bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expansion of the CD4−, CD8− γδ T cell subset in the spleens of mice during non‐lethal blood‐stage malaria
Authors: van der Heyde Henri C. , Elloso M. Merle , Roopenian Derry C. , Manning Dean D. , Weidanz William P. 
Published: March 2007

AbstractSplenic γδ T cells (CD4−, CD8−) increased more that 10‐fold upon resolution of either Plasmodium chabaudi adami or P. c. chabaudi infections in C57BL/6 mice compared to controls. Similarly, a 10‐ to 20‐fold expansion of the γδ T cell population was observed in β2‐microglobulin deficient (β2‐m0.0) mice that had resolved P. c. adami, P. c. chabaudi or P. yoelii yoelii infections. In contrast, increases in the number of splenic αβ T cells in these infected mice were only two to three‐fold indicating a differential expansion of the γδ T cell subset during malaria. Because nucleated cells of β2‐m0/0 mice lack surface expression of major histocompatibility complex class I and class Ib glycoproteins, our findings suggest that antigen presentation by these glycoproteins is not necessary for the increasing number of γδ T cells. Our observation that after resolution of P. c. adami malaria, C57BL/6 mice depleted of CD8+ cells by monoclonal antibody treatment had lower numbers of γδ T. cells than untreated controls suggests that the demonstrated lack of CD8+ cells in β2‐m0/0 mice does not contribute to the expansion of the γδ T cell population during non‐lethal malaria.
Evaluation of functional heterogeneity in the CD8 subset with T cells from T cell receptor‐transgenic mice
Authors: Gaugler Béatrice , Schmitt‐Verhulst And Anne‐Marie , Guimezanes Annick 
Published: March 2007

AbstractThe question of functional differentiation within the CD8 subset has been addressed in a model of TcR‐transgenic (TcR‐tg) mice expressing a TcR specific for H‐2Kb (Ti). CD8+ Ti+ T cells present in the periphery of these mice have no cytotoxic T lymphocyte (CTL) activity unless they are stimulated with H‐2Kb‐expressing cells. In contrast to T cells from normal H‐2k littermates, alloantigen induction of CTL from TcR‐tg mice is independent of CD4+ T helper (Th) cells and is accompanied by high level secretion of interleukin‐(IL)‐2 by Ti+ CD8+ T cells. Precursor frequency analysis performed on CD8+ cells from TcR‐tg mice revealed a high frequency of Th as compared to CTL precursors. This raised the possibility of the existence of distinct subpopulations within CD8+ precursors with different requirements for differentiation to functional CTL. FACS analyses (performed on resting and on in vitro stimulated T cells from normal and TcR‐tg mice) demonstrated a heterogeneous expression of Ly‐6C on CD8+ cells with a large enrichment of Ly‐6C− cells among the Ti+ cells which persisted after stimulation with H‐2b cells in conditions that led to a homogeneous expression of the activation markers pgp‐1 and CD69. The possibility that Ly‐6C expression could mark functionally different subpopulations in CD8+ T cells was investigated. Stimulation of sorted populations of Ly‐6C− and Ly‐6C+ cells allowed detection of CTL precursors in both these subsets and the majority of limiting dilution wells containing one pCTL also scored positive for IL‐2 secretion. Thus, for CD8+ T cells expressing the same TcR, differentiation led to acquisition of both IL‐2 secretion and CTL function and there was no evidence for the existence of a distinct population of helper‐dependent CTL precursors.
B‐1a and conventional B cells from autoimmune NZB. H‐2bm12 mice exhibit similar functional characteristics in vivo
Authors: Klinman Dennis M. , Holmes Kevin L. , Conover Jacqueline , Chiang Bor‐Luen , Gershwin M. Eric 
Published: March 2007

AbstractNZB. H‐2bm12 mice develop an autoimmune syndrome characterized by the overproduction of anti‐DNA antibodies and the expansion of B‐1 B cells. Thus, these animals provide a useful model to examine the antigenic specificity, cross‐reactivity and functional capability of B‐l versus conventional lymphocytes. Neither the repertoire expressed by in vivo activated Ly‐1+ splenic lymphocytes, nor their cross‐reactivity, differed significantly from that of conventional splenic B cells. When Ly‐1+ cells were cultured in vitro in the presence of lipopolysac‐charide plus interleukin‐4 or interferon γ, they underwent isotype switching at the same frequency as conventional B cells. Of interest, B‐l cells from the peritoneal cavity were significantly less likely to undergo isotype switching than those from the spleen. These findings indicate that in vivo activated B‐la and conventional B cells from mice with lupus manifest similar functional characteristics.
Antibody‐induced activation of the hyaluronan receptor function of CD44 requires multivalent binding by antibody
Authors: Lesley Jayne , Kincade Paul W. , Hyman Robert 
Published: March 2007

AbstractCD44 can function as a receptor for hyaluronan (HA). However, many cell lines and normal hematopoietic cells that express CD44 do not constitutively bind HA. A monoclonal antibody (mAb) specific for CD44 (IRAWB14) has been described previously which induces CD44‐mediated binding of HA rapidly (seconds to minutes) in some cell lines and in normal murine T cells. Of 16 CD44‐specific mAb tested in the present study, only 3 exhibited this activity. Monovalent Fab fragments were prepared from two IgG2a antibodies that induce HA binding (IRAWB 14 and IRAWB 26) and used to determine whether multivalent binding was required for induction of HA receptor function. Fab from both antibodies had a tendency to form multivalent aggregates. After addition of iodoacetamide to prevent further aggregation, multimeric and monovalent forms were separated by gel filtration. This made it possible to compare the inducing activity of monovalent and multivalent antibody fragments of identical composition in the absence of Fc determinants. Multimeric forms were very active at inducing binding of fluorescein‐conjugated HA (Fl‐HA). Monovalent Fab fragments of both antibodies had 20‐ to 50‐fold lower binding activity than intact antibody or multimer. IRAWB 26 Fab monomers were completely inactive in the induction of HA‐binding. The observed weak inducing activity of IRAWB 14 Fab monomer could be attributed to very low levels of contaminating multimer. Induction of HA binding could also be achieved by using anti‐immunoglobulin to cross‐link Fab monomers of IRAWB 26. Thus, multivalent binding was required for the activation of HA binding by CD44‐specific antibody, suggesting that the distribution of CD44 molecules on the cell surface is important for HA receptor function.In kinetic studies, induction of HA receptor function occurred simultaneously with antibody binding at 0°C (ice water bath). Furthermore, antibody could induce HA binding in paraformaldehyde‐fixed cells, which were permeable to propidium iodide and trypan blue, suggesting that intracellular signaling mechanisms were not involved in induction of receptor function. We conclude, therefore, that these CD44‐specific antibodies are inducing HA binding by directly influencing the distribution of CD44 on the cell surface. The possibility of a concurrent change in CD44 conformation is not ruled out. We discuss possible mechanisms by which CD44 might be activated to bind HA in vivo.
Expression of immunoglobulin kappa and lambda chains in mink
Authors: Bovkun Ludmila A. , Peremislov Valery V. , Nayakshin Alexander M. , Belousov Evgenij S. , Mechetina Ludmila V. , Aasted Bent , Taranin Alexander V. 
Published: March 2007

AbstractThe ratio of ϰ and λ chains of immunoglobulins varies significantly from one species to another. It has previously been thought that λ was only type expressed in mink. We tested mink immunoglobulin light chains using two monoclonal antibodies G80 and G88. It has been shown that G80 and G88 specifically recognize two antigenically different subpopulations of the light chains. Immunochemical analysis of these subpopulations separated by affinity chromatography suggested that they represent λ and ϰ types of light chains, respectively. Screening of a mink cDNA library with monoclonal antibody G88 resulted in the isolation of clone pIGK‐1 containing ϰ chain‐encoding sequence. The cDNA insert of pIGK‐1 included most of the V segment, as well as the J, C and 3′ untranslated sequences. Mink Vϰ sequence shown the highest homology with the human VϰII subgroup genes (76‐79%). Mink Cϰ sequence was 53‐63% homologous to Cϰ of other species. The striking feature of mink Cϰ chain is the presence of glutamine in the C‐terminal position. Southern blot analysis suggested that mink haploid genome has one Cϰ gene and multiple Vϰ genes. The ϰ: λ chain ratio in the 12 minks studied was, on the average, 46:54. The same ratio was observed for the ϰ‐ and X‐producing cells in the mesenteric lymph nodes. The five previously identified mink light chain allotypes were assigned to the λ chains, thereby confirming that λ chains in this species are additionally subdivided into several subtypes.
Characterization and purification of T lymphocyte aminopeptidase B : A putative marker of T cell activation
Authors: Belhacene Nathalie , Mari Bernard , Rossi Bernard , Auberger Patrick 
Published: March 2007

AbstractWe have previously described that human T lymphocytes express membrane‐associated peptidase activities (Mari et al., EMBO J., 1992,11:3875).We show in this report that intact Jurkat T cells readily cleaved H‐Arg‐paranitroanilide, an aminopeptidase B (AP‐B) substrate. The identification of the hydrolyzing activity as AP‐B was confirmed by its sensitivity to both arphamenine B and bestatin in the nanomolar range. Significant AP‐B activity was released in the supernatant upon incubation of intact T lymphocytes at 37°C. However, AP‐B activity was found mainly in the cytosolic fraction of Jurkat T cells. Cytosolic T cell AP‐B was purified to homogeneity and exhibited a molecular mass of 72 kDa. Purified AP‐B cleaved N‐terminal basic amino acid‐containing peptides such as thymopentin (H‐Arg‐Lys‐Asp‐Val‐Tyr‐OH), indicating that it might play a role in the regulation of the concentration of important soluble mediators of T cell activation. A rabbit polyclonal antibody was shown to recognize AP‐B as assessed by both immunoprecipitation and Western blot experiments. Finally, we found that AP‐B was up‐regulated during activation of normal and leukemic T lymphocytes.
T cell immunity after a viral infection versus T cell tolerance induced by soluble viral peptides
Authors: Kyburz Diego , Aichele Peter , Speiser Daniel E. , Hengartner Hans , Zinkemagel Rolf M. , Pircher Hanspeter 
Published: March 2007

AbstractThe fate of in vivo activated CD8+ cytotoxic T cells was studied in transgenic mice expressing a T cell receptor (TCR) specific for the lymphocytic choriomeningitis virus (LCMV) glycoprotein peptide 33‐41 presented by major histocompatibility complex (MHC) class I molecules. LCMV infection of TCR transgenic mice induced LCMV‐specific effector and memory T cells whereas injection of soluble LCMV glycoprotein peptide 33‐41 resulted in tolerance by peripheral deletion and anergy of LCMV‐specific T cells after an initial expansion phase. Similarly, LCMV peptide 33‐41‐specific tolerance could be achieved in normal C57BL/6 mice and was not abrogated by an LCMV infection. These results obtained with a classically MHC‐restricted peptide antigen parallel previous findings with retroviral or bacterial superantigens and indicate a possibility to modulate specifically mature peripheral cytotoxic T lymphocytes in vivo.
CD4+8− help prevents rapid deletion of CD8+ cells after a transient response to antigen
Authors: Kirberg Jörg , And Ludovica Bruno , von Boehmer Harald 
Published: March 2007

AbstractWe have followed the fate of mature CD8+ T cells with a male‐specific transgenic T cell receptor after antigenic stimulation with hemopoietic cells in the absence or presence of help. Our data show that mature CD8+ T cells can be deleted after a 3‐week period of transient activation and that help, e.g. in the form of interleukin‐2, can considerably delay the deletion. These experiments have implications for the design of protocols aiming at the establishment of specific immunological tolerance in T cells.
Thymus influences the development of extrathymically derived intestinal intraepithelial lymphocytes
Authors: Lin Tesu , Matsuzaki Goro , Kenai Hiroyuki , Nakamura Takao , Nomoto Kikuo 
Published: March 2007

AbstractOverwhelming evidence suggests that the majority of murine small intestinal intraepithelial lymphocytes (IEL) are extrathymically derived. These IEL include those with T cell receptor (TCR) γδ and someTCR αβ (CD8αα and Thy‐1−). In contrast, congenitally athymic nude mice have low numbers of γδ TCR IEL as well as very few αβ TCR IEL, far less than that would be expected if one assumes that γδ TCR IEL and αβ TCR (CD8αα and Thy‐1−) IEL in euthymic mice are extrathymically derived. To examine this discrepancy, we followed extrathymic IEL differentiation in IEL of day 3‐thymectomized (NTX) mice as another athymic mouse model and found that γδ TCRIEL and extrathymically derived αβ TCR IEL in NTX mice are markedly reduced, almost to the level of nude mice. We further show that it is probably the absence of a thymic stroma that is responsible for the lower amounts of extrathymically derived IEL in nude mice, as the low amounts can be corrected to euthymic levels by syngeneic fetal thymus grafting but not by direct injection of F1 thymocytes. Lastly, unlike TCR/CD3+ extrathymically derived IEL, we noted a large proportion of extrathymic CD3−CD8− and CD3−CD8+ IEL; they were threefold more frequent in nude and NTX than in euthymic mice. This suggests that the thymus influences extrathymically derived IEL in its development from CD3− to CD3+ at the small intestinal epithelium.
Pairing of VH gene families with the λ light chain: Evidence for a non‐stochastic association
Authors: Yurovsky Vladimir V. , Kelsoe Garnett 
Published: March 2007

AbstractThe frequencies at which four VH gene families pair with the λ1 light (L) chain were determined by sequential hybridization of VH‐ and λ1‐specific DNA probes to mitogen‐induced colonies of B cells. Analysis of pair frequencies indicates that the repertoire of λ L chain antibodies is generated by the stochastic pairing of smaller 3′‐to‐mid‐locusVH gene families (X‐24, S107, Q52). However, the large 5′ VH J558 family appeared to associate with the λ1L chain non‐stochastically; the frequency of VhJ558/λ1+ colonies among all λ1+ colonies was significantly lower than the frequency of J558 expression among all (Cμ+) B cell colonies. This difference suggests that selection, either intrinsic at the level of rearrangement or heavy and L chain pairing, or extrinsic following surface immunoglobulin expression, may operate to shape the λ antibody repertoire prior to the introduction of exogenous antigen.
Differential induction of Egr‐1 expression in WEHI‐231 sublines does not correlate with apoptosis
Authors: Gottschalk Alexander R. , Joseph Loren J. , Quintáns Jose 
Published: March 2007

AbstractTo determine whether the absence of inducible Egr‐1 expression correlates with apoptosis and growth arrest, we compared the inducible expression of two Egr family members (Egr‐1 and Egr‐2) in three sublines WEHI‐231. Expression of Egr‐2 is induced in all sublines of WEHI‐231 following surface immunoglobulin (sIg) cross‐linking, but Egr‐1 expression is induced in only two. We find that the lack of inducible Egr‐1 expression corresponded to an increase in the methylation pattern of the Egr‐1 gene. In spite of these differences in Egr‐1 expression, all the sublines demonstrate similar inhibition of [3H] thymidine incorporation following anti‐Ig treatment. Growth arrest leads to apoptosis in only two of the sublines, but apoptosis does not correlate with the absence of inducible Egr‐1 expression. Demethylation, by treatment with 5‐azacytidine, in the Egr‐1 non‐expressing subline allows for induction of Egr‐1 expression by anti‐Ig, but fails to prevent growth arrest and apoptosis. Therefore, we conclude that the lack of Egr‐1 expression is not responsible for either the apoptotic response or growth arrest induced by anti‐Ig in WEHI‐231.
Alloactivated cytotoxic T cells recognize the carboxy‐terminal domain of human immunodeficiency virus‐1 gp120 envelope glycoprotein
Authors: Clerici Magio , Shearer Gene , Hounsell Elizabeth F. , Jameson Brad , Habeshaw John , Dalgleish Angus G. 
Published: March 2007

AbstractInfection with the human immunodeficiency virus (HIV) virus leads to clinical disease in humans but not in chimpanzees. Progression to disease is associated with activation of the immune system followed by loss of T helper cell function and a slow decline in CD4‐positive lymphocytes. The presence of autoreactive and cytotoxic cells in humans but not chimpanzees suggests that mechanisms other than, or in addition to, direct virus‐induced cell killing, are required for disease to develop. The observed changes are similar to those seen in chronic allogeneic disease. Here we show that a peptide from the carboxy terminus of gp120, predicted to have a structure similar to the major α‐helices of major histocompatibility complex (MHC) class I and class II, acts as a cytolytic target when presented on syngeneic cells for alloactivated cytotoxic T effector cells. These data add further evidence to the hypothesis that HIV can act as an allostimulant due to its dual properties of CD4 binding and MHC mimicry. The ability to signal nonspecifically through the T cell receptor could explain the initially paradoxical responses of proliferation, anergy and apoptosis.
Increased circulating interleukin‐6 (IL‐6) activity in endotoxin‐challenged mice pretreated with anti‐IL‐6 antibody is due to IL‐6 accumulated in antigen‐antibody complexes
Authors: Martens Erik , Dillen Chris , Put Willy , Heremans Hubertine , van Damme Jo , Billiau Alfons 
Published: March 2007

AbstractMice pretreated with monoclonal anti‐interleukin‐6 (IL‐6) antibody and then challenged with lipopolysaccharide (LPS), paradoxically develop higher levels of circulating biological IL‐6 activity, as measured by the hybridoma growth promotion assay, than mice similarly challenged but not pretreated with antibody. Here we provide evidence that this increased biological activity was entirely accounted for by the presence of increased amounts of IL‐6 protein, which could be isolated by immunoaffinity chromatography and subsequently visualized after gel electrophoresis. Chromatography on a protein G matrix and a sandwich ELISA allowed to demonstrate that all IL‐6 present in the serum was in the form of antigen‐antibody complexes. Serum samples of antibody‐treated animals which contained the highest biological activity typically contained near equimolar concentrations of IL‐6 and antibody. In vitro neutralization tests with pure antibody and IL‐6 demonstrated that, with both antibodies tested, more than 1000‐fold molar excess of antibody is needed for neutralization in the hybridoma growth assay. It is concluded that increased biological activity in serum of the anti‐IL‐6 antibody‐treated mice is due to sequestration of the endogenous IL‐6 in the form of antigen‐antibody complexes which, due to the lack of sufficient antibody excess, produce nearly full activity in the hybridoma growth assay.
Thermostability analysis of major histocompatibility complex class I molecules by temperature gradient gel electrophoresis
Authors: Tulp Abraham , Verwoerd Desirée J. 
Published: March 2007

AbstractEmpty major histocompatibility complex (MHC) class I molecules present on the surface of RMA‐S (26°C) cells were loaded with the iodinated peptides APGNYPAL, FAPGNYPAL (SEV‐9) and RGYVYQGL (VSV‐8), respectively. The thermostability of these peptide‐loaded MHC class I molecules was assessed using temperature gradient native polyacrylamide gel electrophoresis. A linear temperature gradient perpendicular to the direction of electrophoresis yielded a graphical representation of the melting of MHC class I molecules. The class I signal disappeared when the peptide melted out of the groove, and gave rise to a second signal due to released peptide. APGNYPAL‐loaded class I molecules melted at 11°C with considerable release even at 0°C. VSV‐8‐loaded class I molecules melted first at 36°C, whereas SEV‐9‐loaded molecules melted at about 22°C. A discrimination between the binding of SEV‐9 to Kb and Db molecules was seen in the melting patterns. Results are discussed in correlation with known crystallographic structures of class I molecules containing peptides in the binding groove.
Helper activity of CD4+ αβ T cells is required for the avian γδ T cell response
Authors: Arstila T. Petteri , Toivanen Paavo , Lassila Olli 
Published: March 2007

AbstractWe have studied the in vitro activation of chicken γδ T cells. Both splenic αβ and γδ T cells obtained from complete Freund's adjuvant‐primed chickens proliferated in vitro when stimulated with mycobacterial sonicate or purified protein derivative of Mycobacterium tuberculosis. When CD4+ cells or αβ T cell receptor (TcR)‐positive cells were removed, both the proliferation and the blast formation of γδ T cells in response to mycobacterial antigens were abrogated. The response was restored if supernatant from concanavalin A (Con A)‐activated lymphocyte cultures (CAS) as a source of helper factors was added together with the specific antigen purified protein derivative. The CD4‐ or αβ TcR‐depleted cells still proliferated in response to Con A, although a decrease of the response was observed. To analyze the γδ T cell response more specifically we stimulated peripheral blood cells with immobilized monoclonal antibodies against T cell receptor. Anti‐γδ TcR antibody alone did not induce significant proliferation. When CAS was added together with the anti‐γδ TcR monoclonal antibody, a strong proliferation of γδ T cells was observed. In contrast, both Vβ1‐ and Vβ2‐expressing αβ T cells proliferated in vitro in response to stimulation with the relevant anti‐TcR monoclonal antibody alone. Depletion of either Vβ1+ or Vβ2+ T cell subset alone had no negative effect on the proliferation or blast formation of γδ T cells stimulated with mycobacterial antigens. Taken together our results suggest that CD4+ αβ T cells (both Vβl‐ and Vβ2‐expressing) play a role in the activation and response of chicken γδ T cells.