bluuebunny/crossref_metadata_2025 huggingface dataset:
The protein tyrosine kinase p56lck regulates thymocyte development independently of its interaction with CD4 and CD8 coreceptors [corrected]
Authors: Levin S D , Abraham K M , Anderson S J , Forbush K A , Perlmutter R M
Published: June 2004

The lck gene encodes a lymphocyte-specific protein tyrosine kinase of the nonreceptor type that is implicated in signal transduction pathways emanating from the CD4 and CD8 coreceptors. Previous studies also support a role for p56lck in regulating T cell receptor beta gene rearrangements and, more generally, thymocyte development. Here we report that a mutant form of p56lck, which is incapable of interacting with CD4 or CD8, behaves indistinguishably from association-competent p56lck with respect to its ability to affect thymocyte maturation. The effects of p56lck remained specific in that the closely related src-family kinase p59hck was incapable of substituting for p56lck in arresting beta locus gene rearrangements. These data support the view that src-family kinases perform highly specialized and often nonoverlapping functions in hematopoietic cells, and that p56lck acts independently of its association with CD4 and CD8 to regulate thymocyte development.
Inhibition of murine B and T lymphopoiesis in vivo by an anti-interleukin 7 monoclonal antibody.
Authors: Grabstein K H , Waldschmidt T J , Finkelman F D , Hess B W , Alpert A R , Boiani N E , Namen A E , Morrissey P J
Published: June 2004

The effects of interleukin 7 (IL-7) on the growth and differentiation of murine B cell progenitors has been well characterized using in vitro culture methods. We have investigated the role of IL-7 in vivo using a monoclonal antibody that neutralizes IL-7. We find that treatment of mice with this antibody completely inhibits the development of B cell progenitors from the pro-B cell stage forward. We also provide evidence that all peripheral B cells, including those of the B-1 and conventional lineages, are derived from IL-7-dependent precursors. The results are consistent with the rapid turnover of B cell progenitors in the marrow, but a slow turnover of mature B cells in the periphery. In addition to effects on B cell development, anti-IL-7 treatment substantially reduced thymus cellularity, affecting all major thymic subpopulations.
Differentiation of CD3-4-8- human fetal thymocytes in vivo: characterization of a CD3-4+8- intermediate.
Authors: Kraft D L , Weissman I L , Waller E K
Published: June 2004

Human thymocyte differentiation was examined by injecting fetal thymic progenitor populations into human thymic xenografts in SCID-hu mice. Thymic progenitors were fluorescently labeled with the lipophilic dye PKH2. The phenotypes of their progeny could be identified by flow cytometric analysis of cells with a very high fluorescent PKH2 signal. Intrathymic injection of purified triple negative (TN) CD3-4-8- thymocytes resulted in the sequential appearance of CD3-4+8-, CD3-4+8+, and CD3+4+8+ cells, with the subsequent appearance of small numbers of phenotypically mature CD3+4+8- and CD3+4-8+ cells over a 4-d period. Sorted CD3-4+8- thymocytes injected intrathymically rapidly differentiated to CD4+8+ cells. CD4+8+ fetal thymocytes in cell cycle differentiated into phenotypically mature CD3+4+8- and CD3+4-8+ populations, whereas nondividing CD4+8+ cells failed to differentiate after intrathymic transfer. The number of cell divisions that occurred between the injection of TN thymocytes and their progeny at different time points was estimated based on the decrease in the intensity of the PKH2 label. The average length of the cell cycle for the TN population was calculated to be 24 h. The SCID-hu model thus provides a useful tool for studying the kinetics of cell division and differentiation of human thymocytes in vivo.
Pore-forming bacterial toxins potently induce release of nitric oxide in porcine endothelial cells.
Authors: Suttorp N , Fuhrmann M , Tannert-Otto S , Grimminger F , Bhadki S
Published: June 2004

Nitric oxide (NO) is believed to play an important role in sepsis-related hypotension. We examined the effects of two pore-forming bacterial exotoxins, Escherichia coli hemolysin and Staphylococcus aureus alpha-toxin, on NO formation in cultured porcine pulmonary artery endothelial cells. NO was quantified using a difference-spectrophotometric method based on the rapid and stoichiometric reaction of NO with oxyhemoglobin. Endothelial cyclic guanosine monophosphate levels were also monitored. Both exotoxins increased NO synthesis in endothelial cells in a time- and dose-dependent manner to an extent exceeding that observed with the ionophore A23187 or thrombin. The capacity of exotoxins to induce NO formation may be relevant in patients with severe local or systemic bacterial infections.
Tumor cells transfected with a bacterial heat-shock gene lose tumorigenicity and induce protection against tumors.
Authors: Lukacs K V , Lowrie D B , Stokes R W , Colston M J
Published: June 2004

The gene encoding a highly immunogenic mycobacterial heat-shock protein (hsp65) was transfected into the murine macrophage tumor cell line J774. The resulting hsp65-expressing cells (J774-hsp65) were no longer able to produce tumors in syngeneic mice. This loss of tumorigenicity was not mediated through T cells since the transfected cells did not produce tumors in athymic mice. If mice are first immunized with the J774-hsp65 cells and then challenged with the parent J774 cells, the mice do not develop tumors, indicating that the presence of the mycobacterial hsp65 protein greatly enhances immunological recognition of unique structures expressed by the parent tumor cells. This is further confirmed by the demonstration in vitro of T cells derived from J774-hsp65-immunized mice that are cytotoxic for the parent J774 cells. The results provide the basis for a novel strategy for enhancing the immunological recognition and decreasing the tumorigenicity of transformed cells.
Expression of tumor necrosis factor by different tumor cell lines results either in tumor suppression or augmented metastasis.
Authors: Qin Z , Krüger-Krasagakes S , Kunzendorf U , Hock H , Diamantstein T , Blankenstein T
Published: June 2004

Tumor necrosis factor (TNF) produced by tumor cells after gene transfer can effectively suppress the growth of locally growing tumors. We wanted to test the effects of "local" TNF on the growth of a highly metastatic cell line. Therefore, a recombinant retrovirus allowing expression of the TNF gene by the beta-actin promotor has been constructed and used to infect the two tumor cell lines EB and ESB, which grow as solid tumor or metastasize, respectively. Expression of TNF by EB cells resulted in their rapid and dose-dependent rejection. In sharp contrast, mice injected with ESB cells producing similar amounts of TNF showed no signs of tumor suppression, but rather had reduced survival rates that correlated with enhanced hepatic metastases. The accelerated formation of liver metastases by ESB TNF cells could be reversed by an anti-TNF mAb. These results demonstrate the opposite effects TNF may have on tumor growth: suppression of a locally growing tumor and promotion of metastasis formation.
Rapid G protein-regulated activation event involved in lymphocyte binding to high endothelial venules.
Authors: Bargatze R F , Butcher E C
Published: June 2004

The homing of blood borne lymphocytes into lymph nodes and Peyer's patches is mediated in part by recognition and binding to specialized high endothelial venules (HEV). Here we demonstrate that a rapid pertussis toxin-sensitive lymphocyte activation event can participate in lymphocyte recognition of HEV. In situ video microscopic analyses of lymphocyte interactions with HEV in exteriorized mouse Peyer's patches reveal that pertussis toxin has no effect on an initial "rolling" displayed by many lymphocytes, but inhibits an activation-dependent "sticking" event required for lymphocyte arrest. This is the first demonstration that physiologic lymphocyte-endothelial interactions can involve sequential rolling, activation, and activation-dependent arrest, previously shown only for neutrophils. The inhibitory effect of the toxin is dependent on its G protein-modifying ADP-ribosyltransferase activity and can be reversed by phorbol myristic acetate, which bypasses cell surface receptors to trigger activation-dependent adhesion. Lymphocyte sticking can occur within 1-3 s after initiation of rolling. We conclude that a rapid receptor-mediated activation event involving G protein signaling can trigger stable lymphocyte attachment to HEV in vivo, and may play a critical role in regulating lymphocyte homing.
Interleukin 4 reverses T cell proliferative unresponsiveness and prevents the onset of diabetes in nonobese diabetic mice.
Authors: Rapoport M J , Jaramillo A , Zipris D , Lazarus A H , Serreze D V , Leiter E H , Cyopick P , Danska J S , Delovitch T L
Published: June 2004

Beginning at the time of insulitis (7 wk of age), CD4+ and CD8+ mature thymocytes from nonobese diabetic (NOD) mice exhibit a proliferative unresponsiveness in vitro after T cell receptor (TCR) crosslinking. This unresponsiveness does not result from either insulitis or thymic involution and is long lasting, i.e., persists until diabetes onset (24 wk of age). We previously proposed that it represents a form of thymic T cell anergy that predisposes to diabetes onset. This hypothesis was tested in the present study by further investigating the mechanism responsible for NOD thymic T cell proliferative unresponsiveness and determining whether reversal of this unresponsiveness protects NOD mice from diabetes. Interleukin 4 (IL-4) secretion by thymocytes from > 7-wk-old NOD mice was virtually undetectable after treatment with either anti-TCR alpha/beta, anti-CD3, or Concanavalin A (Con A) compared with those by thymocytes from age- and sex-matched control BALB/c mice stimulated under identical conditions. NOD thymocytes stimulated by anti-TCR alpha/beta or anti-CD3 secreted less IL-2 than did similarly activated BALB/c thymocytes. However, since equivalent levels of IL-3 were secreted by Con A-activated NOD and BALB/c thymocytes, the unresponsiveness of NOD thymic T cells does not appear to be dependent on reduced IL-2 secretion. The surface density and dissociation constant of the high affinity IL-2 receptor of Con A-activated thymocytes from both strains are also similar. The patterns of unresponsiveness and lymphokine secretion seen in anti-TCR/CD3-activated NOD thymic T cells were also observed in activated NOD peripheral spleen T cells. Exogenous recombinant (r)IL-2 only partially reverses NOD thymocyte proliferative unresponsiveness to anti-CD3, and this is mediated by the inability of IL-2 to stimulate a complete IL-4 secretion response. In contrast, exogenous IL-4 reverses the unresponsiveness of both NOD thymic and peripheral T cells completely, and this is associated with the complete restoration of an IL-2 secretion response. Furthermore, the in vivo administration of rIL-4 to prediabetic NOD mice protects them from diabetes. Thus, the ability of rIL-4 to reverse completely the NOD thymic and peripheral T cell proliferative defect in vitro and protect against diabetes in vivo provides further support for a causal relationship between this T cell proliferative unresponsiveness and susceptibility to diabetes in NOD mice.
Cytotoxic lymphocyte maturation factor (interleukin 12) is a synergistic growth factor for hematopoietic stem cells.
Authors: Jacobsen S E , Veiby O P , Smeland E B
Published: June 2004

The recently cloned cytotoxic lymphocyte maturation factor (interleukin 12 [IL-12]) has been described as a growth factor for mature lymphocytes. The present study investigated whether purified recombinant murine IL-12 (rMuIL-12) also could affect the proliferation of primitive bone marrow progenitor cells. Using a population of Lin-Sca-1+ murine bone marrow stem cells, we now demonstrate that IL-12 is a potent synergistic factor for primitive hematopoietic stem cells. The synergy of IL-12 was observed in single-cell cloning assays, demonstrating that its effects are directly mediated. Specifically, IL-12 enhanced stem cell factor-induced myelopoiesis of Lin-Sca-1+ cells sevenfold, and synergized with colony-stimulating factors (CSFs) to induce proliferation of Lin-Sca-1+ stem cells. IL-12 increased the number of responding progenitor cells as well as the size of the colonies formed. IL-12 also increased colony formation of high proliferative potential colony-forming cells with multiple CSF combinations. The effects of IL-12 were concentration dependent with a 50% effective dose of 2-20 and 20-200 ng/ml, resulting in maximum stimulation. Furthermore, a neutralizing anti-IL-12 antibody blocked the synergistic effects of rMuIL-12. In addition, IL-12 was found to have synergistic effects on more committed bone marrow progenitors as well. Our results therefore suggest that in addition to being a potent lymphopoietic stimulator, IL-12 is a regulator of the growth of hematopoietic stem cells and their myeloid progeny.
Viral interleukin 10 is critical for the induction of B cell growth transformation by Epstein-Barr virus.
Authors: Miyazaki I , Cheung R K , Dosch H M
Published: June 2004

We have used an efficient cDNA subtraction library procedure to identify newly induced genes in human B lymphocytes infected for 6 h with Epstein-Barr virus (EBV). Among the genes identified by automated sequencing of a random subset of clones from this library, one coded the EBV BCRF1 open reading frame, which specifies the viral interleukin 10 gene (vIL-10). This molecule is highly homologous to human (h)IL-10 and was previously thought to represent a "late" viral gene expressed only during the lytic phase of virus replication. Using gene amplification by reverse transcriptase polymerase chain reaction of B cell RNA obtained at varying times after infection, we detected vIL-10 expression within a few hours of EBV infection, followed, 20-30 h later by expression of hIL-10. Expression of both genes continued beyond the initial transformation phase (5-10 d) and was present in all transformed cell lines tested. When added at the time of viral infection, antisense (but not sense) oligonucleotides for vIL-10 mRNA (cytosolic half-life, approximately 6 h) prevented subsequent B cell transformation. The antisense effect was highly specific, leaving the expression levels of other transformation-related genes intact. Addition of exogenous (h)IL-10 rescued the transformation process in antisense-treated cells. Our observations establish vIL-10 as a new latency gene with a directly transformation-prerequisite function.
PECAM-1 is required for transendothelial migration of leukocytes.
Authors: Muller W A , Weigl S A , Deng X , Phillips D M
Published: June 2004

Platelet/endothelial cell adhesion molecule 1 (PECAM-1; CD31) is crucial to the process of leukocyte transmigration through intercellular junctions of vascular endothelial cells. A monoclonal antibody to PECAM, or recombinant soluble PECAM, blocks transendothelial migration of monocytes by 70-90%. Pretreating either the monocytes or the endothelial junctions with antibody blocks transmigration. If the endothelium is first activated by cytokines, anti-PECAM antibody or soluble recombinant PECAM again block transmigration of both monocytes and neutrophils. Anti-PECAM does not block chemotaxis of either cell type. Light and electron microscopy reveal that leukocytes blocked in transmigration remain tightly bound to the apical surface of the endothelial cell, precisely over the intercellular junction. Thus, the process of leukocyte emigration can be dissected into three successive stages: rolling, mediated by the selectin class of adhesion molecules; tight adhesion, mediated by the leukocyte integrins and their endothelial cell counter-receptors; and now transmigration, which, based on these studies, requires PECAM-1.
Dendritic cell progenitors phagocytose particulates, including bacillus Calmette-Guerin organisms, and sensitize mice to mycobacterial antigens in vivo.
Authors: Inaba K , Inaba M , Naito M , Steinman R M
Published: June 2004

Dendritic cells, while effective in sensitizing T cells to several different antigens, show little or no phagocytic activity. To the extent that endocytosis is required for antigen processing and presentation, it is not evident how dendritic cells would present particle-associated peptides. Evidence has now been obtained showing that progenitors to dendritic cells can internalize particles, including Bacillus Calmette-Guerin (BCG) mycobacteria. The particulates are applied for 20 h to bone marrow cultures that have been stimulated with granulocyte/macrophage colony-stimulating factor (GM-CSF) to induce aggregates of growing dendritic cells. Cells within these aggregates are clearly phagocytic. If the developing cultures are exposed to particles, washed, and "chased" for 2 d, the number of major histocompatibility complex class II-rich dendritic cells increases substantially and at least 50% contain internalized mycobacteria or latex particles. The mycobacteria-laden, newly developed dendritic cells are much more potent in presenting antigens to primed T cells than corresponding cultures of mature dendritic cells that are exposed to a pulse of organisms. A similar situation exists when the BCG-charged dendritic cells are injected into the footpad or blood stream of naive mice. Those dendritic cells that have phagocytosed organisms induce the strongest T cell responses to mycobacterial antigens in draining lymph node and spleen. The administration of antigens to GM-CSF-induced, developing dendritic cells (by increasing both antigen uptake and cell numbers) will facilitate the use of these antigen-presenting cells for active immunization in situ.
Human cord blood cells as targets for gene transfer: potential use in genetic therapies of severe combined immunodeficiency disease.
Authors: Moritz T , Keller D C , Williams D A
Published: June 2004

Human cord blood (CB) contains large numbers of both committed and primitive hematopoietic progenitor cells and has been shown to have the capacity to reconstitute the lympho-hematopoietic system in transplant protocols. To investigate the potential usefulness of CB stem and progenitor cell populations to deliver new genetic material into the blood and immune systems, we have transduced these cells using retroviral technology and compared the efficiency of gene transfer into CB cells with normal adult human bone marrow cells using a variety of infection protocols. Using two retroviral vectors which differ significantly in both recombinant viral titers and vector design, low density CB or adult bone marrow (ABM) cells were infected, and committed progenitor and more primitive hematopoietic cells were analyzed for gene expression by G418 drug resistance (G418r) of neophosphotransferase and protein analysis for murine adenosine deaminase (mADA). Standard methylcellulose progenitor assays were used to quantitate transduction efficiency of committed progenitor cells, and the long term culture-initiating cell (LTC-IC) assay was used to quantitate transduction efficiency of more primitive cells. Our results indicate that CB cells were more efficiently transduced via retroviral-mediated gene transfer as compared with ABM-derived cells. In addition, stable expression of the introduced gene sequences, including the ADA cDNA, was demonstrated in the progeny of infected LTC-ICs after 5 wk in long-term marrow cultures. Expression of the introduced ADA cDNA was higher than the endogenous human ADA gene in the LTC-IC-derived colonies examined. These studies demonstrate that CB progenitor and stem cells can be efficiently infected using retroviral vectors and suggest that CB cells may provide a suitable target population in gene transfer protocols for some genetic diseases.
Mutational analysis of the CD2/CD58 interaction: the binding site for CD58 lies on one face of the first domain of human CD2.
Authors: Somoza C , Driscoll P C , Cyster J G , Williams A F
Published: June 2004

The adhesion interaction between the immunoglobulin superfamily molecules CD2 and CD58 (lymphocyte function-associated antigen 3) plays an important role in T cell and natural killer cell interaction with various antigen-presenting and target cells. Determination of the solution structure of rat CD2 domain 1 has allowed a model of human CD2 domain 1 to be generated, and a series of mutants based on this model have been made. Residues of domain 1 of human CD2 predicted to be solvent exposed were substituted with the equivalent residues present in the rat CD2 molecule. The ability of these mutants to mediate rosetting with human and sheep erythrocytes was studied. Results show that the binding site of CD2 for both human and sheep CD58 maps to the beta sheet containing beta strands CC'C"F and G. Residues K34 and E36 in beta strand C, R48 and K49 in beta strand C', and K91 and N92 in the loop connecting beta strands F and G are shown to be critical in the interaction. The data support the proposition that the interaction between CD2 and CD58 involves the major beta sheet face of CD2.
Autoimmune diabetes can be induced in transgenic major histocompatibility complex class II-deficient mice.
Authors: Laufer T M , von Herrath M G , Grusby M J , Oldstone M B , Glimcher L H
Published: June 2004

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease marked by hyperglycemia and mononuclear cell infiltration of insulin-producing beta islet cells. Predisposition to IDDM in humans has been linked to the class II major histocompatibility complex (MHC), and islet cells often become aberrantly class II positive during the course of the disease. We have used two recently described transgenic lines to investigate the role of class II molecules and CD4+ T cells in the onset of autoimmune insulitis. Mice that are class II deficient secondary to a targeted disruption of the A beta b gene were bred to mice carrying a transgene for the lymphocytic choriomenigitis virus (LCMV) glycoprotein (GP) targeted to the endocrine pancreas. Our results indicate that class II-deficient animals with and without the GP transgene produce a normal cytotoxic T lymphocyte response to whole LCMV. After infection with LCMV, GP-transgenic class II-deficient animals develop hyperglycemia as rapidly as their class II-positive littermates. Histologic examination of tissue sections from GP-transgenic class II-deficient animals reveals lymphocytic infiltrates of the pancreatic islets that are distinguishable from those of their class II-positive littermates only by the absence of infiltrating CD4+ T cells. These results suggest that in this model of autoimmune diabetes, CD4+ T cells and MHC class II molecules are not required for the development of disease.
Anhydroretinol: a naturally occurring inhibitor of lymphocyte physiology.
Authors: Buck J , Grün F , Derguini F , Chen Y , Kimura S , Noy N , Hämmerling U
Published: June 2004

Vitamin A (retinol) is an essential cofactor for growth of B lymphocytes in culture and for activation of T lymphocytes by antigen receptor-mediated signals. 14-hydroxy-4,14-retro-retinol (14-HRR) a metabolite of retinol, has been implicated as the intracellular mediator of this effect. Anhydroretinol (AR) is a retinol derivative with retro structure produced in activated human B lymphocytes and the insect cell lines SF 21 and Schneider S2. AR reversibly inhibits retinol- and 14-HRR-dependent effects and blocks B lymphocyte proliferation as well as activation of resting T lymphocytes. The intracellular signaling pathway blocked by AR in T cell activation is distinct from the calcineurin/interleukin 2 pathway inhibitable by cyclosporine A or FK-506.
FL-160 proteins of Trypanosoma cruzi are expressed from a multigene family and contain two distinct epitopes that mimic nervous tissues.
Authors: Van Voorhis W C , Barrett L , Koelling R , Farr A G
Published: June 2004

The partial sequence of a gene encoding the COOH terminus of a protein of apparent molecular weight of 160 kD associated with the flagellum of trypomastigotes of Trypanosoma cruzi (FL-160 now renamed to FL-160-1) has been previously reported. The COOH terminus of FL-160-1 has an epitope, defined by 12 amino acids, which molecularly miMics a nervous tissue antigen of 48 kD found in myenteric plexus, sciatic nerve, and a subset of cells in the central nervous system. We now report that FL-160 is a family of highly related genes. The sequence has been determined for the entire open reading frame (ORF) of one of the members of the FL-160 gene family (FL-160-2) and three other partial ORFs. Sequence analysis reveals the various members of the FL-160 gene family to be approximately 80% homologous in the predicted amino acid sequence, but all retain the 12-amino acid molecular mimicry epitope on the COOH terminus. Comparison of the sequence of FL-160-2 to other sequences demonstrates amino acid homology to bacterial sialidase (27%), members of the SA85 gene family (25-30%) and the shed acute-phase antigen/neuraminidase/trans-sialidase gene family (25-30%). Quantitative hybridization at high stringency suggests 750 copies of FL-160 are present in the DNA of each parasite. Reverse transcription and sequence analysis demonstrates that at least five of the members of the FL-160 gene family are transcribed. The NH2 terminus of one of the FL-160 gene products was expressed and antibodies prepared. Antibodies directed to either the COOH or the NH2 terminus of FL-160 bind a 160-kD T. cruzi protein. Both antibodies bind the surface membrane in the flagellar pocket of the trypomastigote. Antibodies to the NH2 terminus bind epineurium and scattered linear densities in sciatic nerve in a pattern distinct from the pattern with antibodies to the COOH terminus. Thus, there are at least two distinct molecular mimicry epitopes on the FL-160 molecule and both mimic epitopes found in nervous tissues. FL-160 may be involved in the generation of autoimmunity to nervous tissues by molecular mimicry, observed in chronic Chagas' disease.
Donor CD8 cells prevent allogeneic marrow graft rejection in mice: potential implications for marrow transplantation in humans.
Authors: Martin P J
Published: June 2004

Numerous experimental models have demonstrated that graft-vs.-host disease (GVHD) does not occur in irradiation chimeras when the graft does not contain mature, immunocompetent T lymphocytes, but clinical studies have shown that T cell depletion of donor marrow can be associated with a greatly increased risk of graft failure. We have developed a model where engraftment of (C57BL/6J x C3H/HeJ)F1 (B6C3) marrow in 800-cGy-irradiated (BALB/cJ x C57BL/6J)F1 (CB6) recipients depends on the presence of donor T cells in the graft. Recipients transplanted with 5.0 x 10(6) marrow cells depleted of T lymphocytes showed host lymphoid and myeloid reconstitution, whereas recipients transplanted with the same marrow plus 2.5 x 10(5) purified donor T cells showed donor reconstitution. Adding as few as 0.5 x 10(5) CD8-enriched donor T cells to marrow grafts containing 5.0 x 10(6) T cell-depleted donor cells was sufficient to enable donor reconstitution, while surviving recipients transplanted with the same marrow and 0.5-2.5 x 10(5) CD4-enriched donor cells showed only host reconstitution. To address the question of whether donor CD4 cells could facilitate engraftment under conditions where GVHD would not represent a limiting factor, engraftment of bm1 marrow was tested in major histocompatibility complex (MHC) class I-disparate B6.Ly5a recipients. Results indicated that the donor CD8-enriched population was at least fivefold more active than the CD4-enriched population for facilitating allogeneic marrow engraftment in this strain combination. Thus, the lymphokines and MHC class II-specific cytotoxic T cells generated by CD4 cells were relatively ineffective for enhancing engraftment, possibly reflecting the fact that the host T cells that contain effectors responsible for causing rejection do not express MHC class II antigens. The ability of donor CD8 cells to facilitate engraftment could reflect the activity of a cytokine uniquely elaborated after recognition of an MHC class I disparity. More likely, the graft-enhancing effect of donor CD8 cells may result from the generation of MHC class I-specific or class I-restricted cytotoxic T cells that recognize the host CD4 and CD8 cells responsible for causing rejection. The possibility remains that other mechanisms such as veto inactivation of host T cells by donor CD8 cells may also contribute to the graft-enhancing effect.
Protection against antigenically variable Borrelia burgdorferi conferred by recombinant vaccines.
Authors: Telford S R , Fikrig E , Barthold S W , Brunet L R , Spielman A , Flavell R A
Published: June 2004

Due to local variation in the antigenicity of the agent of Lyme disease (Borrelia burgdorferi), a vaccine derived from any one isolate of this spirochete may fail to protect against the heterogeneous population of organisms that may be present in an enzootic focus. Accordingly, we determined whether antigenically variable spirochetes delivered by naturally infected ticks, collected from a site where transmission is intense, may fail to infect mice actively immunized with recombinant glutathione transferase outer surface fusion proteins A or B (OspA and OspB). Virtually all mice vaccinated by either immunogen appeared not to become infected, as determined by culture or histopathology of their tissues. We conclude that Osp vaccination of mice effectively prevents infection by the agent of Lyme disease in a simulated natural cycle of transmission.
High frequency of normal DJH joints in B cell progenitors in severe combined immunodeficiency mice.
Authors: Pennycook J L , Chang Y , Celler J , Phillips R A , Wu G E
Published: June 2004

The severe combined immunodeficiency (scid) mouse has a defective V(D)J recombinase activity that results in arrested lymphoid development at the pro-B cell stage in the B lineage. The defect is not absolute and scid mice do attempt gene rearrangement. Indeed, approximately 15% of all scid mice develop detectable levels of oligoclonal serum immunoglobulin and T cell activity. To gain more insight into the scid defect and its effect on V(D)J rearrangement, we analyzed DJH recombination in scid bone marrow. We determined that DJH structures are present in scid bone marrow and occur at a frequency only 10-100 times less than C.B-17+/+. The scid DJH repertoire is limited and resembles fetal liver DJH junctions, with few N insertions and predominant usage of reading frame 1. Moreover, 70% of the DJH structures were potentially productive, indicating that normal V(D)J recombinants should be arising continually.
The bone marrow of multiple myeloma patients contains B cell populations at different stages of differentiation that are clonally related to the malignant plasma cell.
Authors: Billadeau D , Ahmann G , Greipp P , Van Ness B
Published: June 2004

One of the distinguishing features of multiple myeloma (MM) is the proliferation of a clonal plasma cell population in the bone marrow (BM). It is of particular interest that the tumor plasma cells appear to be restricted to the microenvironment of the BM and are rarely detected in the peripheral system, yet the disease is found widely disseminated throughout the axial skeleton. Furthermore, isolation of MM tumor cell lines has proven to be quite problematic due to their slow growth rate. These observations have instigated the search for earlier cells in the B cell lineage that are clonally related to the plasma cell tumor and that may represent the growth fraction of the tumor. We used allele-specific oligonucleotides (ASO) derived from the third complementarity determining region of the rearranged tumor immunoglobulin heavy chain gene to detect isotypes clonally related to the plasma cell tumor. By reverse transcribing RNA from the BM with a panel of CH primers (mu, delta, alpha, and gamma), followed by ASO-polymerase chain reaction amplification, we demonstrate the existence of preswitch isotype species that are clonally related to the myeloma tumor. Furthermore, we show that separation of the BM cells into CD45+ and CD38+ cell populations results in a lineage-specific expression of the clonally related RNA molecules, with the C mu and C delta in the CD45+, and C gamma in the CD38+ population. Interestingly, clonally related C alpha transcripts are also derived from the CD45+ fraction. These results confirm the presence of B cell populations clonally related to the plasma cell tumor and are consistent with models that propose the existence of myeloma precursors.
Interleukin 10 (IL-10) inhibits human lymphocyte interferon gamma-production by suppressing natural killer cell stimulatory factor/IL-12 synthesis in accessory cells.
Authors: D'Andrea A , Aste-Amezaga M , Valiante N M , Ma X , Kubin M , Trinchieri G
Published: June 2004

Natural killer cell stimulatory factor or interleukin 12 (NKSF/IL-12) is a heterodimeric cytokine produced by monocytes/macrophages, B cells, and possibly other accessory cell types primarily in response to bacteria or bacterial products. NKSF/IL-12 mediates pleiomorphic biological activity on T and NK cells and, alone or in synergy with other inducers, is a powerful stimulator of interferon gamma (IFN-gamma) production. IL-10 is a potent inhibitor of monocyte-macrophage activation, that inhibits production of tumor necrosis factor alpha (TNF-alpha), IL-1 and also IFN-gamma from lymphocytes acting at the level of accessory cells. Because TNF-alpha and IL-1 are not efficient inducers of IFN-gamma, the mechanism by which IL-10 inhibits IFN-gamma production is not clear. In this paper, we show that IL-10 is a potent inhibitor of NKSF/IL-12 production from human peripheral blood mononuclear cells activated with Staphylococcus aureus or lipopolysaccharide (LPS). Both the production of the free NKSF/IL-12 p40 chain and the biologically active p70 heterodimer are blocked by IL-10. NKSF/IL-12 p40 chain mRNA accumulation is strongly induced by S. aureus or LPS and downregulated by IL-10, whereas the p35 mRNA is constitutively expressed and only minimally regulated by S. aureus, LPS, or IL-10. Although IL-10 is able to block the production of NKSF/IL-12, a powerful inducer of IFN-gamma both in vitro and in vivo, the mechanism of inhibition of IFN-gamma by IL-10 cannot be explained only on the basis of inhibition of NKSF/IL-12 because IL-10 can partially inhibit IFN-gamma production induced by NKSF/IL-12, and also, the IFN-gamma production in response to various stimuli in the presence of neutralizing antibodies to NKSF/IL-12. Our findings that antibodies against NKSF/IL-12, TNF-alpha, or IL-1 beta can significantly inhibit IFN-gamma production in response to various stimuli and that NKSF/IL-12 and IL-1 beta can overcome the IL-10-mediated inhibition of IFN-gamma, suggest that IL-10 inhibition of IFN-gamma production is primarily due to its blocking production from accessory cells of the IFN-gamma-inducer NKSF/IL-12, as well as the costimulating molecule IL-1 beta.
Signal transduction by immunoglobulin is mediated through Ig alpha and Ig beta.
Authors: Sanchez M , Misulovin Z , Burkhardt A L , Mahajan S , Costa T , Franke R , Bolen J B , Nussenzweig M
Published: June 2004

Immunoglobulin (Ig) antigen receptors are composed of a noncovalently-associated complex of Ig and two other proteins, Ig alpha and Ig beta. The cytoplasmic domain of both of these Ig associated proteins contains a consensus sequence that is shared with the signaling proteins of the T cell and Fc receptor. To test the idea that Ig alpha-Ig beta heterodimers are the signaling components of the Ig receptor, we have studied Ig mutations that interfere with signal transduction. We find that specific mutations in the transmembrane domain of Ig that inactivate Ca2+ and phosphorylation responses also uncouple IgM from Ig alpha-Ig beta. These results define amino acid residues that are essential for the assembly of the Ig receptor. Further, receptor activity can be fully reconstituted in Ca2+ flux and phosphorylation assays by fusing the cytoplasmic domain of Ig alpha with the mutant Igs. In contrast, fusion of the cytoplasmic domain of Ig beta to the inactive Ig reconstitutes only Ca2+ responses. Thus, Ig alpha and Ig beta are both necessary and sufficient to mediate signal transduction by the Ig receptor in B cells. In addition, our results suggest that Ig alpha and Ig beta can activate different signaling pathways.
Dendritic cells freshly isolated from human blood express CD4 and mature into typical immunostimulatory dendritic cells after culture in monocyte-conditioned medium.
Authors: O'Doherty U , Steinman R M , Peng M , Cameron P U , Gezelter S , Kopeloff I , Swiggard W J , Pope M , Bhardwaj N
Published: June 2004

A procedure has been developed to isolate dendritic cells to a high degree of purity from fresh blood. Prior enrichment methods have relied upon an initial 1-2-d culture period. Purified fresh isolates lack the characteristic morphology, phenotype, and immunostimulatory function of dendritic cells. The purified cells have the appearance of medium sized lymphocytes and express substantial levels of CD4, but lack the T cell molecules CD3, CD8, and T cell receptor. When placed in culture, the cells mature in a manner resembling the previously described, cytokine-dependent maturation of epidermal dendritic cells (Langerhans cells). The cells enlarge and exhibit many cell processes, express much higher levels of major histocompatibility complex class II and a panel of accessory molecules for T cell activation, and become potent stimulators of the mixed leukocyte reaction. Among the many changes during this maturation process are a fall in CD4 and the appearance of high levels of B7/BB1, the costimulator for enhanced interleukin 2 production in T cells. These changes are not associated with cell proliferation, but are dependent upon the addition of monocyte-conditioned medium. We suggest that the freshly isolated CD4-positive blood dendritic cells are recent migrants from the bone marrow, and that subsequent maturation of the lineage occurs in tissues in situ upon appropriate exposure to cytokines.
Passive immunization of mice against D factor blocks lethality and cytokine release during endotoxemia.
Authors: Block M I , Berg M , McNamara M J , Norton J A , Fraker D L , Alexander H R
Published: June 2004

D factor, also known as leukemia inhibitory factor, is a pleiotropic cytokine whose role during acute injury and inflammation is not known. Intraperitoneal administration of Escherichia coli endotoxin induced D factor gene expression in mice, and passive immunization against D factor protected them from the lethal effects of endotoxin and blocked endotoxin-induced increases in serum levels of interleukin 1 and 6. Peak levels of tumor necrosis factor and interferon gamma were not affected. These results indicate that D factor is an essential early mediator of the inflammatory cytokine response and therefore may be important in the pathogenesis of the many inflammatory conditions, such as sepsis, arthritis, allograft rejection, and cancer immunotherapy.
Selective long-term elimination of natural killer cells in vivo by an anti-interleukin 2 receptor beta chain monoclonal antibody in mice.
Authors: Tanaka T , Kitamura F , Nagasaka Y , Kuida K , Suwa H , Miyasaka M
Published: June 2004

The interleukin 2 receptor beta chain (IL-2R beta) is preferentially expressed in natural killer (NK) cells, but is not detected in a majority of resting T and B cells. We recently established a novel monoclonal antibody (mAb) to murine IL-2R beta and examined in vivo the effect of the mAb in mice. We found that intraperitoneal injection of the anti-IL-2R beta mAb into adult mice resulted in a selective in vivo elimination of splenic NK function in various mouse strains. The reduction of NK cell function is associated with complete disappearance of NK1.1+ cells in C57BL/6 mice. Other lymphocyte subsets in the thymus and spleen were uncompromised. T cell function was not affected by the mAb treatment as judged by allogeneic cytotoxic T cell induction. The single injection of anti-IL-2R beta mAb caused a long-term elimination of splenic NK cells, lasting for at least 5 wk. We also found that NK and/or NK precursor cells become susceptible to the mAb treatment only after birth, suggesting that functional maturation of NK cells in terms of IL-2R beta expression is a later event in the course of NK cell development. The use of the anti-IL-2R beta mAb will be useful in defining the physiological role of NK cells in host defense as well as dissecting their developmental pathway in vivo.
A novel 80-kD cell surface structure identifies human circulating lymphocytes with natural killer activity.
Authors: Maïza H , Leca G , Mansur I G , Schiavon V , Boumsell L , Bensussan A
Published: June 2004

Human lymphocytes with natural killer (NK) activity, including most activated gamma/delta+ T lymphocytes, recognize and lyse tumor target cells without requiring recognition of major histocompatibility complex antigen. However, unlike gamma/delta+ T lymphocytes, NK cells do not express CD3/T cell receptor (TCR) molecules, and the receptors involved in cell-mediated cytotoxicity are unknown. To further delineate circulating NK cells, we developed monoclonal antibodies (mAbs) against the human NK leukemia YT2C2. We report the isolation of a mAb termed BY55, recognizing at the cell surface a novel 80-kD protein with restricted expression. In addition to the immunizing cell line, this mAb binds to circulating NK cells, gamma/delta+ cells, and a minor subset of alpha/beta+ T lymphocytes. Expression of the BY55 mAb-reactive epitope/molecule is regulated by activation, as short-term culture of peripheral blood lymphocytes (PBL) with phorbol ester induced its downmodulation. Furthermore, BY55 mAb reactivity was found neither with the NK nor with the TCR alpha/beta+ gamma/delta+ clones tested. Biochemical studies as well as phenotypic analysis revealed that this structure is different from all previously identified molecules on the lymphocyte cell surface. Interestingly, we found that BY55+ cells exert most NK activity obtained with fresh circulating lymphocytes. We report that within fresh E rosette-positive PBL only a subset of the CD16+, CD56+, and CD57+ cells coexpressed BY55 molecule, indicating that BY55 mAb defines a unique subset mediating NK activity of circulating PBL.
Antibodies against major histocompatibility complex class II antigens directly inhibit the growth of T cells infected with Theileria parva without affecting their state of activation.
Authors: Eichhorn M , Prospero T D , Heussler V T , Dobbelaere D A
Published: June 2004

We have analyzed the effect of antibodies (Abs) directed against major histocompatibility complex (MHC) class II Abs on the proliferation of Theileria parva-infected (Tpi) T cells. Anti-MHC class II Abs exert a direct effect on Tpi T cells causing an acute block in their proliferation. The inhibition does not involve apoptosis and is also entirely reversible. The rapid arrest of DNA synthesis caused by anti-MHC class II Abs is not due to interference with the state of activation of the T cells since the transcriptional activator NF-kappa B remains activated in arrested cells. In addition, interleukin 2 (IL-2), IL-2R, and c-myc gene expression are also unaffected. By analyzing the cell-cycle phase distribution of inhibited cells, it could be shown that cells in all phases of the cell cycle are inhibited. The signal transduction pathway that results in inhibition was shown to be independent of protein kinase C and extracellular Ca2+. Tyrosine kinase inhibitors, however, partly reduced the level of inhibition and, conversely, phosphatase inhibitors enhanced it. The possible relevance of this phenomenon in other systems is discussed.
Ontogeny-related changes in proliferative potential of human hematopoietic cells.
Authors: Lansdorp P M , Dragowska W , Mayani H
Published: June 2004

Blood cells originate from hematopoietic stem cells that are located at different sites during ontogeny. Production of human stem cells and their progeny in culture is expected to have important implications for experimental therapeutic strategies involving gene transfer and transplantation. Here we report striking differences between primitive hematopoietic cells purified from adult bone marrow, umbilical cord blood, and fetal liver in cytokine-supplemented, serum-free cultures. In such cultures both the fraction of responding cells and their ability to produce CD34+ progenitor cells decreased markedly with the age of the cell donor. These results document extensive, ontogeny-related functional differences between primitive hematopoietic cells.
Thymic selection and thymic major histocompatibility complex class II expression are abnormal in mice undergoing graft-versus-host reactions.
Authors: Desbarats J , Lapp W S
Published: June 2004

The graft-vs.-host reaction (GVHR) results in damage to the epithelial and lymphoid compartments of the thymus and thus in abnormal maturation and function of thymocytes in mice undergoing GVHR. In this report, the effects of GVHR on thymic T cell receptor (TCR) expression and usage have been investigated. GVHR was induced in unirradiated F1 hybrid mice by the intravenous transfer of parental lymphoid cells. Expression of the CD3/TCR complex on thymocyte subsets defined by CD4 and CD8 was studied by three-color flow cytometry. The level of CD3/TCR was decreased on CD4+CD8-, but not CD4-CD8+, mature thymocytes. The lack of upregulation of CD3/TCR on CD4 single-positive thymocytes, but not on their CD8+ counterparts, suggested an abnormality of class II major histocompatibility complex (MHC) expression in the thymuses of mice undergoing GVHR. Immunofluorescence staining of thymic frozen sections revealed that MHC class II expression was dramatically decreased in GVH-reactive mice. GVHR-induced changes in positive and negative selection were evaluated by determining the incidence of specific V beta TCR segment usage in the thymus. In normal mice, thymocyte usage of any given V beta segment was highly consistent between individuals of the same strain and age; however, a marked divergence in the incidence of TCR V beta 6hi and V beta 8hi cells between GVH-reactive littermate mice was observed, suggesting that thymic positive selection had become disregulated in these animals. Furthermore, negative selection was defective; the incidence of phenotypically self-reactive V beta 6hi T cells was significantly greater in the thymuses of GVH-reactive mice bearing the endogenous superantigen Mls-1a than in untreated controls. Thus, mice undergoing GVHR showed defective TCR upregulation on CD4+CD8- thymocytes and changes in TCR usage reflecting aberrant thymic selection, in conjunction with decreased expression of MHC class II. Most abnormalities of TCR expression and usage on CD4+ thymocytes observed in GVH-reactive mice were analogous to those of class II knockout mice.