bluuebunny/crossref_metadata_2025 huggingface dataset:
Replacement of N-glycosylation sites on the MHC class II E alpha chain. Effect on thymic selection and peripheral T cell activation.
Authors: Ishikawa S , Kowal C , Cole B , Thomson C , Diamond B
Published: December 2022

MHC class II molecules play a central role in thymic selection of developing T cells, Ag presentation to immunocompetent CD4+ T cells, and T cell activation by superantigens. We have established transgenic A.CA mice expressing either the wild-type E alpha d molecule (E alpha/E beta), or an E alpha d molecule altered at an N-glycosylation site on the E alpha chain (residue 78, 78E alpha/E beta or residue 118, 118E alpha/E beta) to identify a possible role for carbohydrates in thymic selection and peripheral T cell activation. Striking differences were found among these transgenic mice. Although V beta 10+ T cells were selected positively in all three transgenic strains, positive selection of V beta 7+ T cells was impaired in 118E alpha/E beta transgenic mice. Spleen cells from both strains with mutant E alpha chains showed selective defects in presentation of peptides to particular T cell hybridomas. In contrast, neither mutation affected presentation of the superantigen Mycoplasma arthriditis mitogen. These results demonstrate that alterations in the glycosylation of class II E alpha chains might affect both central and peripheral T cell regulation.
Lytic reaction of in vivo primed peritoneal exudate CTL. Induction of high-conductance single channels in the target cell membrane.
Authors: Lavy R , Mika Y H , Rosen D , Berke G , Binah O
Published: December 2022

CTL, primary effectors in immune responses, deliver a "lethal hit" signal to target cells, causing their destruction. The precise membrane events associated with the lethal hit remain elusive. We investigated the signal(s) mediating destruction of tumor target cells (EL4) by perforin-deficient peritoneal exudate CTL (PEL). We utilized patch clamp techniques to record electrophysiological events associated with the cytolytic interaction of PEL and EL4 in isolated conjugates. PEL-EL4 interaction resulted in induction in EL4 cells, of single channels (followed by EL4 destruction), with a mean conductance of 437 pS and a reversal potential of -1.0 mV, suggestive of nonselective pathways. Similar channels were induced in EL4 cells conjugated with perforin-rich PEL blasts (PEB), by perforin, postnuclear extract from PEL (pnPEL) and from other cytotoxic lymphocytes, but not from noncytolytic lymphocytes. As similar channels were induced by pnPEL in EL4 membrane patches, we propose that these channels result from a direct effect of PEL-derived channel-forming substance(s) on the target cell's membrane. Importantly, postnuclear extracts from perforin-devoid cytotoxic PEL-hybridomas induced similar channels, suggesting the presence of a nonperforin, channel-forming activity in PEL and PEL-hybridomas. Based on the present study, we conclude that the delivery of the lethal hit by cytolytic PEL and PEL-hybridoma is associated with induction in the target cell of high-conductance channels, which most likely mediate its destruction. We propose that these channels are related to the Fas pathway of lymphocytotoxicity.
Dendritic cells produce IL-12 and direct the development of Th1 cells from naive CD4+ T cells.
Authors: Macatonia S E , Hosken N A , Litton M , Vieira P , Hsieh C S , Culpepper J A , Wysocka M , Trinchieri G , Murphy K M , O'Garra A
Published: December 2022

Dendritic cells are APCs that are unique in their potency to stimulate proliferation of primary Ag-specific responses in vitro and in vivo. In this study, we demonstrate that dendritic cells can produce IL-12, a dominant cytokine involved in the development of IFN-gamma-producing T cells. This finding resulted from our observations that dendritic cell-induced Th1 development from total CD4+ T cells upon neutralization of endogenous levels of IL-4 was IL-12-dependent. Furthermore, we demonstrate that dendritic cells can induce the development of Th1 cells from Ag-specific naive LECAM-1bright CD4+ T cells obtained from alpha beta-TCR transgenic mice, provided that CD4+ LECAM-1dull T cells, which produce significant levels of IL-4, are not present in the primary cultures. Production of IL-12 by dendritic cells was confirmed by positive immunofluoresence staining with Abs specific for the inducible IL-12 p40 subunit. This suggests that in addition to inducing proliferation and clonal expansion of naive T cells, dendritic cells, by their production of IL-12, play a direct role in the development of IFN-gamma-producing cells that are important for cell-mediated immune responses.
Cell expansion and growth arrest phases during the transition from precursor (CD4-8-) to immature (CD4+8+) thymocytes in normal and genetically modified mice.
Authors: Pénit C , Lucas B , Vasseur F
Published: December 2022

T cell early precursors belong to the CD3-CD4-CD8- triple negative (TN) thymocyte population that can be subdivided on the basis of CD44, CD25, and heat-stable Ag (HSA) expression. The kinetics and precursor product relationships of these subsets, as well as of the CD4/8low intermediates, were studied by using pulse labeling with bromodeoxyuridine (BrdUrd). The highest frequencies of DNA-synthesizing cells were found in CD44+CD25+ and CD44-CD25low or CD25- subsets. The major TN cell type (CD44-CD25high), as well as CD44+ CD25-HSAlow early precursors, contained a majority of resting cells. RAG-2-/- mice contained less cells in DNA synthesis than normal mice, and CD44-CD25-/low cells were absent. In female mice transgenic for the anti-HYTCR, CD44-CD25high cells were almost all cycling, but a high percentage of resting cells was found in CD44-CD25- cells. In days following the BrdUrd pulse, there was a reduction in the number of BrdUrd+ cells in most subsets, with the exception of the labeled CD44-CD25high cells that showed a bell-shaped curve. The kinetics and cell size evolution suggest that the majority of these cells do not give rise to CD4+CD8+ cells. In RAG-2-/- cells, the block at the CD44-CD25high stage involved all cells. In TCR transgenic (Tg) mice, no block was seen at the CD44-CD25high stage, suggesting that early expression of a complete TCR receptor precludes the normal selection step. However, another block in the differentiation process was observed at the CD44-CD25- step in TCR Tg mice, suggesting an additional selection point.
Production of IL-5 by human NK cells and regulation of IL-5 secretion by IL-4, IL-10, and IL-12.
Authors: Warren H S , Kinnear B F , Phillips J H , Lanier L L
Published: December 2022

Human NK cells produce IFN-gamma, TNF-alpha, and granulocyte macrophage-CSF when stimulated with susceptible target cells or through the CD16 and CD94 cell surface molecules. This study reports that NK cells also produce IL-5, a cytokine typically produced by Th2 cells, which mediates mobilization and differentiation of eosinophils. Polyclonal NK cell populations and NK cell clones produce IL-5 when stimulated to proliferate with gamma-irradiated MM-170 melanoma cells or JY B-lymphoblastoid cells and rIL-2. IL-5 is produced in cultures generated from freshly isolated NK cells (primary cultures) and when quiescent NK cells from primary cultures are restimulated to proliferate (secondary cultures). Production of IL-5 is on average 8.8-fold greater in secondary cultures compared with primary cultures (n > 18), suggesting that the ability of NK cells to produce IL-5 matures during primary stimulation. IL-5 secretion, particularly in primary cultures, is augmented by IL-4 and is inhibited by IL-12 and IL-10. By contrast, IL-4 and IL-12 have the reverse effects on IFN-gamma secretion. Cultured NK cells that no longer secrete cytokines can be restimulated to do so with either phorbol 12, 13 dibutyrate and ionomycin or with susceptible target cells in the presence of rIL-2. IL-5 production in these cultures occurs only when NK cells are in an exponential growth phase, whereas IFN-gamma, TNF-alpha, and granulocyte macrophage-CSF are produced also by stimulation of quiescent cells, although to a lesser extent. Furthermore, cytokine production is unrelated to the cytolytic activity of NK cells. In conclusion, proliferating human NK cells have the potential to produce IL-5 with secretion regulated by IL-4, IL-10, and IL-12.
Requirement for peptide in alloreactive CD4+ T cell recognition of class II MHC molecules.
Authors: Weber D A , Terrell N K , Zhang Y , Strindberg G , Martin J , Rudensky A , Braunstein N S
Published: December 2022

To examine the role of peptide in alloreactive class II MHC-restricted responses, we transfected I-A molecules into the Ag-processing defective mutant cell line, T2. Consistent with their defective Ag-processing phenotype, the T2 transfectants predominantly express SDS-unstable I-A molecules on their surface. These cells and phenotypically normal APCs were used to study primary and secondary alloreactive T cell responses in limiting dilution assays. The results demonstrate that the majority of CD4 T cells that participate in primary alloresponses and essentially all the CD4 T cells that participate in secondary alloresponses recognize I-A conformers that depend on the presence of peptide and do not recognize the SDS-unstable I-A expressed by T2 transfectants. To further investigate the requirement for peptide in these responses, we incubated the T2 transfectants with E alpha 52-68 peptide and generated SDS-stable I-A-peptide complexes on the cell surface. The I-Ab-E alpha peptide complexes expressed on T2 cells are stimulatory in secondary alloresponses if the T cells were exposed to the same I-A peptide complex during the priming step. These studies demonstrate that peptide-containing class II MHC is the relevant ligand for alloreactive T cells, and identify an alloreactive response to a peptide (E alpha 52-68) derived from a highly expressed cell surface "self" Ag, the I-E molecule.
Aglycosylated and phosphatidylinositol-anchored MHC class I molecules are associated with calnexin. Evidence implicating the class I-connecting peptide segment in calnexin association.
Authors: Carreno B M , Schreiber K L , McKean D J , Stroynowski I , Hansen T H
Published: December 2022

The endoplasmic reticulum resident protein calnexin interacts with several glycoproteins including class I MHC molecules. Calnexin is thought to retain free class I heavy chains and/or promote their folding and assembly with beta 2-microglobulin and peptide ligand. Whereas with other glycoproteins, Asn-linked glycans seem to be involved in calnexin association, with class I molecules the transmembrane region has been implicated. To critically define the structures on class I molecules that determine their interaction with calnexin, we have studied carbohydrate-deficient and transmembrane-variant class I molecules. Carbohydrate-deficient class I molecules were found to accumulate intracellularly in an open, non-beta 2-microglobulin-associated conformation. However, open as well as conformed class I molecules showed significant calnexin association whether they were aglycosylated or fully glycosylated. Thus, carbohydrate moieties may be necessary for efficient class I folding, but are not required for calnexin association. Calnexin was also found associated with a soluble class I molecule that has a truncated transmembrane segment, demonstrating that membrane attachment of class I is not required for interaction with calnexin. Finally, two isoforms of the class Ib molecule Q7b were compared. Unexpectedly, the glycosylphosphatidylinositol-anchored Q7b isoform was found associated with calnexin, whereas the soluble Q7b isoform was not calnexin associated. These comparisons of Q7b isoforms implicate the class I-connecting peptide segment and not the transmembrane region as a site of interaction with calnexin.
Activation of transcription by binding of NF-E1 (YY1) to a newly identified element in the first exon of the human DR alpha gene.
Authors: Hehlgans T , Strominger J L
Published: December 2022

A previously unrecognized element, located downstream of the start site of transcription in the first exon of the DR alpha gene, has been defined that enhances promoter activity up to eightfold in a position-dependent manner. Mutations in this DNA-binding site abolished binding of a nuclear factor in human B cell nuclear extract and decreased the activity of the DR alpha promoter to a basal level. Significant sequence homology of this element was found in the DNA of the DR beta, DP alpha and -beta, and DQ alpha genes, always located downstream of the transcriptional start site. The nuclear factor binds to the DR alpha and DP alpha element but not to the element in the DQ alpha gene. It was identified as NF-E1 (YY1). This protein, previously identified by its binding to the Ig kappa 3' enhancer and the Ig heavy chain mu E1 site, thus also appears to be quite important in the regulation of MHC class II gene expression.
Alpha 4 integrin directs virus-activated CD8+ T cells to sites of infection.
Authors: Christensen J P , Andersson E C , Scheynius A , Marker O , Thomsen A R
Published: December 2022

This article examines the role of VLA-4 in directing lymphocytes to sites of viral infection using the murine lymphocytic choriomeningitis virus infection (LCMV) as the model system. This virus by itself induces little or no inflammation, but in most mouse/virus strain combinations a potent T cell response is induced, which is associated with marked CD8+ cell-mediated inflammation. Two expressions of LCMV-induced inflammation were studied: meningitis induced by intracerebral infection and adoptive transfer of virus-specific delayed-type hypersensitivity. Our previous studies have shown that LCMV infection results in the appearance of activated CD8+ cells with an increased expression of VLA-4. In this study we have compared various T cell high and low responder situations, and these experiments revealed that acute inflammation correlates directly with VLA-4 expression on splenic CD8+ cells. This correlation could be extended to CD4+ and B cells in chronically infected low responder DBA/2 mice. The vascular ligand for VLA-4, VCAM-1, was found to be up-regulated on endothelial cells in sites of inflammation. Finally, preincubation of virus-primed donor cells with mAb to VLA-4 completely blocked the ability to transfer virus-specific, delayed-type hypersensitivity when the donor cells were given i.v., but not when the cells were injected directly into the test site. Co-transfer of CD8-depleted cells with anti-VLA-4-blocked cells did not reveal any cooperation. Taken together, these results indicate that VLA-4 play a critical role in lymphocyte homing during systemic virus infections and are involved in directing virus-specific CD8+ effector cells to sites of infection.
Stimulation of TCR V gamma 3 cells by gram-negative bacteria.
Authors: Leclercq G , Plum J
Published: December 2022

A distinct feature of most murine TCR-gamma delta cells is that they localize in epithelial tissues that cover the internal and external surface of the body. Therefore, TCR-gamma delta cells have been hypothesized to represent a first line of defense against invading pathogens. In this study, it is shown that TCR V gamma 3 cells are activated to produce cytokines upon interaction with Gram-negative bacteria, whereas Gram-positive bacteria have no effect. Accessory cells are not required. LPS of Gram-negative bacteria is shown to be the stimulating structure for TCR V gamma 3 cells, as the stimulation is inhibited by addition of polymyxin B or anti-LPS Ab and as purified LPS stimulates V gamma 3 T cells. Blocking of the V gamma 3 TCR does not inhibit stimulation by Gram-negative bacteria, whereas suboptimal triggering of the TCR is synergistic. These results demonstrate that LPS is an important stimulus for TCR V gamma 3 cells. This indicates that skin-located V gamma 3 T cells might play a role in the defense against Gram-negative bacteria.
IL-12 is required for natural killer cell activation and subsequent T helper 1 cell development in experimental leishmaniasis.
Authors: Scharton-Kersten T , Afonso L C , Wysocka M , Trinchieri G , Scott P
Published: December 2022

Infection of mice with the protozoan Leishmania major is an established in vivo model for the definition of factors that contribute to CD4+ T helper cell subset development. In the current study, a central role for IL-12 in directing both the innate and adaptive immune responses to L. major is established. We show that in vivo neutralization of IL-12 eliminates the NK cell cytotoxic response and IFN-gamma production by lymph node cells from 2-day L. major-infected C3H mice. Moreover, anti-IL-12 treatment abrogated Th1 cell development and enhanced Th2 cell development. Consistent with these results, elevated IL-12 p40 production and an increase in the number of IL-12 p40-producing cells were observed within 1 day of infection in C3H mice. Because BALB/c mice lack an early NK cell response or a Th1-type immune response after L. major infection, we investigated the possibility that they had a defect in the ability to produce IL-12. Surprisingly, L. major infection stimulated IL-12 p40 production in BALB/c mice early after infection. Further studies suggest that BALB/c mice are unable to generate an early IFN-gamma response because of the simultaneous production of IL-12 and cytokines that inhibit IL-12 function, such as TGF-beta, IL-4, and IL-10. Together, these data show that IL-12 regulates the immune response to L. major, but that even when IL-12 is induced, Th1 cell development may be interrupted by simultaneous production of inhibitory cytokines.
Increased opsonization of a prtH-defective mutant of Porphyromonas gingivalis W83 is caused by reduced degradation of complement-derived opsonins.
Authors: Schenkein H A , Fletcher H M , Bodnar M , Macrina F L
Published: December 2022

Periodontitis is a disease of the supporting structures of the teeth that is caused by bacteria whose common ecologic niche is the gingival crevice or the periodontal pocket. Tissue destruction occurs in spite of both local and systemic immune responses against such bacteria. Porphyromonas gingivalis is considered to be an important pathogen in some forms of human periodontitis and is particularly interesting because of its multiplicity of virulence factors. We have previously observed that phagocytosis-resistant invasive strains of P. gingivalis proteolytically degrade C3 and IgG and accumulate less C3-derived opsonins during complement activation. We recently have cloned the prtH gene from P. gingivalis W83 that encodes a 97-kDa active protease, which has the capacity to degrade purified C3 protein. By using this cloned gene we created an allelic exchange mutant of P. gingivalis W83, designated V2296, in which the prtH gene was inactivated. This mutant was previously shown to be less virulent than its parent strain W83 in a mouse model of bacterial invasiveness. In the present study we have assessed the relative capacity of V2296 and W83 to be opsonized by complement and to be taken up by PMNs. The data demonstrate that V2296, in comparison with its parent strain W83, is less able to degrade C3 and that it accumulates significantly greater numbers of molecules of C3-derived opsonins on the bacterial surface in the form of C3b and iC3b during complement activation. Furthermore, opsonized V2296 is taken up in much higher numbers by human PMNs than W83, suggesting that the prtH gene product may be important in evasion of host defense mechanisms.
Tenidap-modulated proinflammatory cytokine activation of a monocyte cell line.
Authors: Golding S , Emery P , Young S P
Published: December 2022

Dysregulated cytokine production, in particular of the monokines IL-1, IL-6, and TNF, has been implicated in the inflammatory response in rheumatoid arthritis and in promoting the ensuing tissue destruction. The 3-substituted 2-oxindole tenidap has proven anti-inflammatory actions both in vivo and in vitro, among which is the inhibition of TNF and IL-1 production by monocytes following activation by LPS. We have investigated this ability to modulate cytokine activity by studying its effects on cytokine-monocyte interactions and in particular IL-6 production, with the THP-1 monocyte cell line. Tenidap inhibited IL-6 production in a dose-dependent manner when cells were stimulated with a combination of TNF-alpha and IFN-gamma. It also inhibited the priming effect of IFN-gamma, preventing the super-induction of IL-6 production following subsequent stimulation with TNF-alpha and IFN-gamma. These effects occurred under conditions in which the cells were not irreversibly altered with respect to their protein synthetic activity. IFN-gamma-induced up-regulation of HLA-DR was also inhibited by tenidap. Tenidap appears to affect some aspect of the IFN-gamma activation pathway, possibly the differentiation of these immature monocytes to a more mature phenotype. The data presented here indicate that tenidap has the potential to modulate the cytokine network in chronic disease.
Antibacterial proteins of granulocytes differ in interaction with endotoxin. Comparison of bactericidal/permeability-increasing protein, p15s, and defensins.
Authors: Levy O , Ooi C E , Elsbach P , Doerfler M E , Lehrer R I , Weiss J
Published: December 2022

Bactericidal/permeability-increasing protein (BPI), antibacterial 15-kDa protein isoforms (p15s), and defensins (neutrophil peptides or NPs) are granule-associated antibacterial proteins of polymorphonuclear leukocytes (PMN) that have both direct and synergistic growth inhibitory activity against Gram-negative bacteria. In this study, we have compared in vitro the abilities of these antibacterial proteins, alone and in combination, to inhibit the endotoxic activity of isolated LPS and whole bacteria. All three proteins blocked endotoxin activity in: 1) the Limulus amoebocyte lysate assay, 2) priming of PMN for enhanced arachidonate release, and 3) stimulating leukocyte oxidase activity in 1% blood. However, the proteins differ markedly in both relative potency (BPI > p15s = NP1) in the presence of the plasma LPS-binding protein and in the range of LPS chemotypes that can be inhibited. BPI potently neutralizes LPS of any chemotype, but p15s and defensins are less active against long-chain (S-type) LPS. In whole blood ex vivo, the p15s and NP1 are approximately 1000-fold less potent than BPI, but at subinhibitory doses act in synergy with BPI to inhibit the TNF-inducing activity of a serum-resistant encapsulated strain of Escherichia coli (K1/r). The anti-endotoxic effects of p15 and NP1 against E. coli K1/r in whole blood appear secondary to growth arrest, because, in marked contrast to BPI, they are not evident against nonviable bacteria (pretreated with antibiotic) nor isolated LPS. Thus, BPI stands out for its ability to inhibit isolated or bacterial LPS under physiologic conditions. However, p15s and defensins may also contribute to suppression of endotoxic signaling by Gram-negative bacteria via synergistic (with BPI) growth inhibition upon extracellular release of these proteins from PMN during inflammation.
Granulocyte activation via a binding site near the C-terminal region of complement receptor type 3 alpha-chain (CD11b) potentially involved in intramembrane complex formation with glycosylphosphatidylinositol-anchored Fc gamma RIIIB (CD16) molecules.
Authors: Stöckl J , Majdic O , Pickl W F , Rosenkranz A , Prager E , Gschwantler E , Knapp W
Published: December 2022

We report that engagement of a particular epitope near the C-terminal region of complement receptor type 3 (CR3, CD11b/CD18) alpha-chain with CD11b mAb VIM12 induces granulocyte activation with a rise in cytosolic-free Ca2+, actin polymerization, an up-regulation of CR3 cell surface expression and enhanced adhesiveness. Induction of enhanced adhesiveness and homotypic aggregation of human granulocytes represents an active process. It is temperature and energy dependent, requires divalent cations, and an intact cytoskeleton. The mAb VIM12-induced enhanced adhesiveness seems to be mediated, at least in part, by activated CR3 molecules. It can be significantly inhibited, although not completely abolished, with blocking mAbs against adhesiotopes of CR3. VIM12-induced adhesion could be blocked with the serine/threonine inhibitors okadaic acid and calyculin A and with dibuturyl-cAMP but not with the protein kinase inhibitors herbimycin A and staurosporine. We further present evidence that the particular molecular region of CR3 recognized by mAb VIM12 might be involved in the reported intramembrane sugar-lectin type interaction and complex formation between transmembrane CR3 and glycosylphosphatidylinositol (GPI)-anchored Fc gamma RIIIB (CD16) molecules on human granulocytes. Binding of mAb VIM12 to CR3 on granulocytes enhances the release of GPI-anchored Fc gamma RIIIB molecules from granulocytes upon phosphoinositol-phospholipase C treatment. The sugar preparation N-acetyl-D-glucosamine, previously shown to dissociate CR3-Fc gamma RIIIB complex formation, inhibits mAb VIM12 binding. Engagement of CR3 with mAb VIM12 may thus mimic a biologically relevant intramembrane cooperation between two distinct receptor molecules on human granulocytes.
Inherited human complement C5 deficiency. Nonsense mutations in exons 1 (Gln1 to Stop) and 36 (Arg1458 to Stop) and compound heterozygosity in three African-American families.
Authors: Wang X , Fleischer D T , Whitehead W T , Haviland D L , Rosenfeld S I , Leddy J P , Snyderman R , Wetsel R A
Published: December 2022

Hereditary C5 deficiency has been reported in several families of different ethnic backgrounds and from different geographic regions, but the molecular genetic defect causing C5 deficiency has not been delineated in any of them. To examine the molecular basis of C5 deficiency in the African-American population, the exons and intron/exon boundaries of the C5 structural genes from three C5-deficient (C5D) African-American families were sequenced, revealing two nonsense mutations. The nonsense mutations are located in exon 1 (C84AG to TAG) in two of the C5D families (Rhode Island and North Carolina) and in exon 36 (C4521GA to TGA) in the third C5D family (New York). The exon 1 and 36 mutations are contained in codons that encode the first amino acid of the C5 beta-chain (Gln1 to Stop) and residue 1458 in the alpha-chain (Arg1458 to Stop), respectively. Allele-specific PCR and sequence analyses demonstrated that the exon 1 mutation is present in only one of the C5 null genes in both the Rhode Island and North Carolina families, and the exon 36 mutation is contained in only one C5 null gene in the New York family. Neither of the nonsense mutations was found in the European or Caucasian-American C5D individuals examined. Collectively, these data indicate that: 1) C5 deficiency is caused by several different molecular genetic defects, 2) C5 deficiency in the African-American population can be explained in part by two distinct nonsense mutations in exons 1 and 36, and 3) compound heterozygosity exists in all of the reported African-American C5D families.
Quantitation of tryptase, chymase, Fc epsilon RI alpha, and Fc epsilon RI gamma mRNAs in human mast cells and basophils by competitive reverse transcription-polymerase chain reaction.
Authors: Xia H Z , Kepley C L , Sakai K , Chelliah J , Irani A M , Schwartz L B
Published: December 2022

Competitive reverse transcription-PCR assays developed for human tryptase, chymase, Fc epsilon RI alpha, and Fc epsilon RI gamma mRNA molecules were applied to the HMC-1 leukemic mast cell line, the KU812 leukemic basophil cell line, mast cells dispersed from lung and skin, and peripheral blood basophils. Relative amounts of alpha-tryptase and beta-tryptase mRNA were determined by analysis of BseAI digests of PCR products. Tryptase expression was highest in tissue-derived mast cells, lowest in basophils and KU812 cells, and intermediate in HMC-1 cells. beta-Tryptase mRNA predominated in HMC-1 and KU812 cells; mixtures of alpha- and beta-tryptase were found in tissue mast cells; and alpha-tryptase predominated in basophils. Chymase mRNA was more abundant in skin-derived (nearly all of the MCTC type) than lung-derived (variable amounts of MCTC and MCT cells) mast cells. Small amounts of chymase mRNA were detected in HMC-1 cells; none was found in basophils, in KU812 cells, or in the one preparation of 100% MCT cells derived from lung. Comparable amounts of Fc epsilon RI alpha and Fc epsilon RI gamma mRNA molecules were measured in basophils and tissue-derived mast cells, lesser amounts were detected in KU812 cells, and almost none was detected in HMC-1 cells. Thus, steady state levels of the granule and membrane resident molecules examined in our study are transcriptionally regulated in mast cells and basophils.
Cardiac xenografts between primate species provide evidence for the importance of the alpha-galactosyl determinant in hyperacute rejection.
Authors: Collins B H , Cotterell A H , McCurry K R , Alvarado C G , Magee J C , Parker W , Platt J L
Published: December 2022

Transplants performed between phylogenetically disparate species are subject to hyperacute rejection initiated by binding of xenoreactive natural Abs to endothelium in the donor organ. Binding of these Abs activates complement, leading to tissue injury and destruction of the graft. Human xenoreactive natural Abs recognize Gal alpha 1-3Gal beta 1-4GlcNAc (galactose alpha 1-3galactose beta 1-4-N-acetylglucosame); however, the relative importance of this Ag in graft rejection has not been proved. The present study was conducted to test the potential importance of alpha-galactosyl (alpha-Gal) determinants in the pathogenesis of hyperacute rejection. To this end, hearts (n = 3) from New World monkeys (Saimiri scureus, squirrel monkey), which can synthesize Gal alpha 1-3Gal, were transplanted heterotopically into Old World monkeys (Papio species, baboon), which do not synthesize Gal alpha 1-3Gal determinants and which have circulating anti-alpha Gal Abs. The xenografts were rejected in 51 to 56 min (mean +/- SD = 53.3 +/- 2.5), results similar to those observed in porcine grafts transplanted into baboons. Histologic analysis of the hearts revealed thrombosis and intraparenchymal hemorrhage and immune deposits consisting of IgM, Clq, C3, C4, C5b, and the membrane attack complex, but not properdin or factor B of the recipient deposited on graft endothelium. Sera obtained from baboons after perfusion of squirrel monkey kidneys revealed depletion of alpha-Gal-specific Abs and anti-pig endothelial cell Abs. These findings provide strong evidence that the Abs that accumulate in New World monkey organs during perfusion with baboon blood are the same Abs that would accumulate in a porcine organ transplanted into a primate and suggest that hyperacute rejection is not necessarily a reflection of phylogenetic distance but that the expression of terminal alpha-Gal residues provides an adequate target to initiate that process.
Simian immunodeficiency virus (SIV)-specific CTL in cerebrospinal fluid and brains of SIV-infected rhesus macaques.
Authors: von Herrath M , Oldstone M B , Fox H S
Published: December 2022

Simian immunodeficiency virus (SIV)-specific CD8+ CTL were isolated from blood, cerebrospinal fluid, and brains of rhesus macaques infected i.v. with SIV. CTL were found as early as 1 wk postinfection and their appearance correlated with a decrease of viral Ag (p27) found in the blood. CTL isolated from cerebrospinal fluid and/or brain often recognized different viral proteins than CTL isolated from blood, suggesting either a unique migratory pattern to the central nervous system or a difference in activation/retention of lymphocytes in these compartments.
Requirement of CTLA-4 counter receptors for IL-4 but not IL-10 elevations during a primary systemic in vivo immune response.
Authors: Lu P , Zhou X D , Chen S J , Moorman M , Schoneveld A , Morris S , Finkelman F D , Linsley P , Claassen E , Gause W C
Published: December 2022

The CD28/CTLA-4 costimulatory signal is required for TCR-mediated T cell activation resulting in increased IL-2 production in vitro, but its role in IL-4 production is unclear and few studies have examined the function of CTLA-4/CD28 in the in vivo immune response. We have examined the in vivo effects of blocking the interaction of B7 with its ligands, CTLA-4 and CD28, in an IL-4 dominant in vivo immune response to goat anti-mouse IgD. This response is characterized by elevations in serum Igs preceded by elevations in IL-2 and the Th2 cytokines: IL-4, IL-9, and IL-10. The fusion protein CTLA4-Ig administered during the in vivo immune response to goat anti-mouse IgD caused an inhibition in elevations of IL-2, IL-4, and IL-9 gene expression at both day 3 and day 6 after immunization. In contrast, IL-10 cytokine gene expression as late as day 6 after immunization was not decreased. Cell sorting analysis demonstrated that TCR-alpha beta +, CD4+ T cells were the primary source of the elevated IL-10, suggesting that T cell activation leading to IL-10 gene expression may not require CTLA-4 ligand interactions. Similarly CTLA4-Ig completely blocked elevations in the number of IL-4- but not IL-10-secreting cells, as measured by ELISPOT, in both unsorted splenic cells and sorted CD4+, TCR-alpha beta+ T cells. In situ staining of spleen sections also showed inhibition of IL-4-producing cells. These results suggest that, with the notable exception of IL-10, interaction, of B7 with its ligands is required for elevated Th2 cytokine gene expression and secretion during a primary systemic IL-4-dominant response.
Memory B lymphocytes in human tonsil do not express surface IgD.
Authors: Nicholson I C , Brisco M J , Zola H
Published: December 2022

To clarify the phenotype of memory B lymphocytes, we have determined the frequency of somatic hypermutations in purified tonsil B cell populations. Our particular interest was the controversial question of whether any memory B-cells express IgD. Ig heavy chain gene rearrangements that used the nonpolymorphic VH6 gene were amplified by PCR, cloned, and sequenced. All eight sequences obtained from the surface IgD (sIgD)-negative fraction contained point mutations, with frequency of one mutation in every 24 bases of sequence. In contrast, only 4 of 12 sequences obtained from the sIgD-positive fraction contained point mutations, with a mutation frequency of one in 600. This frequency was similar to that found for cord blood B cells (one in 550), a population that does not contain memory B cells. These results indicate that although memory B cells are present in the sIgD-negative fraction, no memory cells can be detected in the sIgD-positive fraction of tonsil B lymphocytes.
Induction of murine gamma delta T cells cytotoxic for xenogeneic rat cells.
Authors: Okumura C , Suto R , Furukawa K , Ahmed S S , Furukawa K , Nakayama E , Fujii T , Shiku H
Published: December 2022

C57BL/6 mice deprived or nondeprived of CD4+ and CD8+ T cells by mAbs were challenged with a rat T cell line, W7TM-1. Spleen cells obtained from CD4- and CD8-depleted animals rejecting W7TM-1 were examined by cytofluorometry, which demonstrated the presence of highly increased gamma delta type CD4-CD8- T cell population (30 to 50% of entire T cells). In vitro sensitization of these spleen cells with W7TM-1 generated a mixture of gamma delta and alpha beta type CD4-CD8- CTL for W7TM-1. Repeated stimulation of these cells with W7TM-1 resulted in a gamma delta-type T cell population with more than 95% purity by day 45. In contrast, alpha beta type CD8+ CTL for W7TM-1 were induced from mice nondeprived of CD4+ and CD8+ T cells. Both gamma delta-type CD4-CD8- CTL and alpha beta type CD8+ CTL were cytotoxic for rat cells in a species-specific manner. However, only reactivity of gamma delta type CD4-CD8- CTL, but not alpha beta type CTL, was inhibited by a mAb for TCR-gamma delta. The gamma delta type CD4-CD8- CTL clones were also prepared from spleen cells derived from CD4- and CD8-depleted mice. They were also reactive for xenogeneic cells in a species-specific manner. Spleen cells derived from CD4- and CD8-depleted mice rejecting the whole-layer rat skin grafts were in vitro sensitized with rat spleen cells, which also generated gamma delta type CD4-CD8- CTL specific for rat cells. V gamma 1 was detected as a major V gamma gene expressed in this gamma delta population by reverse transcriptase-PCR. Cytotoxicity for xenogeneic cells may represent one of major function of gamma delta T cells.
Expression of vitronectin receptor on human NK cells and its role in protein phosphorylation, cytokine production, and cell proliferation.
Authors: Rabinowich H , Lin W C , Amoscato A , Herberman R B , Whiteside T L
Published: December 2022

In this paper, we provide evidence that the vitronectin receptor (VNR) alpha v beta 3 is expressed on human NK cells. The presence of this VNR on freshly purified NK cells was demonstrated by flow cytometry analysis, as well as biochemically, after 125I-labeled surface lactoperoxidase labeling and immunoprecipitation. mAbs LM142 and LM609 specific for alpha v and alpha v beta 3, respectively, precipitated a heterodimer of alpha- and beta-chains with approximate molecular masses of 155 and 110 kDa under nonreducing conditions. Under reducing conditions, there was an apparent decrease in the molecular mass of the alpha-chain, which is likely to result from the release of a protein of 20 to 30 kDa linked by internal disulfide bond to the alpha v-chain. Integrin alpha v beta 3 expressed on NK cells became functional, i.e., was able to bind its ligand, vitronectin (VN), only after cellular activation or when costimulation with an additional signal was provided. Thus, NK cells adhered to plastic-immobilized VN only after IL-2 activation, and RGD-containing synthetic peptides or mAbs specific for alpha v beta 3 complex inhibited this binding. To assess the role of the VNR in signal transduction, anti-beta 3 mAb was used to cluster the VNR on NK cells and, thereby, mimic the process that occurs during formation of adhesive contacts. Cross-linking of VNR on fresh NK cells stimulated phosphorylation on tyrosine residues of several intracellular proteins. The major increase in tyrosine phosphorylation was observed in proteins of approximate molecular masses of 75 and 120 kDa. Therefore, signal transduction by the VNR on NK cells induced activation of intracellular protein kinases. Ligand engagement of the VNR on NK cells also costimulated cytokine production and proliferation of NK cells. Binding of NK cells to plastic-immobilized VN served as a costimulus with either anti-Fc gamma RIII or IL-2 to produce IFN-gamma, TNF-alpha, and cell proliferation. Our findings suggest that occupancy and subsequent clustering of VNRs play a role in the activation and function of human NK cells.
Comitogenic effects of very late activation antigens on CD3-stimulated human thymocytes. Involvement of various tyrosine kinase pathways.
Authors: Ticchioni M , Deckert M , Bernard G , Calandra D , Breittmeyer J P , Imbert V , Peyron J F , Bernard A
Published: December 2022

Thymocytes display several integrins that are involved in cell-extracellular matrix interactions and differentiation processes. We have examined the role of very late activation Ag (VLA) on human thymocyte stimulation. VLA-4, VLA-5, and VLA-6 activated with either mAbs or their natural ligands (fibronectin, laminin, and vascular cell adhesion molecule-1) are able to transduce costimulatory signals in thymocytes activated via the CD3 pathway, i.e., enhancement of thymocyte proliferation, CD25 and CD69 expression, and IL-2 secretion. In contrast, activation of thymocytes with a mitogenic pair of CD2 mAb was not modified by VLA molecules. Cross-linking of both beta 1- and alpha 5-chains induced tyrosine phosphorylation of several proteins, whereas the cross-linking of the alpha 4- and alpha 6-chains did not. Moreover, a different pattern of tyrosine phosphorylation was observed when thymocytes were activated via either beta 1- or alpha 5-chains. These results suggest that VLA molecules activate tyrosine kinase pathways in thymocytes, and that different pathways would be implicated during thymocyte interactions with extracellular matrix or accessory cells, which are likely to play a role in thymocyte differentiation.
Characterization of human Fas gene. Exon/intron organization and promoter region.
Authors: Cheng J , Liu C , Koopman W J , Mountz J D
Published: December 2022

Ligation of the Fas cell-surface molecule induces apoptosis. Defective Fas-mediated apoptosis has been associated with spontaneous autoimmunity in mice. Using human Fas/Apo-1 cDNA as a probe, we have molecularly cloned and characterized the human Fas chromosomal gene. The gene consists of nine exons and spans more than 26 kilobases of DNA. The lengths of introns vary from > 14 kilobases at the 5' end of the gene to 152 base pairs upstream of the exon encoding the transmembrane domain. The domain structure of the human Fas is encoded by an exon or a set of exons. Primer extension analysis revealed three major transcription initiation sites. The promoter region lacked canonical "TATA" and "CAAT" boxes but was a "GC-rich" sequence, and contained consensus sequences for AP-1, GF-1, NY-Y, CP-2, EBP20, and c-myb. These data provide the first characterization of the human Fas gene and insight into its regulatory region.
Ontogeny of TCR V beta 1 expression revealed novel invariant alternative transcripts.
Authors: Dunon D , Schwager J , Dangy J P , Imhof B A
Published: December 2022

Analysis of TCR-beta gene recombination and expression was performed by quantitative PCR amplification technique throughout chicken embryogenesis and development. Our data demonstrated that TCR V beta 1 promoters were turned on by day 10 of embryogenesis, 2 days before detection of TCR-beta gene recombination. The V to D recombination step was first detected by day 11 of embryogenesis whereas DJ and V(D)J rearranged genes were detected 1 day later, on day 12 of embryogenesis. Thus, transcription of unrearranged TCR-beta genes in chickens precedes the expression of V(D)J recombinase activity as in mammals. In contrast, although TCR-beta rearrangement starts with the D to J recombination step in mammals, it can start either by the VD or the DJ step in chickens. Furthermore, reverse transcriptase-PCR amplification of TCR-beta transcripts revealed the presence of two kinds of alternative transcripts. These novel alternatively spliced products appeared in thymocytes from embryonic thymus during colonization periods and were absent in transformed T cell lines. Splicing sites are located in the middle of V beta 1 segments and lead to delta V beta 1-C beta and delta V beta 1-D beta-J beta-C beta transcripts. delta V beta 1-C beta transcripts might lead to synthesis of invariant truncated TCR beta-chains containing the aminoterminal portion of the V beta 1 region followed by the C beta region. Because this type of splicing can be generated by using all known V beta 1 members, these invariant forms could play a role in thymocyte development.
Activation of the 55 kDa TNF receptor is necessary and sufficient for TNF-induced liver failure, hepatocyte apoptosis, and nitrite release.
Authors: Leist M , Gantner F , Jilg S , Wendel A
Published: December 2022

The systemic inflammatory response is characterized by release of circulating TNF which may cause multiorgan failure including septic liver failure. We studied TNF signaling in an appropriate in vitro system with primary murine hepatocyte cultures from normal and genetically altered animals. Either one of the three different TNF species, huTNF-alpha, huTNF-beta, or muTNF-alpha (at concentrations > 1 ng/ml) induced direct hepatocytotoxicity preceded by DNA fragmentation in cells prepared from wild-type C57BL mice. TNF-induced cytotoxicity was preceded by oligonucleosomal DNA fragmentation. Further cellular responses to TNF exposure were induction of nitric oxide synthase and secretion of serum amyloid A. None of the above events occurred in hepatocytes lacking the gene for the 55-kDa TNF receptor (TNF-R1), even after stimulation with > 1 micrograms/ml TNF. However, selective stimulation of the TNF-R1 in wild-type hepatocytes with huTNF-alpha elicited a pattern of responses essentially similar to that seen with muTNF-alpha. We obtained analogous results when we examined the hepatotoxicity of TNF in D-galactosamine-sensitized mice, i.e., DNA fragmentation and liver failure was noted in wild-type mice, whereas TNF-R1-deficient mice were completely resistant. We conclude that the TNF-R1 is not only necessary, but also sufficient for TNF signaling in murine hepatocytes.
Endotoxin-mediated dendritic cell release from the intestine. Characterization of released dendritic cells and TNF dependence.
Authors: MacPherson G G , Jenkins C D , Stein M J , Edwards C
Published: December 2022

Dendritic cells (DC) acquire Ag in peripheral tissues and transport it to lymph nodes where they efficiently activate resting T cells. We have shown that i.v. endotoxin causes increased release of intestinal DC into lymph. In this paper we further characterize the release of DC and the properties of the released cells. A total of 50 micrograms of endotoxin injected i.v. causes an increase in DC output within 6 h that peaks between 12 and 24 h, with a maximum output of 8 to 15 times normal. At the same time lymphocyte output is markedly decreased. The increased output of DC is followed by a decrease to subnormal levels. The stimulated release of DC is almost totally blocked by a monoclonal anti-TNF-alpha Ab. A second injection of TNF-alpha does not result in further DC release. DC are not released from lymph nodes into efferent lymph by endotoxin. DC collected from lymph after endotoxin treatment show increased expression of the p55 IL-2 receptor and the OX48 Ag but otherwise resemble normal lymph DC. In functional assays they show no significant differences from normal in their ability to stimulate a MLR or to present Ags to sensitized T cells. Immunocytochemistry with the use of MRC OX62 suggests that the DC are released into lymph from the lamina propria of the small intestine. The stimulated release of DC mediated by TNF-alpha may be important in regulating Ag presentation in lymph nodes draining inflammatory sites.