bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protection from T helper cell-mediated graft-versus-host disease by the presence of an MHC class I alloantigen is associated with perturbation of MHC class II-restricted responses by class I-derived peptides.
Authors: Leibnitz R R , Lipsky P E , Thiele D L 
Published: December 2022

Abstract
Lethal graft-vs-host disease (GVHD) develops after transfer of CTL-depleted spleen and bone marrow cells from C57BL/6 (B6) mice to irradiated MHC class II disparate (B6xbm12)F1 recipients. Onset of lethal GVHD is significantly delayed in (bm1xbm12)F1 recipients of the same donor inoculum despite the additional MHC class I disparity (H-2Kbm1). To investigate the basis of this protective effect, hybridomas were generated from T cells activated in vivo during GVHD in both strain combinations. T cells from B6--&gt;(B6xbm12)F1 mice generated a significantly higher frequency of B6.C-H-2bm12 (bm12)-specific T hybridomas (110/178, 62%) than T cells from B6--&gt;(bm1xbm12)F1 mice (102/218, 47%). Some bm12-specific T hydridomas exhibited lesser responses to (bm1xbm12)F1 than to (B6xbm12)F1 APC. Moreover, bm1 peptides spanning a 14-amino acid region that includes the three amino acids that differ from H-2Kb were found to inhibit responses of some bm12-specific T hybridomas and to decrease significantly responses of splenic B6 CD4+ T cells to bm12 APC. Notably, the frequency of bm12-reactive hybridomas susceptible to inhibition by bm1 peptides generated from B6--&gt;(B6xbm12)F1 mice was significantly greater than that generated from B6--&gt;(bm1xbm12)F1 mice. Additional analysis using L cell transfectants indicated that hybridomas responding to the bm12 mutation at position 70 alone were rarely inhibited by bm1 peptides. The data indicate that expression of bm1-derived peptides can influence the frequency and specificity of alloreactive CD4+ T cells stimulated in vivo and thus may alter the course of GVHD.
Invariant chain-independent antigen presentation depends primarily upon the pool of newly synthesized MHC class II molecules.
Authors: Swier K , Miller J 
Published: December 2022

Abstract
During biosynthesis, MHC class II molecules are diverted to endocytic compartments in which they bind antigenic peptides to be displayed on the surfaces of APC. For many Ags, the efficiency of class II presentation is enhanced by the intracellular association of class II with invariant chain (li), consistent with a role for newly synthesized class II molecules in Ag presentation. For a subset of Ags, however, efficient presentation does not require li. These Ags may also be bound by class II molecules en route to the cell surface. Alternatively, li-independent Ag presentation may utilize a pool of preexisting class II molecules that may gain access to endosomes following internalization from the cell surface. To examine the role of newly synthesized class II in the presentation of the li-independent Ag, RNase, we placed class II biosynthesis under the translational control of an iron response element. Chelation of iron from the media resulted in efficient diminution of class II synthesis and a marked decrease in the efficiency of RNase presentation. When compared with other cells expressing varying amounts of class II, we found that the ability to present RNase correlates with the level of class II biosynthesis and not with the level of class II surface expression. Because these cells internalize class II at a significant rate, we conclude that even in the absence of li, class II molecules can reach endocytic compartments containing antigenic peptides and they do so on their biosynthetic pathway.
Isolation of Xenopus LMP-7 homologues. Striking allelic diversity and linkage to MHC.
Authors: Namikawa C , Salter-Cid L , Flajnik M F , Kato Y , Nonaka M , Sasaki M 
Published: December 2022

Abstract
The mammalian low molecular mass protein-7 (LMP-7) gene resides in the class II region of the MHC, and its product is most probably involved, as a component of a proteasome, in the processing of Ags to be presented by the MHC class I molecules. To elucidate the evolution of the LMP-7 gene at both the primary structure and genetic levels, we isolated LMP-7 cDNA clones from amphibian Xenopus laevis, which last shared a common ancestor with mammals 350 x 10(6) years ago. Two distinctive clones, showing an 85% predicted amino acid sequence identity with each other and 69 to 72% identity with human and mouse LMP-7, were identified from a liver cDNA library of outbred frogs and named XeLMP-7A and XeLMP-7B. XeLMP-7A- and XeLMP-7B-specific probes were used to detect the corresponding genes by using partially inbred frogs with known MHC haplotypes. DNA of the g and j haplotypes hybridized with the XeLMP-7A probe, whereas the f and r haplotype DNA hybridized with the XeLMP-7B probe. These hybridization patterns cosegregated with the MHC haplotypes among offspring of an f/f x f/g cross, and one recombinant revealed that the LMP-7 gene is linked more closely to class II than to class I or class III genes. Taken together, the data indicate that XeLMP-7A and XeLMP-7B are highly diverse alleles at a single locus in the frog MHC. The great allelic diversity can be explained either by coselection with particular class I alleles or by differential silencing of MHC genes in the polyploid X. laevis.
Diversity of T cell receptor delta-chain cDNA in the thymus of a one-month-old pig.
Authors: Yang Y G , Ohta S , Yamada S , Shimizu M , Takagaki Y 
Published: December 2022

Abstract
Pig TCR delta-chain cDNA sequences were obtained from the anchored PCR products of the reverse-transcribed RNA from the thymus of a 1-mo-old germfree pig. Among 43 sequences analyzed, 4 different J delta sequences were found, and in the cDNA sequences of rearranged V-D-J junctional regions, three putative D delta sequences were assigned. Also, the V delta region sequences were grouped into five families. One family, V delta 1, consisted of a large number of members and the other families consisted of limited members as determined by cDNA sequences as well as genomic Southern blots. Using PCR, V delta 1 gene segments were also obtained from liver genomic DNA of the same individual pig. Thirty-one distinct sequences were found for the V delta 1 family including the sequences obtained from both the thymic RNA and the PCR product of liver DNA. All the V delta 1 genes were found to be associated with almost identical leader gene sequences. The amino acid sequences of the complimentarity-determining region 3 coded by the V-D-J joints gave long and variable lengths with a high content of tryptophan and charged amino acids. The length of the complimentarity-determining region 3 in the porcine TCR delta-chain supports the idea that TCR delta-chain is designed to see Ags directly similar to the Ig heavy chain. Data presented from this study shows that the porcine TCR delta-chain has extensive V region diversity as well as junctional diversity. The combination of these two creates a level of diversity that is the highest of any lymphocyte Ag receptor studied so far.
Affinity maturation of the BR96 anti-carcinoma antibody by codon-based mutagenesis.
Authors: Yelton D E , Rosok M J , Cruz G , Cosand W L , Bajorath J , Hellström I , Hellström K E , Huse W D , Glaser S M 
Published: December 2022

Abstract
We have increased up to 65-fold the avidity of BR96, a mAb recognizing Lewis Y (Le(y))-related Ags expressed on the surface of many human carcinomas. Libraries of mutations in the complementarity-determining regions (CDRs) of BR96 were constructed in an M13 phage Fab expression vector by codon-based mutagenesis, a method that efficiently introduces large numbers and potentially all combinations of amino acid substitutions. Two mutants that improved the affinity of BR96 to tumor Ag were identified by screening the libraries on carcinoma cell lines. One mutant, M1, at position 97 (Asp to Ala) in CDR3 of the heavy chain, resulted in an 8- to 10-fold improvement in Ag binding, as assessed by ELISA. A second mutant, M2, at position 53 (Gly to Asp) in CDR2 of VH increased binding three- to fivefold. When these mutations were combined, the resulting Fab M3 was improved approximately 30-fold. An additional library was constructed in CDR1 of M1. M4, a mutation with three amino acid substitutions in CDR1, was isolated by screening the library with an enzyme conjugate of synthetic Le(y) tetrasaccharide (sLe(y)). This mutant improved BR96 Fab affinity to sLe(y) an estimated 15- to 20-fold by ELISA, and 14-fold as measured by surface plasmon resonance. The M4 IgG had 65-fold improved avidity to sLe(y) relative to the BR96 IgG. The mutants will be useful for comparison of the efficacy of Abs with different affinities for delivery of cytotoxic agents to tumor cells.
Mucoid Pseudomonas aeruginosa growing in a biofilm in vitro are killed by opsonic antibodies to the mucoid exopolysaccharide capsule but not by antibodies produced during chronic lung infection in cystic fibrosis patients.
Authors: Meluleni G J , Grout M , Evans D J , Pier G B 
Published: December 2022

Abstract
Serum opsonophagocytic-killing titers often indicate the level of immune resistance to bacterial pathogens, yet in almost all cystic fibrosis (CF) patients that have chronic lung infections with mucoid Pseudomonas aeruginosa, high titers of opsonic-killing Abs can be measured and the infectious pathology still progresses through pulmonary failure and death. This anomalous finding may be due to the use of suspended cells of P. aeruginosa to evaluate phagocytic killing, whereas in the lungs of CF patients the organisms grow in a microcolony or biofilm, encased in mucoid exopolysaccharide (MEP, also called alginate). To determine whether the microcolony mode of growth contributes to bacterial resistance to host defenses, we evaluated opsonophagocytic killing of mucoid P. aeruginosa growing in a biofilm. Abs from infected CF patients were poorly able to mediate opsonic killing of biofilm, but not suspended, mucoid P. aeruginosa cells. Bacterial resistance to killing could be overcome by disruption of the biofilm layer with an enzyme that degrades MEP. Chronically infected CF patients also fail to produce opsonic-killing Abs specific to MEP, and when these Abs were evaluated in sera of older, noninfected CF patients and humans vaccinated with MEP, comparable killing of P. aeruginosa in biofilms and suspensions was obtained. In this case, C3 was deposited onto the MEP layer and could be visualized by fluorescence microscopy deposited throughout the biofilm. We conclude that opsonic Abs made by CF patients in response to chronic infection are ineffective at mediating phagocytic killing and elimination of bacterial cells growing as microcolonies in their lungs.
The delayed-type hypersensitivity reaction is dependent on IL-8. Inhibition of a tuberculin skin reaction by an anti-IL-8 monoclonal antibody.
Authors: Larsen C G , Thomsen M K , Gesser B , Thomsen P D , Deleuran B W , Nowak J , Skødt V , Thomsen H K , Deleuran M , Thestrup-Pedersen K 
Published: December 2022

Abstract
Cell-mediated immune reactions are essential to our immune response toward foreign organisms such as microorganisms, or in the response toward foreign tissue Ags, as seen in the rejection of allogeneic transplanted organs. Similar reactions form the basis for the development and the progression of delayed-type hypersensitivity (DTH) reactions. We found that the alpha-chemokine IL-8 plays an important pathophysiologic role for the development of a DTH reaction because infusion of a neutralizing anti-IL-8 mAb (WS-4) was able to suppress the development of a tuberculin skin reaction in rabbits, as judged by histologic, biochemical, and clinical examinations. Thus, the number of neutrophil granulocytes and lymphocytes at the site of tuberculin injection was decreased considerably, and the clinical signs of inflammation were suppressed almost completely at 24 h after intracutaneous injection of tuberculin, as judged by the size of the infiltrates. In contrast, we did not see any effect on the visible erythema of the skin. We found that the tissue content of myeloperoxidase (MPO), reflecting the number of infiltrating neutrophils, was lowered significantly. Furthermore, immunohistochemical analysis confirmed that IL-8 immunoreactivity is actually enhanced in the skin of positive tuberculin reactions. The results indicate that IL-8 plays an important role for the early accumulation of leukocytes in the skin and for the clinical signs of a DTH reaction.
Association between Lyn protein tyrosine kinase (p53/56lyn) and the beta subunit of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors in a GM-CSF-dependent human megakaryocytic leukemia cell line (M-07e).
Authors: Li Y , Shen B F , Karanes C , Sensenbrenner L , Chen B 
Published: December 2022

Abstract
The role of the lyn product (p53/p56lyn), a membrane-associated protein tyrosine kinase in the signaling pathway used by granulocyte macrophage-CSFR (GM-CSFR) was investigated by using the GM-CSF-dependent human megakaryoblastic leukemia cell line M-07e. M-07e cells express GM-CSFR and are dependent on GM-CSF for survival and proliferation in vitro. Treatment with anti-lyn Abs coimmunoprecipitated, along with lyn product, the beta subunit of GM-CSFR and a phosphoprotein with a molecular mass of 120 kDa (p120) in the lysates of M-07e cells but not in the lysates of human monocyte-derived macrophages (HMDM) or human lymphoid leukemia cells. That the 120-kDa phosphoprotein coimmunoprecipitated by anti-lyn Abs is the beta subunit of GM-CSFR was confirmed in the immunoprecipitates (IP) of M-07e cells with the use of an agarose-conjugated anti-p-tyr mAb. The formation of GM-CSF/GM-CSFR/lyn signaling complexes was verified in an autoradiographic study with anti-lyn IP of M-07e cells that had been bound with 125I-labeled recombinant human (rh)GM-CSF. The p120 protein (beta subunit) was not detected in the IP of M-07e cells with anti-fyn or anti-PI3 Abs. A direct association of Lyn kinase with the beta subunit of GM-CSFR was illustrated with a reversed approach showing the recovery of Lyn protein in anti-beta (CRS1) but not anti-alpha IP of M-07e cells that had been starved for a prolonged period. Finally, the interaction of Lyn kinase with the GM-CSFR complexes was further corroborated using anti-GM-CSF (G133) mAb, which coimmunoprecipitated both the p120 beta subunit and lyn product in the lysates of M-07e cells that had been bound with rhGM-CSF before cell lysis. Removal of rhGM-CSF from culture medium for 10 to 12 h resulted in a marked decrease in lyn-associated kinase activity but not the beta subunit/lyn kinase complex formation. Taken together, our results showed that, in M-07e cells, Lyn protein tyrosine kinase (p53/p56lyn) is stably associated with a constitutively phosphorylated beta subunit of the GM-CSFR in a manner that seems to be independent of lyn kinase activity.
Cross-linking of CD45 enhances activation of the respiratory burst in response to specific stimuli in human phagocytes.
Authors: Liles W C , Ledbetter J A , Waltersdorph A W , Klebanoff S J 
Published: December 2022

Abstract
The phosphotyrosine phosphatase CD45 is expressed on the surface of all leukocytes and is known to play a critical role in the regulation of both T and B cell function. In contrast, relatively little information exists regarding the role of CD45 in the phagocyte lineage. We present evidence that CD45 modulates activation of the inducible respiratory burst in normal human neutrophils, monocytes, and eosinophils, as measured by luminol-enhanced chemiluminescence. In neutrophils, the respiratory burst induced by FMLP (1 microM), granulocyte-macrophage CSF (GM-CSF; 1 microgram/ml), or TNF-alpha (100 U/ml) was enhanced synergistically by CD45 cross-linking. This effect was most striking upon stimulation with TNF-alpha, in which cross-linking of CD45 resulted in a 30-fold increase in chemiluminescence. Chemiluminescence induced by PMA (100 nM), opsonized zymosan (1 mg/ml), LPS (1 microgram/ml), IFN-gamma (100 U/ml), or granulocyte CSF (1 microgram/ml) was not affected significantly by CD45 cross-linking. Similar results were obtained by using iodination for measurement of the respiratory burst. In monocytes, CD45 cross-linking significantly increased chemiluminescence stimulated by FMLP, GM-CSF, TNF-alpha, and LPS, and GM-CSF- and TNF-alpha-induced chemiluminescence was enhanced significantly by cross-linking of CD45 on eosinophils. Immunoblot analysis demonstrated that both the rate and intensity of TNF-alpha-induced tyrosine phosphorylation were increased by CD45 cross-linking in neutrophils. Major tyrosine-phosphorylated products include proteins with approximate molecular masses of 40 kDa, 70 kDa, 78 kDa, and 110 kDa. These results provide direct evidence that CD45 is capable of regulating the inducible respiratory burst in human phagocytes. On the basis of our findings, we postulate that CD45 may mediate coupling of specific cell surface receptors to downstream tyrosine kinase-dependent signal-transduction pathway(s) in activated phagocytes.
Biased liver T cell receptor V beta repertoire in a murine graft-versus-host disease model.
Authors: Howell C D , Li J , Roper E , Kotzin B L 
Published: December 2022

Abstract
Murine graft-vs-host disease (GVHD) results in destruction of small bile ducts in the liver. We analyzed the TCR V beta repertoire of lymphocytes isolated from the livers and spleens of individual B10.D2 into irradiated BALB/c GVHD mice by means of two-color immunofluorescence. Each mouse showed an increase in at least one V beta population in the liver and spleen, but the expanded V beta populations were heterogeneous and variable among individual GVHD mice. Overall, the repertoire of liver CD4 cells was biased toward V beta 2 and 3 expression with 65 and 88% of mice, respectively, showing an increase in these subsets. The splenic CD4 cell repertoire was biased toward V beta 3 and 4 expression (50% of mice each). The repertoire of CD8 cells was less biased with 20 to 35% of mice showing expansions of V beta 3+, 4+, 5+, 6+, 8.1+, 8.2+, and 8.3+ T cells in both the liver and spleen. V beta 2+ CD4 cells were increased preferentially in the liver compared with the spleen. These results indicate that the infiltrating liver and splenic T cells are polyclonal and suggest that donor T cells recognize multiple host non-MHC Ags in this GVHD model. Alloantigens recognized by V beta 2+ CD4 cells appear to be selective for the liver. Expansion of V beta 3+ CD4 cells may reflect recognition of the host Mls-3 superantigen.
Stimulation of human bone marrow stromal cell tyrosine kinases and IL-6 production by contact with B lymphocytes.
Authors: Jarvis L J , LeBien T W 
Published: December 2022

Abstract
The interaction of normal human B cell precursors with the bone marrow (BM) stromal cells that support their growth and maturation is mediated by adhesion of B cell CD49d/CD29 (alpha 4 beta 1 integrin or VLA-4) to stromal cell signal transduction, we generated CD49d-deficient variants of the RAMOS early b Burkitt's lymphoma cell line. RAMOS was chosen due to its lack of expression of CD49e (alpha 5 integrin) and CD44, which could potentially interact with stromal cells or their extracellular matrix. In contrast to the parental RAMOS cell line, CD49d-deficient RAMOS cell lines did not adhere to primary human BM stromal cells. Tyrosine phosphorylation of several stromal cell proteins was stimulated within 5 to 10 min of contact with either CD49d-expressing or CD49d-deficient RAMOS. These proteins included a 110-kDa substrate tentatively identified as pp125FAK. In contrast, mAb cross-linking of stromal cell CD106 had no significant effect on protein tyrosine phosphorylation. Il-6 production by stromal cells was enhanced up to fourfold over 3 days when stromal cells were cultured in contact with RAMOS cells, regardless of CD49d expression. Stromal cell IL-6 production was not significantly enhanced by RAMOS cells cultured above the stromal cells in Transwell inserts. Thus, we have demonstrated through the use of paired CD49d-expressing and CD49d-deficient RAMOS cell lines that protein tyrosine kinase activity and IL-6 production by primary human BM stromal cells can be enhanced in a manner that is dependent on B cell contact but independent of CD49d-mediated adhesion. These results indicate the potential for B cells to interact with cells in their microenvironment and activate feedback mechanisms mediated by stromal cells, which may regulate lymphopoiesis.
Functional expression and recognition of nonclassical MHC class I T10b is not peptide-dependent.
Authors: Kaliyaperumal A , Falchetto R , Cox A , Dick R , Shabanowitz J , Chien Y H , Matis L , Hunt D F , Bluestone J A 
Published: December 2022

Abstract
Studies of classical and nonclassical MHC class I molecules have shown that unique peptides are associated and functionally recognized by alloreactive T cells. We have recently shown that an alloreactive TCR-gamma delta cell recognizes a nonclassical MHC molecule, T10b. However, T cell recognition of this glycoprotein did not appear to require typical peptide recognition based on studies using transporter-defective mutant cell lines. In the current study, we have analyzed in detail, the role of peptide in T10b expression and recognition. The findings reveal that the recognition of the nonclassical MHC molecule by TCR-gamma delta cells is independent of species, tissue type, both the class I and class II Ag processing and presentation pathways, or the presence of peptides. In fact, biochemical analysis of the T10b chimeric molecule, T10b/Ld, transfected into CHO cells using radiolabeled [3H]leucine, HPLC, and mass spectrometry suggest that peptides are not associated with this nonclassical class I molecule. Therefore, some class I molecules, e.g., T10b, do not associate with polymorphic peptides typical of classical MHC class I molecules and can be expressed in the absence of peptides on the cell surface in a functionally active form.
Kinetics of Th1 and Th2 cytokine production during the early course of acute and chronic murine graft-versus-host disease. Regulatory role of donor CD8+ T cells.
Authors: Rus V , Svetic A , Nguyen P , Gause W C , Via C S 
Published: December 2022

Abstract
Acute and chronic graft-versus-host disease (GVHD) in the parent-into-F1 model are mediated by predominantly cellular or humoral immune responses, respectively, and are strikingly different entities by 2 wk of disease. Both forms of GVHD, however, evolve from a common starting point, i.e., donor CD4+ T cell recognition of host alloantigen and IL-2 production. Our study examines the first 2 wk of GVHD to delineate the events that critically influence GVHD development. Surprisingly, both forms of GVHD are initially characterized by increased Th2 cytokine (IL-4 and IL-10) production and B cell activation which persists into wk 2. The earliest distinguishing features of acute GVHD were detectable at days 5 through 7 of disease and consisted of 1) expansion of donor CD8+ T cells, and 2) increased IFN-gamma production by donor CD4+ and CD8+ T cells. Interestingly, IFN-gamma production by donor CD4+ T cells was not seen if donor CD8+ T cells were not engrafted in comparable numbers. Chronic GVHD in the DBA-into-BDF1 model was found to be caused by a relative defect in the ability of DBA CD8+ T cells to induce acute GVHD and to produce IFN-gamma. These studies demonstrate that both acute and chronic GVHD begin as a Th2 cytokine-mediated, B cell stimulatory response. The transition to acute GVHD is critically dependent on the engraftment of donor CD8+ T cells, which terminate B cell hyperactivity by 1) eliminating activated B cells and 2) promoting IFN-gamma secretion by donor CD4+ T cells.