bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complement activation by IgM: evidence for the importance of the third constant domain of the μ heavy chain
Authors: Shulman Marc J. , Collins Catherine , Pennell Nancy , Hozumi Nobumichi 
Published: March 2007

AbstractWe have isolated and analyzed the DNA encoding the μ heavy chain constant region of a mutant IgM which is defective in initiating complement‐dependent cytolysis. By assaying the expression of μ genes which were constructed in vivo from mutant and normal gene segments, we have mapped the mutation into a 555‐base pair segment. In this segment there is one nucleotide change, such that the mutant μ gene encodes serine rather than the normal proline at amino acid position 436 in the third constant domain. We have used site‐directed mutagenesis to revert this mutation to the normal sequence and shown that this substitution results in the production of IgM with the normal phenotype.
A T cell clone which responds to interkeukin 2 but not to interleukin 4
Authors: Müller Werner , Vandenabeele Peter 
Published: March 2007

AbstractThe T cell clone CSP 2.1 is stimulated into proliferation by interleukin (IL) 2 but not IL 4, whereas many T cells respond to both. This clone is therefore suitable for the identification and quantification of IL 2 in the presence of IL 4.
Effective activation of resting mouse T lymphocytes by cross‐linking submitogenic concentrations of the T cell antigen receptor with either Lyt‐2 or L3T4
Authors: Eichmann Klaus , Jönsson Jan‐Ingvar , Falk Ingrid , Emmrich Frank 
Published: March 2007

AbstractWe studied the activation of small resting mouse T lymphocytes by antibodies to the T cell antigen receptor in combination with antibodies to other T cell surface antigens. Solid‐phase but not soluble antibodies KJ16‐133 and F23.1, both directed to β chains of the Vβ8 family, activate T cells to proliferate in the presence of growth factors, in a dose‐dependent fashion. Antibodies to Lyt‐2 and to L3T4 had no activating effect at any concentration. However, submitogenic concentrations of KJ16‐133 and of F23.1 synergized with a wide range of concentrations of anti‐Lyt‐2 and anti‐L3T4 to cause T cell proliferation similar or greater in magnitude to that caused by high concentrations of anti‐T cell receptor antibody. Synergistic activation was also observed with antibodies to Lyt‐1, LFA‐1 and H‐2 class I antigens but to a significantly lower degree. This was particularly clear in limiting dilution experiments in which the corrected frequencies of T cells proliferating in response to low amounts of anti‐T cell receptor antibody together with anti‐Lyt‐2 were 1/4 to 1/7 for BALB/c T cells. The frequencies of BALB/c T cells responding to high concentrations of anti‐T cell receptor antibody alone were between 1/14 and 1/126 and still lower frequencies of T cells proliferated in synergistic responses with anti‐LFA‐1 or anti‐Lyt‐1. Synergistic activation leads to the induction of functional cytotoxic cells. We interpret these data as suggestive that cross‐linking of the T cell antigen receptor with either Lyt‐2 (CD8) or L3T4 (CD4) represents an optimal activating signal for resting T cells. We think that, in physiological T cell activation, cross‐linking of the T cell receptor to CD8 or CD4 is induced by their simultaneous binding to major histocompatibility complex (MHC) class I (for CD8) or MHC class II (for CD4) molecules on stimulator cells. We consider the possibility that similar cross‐linking requirements may also exist during T cell repertoire selection in ontogeny, thus accounting for the strict coexpression of MHC class I and class II‐restricted T cell receptors with CD8 and CD4 molecules, respectively.
Multiple T cell antigenic determinants identified within a limited region of the horse cytochrome c molecule
Authors: Baumhüter Susanne , Wallace Carmichael J. A. , Proudfoot Amanda E. I. , Bron Claude , Corradin Giampietro 
Published: March 2007

AbstractThe antigen fine specificity of T cell hybridomas recognizing the horse apocytochrome c fragment 1–65, restricted to the I‐Ab molecule, was determined to gain some insight into the molecular nature of T cell antigenic peptides. Two major groups of clones specific for distinct subsites, namely residues 1–38 and 39–65, could be identified. Hybridomas recognizing the latter determinant were further tested with different horse cytochrome c peptides and analogues. This analysis revealed the presence of at least two epitopes encompassed by residues 47–53 and 48–53. Furthermore, clones specific for the amino acid sequence 48–53 showed considerable heterogeneity in respect to the antigen concentration required to obtain 50% of the maximal interleukin 2 secretion. Most prominent was the heteroclitic response towards tuna cytochrome c which differs at positions 44, 46 and 47 from the horse cytochrome c molecule in the relevant region. Comparison of the conformation of the sequence 43–46 between the two cytochrome c suggests that this segment, which forms a 310 bend, may be important in maintaining the proper structure of the antigenic determinant. Moreover, the variations up to 180‐fold in the concentrations of the cross‐reacting cytochrome c and peptides required for stimulation were not always correlated with the maximal interleukin 2 secretion they induced. This indicates that the biological response, that is supposed to be an indication of the affinity of the T cell receptor for its ligand, is not necessarily a function of the antigen concentration.
Detection of HLA‐DP serological allodeterminants by the use of radioiodinated DP molecules
Authors: Tanigaki Nobuyuki , Tosi Roberto , Parodi Barbara , Sorrentino Rosa , Ferrara Giovanni B. , Strominger Jack L. 
Published: March 2007

AbstractHLA class II molecules were partially purified from cells of an HLA deletion mutant cell line, LCL721.82, that lost DR and DQ expression but retained DPw2 specificity and labeled with radioactive 125I. The radioiodinated preparation bound to DP‐specific monoclonal antibody B7/21 as well as rabbit anti‐HLA class II antiserum. On sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, the component involved in these bindings gave, unlike known HLA class II molecules, a sharp and dense band of ∼ 60 kDa under nonreducing conditions and a single but diffuse band of ∼ 30 kDa under reducing conditions. By screening 401 anti‐HLA class II alloantisera, including those distributed in the 9th International Histocompatibility Workshop and also those locally available, eight were found to possess significant binding activity. Specificity analysis of these eight binding‐positive antisera on a panel of DP‐pretyped HLA homozygous typing cells revealed the presence of two clusters, one corresponding to an allodeterminant associated with DPw1, 2 and 3 and the other to that associated with DPw2 and 4. These two determinants were shown by the sequential binding test to reside on the B7/21‐defined HLA class II molecules. Thus, two major conclusions were drawn: (a) two distinct allodeterminants are carried by a single DP molecule; and (b) these serologically detected DP allodeterminants are supertypic to cellularly defined DP allospecificities.
The majority of “natural” immunoglobulin‐secreting cells are short‐lived and the progeny of cycling lymphocytes
Authors: Lévy Martine , Vieira Paulo , Coutinho António , Freitas António 
Published: March 2007

AbstractTreatment of mice with hydroxyurea to selectively kill all cycling cells has been used to study population dynamics and life expectancy of “natural” immunoglobulin‐secreting cells in the bone marrow and spleen of nonimmunized animals. The results show that 50 to 90% of those cells are eliminated 2 to 3 days after one cycle of hydroxyurea administration, demonstrating their recent origin from cycling precursors. Using a protocol of long‐term hydroxyurea treatment which abrogates cell production from the cycling precursors compartments, it was shown that “natural” immunoglobulin‐secreting cells have a very short half renewal time, in the range of 15–60 h.
T cells expressing delayed‐type hypersensitivity can be derived from a humorally immune lymphocyte population
Authors: Leclercq Sharon A. , Bretscher Peter A. 
Published: March 2007

AbstractSpleen cells from mice immunizied to produce a potent humoral response do not express delayed‐type hypersensitivity (DTH). These cells, when cultured at low density in the presence of the specific antigen for about 6 days, are able to produce swelling of the footpads of normal mice 24 h after they are injected s.c. into the footpad with the appropriate antigen. This footpad swelling peaks 24‐48 h after the injection of the cells, requires the presence of Ly‐1+Ly‐2− T cells in the immune population, is due to the interaction of antigen‐specific cells with the appropriate antigen and is therefore due to DTH‐mediating cells. The optimal generation of these cells occurs under conditions similar to those favoring the primary induction of DTH. Furthermore, the in vitro generated cells are also able to produce a systemic state of DTH when injected i.v.; a DTH reaction is elicited in recipient mice when antigen alone is injected into their footpads.The observations reported here demonstrate that a humorally immune population of spleen cells, known to contain T cells able to suppress the induction of DTH, can under appropriate conditions give rise to cells expressing this subclass of cell‐mediated immunity. The decision by the immune system to mount a humoral as opposed to a cell‐mediated response is therefore reversible. These findings provide grounds for believing that it should be possible to develop the means to switch an on‐going in vivo humoral response to a cell‐mediated one, a maneuver that would be of considerable benefit in some well‐recognized clinical situations.
Recognition of alloantigens and induction of experimental allergic encephalomyelitis by a murine encephalitogenic T cell clone
Authors: Sakai Koichiro , Tabira Takeshi , Kunishita Tatsuhide 
Published: March 2007

AbstractIn this communication we report a SJL/J (H‐2s, Mlsc)‐derived encephalitogenic T cell clone 4b.14a which has dual specificities for myelin basic protein/I‐As and allogeneic H‐2Ik gene products. Monoclonal antibodies specific for public class II major histocompatibility complex (MHC) determinants (Ia.17, I‐Ak,r and Ia.7) and anti‐L3T4 antibody inhibited the response of the clone 4b.14a to alloantigens, but a monoclonal antibody specific for a private determinant on I‐Ak (Ia.2) did not inhibit the response. Although this clone proliferated in response to allogeneic spleen cells expressing H‐2Ik determinants regardless of disparate Mlsa,b,c,d alleles, CBA/N cells (H‐2k, Mlsnull) failed to stimulate the clone 4b.14a. These results suggest that recognition of allogeneic class II MHC molecules by this clone requires recognition with non‐MHC gene products such as Mls. In addition, the clone 4b.14a stimulated by alloantigens could mediate clinical signs of experimental allergic encephalomyelitis in syngeneic recipients. However, interleukin 2 of rat spleen cell origin alone failed to activate the clone cells to make them encephalitogenic, though it could make them proliferate. The significance of these findings for T cell recognition and activation is discussed.
Searching for MHC‐restricted anti‐viral antibodies: antibodies recognizing the nucleoprotein of influenza virus dominate the serological response of C57BL/6 mice to syngeneic influenza‐infected cells
Authors: Tamminen Wendy L. , Wraith David , Barber Brian H. 
Published: March 2007

AbstractAn attempt has been made to generate monoclonal antibodies which recognize the same target structures on influenza‐infected cells as those seen by cytotoxic T lymphocyte (CTL) receptors. Such antibodies, if they mimicked the T cell receptor specificity, would be expected to be both virus specific and restricted in their binding by the major histocompatibility complex (MHC) antigens. Approximately 200 hybridomas from C57BL/6 (H‐2b) mice primed and boosted with influenza virus (X‐31)‐infected EL4 (a C57BL/6 T cell lymphoma) were screened for reactivity on infected and uninfected cells of different MHC haplotypes. Of the 10 hybridoma antibodies which were identified as being reactive with X‐31‐infected EL4, but not uninfected EL4, all reacted equally well with X‐31‐infected cells of H‐2b, H‐2d and H‐2k haplotypes, indicating a lack of MHC restriction in their recognition of the infected cells. Unexpectedly, 7 of the 10 monoclonal antibodies were found to react specifically with the purified influenza virus nucleoprotein (NP), a predominant viral antigen in CTL recognition of infected cells. Fluorescence‐activated flow cytometry confirmed that these antibodies were able to recognize NP serological determinants on the surface of viable, infected cells, but the anti‐NP antibodies were unable to block the lytic activity of an NP‐specific CTL clone.
Modulation of expression of class II histocompatibility antigens by secretion of a cellular inhibitor in K562 leukemic cells
Authors: Krief Patricia , Boucheix Claude , Billard Christian , Mishal Zohar , van Agthoven Andreas , Fiers Walter , Azzarone Bruno 
Published: March 2007

AbstractIn this report we show that it is possible to induce the expression of HLA‐DR antigens on K562 cells, previously reported to be unresponsive to interferon‐gamma (IFN‐γ). However, only low cell concentrations and a high dose of IFN‐γ allowed the induction of HLA‐DR antigens. Furthermore, the recombinant glycosylated IFN‐γ is 100‐fold more efficient than the unglycosylated form. This induction of HLA‐DR antigens on K562 was not related to a stage of differentiation or to the presence of cells subsets specifically sensitive to IFN‐γ, since repeated sorting of K562 HLA‐DR‐positive and negative cells did not lead to the selection of a cell subset with a different potential of induction for HLA‐DR. The difficulty in obtaining induction is due to the production of a soluble endogeneous inhibitor of proteic nature, whose action is not restricted to the K562 cell line since it operates also on both epithelial and fibroblastic cells. Treatment of normal human epithelial and fibroblastic cells with conditioned medium from K562 cultures caused a marked decrease in the expression of HLA class II antigens (DR and DP) induced by IFN‐γ (10000 U/ml), but had no effect on cell growth; however, it also affected expression of HLA class I antigens. This inhibition is not mediated by prostaglandin or an IFN‐α or IFN‐β‐dependent mechanism. Production of this inhibitor by pluripotent human leukemic cells could cause an unbalance in the complex control exerted by the immunological system during hematopoietic differentiation or leukemic progression.
Expression of muscarinic cholinergic receptors during T cell maturation in the thymus
Authors: Maśliński Włodzimierz , Gra̧bczewska Ewa , Laskowska‐Božek Hanna , Ryżewski Jan 
Published: March 2007

AbstractThymocytes at various stages of their ontogeny have been studied in relation to their ability to bind [3H]quinuclidinyl benzilate ([3H]QNB), a specific radioligand of the muscarinic cholinergic receptors. [3H]QNB‐specific binding to thymocytes from 15–19‐day fetal, newborn and adult thymuses of mice and rats was compared and correlated. Our experiments showed that the kinetics of [3H]QNB binding to thymocytes at 37°C was similar to that of the lymph node lymphocytes (LNL) with maximum after 5 min of incubation and subsequent decrease to 10% of the maximum after 90 min of incubation. Maximal binding for the entire thymocyte population was twice lower than for the cortisone‐resistant thymocytes (CRT) or for LNL. Binding of [3H]QNB carried out at 4°C resulted in disappearance of the maximum, but did not alter the difference between CRT and entire thymocyte population. Depletion of CRT detectable [3H]QNB‐specific binding to thymocytes until 18th day of gestation but the maximal binding increased up to 20% at the day 19 and reached 90% of adult level on the third day after birth. Moreover, carbamylcholine (a muscarinic agonist) treatment in vivo induced a significant decrease in [3H]QNB binding to the thymocytes.We thus suggest that a subpopulation of thymocytes bearing muscarinic receptors in the periphery acquired these receptors in the thymus as one of the last steps of their maturation. We cannot exclude the possibility that cholinergic stimulation might trigger these lymphocytes to leave the thymus.
Granzyme A secretion by normal activated Lyt‐2+ and L3T4+ T cells in response to antigenic stimulation
Authors: Velotti Francesca , MacDonal H. Robson , Nabholz Markus 
Published: March 2007

AbstractGranzyme A is a serine esterase initially isolated from cytoplasmic granules of cytolytic T cell lines (Masson, D. et al., EMBO J. 1986. 5: 1595). Among normal T lymphocytes activated by allogeneic stimulation it is found in both Lyt‐2+ and L3T4+ subsets in comparable amounts. Here we show that normal alloantigen‐activated T cells secrete the enzyme specifically when mixed with appropriate stimulator cells. Specific enzyme release is dependent on external calcium and removal of calcium blocks further secretion within a few minutes. Both Lyt‐2+ and L3T4+ cells specifically secrete the enzyme with similar rates, and anti‐L3T4 and anti‐Lyt‐2 antibodies block secretion by the responder cells expressing these markers. Anti‐LFA‐1 antibodies, on the other hand, block secretion by either subset.
Immunoregulatory defects in murine aged Peyer's patches
Authors: Kawanishi Hidenori , Kiely Joan 
Published: March 2007

AbstractAging effect on immunoregulatory processes in Peyer's patches (PP) from BALB/c mice of 3–4 months and 24–28 months was studied in vitro. The magnitude of isotype‐specific Ig production by aged or young PP B cells in co‐culture with young or old fresh PP T cells strongly suggested that the suppressor activity of PP T cells was impaired in aged mice. Further studies on in vitro induction of concanavalin A‐activated T helper cells, T suppressor‐inducer cells and T suppressor cells from aged PP indicated that the generation of T suppressor cells was largely impaired, in contrast to a minor defect(s) in that of T helper cells. The findings obtained here at least suggest that in aged PP, a T suppressor‐inducer cell subset appears to be more selectively impaired in the aging process than the other lymphocyte subpopulations, which possess minor intrinsic functional defects. Thus, these abnormal T and B cell responses in PP could be responsible for the senescence‐associated gut mucosal immunologic dysfunction.
Regulation of immunoglobulin gene transcription by labile represser factor(s)
Authors: Kitamura Daisuke , Maeda Hiroaki , Araki Kazuo , Kudo Akira , Watanabe Takeshi 
Published: March 2007

AbstractThe cloned human γ1 heavy chain gene (HIG1) was scarcely expressed in the stable transformants of a mouse fibroblast line, L cell or a T cell line, EL4, and no γ1 heavy chain was produced in these cells. Upon treatment with cycloheximide or other kinds of protein synthesis inhibitors, the transcription of HIG1 gene was induced in L cell transformants as well as in T cell transformants. Transcription rate of bacterial gpt gene, which was derived from the plasmid vector used for transfection of HIG1 gene and located just upstream of HIG1 in the transformants, was also greatly enhanced after cycloheximide treatment. But the expression of several endogenous genes in the L cells tested was not affected by the cycloheximide treatment. Nuclear transcription assay indicated that the appearance of HIG1 gene transcripts after treatment with cycloheximide was mainly due to the induction of the transcription. Deletion of an enhancer element from HIG1 gene lowered the inducing activity of cycloheximide in the L cell transformants, but a low level of HIG1 gene expression was still observed. These results suggested that trans‐acting factors similar to those present in B lymphoid cells are also functioning in non‐B lymphoid cells but their activity is inhibited by short‐lived repressor protein(s). Such repressor protein(s) appear to act on regulatory element(s) of the immunoglobulin heavy chain gene including enhancer region as well as 5′ flanking region.
Antigen presentation and tumor cytotoxicity by interferon‐γ‐treated microglial cells
Authors: Frei Karl , Siepl Christine , Groscurth Peter , Bodmer Stefan , Schwerdel Cornelia , Fontana Adriano 
Published: March 2007

AbstractIn this study microglial cells isolated from brain cell cultures of newborn mice were characterized and investigated for morphology, their responses to growth factors and their functional properties. The microglial cells were phagocytic, contained nonspecific esterase activity and expressed Fc (IgG1/2b) and type‐3 complement receptors. Scanning electron microscopy revealed that in analogy to brain tissue two types of microglial cells are present in the cultures: the ameboid and the ramified type which both display similar appearance by transmission electron microscopy. Interleukin 3 and the granulocyte‐macrophage colony‐stimulating factor were potent growth factors for the cultured microglial cells. The cells were negative for class II antigens (Ia) of the major histocompatibility antigen complex. However, upon treatment with interferon‐γ (IFN‐γ) microglial cells became Ia+ and functioned as antigen‐presenting cells when tested on ovalbumin‐specific Ia‐restricted helper T cells. Furthermore, microglial cells exposed to IFN‐γ and endotoxin developed tumor cell cytotoxicity and produced tumor necrosis factor α. Taken together, microglial cells share the characteristics of cells of the macrophage lineage.
Simultaneous expression of CD4 and CD8 antigens by a substantial proportion of resting porcine T lymphocytes
Authors: Saalmüller Armin , Reddehase Matthias J. , Bühring Hans‐Jörg , Jonjić Stipan , Koszinowski Ulrich H. 
Published: March 2007

AbstractThe existence of four subpopulations in resting porcine T lymphocytes is documented. In addition to the two known subpopulations which are typified by a mutually exclusive expression of either the CD8 or the CD4 differentiation antigen, CD4−CD8+ and CD4+CD8− T lymphocytes, respectively, two unusual subpopulations were prominent not only in peripheral blood, but also in lymphoid tissues: CD4−CD8− T lymphocytes expressing neither of these antigens and CD4+CD8+ T lymphocytes coexpressing both antigens. While CD4+CD8+ lymphoblasts have been found also in other species, resting T lymphocytes with that phenotype are without precedent among all species analyzed to date. This unique composition of the porcine T lymphocyte population has to be taken into consideration when the swine is used as a large animal model in experimental medicine.
Subpopulations of CD4−, CD8− thymocytes
Authors: Gause William C. , Mountz John D. , Steinberg Alfred D. 
Published: March 2007

AbstractA population of highly purified CD4−, CD8− thymocytes was analyzed by both flow microfluorometry and in situ hybridization in an attempt to further elucidate thymocyte subpopulations. The double‐negative cells had a marked increase in expression of the c‐myb and T cell gamma genes relative to unseparated thymocytes. Approximately 27% were Ly‐24+, 8% Ly‐6C+ and 6% 6B2+. All of the Ly‐6C+ cells were also Ly‐24+. A small population (6%) of the CD4−, CD8− thymocytes had surface expression of the T cell receptor for antigen (F23.1); all were bright Ly‐1+ and half were Ly‐24+. These studies demonstrate that there are further subdivisions of the CD4−, CD8− thymocytes based upon cell surface expression of markers previously found on bone marrow cells and their non‐T cell progeny. Studies are in progress to determine whether these represent different stages of activation‐maturation or different lineages of cells.