bluuebunny/crossref_metadata_2025 huggingface dataset:
Antigen recognition by H‐2‐restricted cytolytic T lymphocytes: inhibition of cytolysis by anti‐CDS monoclonal antibodies depends upon both concentration and primary sequence of peptide antigen
Authors: Maryanski Janet L. , Pala Pietro , Cerottini Jean‐Charles , Robson MacDonald H.
Published: March 2007

While it is generally agreed that the specificity of the interaction between cytolytic T lymphocytes (CTL) and their target cells is controlled mainly by antigen‐specific T cell receptors (TcR), the molecular role of cell surface CD8 molecules in this interaction is less well understood. In the present study we have reinvestigated the apparent contribution of CD8 molecules to the overall avidity of interaction between CTL and their targets by using a recently developed system of major histocompatibility complex (MHC) class I‐restricted CTL clones that recognize defined peptide antigens. We demonstrate that under conditions where the density of MHC, TcR and accessory molecules remains constant, the susceptibility of CD8+ CTL to inhibition of cytolysis by anti‐CD8 antibodies is highly dependent upon the concentration and primary structure of the peptide antigen. Although the precise role of the CD8 molecule remains unknown, our results are compatible with models that suggest its contribution to the overall avidity of the CTL‐target cell interaction particularly in cases where the affinity between the TcR and antigen‐MHC is low.
Detection and characterization of functional T cells in mice with severe combined immune deficiency
Authors: Carroll Ann M. , Bosma Melvin J.
Published: March 2007

CD3+ alloresponsive T cell clones were derived from mice with severe combined immune deficiency (scid mice). T cell receptor beta and gamma gene rearrangements were analyzed to obtain insight into the nature and origin of these clones. We hypothesized that developing scid lymphocytes with an active, impaired recombinase system might generate functional lymphocytes by rare productive rearrangements at two critical antigen receptor loci. One alloresponsive clone showed evidence of both normally rearranged T cell receptor genes and genes with abnormal J region‐associated deletions, supporting this hypothesis. Four additional alloresponsive clones, however, showed only conventional gene rearrangements. These data leave open the possibility that the recombinase activity, believed defective in scid mice, may be normalized in rare early B and T lymphoid cells or their precursors, to give rise to functional lymphocytes.
Comparative study of VH gene family usage by newborn xid and non‐xid mice, newborn NZB and adult NZB mice, and by splenic and peritoneal cavity B cell compartments
Authors: Dighiero Guillaume , Lim Annick , Lembezat Marie‐Pierre , Kaushik Azad , Andrade Luis , Freitas Antonio
Published: March 2007

RNA from 170 different Ig‐secreting hybridomas was hybridized with VH gene probes 7183, QUPC52, S107, J558, J606, 36–60, V31, X‐24 and V‐GAM 3.8, with the aim of comparing xid to non‐xid mice, neonatal NZB to adult NZB, and the peritoneal cavity with the splenic compartments for VH gene family expression. Our results indicate that (a) defective F1 male xid mice express with high frequency 36–60 and J606 5′ proximal VH families, when compared to non‐xid F1 females of the same .matings. (b) Neonatal NZB mice express 3′ proximal 7183 and QUPC52 families with high frequency, when compared to adult mice and to the expected values derived from VH complexity. (c) Natural antibodies against cytoskeleton proteins, DNA, rabbit IgG and 2,4,6‐trinitrophenyl did not appear to prefer a particular VH family. The only difference found is related to age; neonatal clones preferentially employ 7183 and QUPC52 while J558 predominates among adult clones. (d) All the 15 antibodies directed against bromelin‐treated mouse red blood cells failed to hybridize with any of the nine VH probes employed. These results confirm previous findings indicating the highly homogeneous pattern of these latter antibodies, and suggest that they are encoded by a new VH family (VH11).
Structural and serological heterogeneity of γ/δ T cell antigen receptor expression in thymus and peripherar blood
Authors: Lanier Lewis L. , Ruitenberg Joyce , Bolhuls Reinder L. H. , Borst Jannie , Phillis Joseph H. , Testi Roberto
Published: March 2007

Monoclonal antibodies (mAb) reactive against the γ/δ T cell antigen receptor (TcR) have been used to characterize the distribution and structural properties of γ/δ TcR‐bearing lymphocytes in blood and thymus. Consistent with prior reports the TcR γ/δ‐1 and δ‐1 mAb react with all γ/δ TcR+ T lymphocytes in blood and thymus. By contrast the TCS‐δ mAb was found only to react with a subset of the γ/δ TcR‐bearing T cell population. Several lines of evidence suggest that this reagent preferentially reacts with the Vδ1 gene product. Using these reagents, it was observed that γ/δ TcR+ T lymphocytes comprise 4.6 ± 3.5% (range 1.0–16.3%) of peripheral blood lymphocytes. However, analysis of peripheral blood from normal adult donors revealed that in 29 of 32 the TCS‐δ (possibly Vδ1)‐bearing cells comprised less than 30% of the total γ/δ‐TcR+ population. Biochemical analysis demonstrated that the predominant form of the γ/δ TcR in adult peripheral blood is a disulfide‐linked heterodimer, indicating preferential use of the C,1 gene. The δ TcR chain from these TcR‐γ/δ‐1+/TCS‐δ− T cells was remarkably basic in charge, as analyzed by nonequilibrium pH gradient electrophoresis. By contrast with peripheral blood the majority of freshly isolated and interleukin 2‐cultured γ/δ TcR+ thymocytes were predominantly TcR‐γ/δ‐l+/TCS‐δ+, and preferentially expressed Vδl. Moreover, both disulfide‐bonded and nondisulfide‐bonded γ/δ TcR heterodimers were expressed in all thymuses examined and both forms were contained within the TCS‐δ+ thymic subset. Similar to recent findings in the mouse, these studies suggest a possible bias in the structural form of γ/δ TcR based on tissue location.
Regulatory circuits in autoimmunity: recruitment of counter‐regulatory CD8+ T cells by encephalitogenic CD4+ T line cells
Authors: Sun Deming , Ben‐Nun Avraham , Wekerle Hartmut
Published: March 2007

In this study, pretreatment of Lewis rats with a syngeneic encephalitogenic T cell line (S1) was found to be able to constantly induce resistance to the subsequent induction of transferred experimental autoimmune encephalomyelitis (tEAE). This treatment was capable of protecting recipient animals for at least 2–4 months. Here we show an enhanced suppressor T(anti‐S1) cell activity, which can be readily detected in the lymphoid organs of animals which recovered from S1‐induced tEAE, or from rats pretreated with attenuated (irradiated, fixative treated or water‐lysed) S1 cells. Anti‐S1 cells, which uniformly express the CD8 phenotype, were selectively stimulated to grow and expand into lines by confronting primed lymphoid cells with irradiated S1 cells in culture. The proliferative response of anti‐S1 cells was independent of myelin basic protein and antigen‐presenting cells, and the responses against unrelated encephalitogenic T cell lines were minimal. It was also found that none of the monoclonal antibodies tested (including CD8 and MHC class I antigen‐specific antibodies) was able to block S1/anti‐S1 interactions. These cells are functionally suppressive to the proliferation of S1 cells in vitro, are specifically cytolytic directed against the EAE‐inducing S1 cells and are able to antagonize encephalitogenic capacity of S1 cells in vivo. In vivo elimination of the CD8+ T subset from Lewis rats, using a combined treatment of thymectomy and OX‐8 antibody injection before the initial cell transfer, totally blocked the induction of resistance. Our experiments document that induction of functionally active suppressor T cells is responsible for the induced resistance observed in tEAE.
A novel human Vδ gene expressed predominantly in the TiγA fraction of γ/δ+ peripheral lymphocytes
Authors: Triebel Frédéric , Faure Florence , Mami‐Chouaib Fathia , Jitsukawa Setsuko , Griscelli Annelise , Genevée Catherine , Roman‐Roman Sergio , Hercend Thierry
Published: March 2007

We have characterized a functional T cell receptor (TcR) δ transcript in a TiγA+ human cloned cell line derived from peripheral blood. This cDNA includes a novel V gene (V‐AB12), whose expression was initially studied in a series of TcR γ/δ′ clones. Nine TiγA+ clones derived independently from distinct donors have been tested: each of them was found to possess a unique V‐AB12/J‐IDP2 5.5‐kb Eco RI rearrangement, which was constantly transcribed. Surface expression of the protein encoded by this unique rearranged gene was demonstrated by immunoprecipitations performed on three TiγA′ polyclonal cell lines using a specific rabbit heteroantiserum. Further analysis strongly suggested that a monoclonal antibody (mAb), designated anti‐BB3, detects a V‐ABl2‐encoded antigenic determinant on the cell surface. Double‐color immunofluorescence analysis of peripheral blood lymphocytes from ten donors indicated that most BB3+ cells are recognized by anti‐TiγA mAb. In previous studies, we have shown that a majority of TcR γ/δ+′ peripheral T cells expresses a γ chain including V9 (TiγA) and most frequently JP‐encoded peptides. Given the present results on the δ chain, it can be concluded that, in many individuals, a predominant fraction (Vγ9+/V‐AB12+) of circulating CD3+ TcRa/β− T lymphocytes expresses a receptor with little, if any, combinatorial diversity.
Identification of a novel monocyte cell surface molecule involved in the generation of antigen‐induced proliferative responses
Authors: Dougherty Graeme J. , Dransfield Ian , Hogg Nancy
Published: March 2007

A monocyte molecule, identified by a monoclonal antibody (mAb) named 24, is involved in the antigen‐specific proliferation of T cells. Several types of antigen‐induced responses are blocked by mAb 24, but mitogen responses, even at low doses, are not. The 24 molecule is found on circulating monocytes and no other cell type. Normally only a proportion of monocytes express the 24 molecule but it can be induced rapidly on monocytes in culture, possibly from intracellular sources. The epitope is present on a heterodimer of 175 and 95 kDa which is similar to the leukocyte cell adhesion molecule (Leu‐CAM) family. These findings suggest that although the 24 molecule shows some functional and biochemical similarities with the Leu‐CAM family of molecules, it represents a novel structure primarily associated with mononuclear phagocytes.
Higher level expression of lymphocyte function‐associated antigen‐1 (LFA‐1) on in vivo natural killer cells
Authors: Nishimura Takashi , Itoh Tsunetoshi
Published: March 2007

Normal mouse spleen cells express low levels of lymphocyte function‐associated anti‐gen‐1 (LFA‐1) as well as other lymphoid cells. However, fractionation of spleen cells with Percoll discontinuous gradients resulted in the appearance of lymphocytes expressing high levels of LFA‐1 molecule (LFA‐1 high lymphocytes) in parallel with the enrichment of natural killer (NK) activity. Lower density spleen cells (fractions 1 and 2) expressed higher level of LFA‐1 antigen than unfractionated spleen cells and showed a higher NK activity. In contrast, higher density spleen cells (fractions 3 and 4) expressed lower levels of LFA‐1 antigen and revealed lower NK activity. LFA‐1 high lymphocytes possessed a high level of asialo GM1, which was the cell surface marker for NK cells. Moreover, sorting of LFA‐1 high lymphocytes from spleen cells caused a great enrichment of NK cells. These results demonstrated that in vivo NK cells expressed higher levels of LFA‐1 molecule, which was an important adhesion molecule for NK cell‐mediated cytotoxicity.
CD4+lymphocytes are extracted from blood by peripheral lymph nodes at different rates from other T cell subsets and B cells
Authors: Washington Elizabeth A. , Kimpton Wayne G. , Cahill Ross N. P.
Published: March 2007

The circulation of lymphocyte subsets through prescapular lymph nodes in sheep has been quantified using a panel of monoclonal antibodies against sheep lymphocyte surface antigens. Differences in the extraction of lymphocyte subsets from blood by the lymph node were found with CD4+ lymphocytes being extracted at a faster rate (1/2) than CD8+, SBU‐T19+, major histocompatibility complex class II+ and B cells (1/4 to 1/5). In order to accommodate existing data on organ‐specific cell migration, the possibility is raised that two distinct families of lymphocyte adhesion molecules, one subset specific and one tissue specific, expressed on vascular endothelium could act jointly to regulate the migration of recirculating lymphocytes.
Processing requirements for T cell activation by Mycoplasma arthritidis‐derived mitogen
Authors: Bauer Andrea , Rutenfranz Inge , Kirchner Holger
Published: March 2007

Mycoplasma arthritidis produces in culture a polyclonal mitogen which is active for murine and human T lymphocytes in the presence of accessory cells (AC). We studied the requirements for processing and presentation by AC of Mycoplasma arthritidis supernatant (MAS) mitogen to human T cells. As inhibitors of AC processing, several agents were used which inhibit lysosomal function: the weak bases chloroquine and NH4Cl, the cationic ionophore monensin and the competitive protease inhibitor leupeptin. When these agents were used to inhibit processing by presenting cells and washed out before T cells were added to culture, they inhibited lymphocyte activation and, therefore, we assume that they interfered with the presentation of the mitogen. Thus, if MAS requires a processing step, it appears to involve lysosomal proteolysis which can be blocked in vitro.
Functional responsiveness in vitro and in vivo of α/β T cell receptors expressed by the B2A2 (J11d)– subset of CD4–8– thymocytes
Authors: Howe Rawleigh C. , Pedrazzini Thierry , Robson MacDonald H.
Published: March 2007

B2A2‐CD4‐8‐ cells represent a rare subpopulation of thymocytes normally comprising 0.5% of the total adult thymus. These cells are known to express CD3‐associated T cell receptor (TcR) α/ß molecules. In the present study we have examined the functional capacity of α/ß heterodimers on B2A2‐CD4‐8‐ cells. In the presence of monoclonal antibody (mAb) specific for either murine CD3 or TcR expressing the Vβ8‐encoded ß chain (F23.1), B2A2‐CD4‐8‐ cells proliferated. Such proliferation was blocked by mAb to interleukin 2 receptor (IL 2R), suggesting an autocrine mechanism involving IL 2 production and subsequent utilization. IL 2 and also IL 3 production by mAb‐stimulated B2A2‐CD4‐8‐ cells was directly confirmed. Furthermore, a panel of B2A2‐CD4‐8‐ clones were derived to assess the role of the TcR in cytolysis. Many clones were isolated which killed Fc receptor‐bearing P815 target cells only in the presence of F23.1 mAb. Finally, in vivo treatment of neonatal mice with F23.1 mAb resulted in a marked reduction of Vβ8 B2A2‐CD4‐8‐ thymocytes. Collectively, these results indicate that the TcR α/ß complex on CD4‐CD8‐B2A2‐ cells is fully capable of transducing signals that lead to proliferation, lymphokine production and cytolysis in vitro, as well as to disappearance of this subset from the thymus in vivo.
Studies on the mechanism of polyclonal B cell stimulation by TH2 cells
Authors: Lohoff Michael , Dirks Meike , Rohwer Peter , Röllinghoff Martin
Published: March 2007

Recently, it has been shown that cloned L1/1 T helper cells of type 2 (TH2 ‐cells), when stimulated with antigen, are able to induce polyclonal B cell proliferation. Here we present evidence that this process is dependent on direct cell‐cell interaction between T and B cells, which in the effector phase, i.e., during stimulation of the B cells by activated T cells, can be mediated by a mechanism other than cognate interaction. This conclusion is derived from experiments in which highly purified, small B cells of high density were polyclonally stimulated by L1/1 T cells triggered by an anti‐T3 monoclonal antibody in the absence of antigen. The triggering process was independent of the presence of the Fc part of the antibody and occurred in cultures devoid of macrophages. Thus, the well‐established cognate recognition does not appear to be the only mechanism of B cell induction by T helper cells.
Inhibition of the responses of a cloned CD4 T cell line to different class II major histocompatibility complex ligands by anti‐CD4 and by anti‐receptor Fab fragments are directly related
Authors: Portoles Pilar , Janeway Charles A.
Published: March 2007

The responses of a single cloned T cell line to three different class II major histocompatibility complex (MHC) ligands have been compared for avidity, determined by inhibition with anti‐T cell receptor Fab fragments directed at two different receptor epitopes, and for ease of inhibition with anti‐CD4 antibody. It has, thus, been directly demonstrated that ease of inhibition of the response of a T cell to a class II MHC ligand by anti‐CD4 is inversely related to the avidity of the T cell receptor for that ligand. The difficulties in inferring from this finding that CD4 acts primarily by increasing receptor avidity for its class II MHC ligand are discussed in the light of evidence suggesting that CD4 is an active signaling component of the T cell receptor for class II MHC ligands.
Immunogenic capacity of macrophage hybridomas
Authors: Tzehoval Esther , Dagan Shlomo , Eisenbach Lea , Atsmon Jacob , Feldman Michael
Published: March 2007

Two clones, E2‐7.7 and E2‐10.50, derived from two macrophage(MΨ)hybridomas, E2‐7 and E2‐10, have been studied. The first clone, E2‐7.7, is Ia and Fc receptor (FcR) negative and manifests a strong antigen‐presenting capacity. When we pulsed its cells in vitro with keyhole limpet hemocyanin (KLH) antigen and injected them into syngeneic animals, we found that as small a dose as 103 cells initiated an immune response in vivo. On the other hand, antigen‐pulsed cells of the E2‐10.50 clone, which are Ia‐ and FcR, were almost incapable of triggering immunity, even when injected at a dose of 105 cells. Thus, the two clones differ in their immunogenic capacity (both cellular and humoral immunity). In experiments aimed at testing the stimulation in vitro of primed lymph node (LN) cells by antigen‐pulsed cells of these two hybridoma clones, we observed that E2‐7.7 stimulated the unfractionated population of LN cells and the LN‐derived population of T cells. The E2‐10.50 cells stimulated only the unfractionated population of LN cells, but not the T cell population. Subsequent tests indicated that the E2‐10.50 cells require an intermediate Ia accessory cell to present the antigen to the T lymphocytes.

Analyzing the molecular structure of the MΨ hybridomas, we discovered that major histocompatibility complex (MHC) genes of the myeloma haplotype (H‐2d), and of the splenic MΨ used for fusion (H‐2k), which were not expressed in the parental myeloma or in the E2‐10.50, were expressed in the E2‐7.7. Thus, somatic cell fusion of MΨ resulted in the activation of suppressed genes of the myeloma partner. It appears that these antigens participate in controlling the immunogenic properties of the E2‐7.7 clone. Testing the effects of interferons on the MΨ hybridomas, we observed that interferon‐γ activated, at both the mRNA and the cell surface‐antigen levels, the expression of H‐2Dk, H‐2Kd and H‐2Dd in the E2‐10.50 cells, but not in the E2‐7.7. Consequently, interferon‐γ augmented significantly antigen presentation by E2‐10.50 but not by E2‐7.7 cells. These two hybridoma clones might represent two distinct subsets of normal MΨ, manifesting two different sets of functional properties. Having described earlier the E2‐10.20 clone that takes up, but does not present antigen, we may in fact be facing three types of MΨ hybridomas, representing three functional subpopulations of MΨ.
B cell precursors are present in the thymus during early development
Authors: Kimoto Hiroshi , Shirasawa Takuji , Taniguchi Masaru , Takemori Toshitada
Published: March 2007

An in vitro system for transforming immature lymphoid cells present in the thymus at early development has been established. By phenotype analysis of the transformants obtained, we observed that B cell precursors, susceptible to Abelson murine leukemia virus (A‐MuLV)‐ or Harvey murine sarcoma virus (H‐MuSV)‐induced lymphogenesis, were present at high frequency in the fetal thymus of BALB/c mice. These precursors recolonized alymphoid thymus lobes in vitro, as do T cell precursors. It was further observed that B precursors in the fetal liver were also capable of recolonizing alymphoid thymus lobes and were stored in a thymic environment. These results suggest that stroma cells of the fetal thymus may possess the capacity to support the growth of B precursors. On the other hand, B cell precursors sensitive to the viral transformation were undetectable in the fetal thymus of C57BL/6, although immunohistochemical analysis suggested their presence. However, in the fetal liver of the same strain, B precursors recolonizing alymphoid thymus in vitro were sensitive to the viral transformation. Based on these results, we will discuss both the role and fate of thymic B precursors. In addition, we also obtained T cell lymphomas at different stages of differentiation from the fetal thymus of C57BL/6 infected with A‐MuLV or H‐MuSV. These data indicate the usefulness of our system in establishing cell lines derived from intrathymic lymphogenesis at early development.
Correlation between ribosylation of pertussis toxin substrates and inhibition of peptidoglycan‐, muramyl dipeptide‐ and lipopolysaccharide‐induced mitogenic stimulation in B lymphocytes
Authors: Dziarski Roman
Published: March 2007

Selective inhibition by pertussis toxin (PT) of mitogenic activation of mouse B lymphocytes by bacterial mitogens (peptidoglycan and lipopolysaccharide) and muramyl dipeptide (a synthetic analog of peptidoglycan fragment) was demonstrated. Mitogenic activation of B cells by protein kinase C activators and ionomycin was insensitive to PT. Also PT did not inhibit peptidoglycan‐ and lipopolysaccharide‐induced differentiation of B cells into Ig‐secreting cells, when it was added to the cultures after the proliferative stage of the response. B lymphocyte membranes contained two major PT substrates (40 and 41 kDa). The extent of PT‐mediated ADP ribosylation of these substrates correlated with the degree of PT‐mediated inhibition of mitogenic stimulation of B cells. B cell stimulation by all mitogens tested was not inhibited by cholera toxin at nontoxic concentrations that are known to cause maximal increase in cAMP in B cells. Since the only known substrates for PT‐mediated ADP ribosylation in mammalian cells are the α subunits of some G proteins, our data suggest that G proteins are present in B cell membranes and that they are involved in B cell activation induced by bacterial mitogens.
Regulation of interleukin 2 gene expression: discrepancy between enhancer activity and endogenous gene expression
Authors: Mårtensson Inga‐Lill , Leanderson Tomas
Published: March 2007

A 630‐bp fragment of the human interleukin 2 (IL 2) promoter (+ 51 to ‐584) permitted expression of a reporter gene transfected into a mouse T cell lymphoma line (EL4) upon induction with phorbol ester. In contrast, when a human T cell lymphoma (Jurkat) was transfected with the same plasmid and subsequently induced with phorbol ester together with phytohemagglutinin, a very low expression of the transfected gene was observed. The endogenous IL 2 gene was equally well expressed in both cell lines upon induction. Thus, the expression of the endogenous and the transfected gene did not correlate in Jurkat cells. An SV 40 enhancer element cloned 5′ of the IL 2 promoter did not result in constitutive expression after transfection to either cell line, rather the IL 2 promoter retained the need for induction. The addition of an enhancer element increased the induced expression of the transfected gene in Jurkat cells into proximity of that observed in induced EL4 cells, indicating that additional sequence elements not contained in the 630‐bp fragment are needed for proper expression of the IL 2 gene in Jurkat cells.
Expression of cytoplasmic granules with T cell‐associated serine proteinase‐1 activity in Ly‐2(CD8) T lymphocytes responding to lymphocytic choriomeningitis virus in vivo
Authors: Kramer Michael D. , Fruth Uli , Simon Hans‐Georg , Simon Markus M.
Published: March 2007

Monoclonal antibodies (mAb) with specificity for the T cell‐associated serine proteinase‐1 of the mouse (MTSP‐1) were used to study expression and storage of this enzyme in T lymphocytes during lymphocytic choriomeningitis (LCM) virus infection in vivo. Immunohistochemical analysis of splenic tissue at the peak of LCM virus‐specific T cell‐mediated cytolytic responses, i.e., at day 7 post infection, revealed high numbers of MTSP‐1 T lymphocytes in the interfollicular T cell‐dependent area of the spleen. More than 50% of Ly‐2(CD8) cells but only low numbers of Ly‐2‐(CD8‐) cells, previously enriched by flow cytofluorometry, contained large amounts of cytoplasmic granules which stained both with MTSP‐1‐specific mAb and the esterase substrate N‐α‐benzyloxycarbonyl‐L‐lysine thiobenzyl ester. These data demonstrate that in vivo generated LCM virus‐induced cytolytic T lymphocytes develop cytoplasmic storage granules containing MTSP‐1 and suggest that the mechanism of granule exocytosis is operative in vivo; possibly MTSP‐1 is one effector molecule participating in the Ly‐2(CD8) T lymphocyte‐mediated control of virus infection.
Mechanism of immune complex‐mediated damage: induction of interleukin 1 by immune complexes and synergy with interferon‐γ and tumor necrosis factor‐α
Authors: Chantry David , Winearls Chris G. , Maini Ravinder N. , Feldmann Marc
Published: March 2007

The ability of immune complexes derived from patients with type II mixed essential cryoglobulinemia to trigger the production of interleukin 1 (IL 1) was investigated. Immune complexes containing either IgM/IgG or IgA/IgG aggregates were shown to induce IL 1 production in human peripheral blood monocyte‐enriched populations. Interferon‐γ alone did not induce detectable IL 1, but increased the IL 1 production induced by the immune complexes. Tumor necrosis factor‐α, which is a potent inducer of IL 1, also enhanced IL 1 production following stimulation with suboptimal doses of the immune complex. The findings suggest that immune complexes may induce inflammation partly due to their capacity to induce the synthesis of IL 1.
The expression of I‐A correlates with the uptake of interferon‐γ by macrophages
Authors: Celada Antonio , Maki Richard A.
Published: March 2007

The current studies were designed to examine some of the requirements for I‐A expression when macrophages (MΨ) were treated with interferon‐gamma (IFN‐γ). In order to define the minimum time required for IFN‐γ to induce surface expression of I‐A antigen on bone marrow‐derived MΨ, cells were incubated with IFN‐γ for varying lengths of time, washed and thereafter incubated for 72 h before assaying I‐A surface expression. Using saturating amounts of IFN‐γ (300 IRU/ml), we found that between 0 and 30 min of IFN‐γ treatment there is a direct correlation between the length of treatment and the level of I‐A surface expression. When the steady state level of RNA for the I‐Aβ gene was assayed, a low level of I‐Aβ RNA was seen in cells treated for 10 min with saturting amounts of IFN‐γ (300 IRU/ml) while a 30‐min or 60‐min exposure of cells to the same concentration of IFN‐γ resulted in a steady increase in the level of I‐Aβ RNA. Similar results were found when we measured the levels of RNA for the tumor necrosis factor and C3 complement genes, both of which are induced by IFN‐γ in MΨ. MΨ treated with low amounts of IFN‐γ (3 IRU/ml) for 30 min do not express cell surface I‐A. Cells incubated continuously for 72 h with 3 IRU/ml of IFN‐γ expressed a level of I‐A on the surface equivalent to the level of I‐A expressed on cells treated for only 30 min with 300 IRU/ml of IFN‐γ. Based on the observed correlation between either the IFN‐γ concentration or the length of time the cells were exposed to IFN‐γ, or the level of I‐A expression on MΨ, we conclude that the expression of I‐A correlates with the uptake of IFN‐γ.
Interleukin 1 and tumor necrosis factor‐α additively increase the levels of granulocyte‐macrophage and granulocyte colony‐stimulating factor (CSF) mRNA in human fibroblasts
Authors: Seelentag Walter , Mermod Jean‐Jacques , Vassalli Pierre
Published: March 2007

Recombinant interleukin (IL) 1 β and tumor necrosis factor/cachectin (TNF‐α) induce, usually within 2 h, a dose‐dependent increase in the levels of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) and G‐CSF mRNA in cultured human fibroblasts. Maximal induction is reached at about 4–8 h and usually last for at least 48 h. IL 1β and TNF have additive effects on the levels of GM‐ and G‐CSF mRNA, and on the secretion of G‐CSF activity into the culture medium. IL 1α has the same additive effect that IL 1β has with TNF, but no additive effect with IL 1β. In contrast, the high basic level of M‐CSF (CSF‐1) mRNA shows little or lower variations in response to IL 1, TNF‐α or both IL 1 and TNF‐α also induce, with similar kinetics, an increase in IL 1β but not mRNA level. In contrast to what is observed with macrophages and endothelial cells, E. coli lipopolysaccharide does not modify the fibroblast CSF mRNA level up to 48 h of culture.
Absence of homologous restriction factor does not affect CTL‐mediated cytolysis
Authors: Krähenbühl Olivier P. , Peter Hans H. , Tschopp JÜRg
Published: March 2007

Homologous restriction factor (HRF) is a membrane protein of erythrocytes and leukocytes that inhibits the complement (C5b‐9)‐mediated lysis in a species‐restricting manner. HRF has also been reported to inhibit perforin‐mediated cytolysis and postulated to play a role in cytotoxic T lymphocyte (CTL) self‐protection. We show that paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes, lacking HRF, are no more sensitive to Ca2+‐dependent human CTL‐mediated lysis than normal erythrocytes. Furthermore, mouse and normal human erythrocytes, as well as PNH erythrocytes, are similarly lysed by isolated murine perforin‐containing granules. We conclude that HRF does not inhibit perforin‐mediated lysis and therefore is not likely to play a role in CTL self‐protection.
Immunoregulation through CD8 (Ly‐2): state of aggregation with the α/β/CD3 T cell receptor controls interleukin 2‐dependent T cell growth
Authors: Jönsson Jan‐Ingvar , Boyce Neil W. , Eichmann Klaus
Published: March 2007

The activation of T lymphocytes by an antigenic challenge requires that the CD3 T cell receptor α/β (TcR) is bound to an appropriate ligand, i.e. major histocompatibility complex antigen, on an antigen‐presenting cell. In addition, numerous studies suggest that the accessory molecules CD4 and CD8 participate in the recognition process, and may have inhibitory as well as augmenting effects depending on the ways in which they participate. In the present study we attempt to define the conditions by which CD8 exerts enhancing and inhibitory effects on resting CD8 T cell activation, and which parameters of activation are regulated through participation of CD8/CD4. We find that experimental procedures leading to TcR‐CD8 aggregation induce T cell activation whereas experimental procedures preventing TcR‐CD8 aggregation inhibit T cell activation. CD8/CD4‐induced variations in the extent of T cell activation are apparent as variations in interleukin 2 (IL 2)‐dependent growth and in the number of blastoid cells bearing IL 2 receptors. Inhibition of CD8 T cell activation is successful only if the majority, if not all CD8 molecules are occupied by soluble antibody. This latter finding argues against the suggestion of other groups that CD8 may be a receptor for negative signaling. Rather, the results support the alternative notion that a basal level of TcR‐CD8 aggregation, existing in the resting state or induced by TcR‐ligand interaction, is an essential prerequisite for CD8 T cell activation. Enhancement or depression of this basal level of aggregation causes facilitation or inhibition, respectively, of activation. This may be a mechanism for the regulation of IL 2‐dependent clonal expansion of T cells in immune responses.
Two classes of CD1 genes
Authors: Calabi Franco , Jarvis John M. , Martin Luis , Milstein Cesar
Published: March 2007

Herein, we report the DNA sequence of two human CD1 genes, R2 and R3, distinct from those encoding the CD1a, ‐b and ‐c antigens. Both genes appear to have an exon/intron structure analogous to the previously analyzed CD1 genes and to be functional on the basis of their sequence. Analysis of the variability patterns, potential intramolecular interactions and predicted secondary structure profile on an alignment of all known CD1 α chains suggest some shared structural features with major histocompatibility complex class I molecules in the α1 domains but substantial differences in the α2 domains. Sequence comparison shows that, while R2 is most related to CD1a, ‐b and ‐c, albeit to a somewhat lower degree than the latter are to themselves, R3 is more homologous to mouse than to human CD1, suggesting the existence of two functional classes within the CD1 gene family. We propose to retain the non‐committal R2 and R3 names until the putative antigens have been identified and their tissue distribution has been established.
Differential regulation of lipopolysaccharide‐induced interleukin 1 and tumor necrosis factor synthesis: effects of endogenous and exogenous glucocorticoids and the role of the pituitary‐adrenal axis
Authors: Zuckerman Steven H. , Shellhaas James , Butter Larry D.
Published: March 2007

Intraperitoneal injection of a sublethal dose of lipopolysaccharide (LPS) into mice resulted in the appearance of tumor necrosis factor (TNF) in the serum within 45 min. Maximal serum TNF was detected by 1 h, and by 3–4 h TNF levels were no longer significantly above baseline. Injection of mice with an additional dose of LPS at 4 h resulted in no further increase in serum TNF. The in vivo kinetics of TNF appearance correlated with in vitro studies in which TNF mRNA was detected in murine peritoneal macrophages 30 min after LPS stimulation. The increase in serum TNF was not detected in mice treated with dexamethasone, 3 mg/kg, prior to LPS stimulation. The decrease in TNF correlated with the appearance of significant amounts of endogenous serum corticosterone which were maximal by 3 h. Further evidence for the role of endogenous steroids in the modulation of serum TNF levels was obtained in studies with adrenalectomized or hypophysectomized mice. Compared to sham‐operated animals, serum TNF levels remain elevated 5 h post LPS stimulation in adrenalectomized or hypohysectomized mice. In contrast with the transient increase in TNF, serum IL 1 was maximal 4 h post LPS injection and remained elevated at 24 h. In vitro studies with primary cultures of human peripheral blood monocytes and human umbilical cord vein endothelial cells demonstrated that LPS‐induced mono‐cyte IL 1 levels were reduced approximately 5‐fold by 10‐1 M dexamethasone while dexamethasone had only minimal effects on endothelial cell IL 1. Therefore, the in vitro data would suggest that the maintenance of elevated IL 1 levels coincident with the appearance of endogenous corticosteroids during LPS shock is related to the synthesis of IL 1 by both monocyte‐macrophages and non‐myeloid cell populations including endothelial cells.
Alternative molecular form of human T cell‐specific antigen CD27 expressed upon T cell activation
Authors: Borst Jannie , Sluyser Carlotte , Vries Evert De , Klein Hanneke , Melief Cornelis J. M. , Van Lier René A. W.
Published: March 2007

The CD27 membrane antigen is exclusively present on a large subset of human peripheral blood T lymphocytes and on mature thymocytes. Several observations point towards a specific role of this molecule on activated T cells. Upon T cell activation induced via the T cell receptor complex, CD27 expression greatly increases, while addition of anti‐CD27 monoclonal antibodies amplifies the proliferative response. Within the CD4 subset, only CD27 T cells provide helper activity for B cell differentiation. Interestingly, CD27 expression differs not only quantitatively, but also qualitatively between resting and activated T cells. On resting cells, CD27 is a disulfide‐linked homodimer with subunits of 55 kDa molecular mass. Upon activation, also a 55‐kDa monomer seems to occur, while in addition a 32‐kDa component is found. The relationship between these two proteins has been investigated. The 55‐kDa and 32‐kDa molecules do not seem to be physically associated. The two CD27 components are structurally highly homologous as determined by two‐dimensional mapping of tryptic peptides. They both express the epitopes recognized by anti‐CD27 antibodies, indicating that the 32‐kDa molecule is also T cell specific. Both 55‐kDa and 32‐kDa molecules carry N‐linked carbohydrate groups. However, they differ in other, not yet specified, post‐translational modifications, and do not arise from a common precursor simply by alternative N‐glycosylation. The 32‐kDa form may be derived by proteolytic processing from the 55‐kDa protein, but most likely not from a larger (common) precursor. Alternatively, both molecules may arise from a common gene by alternative mRNA splicing, or be derived from highly homologous genes. The dramatic change in molecular composition of CD27 suggests a newly acquired function for CD27 on activated T cells.
The improved lytic function and in vivo efficacy of monovalent monoclonal CD3 antibodies
Authors: Clark Mike , Bindon Carol , Dyer Martin , Friend Peter , Hale Geoff , Cobbold Steve , Calne Roy , Waldmann Herman
Published: March 2007

A series of hybrid‐hybridomas were derived by the cell fusion of a CD3 antibody‐secreting hybridoma with other Ig‐producing cell lines. The Ig molecules secreted by these hybrid‐hybridomas were fractionated by ion‐exchange chromatography, and fractions containing monovalent CD3 antibodies were tested for complement‐mediated lysis of T cells. Two monovalent CD3 antibodies with mixed heavy chain isotypes were very poor in lysis but, in contrast, a monovalent antibody possessing two identical rat γ2b heavy chains but two non‐identical light chains was found to be more lytic with human complement than the parental bivalent CD3 antibody. The difference in lysis was not readily explicable in terms of a difference in complement activation at the level of C1q binding or cell‐associated C3. A highly purified batch of this lytic monovalent CD3 antibody was prepared in a form suitable for in vivo therapy. In a preliminary clinical study in one patient with a T lymphoma in leukemic phase this monovalent CD3 antibody was found to be very effective in depleting CD3 tumor cells in the peripheral blood and bone marrow. The cells in the peripheral blood were completely cleared and there was no evidence for antigenic modulation. In addition the antibody was able to reverse cell‐mediated kidney rejection in three kidney graft patients. These results suggest that monovalent antibody may be effective in vivo as well as in vitro and that a fuller clinical evaluation is justified.
Mitogenic lectins bind to the antigen receptor on human lymphocytes
Authors: Chilson Oscar P. , Kelly‐Chilson Anne E.
Published: March 2007

The specificity of interactions between mitogenic and non‐mitogenic lectins and disulfide‐linked cell surface receptors on human lymphocytes was explored. Lysates (Nonidet‐P40) of surface‐radioiodinated tonsil lymphocytes and T lymphoblastoid cells (HPB‐ALL) were absorbed with lectin‐agarose derivatives (or bovine serum albumin, BSA‐agarose) or immunoprecipitated with appropriate monoclonal antibodies (mAb). Lectin eluates and solubilized immunoprecipitates were analyzed by two‐dimensional (nonreduced/reduced) sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Radiolabeled polypeptides were visualized by autoradiography. Among the various lectin‐binding polypeptides, two disulfide‐linked heterodimers (II and III) and two apparent homodimers (I and IV) are bound by pea lectin, con‐canavalin A and lentil lectin on tonsil lymphocytes; II, III and IV are bound both leukoagglutinating (L)‐ and erythroagglutinating (E)‐phytohemagglutinins from Phaseolus vulgaris (PHA). Pokeweed mitogen recognizes only II and III. These molecules are weakly bound by peanut agglutinin, soybean agglutinin, Ulex europaeus agglutinin‐I, Dolichos biflorus agglutinin, Vicia villosa agglutinin and Sophora japonica agglutinin, but are not bound by Helix pomatia agglutinin or BSA‐agarose. Heterodimer II (82–88 kDa), comprized of 50–55‐kDa and 40–43‐kDa subunits, probably represents the α/β T cell antigen receptor (TcRα/β). Heterodimer III (64–72 kDa), comprized of 41‐kDa and 37‐kDa subunits, may represent TcRγ. The homodimers, I (120–130 kDa) and IV (55–61 kDa), comprized of 55–60‐kDa and 30‐kDa polypeptides, respectively, have apparently not been previously described. Evidence that H1‐2D4, a mAb directed against the antigen receptor on HPB‐ALL cells, and E‐PHA interact with a common molecule includes: (a) immunoprecipitation of TcR with H1‐2D4 from the glycopeptide fraction specifically eluted from insolubilized lectin with N‐acetylgalactosamine; and (b) adsorption of TcR from a solubilized H1‐2D4 immunoprecipitate by E‐PHA‐agarose. Recognition of CD3 by E‐PHA is indicated by immunoprecipitation of CD3 protein by UCHT1 from the glycopeptide fraction specifically eluted from E‐PHA. The results are consistent with the view that mitogenic lectins interact with certain disulfide‐linked molecules on human lymphocytes, including the TcR α/β and perhaps TcR γ; while some nonmitogenic lectins also recognize these receptors, the interaction is of low affinity.
Triggering of the alternative pathway of human T cell activation involves members of the T 200 family of glycoproteins
Authors: Schraven Burkhart , Roux Matthias , Hutmacher Beate , Meuer Stefan C.
Published: March 2007

The present report describes functional characteristics of a monoclonal antibody (mAb), TA/211, which is reactive with a common determinant of the human CD45 molecules. When added to purified testing human T cells, TA/211, which is itself not mitogenic, leads to a strong proliferative response in combination with submitogenic concentrations of anti‐T112 plus anti‐T113 mAb. Interestingly, while amplifying anti‐CD2‐mediated immune responses, T cell activation induced through triggering of the CD3 molecule is not enhanced by TA/211, indicating that the triggering signal provided through CD45 is restricted to alternative pathway activation.

Employing T cell subsets negatively selected for the expression of CD45R molecules defined by the mAb anti‐2H4 or UCHL1, respectively, it is demonstrated that resting T cells expressing the 2H4 molecules proliferate much stronger to TA/211 than the UCHL11 T cell subset. Together with the finding that the 2H4 T cell subset can be activated by the concomitant binding of anti‐CD2 antibodies plus anti‐2H4, these data strongly suggest that the high molecular weight species of CD45 expressed by unprimed T cells are themselves involved in T cell activation via the alternative pathway.
The conformation of the CD3 complex on T lymphocytes is modified by calcium ions
Authors: Breittmayer Jean‐Philippe , Schaffar Laurence , Bourel Dominique , Fehlmann Max
Published: March 2007

While calcium ions are known to play a prominent role in signal transduction in the activation of T lymphocytes, its mechanism of action, target and function have not been elucidated. One crucial event in the calcium‐dependent process is the activation of the CD3 complex, and this, too, is not understood. While studying the release of Ca2+ from intracellular stores by several monoclonal antibodies (mAb) against CD3, we found that one of them, mAb 141, was ineffective unless free Ca2+ was present in the external medium. By flow cytometric analaysis of the binding of this mAb to Jurkat T cells and peripheral blood lymphocytes we showed that 141 does not recognize the CD3 complex when external Ca2+ is chelated by EGTA. The binding was restored by addition of Ca2+ but not Mg2+. Finally at least one subunit of the CD3 complex displayed a modified electrophoretic migration rate when immunoprecipitated by Leu‐4 in the absence of external free Ca2+. These results suggest that the conformation of the CD3 complex depends on Ca2+, the epitope recognized by 141 being concealed at low Ca2+ concentration.
Comparison of the effects of recombinant interleukin 6 and recombinant interleukin 1 on nonspecific resistance to infection
Authors: Van Der Meer Jos W. M. , Helle Maarten , Aarden Lucien
Published: March 2007

Interleukin 1 (IL 1) is a potent enhancer of nonspecific resistance to infection in mice. Since IL 1 also induces interleukin 6 (IL 6), we tested the hypothesis that IL 6 mediates the effect of IL 1 on nonspecific resistance. In a lethal Pseudomonas aeruginosa infection in granulocytopenic mice, in which 80 ng of recombinant human IL 1α protects against death, IL 6 appeared to be much less effective. Dosages of 8 ng, 80 ng and 320 ng IL 6 did not differ from the control, whereas 800 ng had a marginal protective effect (0.05 < p < 0.1). IL 1 and IL 6 did not potentiate each other in animals treated with suboptimal dosages of both cytokines. Numbers of bacteria cultured from the blood, thigh muscle, liver, spleen, and kidney were similar in animals treated with 800 ng IL 6 and in control animals, arguing against activation of microbicidal mechanisms. The serum concentration profile of IL 6 after an i.p. injection of 80 ng IL 1 was similar to that after 80 ng IL 6 i.p. Only minute amounts of IL 1 were detected in serum after an i.p. injection of IL 6. Taken these data together, it appears that increased resistance to infection induced by IL 1 is not mediated by IL 6.
Role of interferon‐gamma in the modulation of the IgE response by 2,4‐dinitrophenyl‐Bordetella pertussis vaccine in the mouse
Authors: Hagen Michael , Essani Naeem A. , Strejan Gill H.
Published: March 2007

Immunization of mice with 2,4‐dinitrophenyl‐Bordetella pertussis (DNP‐BP) failed to induce anti‐DNP IgE responses. Administration of DNP‐BP induced, however, the formation of anti‐DNP IgE B memory cells, as demonstrated by adoptive transfer. Furthermore, mice pretreated with DNP‐BP and primed with 2 μg DNP‐ovalbumin (OA) in alum 2 weeks later produced high day‐7 anti‐DNP IgE levels. These subsided to near undetectable levels by day 12–14. The transient expression of serum IgE levels was accompanied by normal levels of anti‐DNP IgG. The anti‐OA response induced as a result of priming with DNP‐OA in alum was not affected by pretreatment with DNP‐BP. IgG subclass analysis revealed that mice pretreated with DNP‐BP had elevated levels of IgG2a and reduced levels of IgG1 as compared to control (TNP‐keyhole limpet hemocyanin‐pretreated) mice. Treatment of mice with an anti‐interferon‐γ monoclonal antibody, shortly after immunization with DNP‐BP, not only reduced anti‐DNP IgG2a levels, but prevented the sharp anti‐DNP IgE decline that occurred after priming with DNP‐OA in alum. These results suggest that DNP‐BP‐induced interferon‐γ production modulates Ig isotype expression in vivo in an antigen‐specific manner.