bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiple types of chimeric germ-line Ig heavy chain transcripts in human B cells: evidence for trans-splicing of human Ig RNA.
Authors: Fujieda S , Lin Y Q , Saxon A , Zhang K 
Published: January 2023

Abstract
Germ-line transcripts from Ig heavy chain loci precede the occurrence of isotype switching and are thought to play an important though still controversial role in Ig class switching. In this study, we employed a reverse transcriptase-PCR approach to detect human chimeric Ig germ-line mRNA transcripts. Multiple types of chimeric Ig germ-line transcripts (Imu-Cepsilon, Iepsilon-Cmu, Imu-Cgamma4, Igamma-Cmu, Igamma-Cepsilon, Iepsilon-Cgamma, and Igamma4-Calpha1 transcripts) were readily detected in human B cells stimulated with IL-4 alone. Sequence analysis revealed that all of these chimeric Ig germ-line transcripts represented the I exons from one Ig locus spliced to the CH exons from another locus by using consensus sequences for splicing donor and acceptor sites, indicating that they were generated through splicing machinery. In the case of stimulation of human resting B cells with IL-4 alone, the chimeric Ig germ-line transcripts are likely derived from a trans-splicing mechanism, as the extensive searching did not find evidence that Ig class-switch recombination had occurred, which alternatively could give rise to chimeric Ig mRNA by mechanisms other than trans-splicing. Similarly, an EBV-transformed gamma2 rearranged B cell line, GM1500, which produces IgG2 and contains both gamma2 productive and epsilon germ-line transcripts, also expressed chimeric germ-line RNA (Iepsilon-Cgamma2) and epsilon-productive transcripts (VDJ-Cepsilon). This line had no further sequential Sgamma2-Sepsilon rearrangements, providing evidence that the productive VDJ-Cepsilon mRNA was derived from a transcriptionally active unrearranged epsilon gene locus by trans-splicing. Taken together, these results provide possible evidence that trans-splicing of germ-line Ig RNA transcripts occurs in human B cells.
A critical role of Sp1- and Ets-related transcription factors in maintaining CTL-specific expression of the mouse perforin gene.
Authors: Youn B S , Kim K K , Kwon B S 
Published: January 2023

Abstract
This study was designed to determine the potential cis-elements involved in transcriptional regulation of the mouse perforin gene. DNase I hypersensitive site (DHS) mapping revealed that the perforin locus contained six DHS within 7.0 kb of the 5' upstream sequence (-7.0 kb) and two DHS in intron 2. The six 5' upstream and one intronic DHS were detected in only perforin-expressing lymphocytes. Chloramphenicol acetyltransferase (CAT) activities directed by 5' upstream promoter were detected preferentially in perforin-expressing cell lines. A construct termed PFP5a containing -795 bp exhibited the highest CAT activity, and PFP9a20 containing only -73 bp also produced significantly high CAT activity in CTLL-R8 cells. The proximal region in PFP9a20 contained two potential Sp1 binding sites (GC box and GT box) and one Ets binding site (EBS). Electrophoretic mobility shift assay showed that each of the cis-elements bound specific protein factors. When single-point mutation was introduced to each GC box, EBS, and GT box in PFP9a20, at least 3-fold less CAT activity was observed in CTLL-R8 cells. To confirm the importance of the three cis-acting elements in the perforin gene expression, point mutation was introduced again to each proximal GC box, EBS, and GT box of PFP5a. The point mutations resulted in a 2.5- to 3-fold reduction of CAT activity. The results suggest that a combination of the three proximal cis-acting elements may constitute a minimal region responsible for CTL-specific expression of perforin.
Control of parasitemia and survival during Trypanosoma brucei brucei infection is related to strain-dependent ability to produce IL-4.
Authors: Bakhiet M , Jansson L , Büscher P , Holmdahl R , Kristensson K , Olsson T 
Published: January 2023

Abstract
We studied non-MHC gene-dependent expression of a number of cytokines in relation to host defense and survival during Trypanosoma brucei brucei (Tbb) infection in mice. In particular, the role of IL-4 was explored with use of genomically IL-4-disrupted mice and in vivo Ab blocking. Splenocytes from MHC-identical B10.Q (relatively resistant) mice showed day 5 postinfection higher numbers of IL-4 mRNA expressing cells than C3H.Q (highly susceptible). A trypanosome-derived lymphocyte triggering factor, which is released by Tbb to polyclonally activate CD8+ T cells, stimulated naive splenocytes in vitro to a higher IL-4 response in B10.Q than in C3H.Q mice. The C3H.Q mice developed an extremely high parasitemia, showed a low Ab response against the variant surface glycoprotein (VSG), and had a mean survival time of 42 days. Conversely, B10.Q mice had lower parasitemia, mounted higher anti-VSG response, and had a mean survival time of 56 days. Deletion of the IL-4 gene had no influence on the infection in C3H.Q mice, while in B10.Q mice the deletion was associated with lower anti-VSG Ab levels and higher parasitemia. Paradoxically, B10.Q mice with disrupted IL-4 gene survived longer than the wild type. Anti-IL-4 Ab-blocking experiments in vivo displayed an enhanced parasitemia and prolonged survival in infected B10.Q mice. We conclude that 1) a non-MHC gene-related and CD8+-dependent ability to produce IL-4 partly determines the susceptibility to Tbb infection; and 2) IL-4, although involved in controlling the levels of parasitemia by its effects on immunoglobulin synthesis, also can have toxic effects on the animals.
Induction of nitric oxide synthase in mouse dendritic cells by IFN-gamma, endotoxin, and interaction with allogeneic T cells: nitric oxide production is associated with dendritic cell apoptosis.
Authors: Lu L , Bonham C A , Chambers F G , Watkins S C , Hoffman R A , Simmons R L , Thomson A W 
Published: January 2023

Abstract
Nitric oxide (NO) is an important effector molecule that is involved in immune regulation and host defense. In this study, highly purified NLDC 145+ (DEC-205+) MHC class II(bright) B7-2+ dendritic cells (DC) propagated from normal mouse bone marrow in response to granulocyte-macrophage CSF + IL-4 were induced to produce NO by IFN-gamma and LPS. NO production was inhibited by the nitric oxide synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (NMMA). Nitrite also accumulated in mixed leukocyte culture supernatants as the result of coculture of DC with purified naive allogeneic T cells. Furthermore, NO production was induced by CD40 ligation. Suboptimal T cell proliferation observed at high relative concentrations of DC correlated with increased NO production and was mitigated by NMMA. Induction of mRNA for an inducible NOS (iNOS) in DC was confirmed by Northern blotting, whereas intracellular iNOS was visualized by two-color flow cytometry and by both immunofluorescent and immunogold labeling in a subpopulation of IFN-gamma + LPS-stimulated cells. Both endogenous NO production and exposure of unstimulated DC to the NO donor S-nitroso-N-acetyl-penicillamine (SNAP) resulted in DC apoptosis. Thus, although DC function initially as the most potent APCs for T cell activation, DC induced to synthesize NOS by IFN-gamma may inhibit (allogeneic) T cell proliferation: NO may suppress lymphocyte proliferation and also induce apoptosis of the most potent source of alloantigenic stimulation.
CD63 associates with tyrosine kinase activity and CD11/CD18, and transmits an activation signal in neutrophils.
Authors: Skubitz K M , Campbell K D , Iida J , Skubitz A P 
Published: January 2023

Abstract
As a member of the tetraspan family, it has been hypothesized that CD63 may be associated with signal transduction; however, its role in leukocyte function is unknown. To examine the potential ability of CD63 to activate neutrophils, the effects of five CD63 mAbs, AHN-16, -16.1, -16.2, -16.3, and -16.5, were examined for their ability to alter neutrophil adhesion to HUVEC monolayers. These CD63 Abs increased neutrophil adhesion to resting and TNF-stimulated HUVEC monolayers. This increase in neutrophil adhesion caused by CD63 Abs was blocked by a CD18 Ab and was associated with up-regulation of CD11/CD18 and down-regulation of CD62L on the neutrophil surface. CD11/CD18 was also found to be associated with CD63. This increase in neutrophil adhesion required physiologic extracellular calcium concentrations at or near the time of CD63 Ab binding. The incubation of CD63 Abs with cells in the absence of calcium for 10 min before repletion of calcium resulted in no increase in neutrophil adhesion. Protein kinase activity was detected in neutrophils associated with CD63. Most of the protein kinase activity associated with these Ags was tyrosine kinase activity, with a lesser amount of threonine and serine kinase activities. Src family kinases Lyn and Hck accounted for much of the associated tyrosine kinase activity. The data suggest that CD63 Ab binding to the neutrophil surface triggers a transient activation signal that requires extracellular calcium and regulates the adhesive activity of CD11/CD18. Associated protein kinase activity may play a role in signal transduction by CD63 to regulate other cell functions.
Reverse signaling via CD30 ligand.
Authors: Wiley S R , Goodwin R G , Smith C A 
Published: January 2023

Abstract
CD30 ligand (CD30L), a member of the TNF family, is a type II membrane protein with a C-terminal extracellular domain that is homologous with the extracellular domains of other TNF family members. Also, like most TNF family members, the N-terminal cytoplasmic domain of CD30L is conserved across species, but not between family members, suggesting a possible biological function. Motivated by this observation, we investigated the potential for CD30L, when activated by cross-linking, to directly transduce a signal to the ligand-bearing cell. Cross-linking of CD30L by a mAb or by CD30-Fc fusion protein induced the production of IL-8 by freshly isolated neutrophils. Further, both cross-linking mechanisms produced a rapid oxidative burst. Indirect effects through CD30 were ruled out, since CD30L, but not CD30, is expressed on neutrophils. Expression of CD30L can be induced in peripheral blood T cells by cross-linking the CD3 component of the TCR. Peripheral blood T cells exposed to suboptimal concentrations of anti-CD3 increased metabolic activity, proliferated, and produced IL-6 in response to cross-linking of CD30L. These results indicate that cross-linked CD30L can transduce a signal to the ligand-bearing cell. This "reverse signaling" via CD30L taken together with previously published data concerning other ligands in the TNF family strongly suggest that, as a rule, TNF family members and their cognate receptors signal bidirectionally, blurring the distinction between ligand and receptor.
Regulation of surface and soluble TNF receptor expression on human monocytes and synovial fluid macrophages by IL-4 and IL-10.
Authors: Hart P H , Hunt E K , Bonder C S , Watson C J , Finlay-Jones J J 
Published: January 2023

Abstract
By regulating monocyte and macrophage production of IL-1, its receptor, and its receptor antagonist, IL-4 and IL-10 may exert significant anti-inflammatory activity. We determined whether a similar multicomponent process controlling TNF activity was regulated by IL-4 and IL-10 in nonadherent monocytes and synovial fluid macrophages. Previous studies differed in their conclusions. For both the p75 and p55 TNF receptors, mRNA levels, surface receptor expression, and soluble receptor levels were measured for blood monocytes incubated in vitro for 17, 40, or 64 h with IL-4 or IL-10. The predominant TNF receptor on monocytes, the p75 receptor, was down-regulated by IL-4 at the mRNA level. In turn, both surface and soluble receptor levels on LPS-stimulated cells were reduced and the inhibitory effects were maintained for at least 64 h. In contrast, IL-10 increased surface and soluble p75 TNF receptor levels on monocytes for approximately 40 h, which reflected an increase in receptor mRNA. These studies suggest that IL-4 and IL-10 do not directly regulate the cleavage of TNF receptors from monocytes and macrophages. Addition of an Ab to IL-10 suggested that the stimulatory effects of LPS on p75 TNF receptor expression were due, at least in part, to LPS stimulation of IL-10 production and that IL-4 acted, in part, by decreasing IL-10 production. IL-4 was down-regulatory and IL-10 stimulatory for TNF receptor expression by synovial fluid macrophages. By increasing surface receptor levels, IL-10 enhanced the activities of TNF on monocytes for IL-1beta production. By increasing soluble TNF receptor levels, IL-10 may limit only temporarily the activity of other TNF-responsive cells. This study questions the benefit of IL-10 to resolving TNF-associated inflammation.
IL-15 stimulates the expansion of AIDS virus-specific CTL.
Authors: Kanai T , Thomas E K , Yasutomi Y , Letvin N L 
Published: January 2023

Abstract
It has been assumed that the maturation of pre-CTL to virus-specific effector CTL is dependent upon IL-2-mediated T cell triggering through the IL-2R. In view of its similarity to IL-2 in its effects on immune cells, we sought to determine whether IL-15 can induce the expansion of AIDS virus-specific pre-CTL to mature CTL. PBL of SIV(mac)-infected rhesus monkeys or HIV-1-infected humans have previously been shown to expand to effector CTL when cultivated with a predicted CTL epitope peptide and rIL-2. We now demonstrate that rIL-15 facilitates this expansion of effector CTL. In fact, rIL-15-driven expansion of virus-specific CTL occurs in the presence of IL-2-neutralizing or anti-IL-2R Abs, indicating that this cellular maturation can occur in an IL-2-independent fashion. These studies suggest a mechanism by which CTL may be capable of expanding in vivo in the absence of IL-2 and functional CD4+ T lymphocytes.
The immune response to 52-kDa Ro and 60-kDa Ro is linked in experimental autoimmunity.
Authors: Keech C L , Gordon T P , McCluskey J 
Published: January 2023

Abstract
Clustering of autoantibody specificities is a consistent finding in patients with systemic autoimmune diseases. Patients with Sjögren's syndrome frequently have autoantibodies to La, 60-kDa Ro(SS-A) protein (Ro60), and 52-kDa Ro(SS-A) protein (Ro52). In the case of anti-Ro60 and anti-La, there is evidence that these specificities occur together because of the physical association of the Ro60 and La proteins that form a ribonucleoprotein particle (RNP). Thus, the autoantibody response may spread from a single epitope to involve new epitopes located within other components of the RNP. The physical association of Ro52 with the Ro/La RNP has remained controversial, implying that Abs to Ro52 are not a consequence of intermolecular spreading and may be triggered independently of the anti-Ro60 response. To examine this relationship of the immune response to Ro52 and Ro60, mice were immunized with recombinant Ro52, Ro60, or La, and examined for autoantibody production. Immunization with Ro52 resulted in rapid, high titer Ab production to Ro52, followed 7 to 14 days later by lower titer autoantibody production to Ro60. Immunization with Ro60 led to anti-Ro60, which was also followed 7 to 14 days later by a lower titer anti-Ro52 response. Cross-reactivity of affinity-purified Abs from immune mouse sera was not observed. These observations suggest that the autoimmune responses to Ro60 and Ro52 are linked intrinsically, despite previous evidence suggesting they are not associated in vivo. The mechanism of linkage remains unclear, but the data are most consistent with some physical association of Ro52 and Ro60 allowing autoimmunization, presumably as a result of normal cell turnover or specific injury in vivo.
High density insulin receptor-positive T lymphocytes from nonobese diabetic mice transfer insulitis and diabetes.
Authors: McInerney M F , Flynn J C , Goldblatt P J , Najjar S M , Sherwin R S , Janeway C A 
Published: January 2023

Abstract
In the nonobese diabetic mouse, insulin-dependent diabetes is an autoimmune disease characterized by T cell-mediated invasion and destruction of pancreatic islet beta cells. The importance of insulin receptor (IR) expression in the pathogenesis of diabetes was examined, since it has been shown that the IR is a chemotactic receptor capable of directing cell movement in response to insulin. Using polyclonal antisera to the IR, phenotypic analysis of purified splenic T cells from diabetic mice showed that about 15% of T cells expressed high density IR (IRhigh). In addition, IRhigh T cells were already a dominant phenotype in the insulitis of young prediabetic mice. To determine the ability of IRhigh T cells to transfer diabetes, cells were sorted by flow cytometry before adoptive transfer into young (6- to 8-wk-old) nondiabetic irradiated nonobese mice. Transfer of as few as 3 x 10(6) purified IRhigh T cells alone resulted in rapid onset of insulitis and diabetes, and IRhigh-depleted T cells were essentially unable to passage either insulitis or diabetes. The adoptive transfer of disease was not due to the transfer of activated cells, since removal of IL-2R+ or transferrin R+ cells did not alter diabetes transfer. Therefore, IRhigh T cells are aggressively diabetogenic, suggesting that increased IR expression may provide a mechanism for delivering potentially autoreactive T cells to the islet, regardless of their activation state.
Expression of acetylcholine receptor genes in human thymic epithelial cells: implications for myasthenia gravis.
Authors: Wakkach A , Guyon T , Bruand C , Tzartos S , Cohen-Kaminsky S , Berrih-Aknin S 
Published: January 2023

Abstract
The intrathymic presence of the muscle acetylcholine receptor (AChR) is controversial, and the nature of the cell(s) expressing it is unclear. We thus analyzed the molecular expression of muscle AChR in human thymi. mRNA studies indicated that the two isoforms (P3A+ and P3A-) of the alpha-subunit were present in thymic extracts and in cultured thymic epithelial cells (TEC), while expression in thymocytes was low and not consistently detectable. The amount of mRNA coding for the alpha-subunit, evaluated by means of quantitative PCR, was about 20 times less in TEC than in muscle, and was similar in TEC from normal subjects and from patients with myasthenia gravis (MG). The beta- and epsilon-subunits present in adult AChR were also expressed in TEC (but not in thymocytes), while the embryonic subunit (gamma) was absent. In TEC cultures, the AChR alpha- and epsilon-subunit mRNA levels were down-regulated by forskolin, as also observed in the TE671 rhabdomyosarcoma cell line, suggesting similar regulation of AChR subunits in thymus and muscle. Protein expression was evidenced on TEC (but not on thymocytes), by Western blotting as well as by immunofluorescence, thus demonstrating AChR expression on human thymic epithelial cells. There was no difference in the expression of AChR between TEC from MG patients and controls, meaning that the expression of AChR subunits alone is not sufficient to explain the onset of MG.
Genetic susceptibility to experimental autoimmune uveitis involves more than a predisposition to generate a T helper-1-like or a T helper-2-like response.
Authors: Sun B , Rizzo L V , Sun S H , Chan C C , Wiggert B , Wilder R L , Caspi R R 
Published: January 2023

Abstract
This study examines whether genetic susceptibility vs resistance to experimental autoimmune uveoretinitis (EAU) in mice is associated with dominant type 1 vs type 2 cytokine response profiles. Mice from six strains were immunized with the uveitogenic retinal Ag IRBP. EAU was evaluated by histopathology. As judged by disease scores, three of the strains were susceptible, one was minimally susceptible, and two were resistant. Ag-specific type 1 vs type 2 cytokine responses (protein and/or mRNA) in draining lymph node cells, and IgG2a vs IgG1 Ab isotypes to IRBP, were measured as indicators of Th1-like vs Th2-like responses, respectively. The three susceptible strains (B10.A, C57BL/10, and BALB/k) showed a dominant Th1-like response profile characterized by high IFN-gamma and IL-12p40 (but not IL-4) responses, and a predominance of IgG2a Abs. The minimally susceptible strain (A/J) had an IFN-gamma response detectable only at the mRNA level, but produced predominantly IgG2a Abs. One of the two resistant strains (BALB/c) showed a characteristic Th2-like response with dominant Ag-specific IL-4 and IL-10 responses but no IFN-gamma, and predominantly IgG1 Abs. However, the other resistant strain (AKR) did not show a Th2-dominated response pattern, in that it had low, or no, IL-4 and IL-10 responses, and made predominantly IgG2a Abs to IRBP. These results suggest that whereas a Th1 response is required for susceptibility, resistance is not dependent on a Th2 response pattern. We suggest that regulatory influences other than skewing the response toward the Th2 pathway may be equally effective at conferring genetic resistance to EAU.
B cell genotype determines the fine specificity of autoantibody in lpr mice.
Authors: Kakkanaiah V N , Sobel E S , MacDonald G C , Cheek R L , Cohen P L , Eisenberg R A 
Published: January 2023

Abstract
Anti-Sm Abs are specific markers of human systemic lupus erythematosus (SLE) and of murine models of this disease. In humans, anti-Sm Abs are mostly IgG1, and in MRL/lpr mice, IgG2a; both are T-dependent isotypes. Other lpr strains, such as B6/lpr, do not produce anti-Sm Ab spontaneously. The present study was aimed at identifying the cellular expression of background genes responsible for generation of the anti-Sm Ab response in MRL/lpr mice. We used double chimeric mice made by transferring MRL/lpr and B6/lpr bone marrows into irradiated allotype heterozygous F1 mice. Five mo after reconstitution, FACS analysis of lymph node (LN) and spleen cells revealed that both MRL/lpr and B6/lpr cells coexisted in roughly equal numbers. Ab produced by each donor could be distinguished by allotype-specific assays. IgG2a anti-Sm was made only by MRL-derived B cells despite the presence of T cells that might potentially provide help to the B6/lpr B cells. The frequency of anti-Sm Ab-producing individuals was similar to that of unmanipulated MRL/lpr mice (about 25%). IgG2a anti-chromatin and total IgG2a was mostly dominated by the MRL-derived B cells. B6-derived B cells produced more rheumatoid factor (RF) against their own IgG2b(b), while RF against IgG2a was dominated by MRL-derived B cells. This suggests that the control of the production of particular autoantibody specificities, such as anti-Sm, is determined by the expression of MRL or B6 background genes in B cells.
Reconstitution of the extrathymic intestinal T cell compartment in the absence of irradiation.
Authors: LefrançoisL  , Olson S 
Published: January 2023

Abstract
Extrathymic development of intestinal intraepithelial lymphocytes was studied using a reconstitution model that does not require irradiation. WBB6F1/J-Kit(W)/Kit(W-v) mice were reconstituted with normal fetal liver cells. In this system, reduced c-Kit activity in host hemopoietic progenitors imparts normal precursors with a growth advantage and, thus, chimerism can be established without irradiation. In control mice, TCR gammadelta and TCR alphabeta intraepithelial lymphocytes (IEL) developed efficiently from fetal liver cells, with a predominance of TCR alphabeta over TCR gammadelta IEL. In contrast, development in reconstituted thymectomized mice was heavily skewed toward TCR gammadelta IEL generation. In thymectomized mice, development of CD4+ 8- and CD4+ 8+ TCR alphabeta IEL did not occur, while TCR alphabeta CD8 alphabeta development was nearly absent. The results indicated that without irradiation the majority of TCR alphabeta IEL were thymus dependent, whereas TCR gammadelta IEL developed extrathymically. Thus, the discrepancies observed between different models of athymic development may be explained by the induction of T cell development as a result of irradiation.