bluuebunny/crossref_metadata_2025_split huggingface dataset:
The novel subset of CD14+/CD16+ blood monocytes exhibits features of tissue macrophages
Authors: Ziegler‐Heitbrock H. W. Löms , Fingerle Günter , Ströbel Marion , Schraut Winfried , Stelter Felix , Schütt Christine , Passlick Bernward , Pforte Almuth 
Published: March 2007

AbstractThe CD14+/CD16+ cells account for about 10 % of all blood monocytes. They are characterized by a low level expression of the CD14 molecule and a high level expression of the CD16 (FcγR III) molecule. Polymerase chain reaction analysis of mRNA prevalence in CD14+/CD16+ cells (compared to the regular CD14+ + blood monocytes) demonstrates low levels of CD14 transcripts and high levels of CD16 transcripts, suggestive of a transcriptional control for both of these proteins. Analysis of additional cell surface molecules in three‐color immunofluorescence reveals that CD14+/CD16+ cells express the FcγR II in all, and FcγR I and ICAM‐1 in some donors. Furthermore, class II antigens are expressed at fourfold higher levels, while both, CD11b and CD33 cell surface proteins, are decreased by a factor of two. Transcript levels were reduced in CD14+/CD16+ cells for all three cell surface molecules. Since these phenotypic markers of the CD14+/CD16+ blood monocytes are reminiscent of tissue macrophages, we performed a comparative analysis with alveolar macrophages (AM). These cells are similar to the CD14+/CD16+ monocytes in that they show low levels of CD14 and strong expression of CD16. Furthermore, similar to the CD14+/CD16+ cells, the AM also exhibit higher levels of class II and lower levels of CD11b and CD33 when compared to the regular CD14++ blood monocytes.In vitro induction of maturation of blood monocytes by 5 day culture of peripheral blood mononuclear cells in 10 % human serum will result in decreased CD14 and increased CD16 cell surface expression on the monocyte derived macrophages. At the same time, these cells acquire increased levels of class II and decreased levels of CD11b and CD33. Taken together, these data show that CD14+/CD16+ monocytes, while still in circulation, have acquired features in common with mature tissue macrophages.
CD23‐mediated homotypic cell adhesion: The role of proteolysis
Authors: Moulder Kevin , Barton Aisling , Weston Beverley 
Published: March 2007

AbstractCD23 is a multifunctional molecule expressed by cells of lymphoid, myeloid and hematopoietic lineages. As a cell surface molecule CD23 acts both as a low‐affinity receptor for IgE (FcεRII) and as a cell adhesion molecule. CD23 can undergo autoproteolysis to release soluble 37–25‐kDa CD23 (s‐CD23) molecules with a range of cytokine activities. Here we show a causal link between the two apparently disparate functions of autoproteolysis and cell adhesion. The Epstein‐Barr virus‐transformed B cell line RPMI‐8866 formed macroscopic cell clusters solely via CD23. Cell adhesion was inhibited by mAb to CD23 and by IgE. Cell adhesion was also dependent on serum as cells grown in serum‐free media failed to form clusters. In serum‐free conditions cell adhesion could be induced by the addition of not only 10 % FCS but also s‐CD23. As s‐CD23 is reported to possess proteolytic activity we screened a range of proteases to determine whether they also could induce cell adhesion in serum‐free medium. It was found that chymotrypsin and elastase induced cell: cell adhesion in RPMI‐8866 cells. The same panel of proteases were screened against a range of CD23‐positive (Jijoye, AF‐10, T2, U937, ICH‐1) and CD23‐negative (RPMI‐8226, U266, MOLT‐4, Ramos) cell lines. It was found that chymotrypsin and elastase induce cell adhesion only in cells expressing CD23. Peptide mapping studies showed that chymotrypsin and elastase cleaved immunoprecipitated CD23 near the same site by which 37‐kDa S‐CD23 is released (Ala 80). Serum demonstrated no proteolytic activity towards CD23. However, it was found that cells grown in serum‐free medium released 25‐kDa S‐CD23 without the need for prior cleavage at the 37‐kDa cleavage site. To confirm the role of proteolysis in CD23‐mediated cell adhesion we screened a range of protease inhibitors for their ability to antagonize this process. It was found that tosyl‐lysine chloromethyl ketone inhibited CD23‐mediated cell adhesion. Lactoperoxidase treatment, which inhibits CD23 cleavage, also inhibited cell adhesion. Addition of chymotrypsin and elastase to lactoperoxidase‐treated cells induced cell adhesion. From these data we propose that intact CD23 has no demonstrable role in cell adhesion; instead, the portion of CD23 remaining on the cell surface following cleavage appears to mediate cell adhesion.
In vitro induction of human cytotoxic T lymphocyte responses against peptides of mutant and wild‐type p53
Authors: Houbiers Jos G. A. , Nijman Hans W. , Van Der Burg Sjoerd H. , Drijfhout Jan Wouter , Kenemans Peter , Van De Velde Cornelis J. H. , Brand Anneke , Momburg Frank , Kast W. Martin , Melief Cornells J. M. 
Published: March 2007

AbstractThe central role of the p53 tumor suppressor gene product in oncogenesis is gradually being clarified. Point mutations in the p53 tumor suppressor gene are common in most human cancers and are often associated with p53 protein overexpression. Overexpressed wild‐type or mutant determinants of the p53 protein thus represent an attractive target for immunotherapy of cancer directed against a structure involved in malignant transformation. An important step towards this goal is identification of epitopes of p53 that can be recognized by human cytotoxic T lymphocytes. We identified peptides of (mutant) p53 capable of binding to HLA‐A2.1 in an in vitro assay. These HLA‐A2.1‐binding peptides were utilized for in vitro induction of primary cytotoxic T lymphocyte responses using a human processing‐defective cell line (174CEM.T2) as antigen‐presenting cell. These cells display “empty” HLA class I surface molecules, that can efficiently be loaded with a single peptide. We obtained CD8+ cytotoxic T lymphocyte clones capable of specifically lysing target cells loaded with wild‐type or tumor‐specific mutant p53 peptides. This strategy allows the in vitro initiation of human cytotoxic T lymphocyte responses against target molecules of choice.
Ontogeny of fetal CD8lo4lo thymocytes: Expression of CD44, CD25 and early expression of TcR α mRNA
Authors: Andjeli Sofija , Jain Nada , Nikolić‐Žugi Janko 
Published: March 2007

AbstractCD8lo 4lo cells are the immediate precursors of immature CD8hi4lcTcRlo, CD8hi 4hiTcRlo and CD8hi4hiTcRlo double‐positive (DP) thymocytes in the adult murine thymus. These cells are the first subset in the adult thymus to express accessory CD8 and CD4 molecules, to rearrange the T cell receptor (TcR) a chain genes and to express the TcR αβ heterodimer at low levels at the surface. Here, we investigate the fetal ontogeny of CD8lo 4lo cells. We detect these cells on day 15 of fetal development. They dominate the thymus on day 15.5, to become progressively less prominent thereafter. An important characteristic of fetal CD8lo 4lo cells is the early expression of TcR α mRNA (on fetal day 15, 36–48 h earlier than reported previously). Our results also suggest, but do not prove, that the receptor may be expressed on the surface as early as day 15.5.Fetal CD8lo 4lo cells, like their adult counterparts, become DP in vitro. However, early fetal CD8lo 4lo thymocytes express both CD44 and CD25 – unlike the adult subset ‐ and that links them to their putative precursors, fetal CD44+CD25+ double‐negative cells. This finding underscores the difference between adult and fetal thymocytes in turnover of membrane molecules and/or the kinetics of progression through phenotypic stages.
Release from a human monocyte‐like cell line of two different soluble forms of the lipopolysaccharide receptor, CD14
Authors: Labeta Mario O. , Durieux Jean‐Jacques , Fernandez Nelson , Herrmann Richard , Ferrara Pascual 
Published: March 2007

AbstractLipopolysaccharide (LPS) stimulates mononuclear phagocytes to synthesize and secrete immunoregulatory and inflammatory molecules such as interleukin‐1 (IL‐1), IL‐6, and tumor necrosis factor‐α (TNF‐α). LPS forms complexes with either the serum protein termed LPS‐binding protein or a serum factor, septin. These complexes are more stimulatory than LPS alone. The myeloid differentiation antigen CD14 is known to be the receptor for such complexes. In the present study, by using a monocytic cell line, we demonstrate the release of two different soluble forms of CD14 (sCD14) which are secreted by different mechanisms. We show that the two sCD14 forms differ in their electrophoretic mobility, two‐dimensional gel electrophoretic patterns, sensitivity to endoglycosidases and peptide maps. One of the sCD14 molecules, apparent molecular mass 48 kDa, was found in supernatants of both surface iodinated and [35S] methionine biosynthetically labeled cells. The other sCD14 molecule (56 kDa) was found labeled only in supernatants of [35S] methionine‐labeled cells. Furthermore, purified 48 kDa sCD14 enhanced the LPS‐induced TNF‐a and IL‐6 release by the monocytic cells suggesting that a cell‐surface signal transducer molecule may be involved in signaling. The data suggest a possible novel role for sCD14 in the monocyte response to LPS.
Somatic hypermutation in 5′ flanking regions of heavy chain antibody variable regions
Authors: Rothenfluh Harald S. , Taylor Linda , Bothwell Alfred L. M. , Both Gerald W. , Steele Edward J. 
Published: March 2007

AbstractThe aim of this study has been to determine the distribution of somatic mutations in the 5′ flanking regions of rearranged immunoglobulin heavy chain variable region genes (VDJ).We sequenced the 5′ flanking region in 12 secondary immune response antibodies produced in C57BL/6J mice against the hapten (4‐hydroxy‐3‐nitrophenyl)acetyl (NP) coupled to chicken‐Y‐globulin. In these and previously published sequences, almost 97 % of the mutations occurred in the transcribed region of the gene, and only a minority of genes (5/29) contained mutations upstream of the transcription start (cap) site. No potential germ‐line donor was found for a cluster of five base changes previously found in a single heavy chain gene, 3B62. However, the uniqueness of this mutational cluster and its distance from the normally mutated region suggests that the nucleotide changes may not be due to the normal mutator mechanism. Thus, as this was the only instance of somatic mutations that far upstream of the promoter/cap site region, the reverse transcriptase model for somatic hypermutation is still a possibility. The data are consistent with a mutational mechanism that requires transcription of the rearranged target V(D)J gene which appears to result in the generation of a positively skewed asymmetrical distribution of somatic mutations. A single mode is centered near the V(D)J and a long tail extends into the 3′ non‐translated region of the J‐C intron. Two classes of model could explain this mutation distribution pattern: those where transcription products (RNA, cDNA) are the direct mutational substrates, or those that postulate local unfolding of the chromatin around a V(D)J rearrangement directly exposing the DNA of the transcribed region to specific mutational enzymes.
The evolutionary origin of the major histocompatibility complex: Polymorphism of class II α chain genes in the cartilaginous fish
Authors: Kasahara Masanori , McKinney E. Churchill , Flajnik Martin F. , Ishibashi Teruo 
Published: March 2007

AbstractT cells recognize antigen (Ag) in the form of peptides bound to the major histocompatibility complex (MHC) molecule. One of the important issues in evolutionary immunology is to identify the stage in phylogeny when this mode of Ag recognition emerged. At present, there is a considerable controversy as to whether the cartilaginous fish have the bona fide MHC. In our previous study, we showed that the nurse shark, a member of the cartilaginous fish, has (a) gene(s) capable of encoding MHC class II a chains. In the present study, we examined the polymorphism of nurse shark MHC class II a chain genes designated Gici‐DAA and Gici‐DBA using the polymerase chain reaction. The Gici‐DAA and Gici‐DBA genes had six and five alleles, respectively, and individual alleles usually differed by multiple nucleotides. In addition, most of the nucleotide substitutions were located at the putative Ag‐binding sites, where non‐synonymous substitutions occurred more frequently than synonymous substitutions. The fact that the Gici‐DAA and Gici‐DBA genes display a polymorphism pattern essentially similar to that of mammalian MHC genes playing a major role in Ag presentation suggests that the cartilaginous fish have the bona fide MHC. Thus, the MHC‐peptide‐based T cell recognition system appears to have arisen at or before the emergence of the cartilaginous fish.
C1q, the collagen‐like subcomponent of the first component of complement C1, is a membrane protein of guinea pig macrophages
Authors: Kaul Marcus , Loos Michael 
Published: March 2007

AbstractC1q, a subcomponent of C1 ‐ the first component of complement, is synthesized by macrophages (Mϕ). Immunofluorescence and immunoperoxidase studies first indicated the presence of Clq on the surface of guinea pig (gp) and human peritoneal Mϕ (Loos, M., Storz, R., Müller, W. and Lemmel, E.M., Immunobiology 1981. 158: 213). In our study different methods for labeling of gp serum and gp Mϕ C1q were employed. The presence of C1q protein on the surface of gp peritoneal Mϕ is shown by cell surface labeling with the biotin derivative sulfosuccinimdyl–6–(biotinamido)‐hexanoate and subsequent immunoprecipitation. The mechanism by which Clq is attached to the cell membrane was also investigated. Intact cells were treated with acid stripping‐buffers or phosphati‐dylinositol‐specific phospholipase C and separated membranes were extracted with a buffer containing 1 M KC1 and 3 M urea. Regardless of which method was used, Clq remained attached to the membrane. When surface‐labeled cells were cultured, they were found to release the Clq from their surface membrane into the culture medium. Lysates of biosynthetically labeled cells were used to show that, like secreted or serum Clq, cellular Mϕ Clq binds to immobilized homologous IgG. This implies that the globular regions of the cellular Clq are functionally active. The results reveal that (i) cellular Mϕ C1q is firmly located in the membrane throughout the biosynthetic pathway, such that it is comparable with an integral membrane protein, (ii) cellular Mϕ C1q is not reversibly bound to the cell surface via a receptor. We suggest that C1q, as a membrane protein of Mϕ, serves as an Fc binding factor that also is secreted into the environment.
The B7 adhesion molecule is expressed on activated human T cells: Functional involvement in T‐T cell interactions
Authors: Wyss‐Coray Tony , Mauri‐Hellweg Daniela , Baumann Kaspar , Bettens Florence , Grunow Roland , Pichler Werner J. 
Published: March 2007

AbstractThe B cell antigen B7 delivers a strong co‐stimulatory signal for the activation of T cells by binding to its ligands CD28 and CTLA4. Here we demonstrate the surface expression of the B7 molecule on activated human T cells in vitro and under certain conditions in vivo and its functional importance in T‐T cell interactions. B7 was detected by flow cytometry on antigen‐specific CD4+ and allospecific CD8+ cloned T cells from different donors with anti‐B7 monoclonal antibody (mAb) or a soluble CTLA4‐Cγ1 chimera molecule and by reverse transcription‐polymerase chain reactions. The expression of B7 was up‐regulated following restimulation of the T cell clones and peaked after 7‐9 days. Moreover, we show that the B7 molecule on T cells is functionally involved in T‐T cell interactions: mAb to CD28 and the CTLA4‐Ig fusion protein could inhibit the proliferation of specific T cell clones in response to T cells as antigen‐presenting cells (APC) or the proliferation of peripheral blood mononuclear cells in a primary allostimulation with activated T cells as stimulator cells. Finally, we found that B7 can be expressed on freshly isolated circulating T cells since in a preliminary study with a limited number of patients, B7 was present on a subset of CD3+ cells. B7 was expressed on activated T cells (CD4+ and CD8+) of certain human immunodeficiency virus (HIV)‐infected individuals (0.5–20% B7+CD8+ cells) or some patients with autoimmune diseases whereas CD3+ cells of healthy individuals did not express B7. The coexpression of major histocompatibility complex class II molecules and B7 may be relevant for the capacity of activated T cells to function as APC. The expression of B7 on T cells in vivo in autoimmune diseases and in HIV infection may be important for a better understanding of these diseases.
Physical association of the cytoplasmic domain of CD2 with the tyrosine kinases p56lck and p59fyn
Authors: Carmo Alexandre M. , Mason Don W. , Beyers Albertus D. 
Published: March 2007

AbstractIn T lymphocytes, CD2 forms part of a loosely associated membrane complex which includes the T cell receptor (TcR) for antigen, the CD3 subunits, CD4 or CD8, CD5 and the protein tyrosine kinases p56lck and p59fyn. The interaction of CD2 with tyrosine kinases in this complex provides a possible mechanism for transmembrane signal transduction by CD2. We have investigated whether the interaction of CD2 with the kinases is dependent on other known members of the complex, or whether an independent association can be observed. Using in vitro kinase assays with immune complexes precipitated from cell lysates, we demonstrate that CD2 can associate with p56lck and p59fyn in a rat thymoma line that does not express CD4 or CD8, and in a TcR‐negative Jurkat cell line. In TcR‐positive Jurkat cells that express rat CD2, interaction of CD2 with p56lck and p59fyn Was clearly seen, but it was absent in cells where the cytoplasmic tail of CD2 is truncated, indicating that the interactions are mediated by the cytoplasmic region of CD2. Furthermore, using cells expressing CD2 molecules with partial truncations in the cytoplasmic domain, we show that the association of CD2 with p56lck: is progressively lost as the cytoplasmic domain is shortened, and that the capacity of the mutants to associate with p56lck correlates with their capacity to transduce transmembrane signals.
KIM185, a monoclonal antibody to CD18 which induces a change in the conformation of CD18 and promotes both LFA‐1‐ and CR3‐dependent adhesion
Authors: Andrew David , Shock Anthony , Ball Elaine , Ortlepp Susan , Bell Joanne , Robinson Martyn 
Published: March 2007

AbstractUnactivated peripheral blood leukocytes show little tendency to bind to other cells or matrix components, whilst, in the presence of inflammatory mediators, adhesive interactions can rapidly increase. The Leu‐CAM (β2 integrin) family of adhesion molecules have been shown to mediate a variety of these induced adhesion events. Here we describe a monoclonal antibody against CD18, KIM185, which stimulates JY cell homotypic aggregation by a CD11a pathway as well as inducing the adherence of neutrophils to protein‐coated plastic by a CD lib‐dependent mechanism. The antibody recognizes an epitope distinct from the previously described KIM127 antibody and evidence is presented that the binding of KIM185 can cause a change in the conformation of the CD18 molecule.
Vaccination with cytotoxic T lymphocyte epitope‐containing peptide protects against a tumor induced by human papillomavirus type 16‐transformed cells
Authors: Feltkamp Mariet C. W. , Smits Henk L. , Vierboom Michel P. M. , Minnaar René P. , De Jongh Barteld M. , Drijfhout Jan Wouter , Schegget Jan Ter , Melief Cornelis J. M. , Kast W. Martin 
Published: March 2007

AbstractCytotoxic T lymphocyte (CTL) peptide epitopes can be used for immunization of mice against lethal virus infection. To study whether this approach can be successful against virus‐induced tumors we generated a B6 (H‐2b) tumorigenic cell line transformed by human papillomavirus (HPV). This virus is detected in over 90% of all human cervical cancers. To identify vaccine candidates, we generated a set of 240 overlapping peptides derived from the HPV type 16 (HPV16) oncogenes E6 and E7. These peptides were tested for their ability to bind H‐2Kb and H‐2Db MHC class I molecules. Binding peptides were compared with the presently known peptide‐binding motifs for H‐2Kb and H‐2Db and the predictive value of these motifs is shortly discussed. The high‐affinity H‐2Db‐binding peptide and putative CTL epitope E7 49‐57 (RAHYNIVTF) was used in vaccination studies against HPV 16‐transformed tumor cells. Immunization with peptide E7 49‐57 rendered mice insensitive to a subsequent challenge with HPV 16‐transformed tumor cells in vivo, and induced a CTL response which lysed the tumor cells in vitro.
Human immunoglobulin class and IgG subclass regulation: Dual action of interleukin‐4
Authors: Kotowicz Karolena , Callard Robin E. 
Published: March 2007

AbstractEpstein‐Barr virus (EBV) was used as a polyclonal human B cell mitogen to investigate the regulation of immunoglobulin class and IgG subclass responses by interleukin‐4 (IL‐4). Activation of tonsillar B cells with EBV resulted in an early peak of polyclonal immunoglobulin secretion between days 13 and 14 consisting of IgM, IgA, and IgG1, IgG2, IgG3 and IgG4, but not IgE. Addition of IL‐4 to EBV‐activated B cells at concentrations of 100 U/ml or greater induced the production of IgE and enhanced IgG4 secretion, but had no effect, or more often inhibited the other isotypes. In contrast, low concentrations of IL‐4 (1‐5 U/ml) significantly increased the production of IgM, IgA, IgG1, IgG2and IgG3, but had no effect on IgG4 or IgE. The increase in immunoglobulin secretion obtained with low concentrations of IL‐4 was found to occur only with high‐density (resting) B cells, suggesting that IL‐4 was not functioning simply as a late‐acting differentiation factor. Low concentrations of IL‐4 significantly increased IgG1, IgG2, IgG3, and IgA production by surface (s)IgM+ (sIgG−/sIgA−) B cells which is consistent with heavy chain switching. In some experiments, however, IL‐4 enhanced IgM secretion by sIgM+ B cells, and IgA, IgG1, IgG2, IgG3 by sIgM B cells, suggesting that it may have an additional B cell differentiation factor activity which was not isotype specific. The different effect of IL‐4 at high and low concentrations were similar to those observed in B cell activation experiments, and may be due to the existence of high‐ and low‐affinity IL‐4 receptors.