bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of proliferative and cytotoxic responses in resting Lyt‐2+ T cells with lectin and recombinant interleukin 2
Authors: Vohr Hans‐W. , Hünig Thomas 
Published: February 2007

AbstractThe lectin leucoagglutinin has been used to induce reactivity to interleukin 2 (IL2) in unseparated spleen cells and in highly purified Lyt‐2+ lymph node T cells. Recombinant human IL2 and various other IL2‐containing preparations, including con‐canavalin A‐induced spleen cell supernatant, were compared for their capacity to support DNA synthesis and cytotoxic activity. In contrast to published reports, we found that the capacity of all preparations tested was identical in both functional assays, if they were adjusted to the same IL2 titer. Our inability to detect a requirement for an externally added cytotoxic T cell differentiation factor could either mean that IL2 is sufficient for the promotion of both proliferation and differentiation in leucoagglutinin‐activated resting cytotoxic T cell precursors, or that under our experimental conditions, T cell differentiation factor is endogenously produced by Lyt‐2+ T cells.
Mycoplasma infection of cell lines can simulate the expression of Fc receptors by binding of the carbohydrate moiety of antibodies
Authors: Lemke Hilmar , Krausse Rea , Lorenzen Johann , Havsteen Bent 
Published: February 2007

AbstractDuring the production of Fc receptor (FcR)‐bearing hybridomas it was observed with a particular monoclonal anti‐sheep red blood cell antibody (anti‐SRBC 1/5, IgG1) that the contamination with Mycoplasma arginini of in vitro cultured cell lines leads to an apparent FcR activity. This property did not correspond with the serological typing since other antibodies of the same isotype could not support FcR rosette formation. Another mycoplasma strain M. orale lacked this property. Analysis of the binding reaction revealed that M. arginini contains a lectin which binds the carbohydrate moiety of the anti‐SRBC 1/5 antibody, i.e. anti‐SRBC 1/5 synthesized under the influence of tunicamycin or deglycosylated by NaIO4 oxidation did not support rosette formation. These data suggest that binding of antibodies to certain mycoplasma strains may be a pathogenic factor during mycoplasma infections by masking the microorganisms with the host's own defense molecules.The experiments with M. arginini‐infected cell lines gain immunological importance since we obtained identical results with staphylococcal protein A, as another bacteriological FcR, and cell lines expressing intrinsic membrane FcR. Although it is an open question whether the glycoconjugates are directly bound by the FcR or else by influencing the three‐dimensional structure of the antibodies, it seems possible that FcR in general may be lectins.
Analysis of autoreactive I region‐restricted T cell colonies isolated from the guinea pig syngeneic mixed leukocyte reaction and from immune responses to conventional foreign antigens
Authors: Dosreis George A. , Shevach Ethan M. 
Published: February 2007

AbstractGuinea pig proliferating T cell colonies were isolated from T cell populations stimulated during the syngeneic mixed leukocyte reaction (SMLR) or following positive selection of immune T lymphocytes specific for pork insulin (PI) or the copolymer of L‐glutamic acid, L‐lysine (GL). SMLR‐responding T cell colonies could be isolated in the absence of any extrinsic antigen and were strictly restricted to the recognition of Ia molecules on stimulator peritoneal exudate cells (PEC) and required both stimulator cells and interleukin 2‐enriched fluids for optimal proliferative responses. Blocking of T cell colony proliferation with a panel of monoclonal anti‐la antibodies showed that SMLR T cell colonies were restricted by discrete and distinct self‐la epitopes. Analysis of individual T cell colonies generated against PI and GL revealed three types of colonies: (a) antigen specific, I region‐restricted; (b) autoreactive, I region‐restricted; and (c) antigen specific, but also autoreactive. These doubly reactive colonies were restricted to the same Ia epitope when stimulated with self‐PEC alone or when stimulated with self‐PEC in the presence of the relevant exogenous antigen. These results substantiate the hypothesis that both the SMLR and antigen‐specific responses are mediated by a common set of precursor T lymphocytes and that the guinea pig SMLR is at least in part the result of the polyclonal proliferative responses of several distinct antigen‐reactive T cell clones in the absence of exogenous antigen.
Regulation of Epstein‐Barr virus infection by recombinant interferons. Selected sensitivity to interferon‐γ
Authors: Lotz Martin , Tsoukas Constantine D. , Fong Sherman , Carson Dennis A. , Vaughan John H. 
Published: February 2007

AbstractInterferons (IFN) are antiviral proteins that may be important in mediating cellular defenses against Epstein‐Barr virus (EBV) infection. However, the means by which IFN‐α, ‐β and ‐γ modify EBV infectivity are not clear. We have evaluated the effects of purified recombinant preparations of all three classes of IFN on EBV‐induced B lymphocyte proliferation and Ig secretion. When added early after EBV infection, all three recombinant IFN reduced B cell outgrowth and Ig secretion. IFN‐γ exerted a 7‐10‐fold more potent antiviral effect than IFN‐α or ‐β. All three types of IFN act directly on B cells. Monocytes and natural killer cells are not necessary for the anti‐EBV activity. Of the three recombinant IFN, only IFN‐γ reduced EBV‐induced proliferation and Ig secretion when added 3–4 days after virus infection; IFN‐α/β were only effective up to 24 h. B lymphoblastoid lines already transformed by EBV are insensitive to the anti‐proliferative actions of all three types of IFN.On the basis of these findings, we propose three phases of regulation during EBV infection. In the early phase, EBV‐infected cells can be regulated by all IFN. Subsequently, there is an intermediate period where only IFN‐γ is capable of directly affecting EBV‐induced B cell responses. In the third phase, B lymphocytes become insensitive to direct actions of all IFN and are now subject to regulation only by cytotoxic cells.
Differentiation in the murine B cell lymphoma 1.29: inductive capacities of lipopolysaccharide and Mycoplasma fermentans products
Authors: Sitia Roberto , Rubartelli Anna , Deambrosis Sandro , Pozzi Donata , Hammerling Ulrich 
Published: February 2007

AbstractCells from the murine B lymphoma 1.29, expressing IgM or IgA of identical idiotype, were found inducible by lipopolysaccharide to differentiate into plasma cells. Within 3 days, differentiating cells lost membrane‐bound immunoglobulin (Ig) and accumu‐ lated large quantities of intracytoplasmic Ig. At day 6 of culture, IgA secretion increased 50‐100‐fold, as determined by enzyme‐linked immunoassay. Proliferation increased for the first days of culture but decreased thereafter; by day 10 very few viable cells were present in lipopolysaccharide‐stimulated cultures. Similar results were obtained by culturing 1.29 cells in the presence of supernatants of certain B cell lines (e.g. BF0.3). The finding of a strict correlation between the inductive activity and presence of contaminating Mycoplasma fermentans suggested that factor(s) released by mycoplasma were responsible for the mitogenic activities. This was further indicated by the findings that: (a) the supernatants of BF0.3 that were rendered free of mycoplasma were not inductive, and (b) a nonactive cell line could be made active by infection with supernatants of BF0.3 cells containing viable micro‐ organisms. Thus, supernatants of mycoplasma‐infected cell lines may act as potent polyclonal activators on both normal and malignant B lymphocytes. The ability to induce membrane Ig on 70Z/3 cells indicates that mycoplasma‐related mitogens are also active on pre‐B cells. The possibility of mycoplasma contamination should thus be carefully excluded when presumptive factors of cloned cell lines are being evalu‐ ated.
Human clones with natural killer function can activate B cells and secrete B cell differentiation factors
Authors: Vyakarnam Anna , Brenner Malcolm K. , Reittie Joyce E. , Houker Clare H. , Lachmann Peter J. 
Published: February 2007

AbstractLarge granular lymphocyte clones were prepared from normal human mononuclear cells. Seven clones were studied in detail. All had high cytotoxic activity against the natural killer (NK) cell target K562 and all were T11‐ and DR‐positive but T4‐ and T8‐negative: none released migration inhibitory factor, a characteristic of helper T cell clones. When these NK cell clones were co‐cultured with autologous B cells in a 1:1 ratio, 4 of the 7 induced both IgM and IgG synthesis. Ig production could not be further enhanced by the addition of B cell differentiation factors. The cells stimulated included antigen‐specific memory B cells, as the Ig induced contained specific antibody to an antigen, tetanus toxoid, to which the B cell donors had recently been immunized. Supernatants from the helper/NK clones contained B cell differentiation factors, and were able to induce IgG synthesis from the lymphoblastoid cell line CESS and from co‐cultured T and B cells. However, NK clone supernatants, unlike the clones themselves, were not effective at inducing Ig synthesis from purified B cells. Instead it appears that NK clones first activate B cells and thus render them responsive to the factors that the clones secrete.
Immunoglobulin‐bearing stem cells for clones of B (bursa‐derived) lymphocytes
Authors: Pink J. Richard L. , Ratcliffe Michael J. H. , Vainio Olli 
Published: February 2007

AbstractTreatment of neonatal chickens with cyclophosphamide depletes bursal lymphocytes while maintaining the bursal epithelium intact. The bursae of normal young chickens contain “bursal stem cells” which can reconstitute the lymphoid compartment in the bursa of the cyclophosphamide‐treated recipient. Using bursal stem cells from IgM allotype‐heterozygous donors we show that most bursal follicles in the reconstituted host are colonized by single stem cells which are committed to the expression of one or other IgM allotype. In addition we show that the reconstituting bursal stem cells express allelically excluded surface IgM at the time of transfer. Our results suggest that B lymphocyte numbers in hatched chickens are maintained by self‐renewal of committed precursors rather than by de novo production from multipotential stem cells.
Early B cell precursors in long‐term bone marrow culture: selective development in the bone marrow of irradiated recipients
Authors: Nishikawa Shin‐Ichi , Kina Tatsuo , Amagai Takashi , Katsura Yoshimoto 
Published: February 2007

AbstractThe primary site for the growth and differentiation of B cell precursors in irradiated recipient mice was investigated. Bone marrow (BM) cells from lipopolysaccharide (LPS)‐responder C57BL/6 mice were transferred into irradiated LPS‐nonresponder C57BL/10ScCr mice, and the generation of donor‐derived B cells in the recipient was monitored by determinating the immunoglobulin‐producing cells developed in the LPS‐stimulated cultures of recipient's spleen cells as well as BM cells. As previously stated, the transfer of fresh BM cells resulted in the development of LPS‐reactive cells both in spleen and BM simultaneously. On the other hand, when long‐term cultured BM cells which were shown to be devoid of B cells and pre‐B cells were used as the donor cells, the development of LPS‐reactive cells was first observed only in BM, and subsequently in both BM and spleen. The failure to detect LPS‐reactive cells in the spleen in the early phase, or day 11 after irradiation and reconstitution, was not attributed to the culture condition or the existence of suppressive activity in day 11 spleen cells. These results indicate that B cell precursors lodge only in the BM of irradiated recipients, grow and differentiate in the same place, and then the differentiated progeny migrate to peripheral lymphoid organs.
Regulation of interleukin 2 (IL2) receptor expression: IL 2 as an inducing signal for the expression of its own receptor on a murine T helper cell line
Authors: Bismuth Georges , Moreau Jean‐Louis , Sommé Gérard , Duphot Maryse , Dautry‐Varsat Alice , Robb Richard J. , Thezè Jacques 
Published: February 2007

AbstractThe interleukin 2 receptor (IL2R) expression of a terpolymer of L‐Glu60, L‐Ala30, L‐ Tyr10 (GAT)‐specific T helper (Th) cell line, L14, was studied using two different rat monoclonal antibodies specific for the murine IL2R, 7D4 and 5A2‐2. L14 T cells expressed IL2R transiently, but contrary to the general assumption that IL2R expression is maintained only by periodic antigen stimulation, we observed that IL2 itself was able to regulate the level of IL2R on L14 Th lymphocytes. In particular, it was found that L14 T cells, which had not been recently stimulated and which expressed a very low level of high affinity IL2R, could be induced to exhibit a high level of this receptor after exposure to recombinant IL2, in the absence of any specific signal. In contrast, the Th cell line 52.3 used as control could be induced to express high levels of IL2R only after exposure to GAT; nevertheless, IL2 seems to play a critical role in the in vitro survival of the resting state of 52.3 T cells.
T15‐specific helper T cells: analysis of idiotype specificity by competitive inhibition analysis
Authors: Dunn Eileen Becker , Bottomly Kim 
Published: February 2007

AbstractOptimal activation of T15 idiotype‐bearing B cells has been shown previously to be influenced by two subsets of Thy‐1+, Ly‐1+,2−sIg− helper T cells. One of the helper T cell sets appears to be T15 specific in that its presence results in a selective augmentation of T15‐bearing anti‐phosphorylcholine (PC) plaque‐forming cell responses. To determine the precise specificity of the idiotype‐specific helper T cell (ThId), Ly‐1 T cells were tested in an in vitro anti‐PC response for their ability to bind directly to T15 myeloma protein‐coated plastic plates. Specificity of this binding was ascertained by competitive inhibition of plate binding using idiotypically related myeloma or hybridoma proteins. These data suggest that the Ly‐1 T cells which augment T15‐bearing plaque‐forming cell responses can bind to T15‐coated plates and are T15 idiotype specific. This approach is being used currently to attempt to clone ThId cells to further analyze their activation requirements and specificities.
Rapid activation of ornithine decarboxylase by mitogenic (but not by nonmitogenic) ligands in human T lymphocytes
Authors: Scott Ian G. , Poso Hannu , Akerman Karl E. O. , Andersson Leif C. 
Published: February 2007

AbstractThe T cell mitogens, concanavalin A and the monoclonal antibody OKT3, cause a rapid activation of ornithine decarboxylase (ODC) activity in human T lymphocytes, maximal within 10 min of mitogen addition. Nonmitogenic ligands to T cell surface structures do not induce ODC. The enzyme induction is dependent upon an intact mobility of ligand‐receptor complex, requires a functioning energy metabolism, but is independent of de nuvo protein synthesis. The early induction of pre‐existing ODC molecules appears to be specifically linked to the initiation of T lymphocyte proliferation.
Enhancement of IgG anti‐carrier responses by IgG2 anti‐hapten antibodies in mice
Authors: Coulie Pierre G. , van Snick Jacques 
Published: February 2007

AbstractIsologous IgG2a, and IgG2b anti‐hapten antibodies injected along with trinitrophenylated or fluoresceinated keyhole limpet hemocyanin (KLH) were found to considerably stimulate primary IgG responses to the carrier protein in mice. No such stimulation was observed with IgG1, IgM and IgA anti‐hapten antibodies. Depending on the antigen antibody combination, the amplification obtained after a single injection of IgG2‐complexed haptenated KLH ranged from 20‐ to 1000‐fold. By comparison, secondary responses were only marginally enhanced (≈ 3‐fold) when IgG2‐complexed rather than free antigen was used to boost irradiated recipients previously reconstituted with primed spleen cells. The IgG2‐mediated enhancement was effective over a wide range of antigen/antibody ratios, did not require the use of high affinity antibodies and occurred whatever the route of injection. The stimulation was specific for the complexed antigen and developed to the same extent whether complexes were formed in vitro or in vivo. A comparable stimulation of the anti‐carrier response was obtained with several other haptenated proteins but with formaldehyde‐treated diphtheria and tetanus toxoids inhibition rather than stimulation was observed.
Interactions of small B lymphocytes with unprimed noncytolytic T cells: dissociation between “presentation” and growth induction
Authors: Bandeira Antonio , Pereira Pablo , Martinez‐A Carlos , Coutinho Antonio 
Published: February 2007

AbstractThe accessory cell requirements in lectin‐dependent triggering and growth of unprimed Lyt‐2− T lymphocytes were analyzed by quantitatively comparing the ability of small B cells and peritoneal macrophages to either induce reactivity to growth factors or support growth.Lightly or nonirradiated small B cells were 15 to 30‐fold less efficient as compared to T cell‐depleted peritoneal cell populations, in the support of lectin‐stimulated Lyt‐2− T cell proliferation. In contrast, lightly irradiated small B lymphocytes were quantitatively as efficient as macrophages in mediating lectin‐driven Lyt‐2− T cell proliferation, if relevant supernatants were added into culture. Finally, supernatants derived from cultures where T‐small B cell ratios were optimal for growth of responder Lyt‐2− lymphocytes were two orders of magnitude less efficient than conditioned medium obtained from cultures containing optimal T‐macrophage ratios, in their ability to support growth of activated T cells.We conclude from these experiments that: (a) in contrast to cytolytic T cell precursors, lectin‐dependent induction of unprimed Lyt‐2− T lymphocytes requires accessory cells; (b) small B cells and macrophages are equally competent in this respect; and (c) growth support by small B cell populations is due to contamination by macrophages which are the only cell type performing this function. We therefore interprete reports on Lyt‐2− T cell proliferation upon stimulation with high numbers of small B cells as a two‐step process: “presentation” and induction of T cells which is essentially B cell dependent, and factor production ensured by contaminating macrophages.
Effects of monoclonal antibodies to the a and β chains of the human lymphocyte function‐associated (H‐LFA‐1) antigen on T lymphocyte functions
Authors: Dongworth David W. , Gotch Frances M. , Hildreth James E. K. , Morris Alan , McMichael Andrew J. 
Published: February 2007

AbstractThe ability of two antibodies, one specific for the a chain, p180, and the other for the β chain, p95, of the human lymphocyte function‐associated (LFA‐1) antigens, to inhibit T cell function was measured. Both antibodies inhibited T cell‐mediated lysis of virus‐infected target cells and of K562 cells. Only the anti‐β chain antibody inhibited natural killer cell lysis of K562. The antibodies inhibited cytotoxic T lymphocyte cell (CTL) lysis of HLA‐mismatched target cells in the presence of concanavalin A at 6.25–12.5 μg/ml, but at higher doses of Con A no inhibition was seen. When the lytic process was divided into calcium‐independent (adherence) and ‐dependent (lysis) steps the antibodies were found to block at the initial step of conjugate formation. The effects of these antibodies on T cell proliferative responses showed that responses to antigens, alloantigens, mitogens and anti‐CD3 (UCHT1) antibody were greatly inhibited. All of these responses are adherent cell dependent and proliferation of adherent cell‐depleted mononuclear cells to Sepharose‐coupled UCHT1 was not inhibited by anti‐LFA‐1 antibodies. Proliferation to paired anti‐CD2 (T11) antibodies was also only weakly inhibited. Release of interferon‐γ by CTL on contact with target cells was also inhibited by anti‐LFA antibody. These results are evidence that the LFA antigen is necessary for a nonspecific interaction with antigen ‐presenting cells that is essential for activation of T cells through the CD3‐T cell receptor complex.
Degradation of specificity in cytolytic T lymphocyte clones: two broad specificity, H‐2‐independent recognition systems, one natural killer‐like, develop during culture, in addition to the clonally distributed antigen‐specific receptor
Authors: Wilson Anne , Shortman Ken 
Published: February 2007

AbstractLy‐2+ CBA mouse T lymphocytes stimulated with concanavalin A in limiting dilution culture produce clones of cytotoxic T lymphocytes (CTL) which, although initially specific, eventually lyse a wide range of target cells. The nature of the recognition system for this apparently “nonspecific” cytolysis was examined using a range of tumor cells as labeled targets and as cold target inhibitors. Most syngeneic and allogeneic murine tumor cells were lysed but the degree of lysis varied, even for different sublines of the same tumor. All tumor cells cold target inhibited their own lysis, and cross‐inhibited lysis of other targets to varying degrees. The recognition stage of “nonspecific” cytolysis appeared to be independent of target cell H‐2 expression; some H‐2‐negative murine target cells were lysed and some were not, but all gave cold target inhibition of “nonspecific” cytolysis. Xenogeneic tumor cells were resistant to lysis, but some nevertheless gave cold target inhibition of the “nonspecific” cytolysis of murine targets. A study of the specificity of cold target cross‐inhibition revealed two distinct patterns of recognition which existed simultaneously in “nonspecific” CTL; one was like that of natural killer cells and was directed to targets such as YAC‐1, the other was distinct from that of natural killer cells and was directed to targets such as P815. Thus, murine CTL may express three distinct receptors, the clonally distributed, H‐Zrestricted, antigen‐specific T cell receptor and two different “broad‐range” receptors common to most clones.
A self‐Ia reactive T cell clone directly stimulates every hundredth B cell and helps antigen‐specific B cell responses
Authors: Saito Takashi , Rajewsky Klaus 
Published: February 2007

AbstractA self‐I‐A reactive T cell clone has been isolated that proliferates in the presence of irradiated syngeneic spleen cells in mouse serum. The cells directly stimulate approximately every hundredth B cell, which includes small B cells, into both proliferation and antibody formation in the absence of added antigen. There is evidence to suggest that cells of this type are generally present in murine T cell populations. The cells may recognize self‐I‐A as such. We failed to obtain evidence, but cannot exclude that they recognize an antibody idiotype in addition. The clone also augments antigen‐specific antibody responses in vivo and in vitro in the presence of antigen. In the in vitro response to a T‐independent TI‐2 antigen, the T cells in co‐culture with B cells induced specifically the production of IgG1 antibodies, thus mimicking the function of major histocompatibility complex‐restricted, antigen‐specific helper T cells. However, IgG1 production was not observed when splenic T cells were added to this system. Thus, self‐I‐A reactive T cells, generally inactive in the system, may locally help B cell responses to antigens which the T cells do not themselves recognize. In such instances one might attribute to the T cells antigen or idiotype‐binding specificities which the cells in reality do not display.