patients with Crohn's disease could be used as probes for detecting potentially etiologic Ag in the patients' tissues, we found that peroxidase (HRP)-labeled IgG from healthy persons, as well as from the patients, bound to normal colonic and small intestinal epithelium, mostly or entirely to goblet cells. The binding was due to a reaction involving the Fc region of IgG because HRP-labeled Fc fragments of IgG bound, but HRP-Fab, HRP-IgA, and HRP-bovine albumin did not, and because binding of HRP-IgG was inhibited competitively by unlabeled IgG or Fc fragments but not by IgG Fab fragments or IgA. These immunohistochemical results were confirmed by ELISA with microtiter wells coated with a sonicated homogenate from human colonocytes. The epithelial IgG Fc binding site was characterized by SDS-PAGE as consisting of a high Mr (greater than 200,000 Da) and a 78,000-Da component. It bound all four subclasses of human IgG and bound aggregated as well as monomeric IgG. It is distinct from known human Fc-gamma R by lack of recognition by mAb to those receptors and differences in affinity for various subclasses of human and murine IgG. This unique IgG Fc binding site might be involved in immunologic defense of the gut, perhaps by mediating reactions between foreign Ag and the contents of goblet cells.
Studies of aglycosylated chimeric mouse-human IgG. Role of carbohydrate in the structure and effector functions mediated by the human IgG constant region.
Authors: Tao M H , Morrison S L
Published: December 2022

Chimeric mouse-human IgG was used to study the structural and functional roles of the carbohydrate present in the CH2 domain of human IgG molecules. To remove this N-linked carbohydrate, Asn-297, the oligosaccharide attachment residue, was changed to either Gln (a conservative replacement) or His for IgG1 or Lys for IgG3 (nonconservative replacements) by site-directed mutagenesis. Carbohydrate-deficient antibodies are properly assembled and secreted and bind Ag and protein A. However, aglycosylated IgG are more sensitive to most proteases than their corresponding wild-type IgG, indicating some conformational changes have occurred. Aglycosylated IgG do not bind to the human Fc gamma RI and do not activate C; depending on the isotype, C1q binding ability is either completely lost (IgG1) or dramatically decreased (IgG3). The serum half-life in mice of aglycosylated IgG1-Gln remains the same as wild-type IgG1, 6.5 +/- 0.5 days, whereas aglycosylated IgG3-Gln has a shorter half-life, 3.5 +/- 0.2 days, compared to that of wild-type IgG3, 5.1 +/- 0.4 days. These results indicate the carbohydrate interposed between CH2 domain of human IgG is necessary to maintain the appropriate structure for the maintenance of many of the effector functions dependent on the CH2 domain.
HIV promoter activity in primary antigen-specific human T lymphocytes.
Authors: Horvat R T , Wood C
Published: December 2022

Human retroviruses, such as the HIV, infects human T cells, and efficient HIV replication occurs primarily in activated T cells rather than resting cells. Increased HIV production is likely caused by the activation of the retroviral promoter, and the HIV promoter may be regulated by intracellular signals induced during immune stimulation. To examine the regulation of retroviral promoter activity in normal, Ag-specific primary T lymphoblasts, a heterogeneous population of primary human T cells was transfected with either the HIV promoter or a promoter from a different retrovirus, Rous sarcoma virus (RSV) by protoplast fusion technique. Transfected T cells responded normally to Ag or mitogen stimulation, and activation of these T cells increased both the HIV and RSV promoter activity. Promoter activity was assessed by using transient expression assays after the T cells were restimulated with Ag, mitogen, or IL-2. In situ hybridization of transfected human T cells showed that 68 to 95% of activated lymphocytes expressed CAT mRNA directed by HIV or RSV. Thus, protoplast transfection of primary T cells was efficient in that the majority of cells expressed CAT message. By deletion of different regions of the HIV promoter, the enhancer region was identified as necessary for effective HIV promoter activity. In addition these deletion studies identified a region that negatively affects HIV promoter activity in primary T cells. Cotransfection of the HIV promoter with the HIV transactivator protein, tat, increases HIV promoter activity in both resting and activated primary human T cells only when the tat target sequences were present.
Sequences outside a minimal immunodominant site exert negative effects on recognition by staphylococcal nuclease-specific T cell clones.
Authors: Vacchio M S , Berzofsky J A , Krzych U , Smith J A , Hodes R J , Finnegan A
Published: December 2022

In recent years, synthetic peptides have been utilized extensively to characterize the minimal essential immunodominant sites on model protein Ag. However, little work has focused on the effect that sequences flanking these minimal recognition sites may exert on T cell recognition. Previous work with staphylococcal nuclease (Nase) demonstrated that I-Ek-restricted clones recognize the peptide 81-100, whereas I-Ab-restricted clones recognize the over-lapping but non-cross-reacting peptide 91-110. Further analysis with 15 or 10 residue peptides within the region 81-110 reveals that the minimal sequence capable of stimulating I-Ek-restricted clones is contained within the decapeptide 91-100. Addition of residues 86-90, to give the peptide 86-100, enhanced the recognition substantially, whereas addition of residues 101-105 produced a 91-105 peptide with no stimulatory ability. These results suggest that interactions between the antigenic peptide 91-100 and residues within the flanking 101-105 sequence have negative consequences for presentation of the immunodominant epitope to T cell clones. Introduction of single amino acid substitutions within 91-105 produced peptides that induce responses comparable to those seen with 91-100. These results are consistent with the suggestion of negative interactions between the minimal immunodominant site and flanking sequences in that single residue substitutions may remove these negative interactions and lead to restoration of stimulatory ability. The negative effect of flanking sequences on T cell recognition of immunodominant sites presents new considerations for development of synthetic vaccines as well as for understanding the biology of Ag processing and presentation.
Ig-binding bacterial proteins also bind proteinase inhibitors.
Authors: Sjöbring U , Trojnar J , Grubb A , Akerström B , Björck L
Published: December 2022

Protein G is a streptococcal cell wall protein with separate binding sites for IgG and human serum albumin (HSA). In the present work it was demonstrated that alpha 2-macroglobulin (alpha 2M) and kininogen, two proteinase inhibitors of human plasma, bound to protein G, whereas 23 other human proteins showed no affinity. alpha 2M was found to interact with the IgG-binding domains of protein G, and in excess alpha 2M inhibited IgG binding and vice versa. A synthetic peptide, corresponding to one of the homologous IgG-binding domains of protein G, blocked binding of protein G to alpha 2M. Protein G showed affinity for both native and proteinase complexed alpha 2M but did not bind to the reduced form of alpha 2M, or to the C-terminal domain of the protein known to interact with alpha 2M receptors on macrophages. Binding of protein G to alpha 2M and kininogen did not interfere with their inhibitory activity on proteinases, and the interaction between protein G and the two proteinase inhibitors was not due to proteolytic activity of protein G. The finding that protein G has affinity for proteinase inhibitors was generalized to comprise also other Ig binding bacterial proteins. Thus, alpha 2M and kininogen, were shown to bind both protein A of Staphylococcus aureus and protein L of Peptococcus magnus. The results described above suggest that Ig-binding proteins are involved in proteolytic events, which adds a new and perhaps functional aspect to these molecules.
Identification and characterization of T helper epitopes in the nucleoprotein of influenza A virus.
Authors: Gao X M , Liew F Y , Tite J P
Published: December 2022

By using a series of overlapping synthetic peptides that cover more than 95% of the amino acid sequence of nucleoprotein (NP) of influenza A/NT/60/68 virus, five Th cell epitopes in B10.S (H-2s), BALB/c (H-2d), CBA (H-2k), and B6 (H-2b) mice have been identified. The specificity of Th cell recognition of epitopes is largely dependent on the H-2 haplotype of the responding mouse strain. However, two out of the five Th epitopes defined could be recognized by mice of more than one haplotype, implying that the primary sequence of protein antigens could also influence the selection of dominant T cell epitopes by the immune system. Immunization of B10.S mice with peptide 260-283 generated strong Th cell response against type A influenza viruses. In the other three strains of mice tested, priming with helper peptides induced a stronger antipeptide than antiviral T cell response. However, the low responsiveness to virus in these mice could be partially overcome by immunization with a mixture of several helper peptides. The Th epitopes are defined by the ability of the peptides to stimulate class II MHC restricted CD4+ T cells to proliferate and to produce IL-2 in vitro. When compared with the known epitopes on NP recognised by class I restricted CD8+ cytotoxic T cells, it appears that Th and cytotoxic T cell epitopes are nonoverlapping. The AMPHI and Motifs methods were employed to analyze the sequence of NP and predict the potential dominant sites in the molecule. The predictions are compared with the experimental data obtained and the implications discussed.
HLA-DRB1 and -DRB4 genes are differentially regulated at the transcriptional level.
Authors: Stunz L L , Karr R W , Anderson R A
Published: December 2022

The mechanism regulating the differential expression of DR beta 1 and DR beta 4 proteins on the surfaces of cultured EBV-transformed DR7 cell lines was investigated at the level of gene transcription. Steady-state levels of mRNA coding for DR7 beta 1 and DR beta 4 proteins were evaluated with the use of locus-specific oligonucleotide probes and relative transcriptional activity at the DR7B1 and DRB4 gene loci was measured with nuclear run-on transcription assays. Steady-state levels of DR7B1 mRNA were found to be three- to nine-fold higher than those of DRB4 in DR7,Dw7 cell lines, but no mature steady-state DRB4 mRNA was detectable in a DR7,Dw11 cell line which shows no detectable DR beta 4 protein. Run-on transcription assays performed with nuclei isolated from DR7,Dw7 cells showed a five-fold excess of DRB1 over DRB4 transcriptional activity, but, surprisingly, no difference in activity at the two DRB loci in nuclei isolated from DR7,Dw11 cells. Both DRB mRNA were quite stable as indicated by actinomycin D time course experiments. Thus the differential expression of the DR7 beta 1 and DR beta 4 proteins in the DR7,Dw7 cell lines arises at the level of mRNA production; the lack of detectable DR beta 4 protein in the DR7,Dw11 cell line, however, appears to be due to a different mechanism in which transcribed DRB4 sequences fail to be processed into mature mRNA molecules.
IL-5 up-regulates but IL-4 down-regulates IL-2R expression on a cloned B lymphoma line.
Authors: Yoshimoto T , Nakanishi K , Matsui K , Hirose S , Hiroishi K , Tanaka T , Hada T , Hamaoka T , Higashino K
Published: December 2022

Both IL-4 and IL-5 demonstrate B cell growth activity. IL-5 can render a cloned neoplastic B cell line, BCL1-CL-3 cells, responsive to IL-2, whereas IL-4 has no such activity. The response to IL-5 and IL-2 proceeds in two phases: the first phase which clearly depends upon IL-5 is the obvious increase in number of high affinity IL-2R (3.1-fold) with modest increase of low affinity IL-2R (1.2-fold) and gain of the ability of facilitated IL-2-binding and internalization of IL-2, and the second phase which is induced by IL-2 in the IL-5-stimulated CL-3 cells comprises the striking increase of low affinity IL-2R (8.5-fold). Kinetic study has revealed that high affinity IL-2R expressed on CL-3 cells begins to increase at 6 h and reaches to maximum at 12 h after stimulation with IL-5 or IL-5 plus IL-2, whereas low affinity IL-2R expression increases at 18 h and becomes maximal at 24 h after stimulation of CL-3 cells with IL-5 and IL-2. However, in the presence of IL-4, IL-5 cannot induce an increase in number of high affinity IL-2R on CL-3 cells. Thus, CL-3 cells stimulated with the mixture of IL-5 and IL-4 cannot respond to IL-2, and fail to show up-regulated expression of low affinity IL-2R. IL-4 also has a capacity to modestly interfere with the action of IL-2 to up-regulate low affinity IL-2R expression on IL-5-pretreated CL-3 cells. Thus, this monoclonal B cell system provides an excellent model system to define the roles of IL-5 and IL-4 involved in the B cell differentiation and to characterize the properties of B cells competent to IL-2 stimulation and the signal transduction mechanism which operates through IL-2/IL-2R system.
Tissue-specific expression of allogeneic class II MHC molecules induces neither tissue rejection nor clonal inactivation of alloreactive T cells.
Authors: Miller J , Daitch L , Rath S , Selsing E
Published: December 2022

To analyze the control of self tolerance to tissue-specific Ag, we have constructed C57BL/6 (H-2b) transgenic mice that express allogeneic class II (I-Ad) molecules exclusively on pancreatic islet cells. By a number of criteria, including I-Ad mRNA, and tissue and cell surface I-Ad protein levels, the islet cells appear to be expressing levels of I-Ad similar to B lymphocytes. Although one of the transgenic lines that expresses only the beta-chain occasionally displays slightly elevated glucose levels, this hyperglycemia is not enhanced when alpha and beta are coexpressed, allowing for cell surface I-Ad expression. None of the mice examined has demonstrated any autoimmune reaction to the I-Ad+ islet cells. Despite this apparent lack of recognition of the I-Ad+ islet cells, these animals demonstrate no reduction in the in vitro MLR generated to the same MHC molecule. Therefore, these mice remain functionally tolerant to the transgene product without inactivating those T cells that can recognize this same MHC molecule in vitro.
Regulation of the anti-alpha(1----3) dextran IgG antibody response of BALB/c mice by idiotype-specific T suppressor lymphocytes.
Authors: Stäb F , Austrup F , Kölsch E
Published: December 2022

The immune response of BALB/c mice against the so-called thymus-independent bacterial Ag alpha(1----3) dextran (Dex) is restricted to the expression of few major idiotypes (Id). It is furthermore under the control of T lymphocytes which regulate the isotype expression in such a way that they prevent anti-Dex IgG antibody production upon immunization. At the same time these T cells are part of a regulatory system for Dex-specific B cell memory formation. The underlying Ts cell activity has previously been analyzed by using euthymic and athymic congenic animals. Now we have isolated CD4-positive Id-specific T cell lines and clones which by several criteria are representatives of the above Ts cells. They inhibit in vitro proliferation and antibody secretion of Dex-specific hybridoma B cells. They prevent Id-restricted in vivo IgG anti-Dex antibody formation in T cell-reconstituted BALB/c nu/nu mice. At the same time they enforce, again Id-specific, accumulation of Dex-specific B memory cells. As has been shown previously under the influence of splenic Ts cells, these B memory cells are arrested in the original host but can be expanded and activated for anti-Dex IgG antibody formation upon adoptive transfer into X-irradiated allotype congenic nonresponder BALB.Ighb mice. The data show that the regulatory influence of T cells on the anti-Dex response is Id specific. It can now be studied by means of cloned Ts cells.
In situ localization of CD45 isoforms in the human thymus indicates a medullary location for the thymic generative lineage.
Authors: Gillitzer R , Pilarski L M
Published: December 2022

Previous work has suggested that the generative lineage within the human thymus can be defined by the selective expression of CD45 isoforms and is CD45RO- and predominantly CD45RA+. In order to physically localize these cells we have stained frozen sections of human thymus with antibodies to CD45RO (p180), and CD45RA (p205/P220), as well as with CD1 and HLA class I to define cortical and medullary areas, respectively. In the cortex, 70 to 90% of thymocytes were CD45RO+, whereas only 0.5% expressed CD45RA. Medullary cells were 30% CD45RO+, 29% CD45RA+; approximately 40% did not express detectable levels of either isoform but did express CD45 common determinants. To assess the degree of proliferation of cells expressing CD45 isoforms, we stained adjacent sections, or used double staining, with Ki67, an antibody that detects a nuclear Ag on proliferating cells. We found that CD45RA+ thymocytes are predominantly a resting medullary population with a small component in cell cycle, consistent with our analysis of human thymocytes by immunofluorescence, and with data in murine systems defining the generative lineage. To confirm that the CD1- or low, CD45RO-CD45RA+ thymocytes defined by immunofluorescence analysis were likely to have a medullary location, we analyzed the CD4/CD8 subset distribution of CD1-cells. From 80 to 90% of CD1-thymocytes are CD4+ or CD8+ single positives or CD-8- double negatives. CD1-thymocytes also include 12 to 14% CD4+8+ cells with a probable medullary location. A similar analysis of lymphocytes expressing a high density of HLA class I, which have a medullary location, confirmed the existence of CD4+8+ thymocytes in the medulla. Purified CD3-4-8- cells, previously shown to be CD1-CD45RA+, were also shown to bear a high density of HLA class I, indicating a medullary location. Correlative localization of a panel of Ag thus supports the argument for a medullary location of the thymic generative lineage.
Murine interstitial nephritis. IX. Induction of the nephritogenic effector T cell repertoire with an antigen-specific T cell cytokine.
Authors: Hines W H , Mann R A , Kelly C J , Neilson E G
Published: December 2022

The experiments presented in this report describe the biochemical and functional characteristics of a soluble Th cell factor (ThF) which can induce a nephritogenic effector T cell repertoire producing autoimmune interstitial nephritis. The ThF is Ag-specific, I-A-restricted, and comprises two chains noncovalently linked as a heterodimer. One chain at approximately 78,000 Mr is related to the TCR/Id and expresses a framework determinant (14-30) common to Ag-binding factors, and the other chain at approximately 82,000 Mr is I-A+. Together these chains can replace their parent cell by providing cognate help to precursor effector T lymphocytes in the presence of accessory cells, tubular Ag, and IL-2.
An intracellular calcium increase and protein kinase C activation fail to initiate T cell proliferation in the absence of a costimulatory signal.
Authors: Mueller D L , Jenkins M K , Chiodetti L , Schwartz R H
Published: December 2022

Resting T lymphocytes proliferate in response to a combination of a calcium ionophore and a phorbol ester. This observation suggests that an increase in intracellular calcium free ion concentration [Ca2+]i and activation of protein kinase C (PKC) are sufficient signaling events for the initiation of T cell proliferation. In contrast, an accessory cell-generated costimulatory signal, acting independently of the rise in [Ca2+]i and PKC activation, is required for Ag-induced proliferation of type I T cell clones. We now report that this costimulatory signal is unexpectedly also being delivered via a cell-cell interaction during the response to ionomycin and phorbol ester. In the absence of this signal (at limiting cell numbers), T cells fail to divide. We also demonstrate that proliferation in response to immobilized anti-CD3 mAb requires the cell-cell interaction. These results suggest a model of T cell stimulation in which activation of a costimulatory signaling pathway is important in the regulation of the IL-2 gene, and only in the presence of this (third) signal can an increase in [Ca2+]i and PKC activity induce T cell proliferation. Such a model predicts that IL-2-dependent expansion of T cell clones in vivo in response to Ag receptor occupancy requires the delivery of an independent accessory cell-derived co-stimulatory signal.
IL-1 beta modulation of spontaneous autoimmune diabetes and thyroiditis in the BB rat.
Authors: Wilson C A , Jacobs C , Baker P , Baskin D G , Dower S , Lernmark A , Toivola B , Vertrees S , Wilson D
Published: December 2022

Long term effects of in vivo treatment with human rIL-1 beta on diabetogenesis and thyroid disease were determined in the Biobreeding rat. Administration of high dose (10 micrograms/kg) IL-1 beta accelerated the onset of insulin-dependent diabetes mellitus compared to saline-injected controls. High dose treatment resulted in goiter development, pronounced LT, reduced serum T4 levels, and overall growth reduction. In contrast, low dose IL-1 beta (0.5 microgram/kg) administration significantly reduced the frequency of insulin-dependent diabetes mellitus (48%) compared to placebo (86%) and high dose IL-1 beta (93%) treatment groups. Rats protected by low dose IL-1 beta had unaffected growth rates and minimal to no pancreatic and thyroid pathology. Our results demonstrate that exogenous administration of IL-1 beta modulates Biobreeding rat idiopathic autoimmune diabetes and thyroid disease in a dose-dependent manner.
Production of hemopoietic colony-stimulating factors by astrocytes.
Authors: Malipiero U V , Frei K , Fontana A
Published: December 2022

Astrocytes may play a central role in regulation of immune mediated processes in the central nervous system. By their inducible expression of MHC class II Ag and secretion of cytokines they may propagate expansion and activation of T and B lymphocytes invading the brain tissue. Here we report that astrocytes may also contribute to the macrophage response observed in inflammatory and degenerative diseases of the brain. Murine astrocytes secrete granulocyte-macrophage CSF (GM-CSF) as evidenced by induction of colony formation in bone marrow cells and growth of FDC-P1 cells. Both effects are neutralized with anti-GM-CSF- but not with anti-IL-3-antibodies. Some residual activity detected in the bone marrow assay after antibody treatment can be explained by concomitant production of granulocyte CSF (G-CSF). The mRNA of both G- and GM-CSF are identified by Northern blots in astrocytes. Furthermore, mRNA for IL-1 alpha and IL-1 beta are detected in comparable amounts in astrocytes and brain macrophages, the latter, however, comprising much more potent sources of TNF-alpha.
Superoxide responses of immune complex-stimulated rat alveolar macrophages. Intracellular calcium and priming.
Authors: Hagenlocker B E , Walker B A , Ward P A
Published: December 2022

ATP is known to induce calcium transients in rat and human neutrophils and to "prime" these cells for enhanced oxygen radical responses after stimulation with chemotactic peptide, FMLP, or immune complexes. Calcium ionophores are also well known for their ability to prime phagocytic cells. In the current studies, nonelicited rat alveolar macrophages were analyzed for the ability of ATP as well as FMLP, C5a, platelet-activating factor and calcium ionophore (A23187) to modify levels of intracellular calcium and to enhance superoxide anion (O2-) production in response to immune complexes. Although none of these agents induced a O2- response under the conditions employed, all, except FMLP and C5a (human, recombinant) increased intracellular calcium, although the temporal features of the increases varied with the agent. In contrast to the inability of FMLP and C5a to cause intracellular calcium increases in macrophages, these same peptides caused dose-dependent intracellular calcium increases in rat neutrophils, whether the cells were derived from the blood or from the peritoneal cavity. On the basis of the effects of EGTA, the calcium increases in alveolar macrophages were caused by intracellular release of calcium in addition to some influx of extracellular calcium. Although ATP caused a dose-related increase in the level of intracellular calcium in alveolar macrophages, the cells were not "primed" for enhanced O2- responses to immune complexes. In contrast, platelet-activating factor and A23187, each of which induced increased intracellular levels of calcium, were able to prime macrophages for enhanced O2- responses. C5a and FMLP neither increased intracellular calcium levels nor primed macrophages for enhanced O2- responses to immune complexes. It is not clear if the inability of ATP to prime alveolar macrophages is caused entirely by insufficient increases in intracellular calcium or if ATP is unable to bring about additional changes that are relevant to the priming phenomenon.
Inhibition of antigen-induced airway hyperresponsiveness, but not acute hypoxia nor airway eosinophilia, by an antagonist of platelet-activating factor.
Authors: Ishida K , Thomson R J , Beattie L L , Wiggs B , Schellenberg R R
Published: December 2022

The role of platelet-activating factor (PAF) in Ag-induced airway hyperresponsiveness was evaluated in a guinea pig model using the PAF antagonist SDZ 64-412. Repeated OVA challenge by aerosol (twice weekly x 4 wk) of previously sensitized guinea pigs produced striking airway hyperresponsiveness as determined by pulmonary resistance changes to increasing doses of inhaled acetylcholine given 3 days after the last OVA challenge. Each OVA challenge produced significant hypoxia that was unaffected by oral pretreatment with 20 mg/kg SDZ 64-412, 2 h before each challenge (pO2 = 35 +/- 2 mm Hg for OVA alone vs 40 +/- 6 mm Hg for SDZ and OVA groups, respectively). SDZ 64-412 pretreatment abolished the airway hyperresponsiveness resulting from repeated Ag challenge. Morphometric analysis revealed that SDZ 64-412 treatment had no effect on the increased numbers of eosinophils that infiltrated the airways of OVA-challenged guinea pigs. These results suggest that PAF may be a primary mediator of airway hyperresponsiveness, but not acute bronchoconstriction, induced by repeated Ag challenge. This activity of PAF appears independent of eosinophil recruitment to airways.
Fluctuations in subsets of splenocytes and isotypes of Ig in young adult and aged mice resulting from Trypanosoma musculi infections.
Authors: Albright J W , Holmes K L , Albright J F
Published: December 2022

A prominent feature of parasitic infections is the marked hyperplasia of lymphoid tissues. The resultant disruption of those tissues may be a major cause of the immunodepression that typifies parasitic infections. Trypanosoma musculi infections in mice evoke lymphoid hyperplasia and depressed immune responses. T. musculi infections are more severe in C3H than in C57BL/6 (B6) mice; and more severe in aged mice of either strain, compared with young adults. This report concerns a flow cytometric analysis of splenic leukocytes, identified by various surface Ag, in young and aged, trypanosome-infected mice of C3H and B6 strains. Companion studies included quantification of serum Ig isotypes at intervals during infection. The results support the following conclusions: a) all major types of splenic leukocytes were activated by trypanosome infection resulting in enlargement of the cells and proliferation ("blastogenic response"); b) in all young-adult mice and in aged B6 mice (but not aged C3H mice) Thy-1+, Ly-1+, and Ly-4+ cells increased moderately during infection whereas the number of Ly-2+ cells remained constant; c) all cells of the B lineage increased during the course of infection (except in aged C3H mice) with disproportionate increases in the most mature stage (IgG+); d) the responses of young adult C3H and B6 mice to infection differed as illustrated by the ability of B6, but not C3H, mice to limit hyperplasia and reverse the effect; e) aging of B6 mice was reflected by relative inability to regulate generation of mature Ig-producing cells; f) aging of C3H mice was severe as reflected by the relative inability of most subsets of leukocytes to react to the infection, possibly because of abnormalities that were intrinsic in aged, normal C3H mice. It is likely that: a) disruption of lymphoid tissue, probably mediated by alterations in the production of and responsiveness to cytokines, is responsible for the depressed ability of the immune system to defend against parasites; and b) such disruptive effects, being more pronounced in aged animals and less easily brought under control, account for the greater vulnerability of aged animals to parasitic infection.
Antigen-induced Ca2+ signaling and desensitization in B cells.
Authors: Lazarus A H , Mills G B , Delovitch T L
Published: December 2022

Cross-linking of B cell surface Ig (sIg) by anti-Ig results in transmembrane signaling. However, the capacity of a thymus-dependent (TD) Ag to mediate B cell signal transduction has been less well documented. Therefore, we examined Ag-induced intracellular free calcium concentration [( Ca2+]) in B cells by using TD Ag that would be expected to either cross-link or not cross-link sIgM and/or induce the coupling of sIgM to FcR. Stimulation of mouse TA3 hybridoma B cell transfectants that express the SP6 anti-TNP specific sIgM with either TNP-OVA or anti-IgM antibodies resulted in a maximal fourfold increase in [Ca2+]i. The net increase in [Ca2+]i in response to TNP-OVA was dependent upon both the Ag dose and the TNP:OVA molar ratio. Because occupancy of several cell-surface receptor types leads to a loss of response to subsequent stimulation by ligand (homologous desensitization), we examined the ability of Ag to induce homologous desensitization of sIgM in these B cells. TNP1-OVA at all concentrations tested (up to 500 micrograms/ml) did not lead to any change in [Ca2+]i or desensitization. Cross-linking of TNP1-OVA (10 micrograms/ml) with F(ab')2 of anti-OVA antibody induced both a rise in [Ca2+]i and homologous desensitization of sIg, suggesting that cross-linking of sIgM by Ag is sufficient to induce both these processes. TNP6-OVA at a concentration of 10 micrograms/ml induced changes in [Ca2+]i and partially desensitized TNP-specific B cells to stimulation by anti-IgM. Interestingly, a high dose (180 micrograms/ml) of TNP6-OVA stimulated minimal changes in [Ca2+]i yet did not lead to desensitization. However, cross-linking of TNP6-OVA at this high dose with F(ab')2 of rabbit anti-OVA elevated [Ca2+]i and elicited partial desensitization. Complete desensitization of sIgM by Ag was achieved when intact (Fc-containing) anti-OVA antibody was used, suggesting that the FcR can play a role in desensitization. Ag- and antibody-mediated desensitization was not caused by steric hindrance of sIg. Thus, we have observed two forms of Ag-induced desensitization of sIgM, both of which involve sIg cross-linking and one of which is mediated by the physiologic coupling of sIg to FcR.
Orally inducible immune unresponsiveness is abrogated by IFN-gamma treatment.
Authors: Zhang Z Y , Michael J G
Published: December 2022

The role of murine epithelial cells from small intestine (IEC) in orally induced immune unresponsiveness has been investigated. Murine IEC were shown to express a relatively low level of class II MHC Ag and were incapable of presenting BSA to Ag-specific Th cells. IFN-gamma treatment of the animals dramatically enhanced expression of class II MHC Ag by IEC enabling Ag presentation to Th cells. Ag-presenting function of IEC after IFN-gamma treatment was not affected by IEC panning on anti-IgG or anti-MAC-1-coated plates but it was blocked by a class II MHC-specific mAb. IFN-gamma-treated mice were responsive to parenteral BSA challenge after oral administration of the Ag, whereas untreated mice were immunosuppressed. Our data support the concept that poor expression of class II MHC Ag on IEC contributes to immunosuppression induced by oral administration of a protein Ag.
Decreased HLA-DR antigen expression on monocytes causes impaired suppressor cell activity in multiple sclerosis.
Authors: Baxevanis C N , Reclos G J , Papamichail M
Published: December 2022

Mitogen-induced Ts cell activity and (DR) expression on monocytes have recently been shown to be reduced in patients with multiple sclerosis (MS). In our study, T cells were cultured with autologous monocytes in the presence of Con A for 6 days (primary cultures). At the end of the culture T cells were isolated and were 1) tested for surface DR expression and 2) treated with mitomycin C and placed in a secondary culture of allogeneic responder cells and Con A, to test their suppressor function. Treatment of monocytes of the primary culture with an anti-HLA-DR antibody abolished the expression of DR Ag on the T cells as well as their ability to function as Ts cells in the secondary culture. Monocytes from patients with active MS expressed low levels of surface DR Ag and induced reduced amounts of DR Ag on the surface of autologous T cells in primary cultures, which in turn expressed deficient suppressor function when placed in secondary cultures. In contrast, monocytes obtained from patients with inactive disease expressed higher levels of DR and induced higher amounts of DR Ag on autologous T cells, which expressed normal suppressor function. We conclude that the deficient expression of DR Ag on MS monocytes causes reduced suppressor function in activated autologous T cells and may be a primary abnormality in the immunopathogenesis of MS.
IL-6 stimulates osteoclast-like multinucleated cell formation in long term human marrow cultures by inducing IL-1 release.
Authors: Kurihara N , Bertolini D , Suda T , Akiyama Y , Roodman G D
Published: December 2022

IL-6 enhances the differentiation of pluripotent hematopoietic stem cells but predominantly affects the differentiation of hematopoietic cells in the granulocyte-macrophage lineage. We have previously shown that multinucleated cells (MNC) with many features of the osteoclast phenotype form in long term human marrow cultures. Addition of rhIL-6 (10 to 100 pg/ml) to these cultures significantly increased MNC formation, with greater than 80% of the MNC expressing an Ag that cross-reacts with the mAb 23c6. This antibody preferentially binds to osteoclasts. rhIL-6 did not enhance MNC formation in marrow cultures treated with 1,25 dihydroxyvitamin D3, a potent stimulator of MNC formation, but significantly increased the percentage of MNC that cross-reacted with the 23c6 mAb. Addition of antihuman IL-1 to cultures treated with rhIL-6 totally inhibited the increase in MNC formation stimulated by rhIL-6. In contrast, anti-IL-1 did not affect MNC formation stimulated by 1,25 dihydroxyvitamin D3. Further, conditioned media from marrow cultures exposed to rhIL-6 contained elevated levels of IL-1 beta (500 pg/ml compared to 23 pg/ml in control cultures 15 h after IL-6 addition). These results suggest that the capacity of rhIL-6 to stimulate formation of MNC which cross-react with 23c6 is mediated by induction of release of IL-1 beta.
Regulation of arachidonic acid release in mouse peritoneal macrophages. The role of extracellular calcium and protein kinase C.
Authors: Balsinde J , Fernández B , Diez E
Published: December 2022

Primary cultures of [3H]arachidonic acid-prelabeled mouse peritoneal macrophages were stimulated with the physiologic agonists zymosan and Con A. The cells released a large quantity of labeled compounds into the extracellular medium. When the cells were preincubated for 10 min with PMA at concentrations from 10 to 1000 ng/ml, zymosan- and Con A-stimulated compound release was greatly enhanced. PMA also potentiated arachidonic acid release when cells were stimulated with the calcium ionophore A23187. However, under the same conditions, PMA treatment blocked agonist- and ionophore-mediated phosphoinositide hydrolysis in cells prelabeled with [3H]inositol. Thus, PMA treatment appears to have dissociated agonist-induced arachidonic acid liberation (index of phospholipase A2) from phosphoinositide hydrolysis (index of phospholipase C), suggesting that these two coupling processes can occur in a parallel and independent manner in mouse peritoneal macrophages. Furthermore, the ligand-induced arachidonic acid release from PMA-treated macrophages was shown to be directly dependent on the extracellular calcium concentration. Considering that in PMA-pretreated cells, receptor-mediated phosphoinositide breakdown and intracellular calcium mobilization were abolished, our data suggest that the extracellular calcium influx that takes place after receptor-ligand interaction may be a required event for arachidonic acid mobilization in mouse peritoneal macrophages.
Activation of mouse peritoneal macrophages during infection with Salmonella typhimurium does not result in enhanced intracellular killing.
Authors: Langermans J A , van der Hulst M E , Nibbering P H , van Furth R
Published: December 2022

Our study was performed to investigate whether macrophages become activated during an infection with Salmonella typhimurium and, if so, whether these activated macrophages kill S. typhimurium faster than resident macrophages. Mice received i.v. injections with a sublethal number of S. typhimurium; on about day 12 of the infection the numbers of bacteria in the liver and the spleen were maximal. During the infection, activation of peritoneal macrophages could be demonstrated on the basis of three criteria, i.e., the ability to inhibit the proliferation of Toxoplasma gondii, an enhanced production of H2O2 and an increased expression of Ia Ag. The rate of in vitro intracellular killing of S. typhimurium by these activated macrophages was not increased compared to that for resident macrophages. To determine the growth of S. typhimurium in activated mice a nalidixic acid-resistant mutant strain, called S. typhimurium 510R, was used. The net growth rates of the mutant S. typhimurium 510R in the spleen of S. typhimurium 510-activated and normal mice were similar. However, in the liver of S. typhimurium 510-activated mice the number of S. typhimurium 510R did not change during 3 to 48 h after injection. The role of specific antibodies during the initial phase of the infection was negligible, because only low levels of antibodies were detected during the first 15 days of infection and the growth rates of S. typhimurium 510 in the spleen and liver of mice with high titers of antibodies were not significantly different from the rates in normal mice. The results of this study demonstrate that although macrophages become activated during an infection with S. typhimurium, these cells do not display an enhanced bactericidal activity in vitro and in vivo no significant effect on the growth rate of S. typhimurium in the spleen and a bacteriostatic effect in the liver is found. Hence macrophage activation is probably not very important in the host defense against S. typhimurium.
Recombinant IL-2 therapy reverses diminished granulomatous responsiveness in anti-L3T4-treated, Schistosoma mansoni-infected mice.
Authors: Mathew R C , Ragheb S , Boros D L
Published: December 2022

We have previously shown, that anti-L3T4 mAb treatment strongly suppressed granuloma formation in the liver, and IL-2 production in the spleen of Schistosoma mansoni-infected mice. In the present study the dynamics of IL-2 production was delineated during the infection, and the effect of rIL-2 treatment on granulomatous responsiveness was examined. IL-2 production in soluble egg Ag-stimulated spleen cells of mice was detectable at 6, peaked at 8 and waned by 20 wk of the infection. In contrast, Con A stimulus elicited high levels of IL-2 production by 8 wk which remained nearly unchanged throughout the infection. Administration of rIL-2 to acutely infected, anti-L3T4 mAb-treated, or chronically infected mice reversed the diminished or modulated granulomatous responses without restoring the ability for endogenous IL-2 production. Transfer of spleen cells of anti-L3T4 mAb-treated, chronically infected mice did not indicate a role for Ts cells in the impaired production of IL-2 in recipients. These data suggest that lack of IL-2 production can play an important role in the immunoregulation of the granulomatous response.
Mechanisms of anti-CD4-mediated depletion and immunotherapy. A study using a set of chimeric anti-CD4 antibodies.
Authors: Alters S E , Sakai K , Steinman L , Oi V T
Published: December 2022

A family of rat-mouse chimeric anti-murine CD4 antibodies was used to study the mechanisms of anti-CD4-mediated depletion and immunotherapy. The chimeric antibodies retain identical affinity and specificity as the therapeutically effective prototype antibody, rat GK1.5, but are of different mouse isotypes. GK1.5 gamma 1, GK1.5 gamma 2a, and GK1.5 gamma 2b are significantly more effective at CD4+ cell depletion than rat GK1.5 when low doses of antibody are administered. In contrast, no depletion is seen with GK1.5 gamma 3 at any dose. Depletion of CD4+ cells in vivo is not correlated with either the ability of the antibody to mediate C-dependent cytotoxicity or antibody-dependent cell-mediated cytotoxicity in vitro, implying that additional antibody-mediated cytotoxic mechanisms occur in vivo. The chimeric antibodies were used to investigate the mechanism of GK1.5-mediated immunotherapy in a prototypic model of T cell-mediated autoimmunity, experimental allergic encephalomyelitis. Mice treated with a single dose of 100 micrograms of either GK1.5, GK1.5 gamma 1, or GK1.5 gamma 2a showed significant recovery within 72 h. In contrast, mice treated with 100 micrograms of GK1.5 gamma 3 showed only marginal improvement within the first 72 h and regressed within 5 days of treatment initiation. These data suggest that anti-CD4-mediated immunotherapy of murine experimental allergic encephalomyelitis is correlated with depletion of CD4+ cells.
A study of in vivo immune complex formation and clearance in man.
Authors: Davies K A , Hird V , Stewart S , Sivolapenko G B , Jose P , Epenetos A A , Walport M J
Published: December 2022

C and CR1 have been shown to participate in the clearance of injected, preformed, immune complexes in humans and in non-human primates. Their role in the physiologic disposal of immune complexes formed in vivo in humans was investigated in three patients receiving radioimmunotherapy for ovarian carcinoma. On day 0 each patient received, by intraperitoneal injection, 10 mg of 131I-mouse anti-tumor mAb (10 mCi/mg). On days 1 and 2, 18 mg of trace-labeled, 125I-human anti-mouse IgG was administered by i.v. infusion over 15 min, to accelerate the clearance of the 131I-anti-tumor antibody from the circulation and reduce the radiation dose to the marrow. Sequential blood samples were obtained after the injection of the second (anti-mouse) antibody, to monitor clearance. Immune complexes (shown by sucrose gradient centrifugation to be 19 to 40 S in size) formed within 5 min, and were cleared with a half-life of 11 +/- 1.7 min in the liver. Complexes were measured by 4% polyethylene glycol precipitation, and by solid phase C3d- and C1q-binding assays. Between 8 and 11% of the total available complexed material bound to CR1 on E. Peak binding of immune complexes to red cells occurred 10 min after the maximal complex load was detected by precipitation with polyethylene glycol. At that time, immune complexes bound to E constituted one-fifth of the total circulating pool of complexes. Coincident with immune complex formation and clearance, a 47% fall in serum C4, C3, and CH50 was measured, with the deposition of up to 1230 molecules of C4, and 2590 molecules of C3 on the surface of red cells. During 20 min after immune complex formation there was a mean loss of 32% of erythrocyte CR1. The changes in complement and CR1 on E and in serum observed in these patients resembled those seen in patients with SLE: i.e., a reduction in CR1 and an increase in C3 and C4 on E, and reduced serum C.