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O Lantz

Publications and source records attributed to O Lantz.

At least 37 records · Page 2Linked to original sources
PubMed1997

Upregulation of CD9 expression during TPA treatment of K562 cells.

The CD9 antigen, a major platelet glycoprotein, is a member of the tetraspan superfamily. We show that treatment of K562 cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) which induces megakaryocytic differentiation, leads to a seven-fold increase in CD9 expression, which becomes associated with the integrin beta1, suggesting that it is functionally relevant. The upregulation of CD9 expression precedes the appearance of the megakaryocytic-specific marker GPIIb (CD41) as well as integrins beta3 (GPIIIa/CD61), alpha v (CD51) and VLA-2 (CD49b). Both GPIIb/IIIa expression and CD9 upregulation are dependent on protein kinase C (PKC) activation since they are blocked by the specific inhibitor GF109203X. Steady-state levels of CD9 and GPIIb mRNA were also measured by quantitative RT-PCR. Both messengers were detected on resting cells and were shown to accumulate during TPA treatment. However, the increase of the CD9 mRNA was detected much earlier than the increase of GPIIb mRNA (1-2 h vs 24-48 h). Using different constructs of the 5'-flanking domain of the CD9 gene cloned ahead of the CAT reporter gene, we could demonstrate that a responsive element was located in a 52 bp fragment of the promoter of the CD9 gene. Altogether, these data suggest that CD9 upregulation in the megakaryocytic lineage could occur at early stages of differentiation.

Antigens, CD↗
PubMed1996

Increased interleukin 4 and immunoglobulin E production in transgenic mice overexpressing NK1 T cells.

Natural Killer (NK)1.1+ (NK1) T cells are a specialized subset of alpha/beta T cells that coexpress surface receptors that are normally associated with the NK cell lineage of the innate immune system. On recognition of the conserved, major histocompatibility complex class I-like CD1 molecule, these cells are able to release explosive bursts of interleukin 4 (IL-4), a cytokine that promotes the T helper type 2 (Th2) effector class of an immune response. A unique feature of their T cell receptor (TCR) repertoire is the expression of an invariant TCR alpha chain, V alpha 14-J alpha 281, and of a restricted but polyclonal set of V beta gene families, V beta 8, V beta 7, and V beta 2. Here, we show that transgenic expression of this TCR alpha chain during thymic development is sufficient information to bias the differentiation of mainstream thymocytes towards the NK1 developmental pathway. It markedly increases the frequency of cells with the NK1 pattern of T cell differentiation and also has drastic consequences for the selection of the V beta repertoire. Transgenic CD4 cells exhibited a 10-100-fold increase in IL-4 production on mitogen stimulation in vitro and in vivo, and baseline levels of the Th2-controlled serum immunoglobulin isotypes, IgE and IgG1, were also selectively elevated in vivo.

Animals↗
PubMed1996

Regulation of interleukin-10 production by beta-adrenergic agonists.

Catecholamines have been shown to inhibit some aspects of macrophage activation through a beta receptor-dependent mechanism. This study was undertaken to analyze the effects of isoproterenol, a specific beta-adrenergic agonist, on the synthesis of interleukin-10 (IL-10), a major macrophage-deactivating factor. Isoproterenol increased IL-10 release from lipopolysaccharide-(LPS)-activated mouse peritoneal macrophages in a dose-dependent manner. A significant effect was already observed with 1 microM isoproterenol, while a 4.5-fold increase was achieved with 10 microM. This increase was observed only if macrophages were exposed to isoproterenol for at least 2 h before LPS challenge. It was apparent within 0.5 h and persisted through 24 h at all the LPS concentrations used. A similar increase was observed at the IL-10 mRNA level, as judged by enzyme-linked immunosorbent assay-polymerase chain reaction. The macrophage response to isoproterenol that led to cyclic AMP accumulation was markedly inhibited by H-89, a potent inhibitor of protein kinase A. These data suggest the involvement of cyclic AMP in the regulation of IL-10 synthesis by isoproterenol. IL-10 was in turn partly responsible for a reduction in tumor necrosis factor-alpha synthesis. In vivo, the administration of oxprenolol, a beta-receptor antagonist, significantly reduced serum IL-10 levels 90 min after LPS challenge. Thus, the present study provides the first evidence that endogenous catecholamines are of critical importance in determining the magnitude of the IL-10 response in experimental endotoxemia.

Adjuvants, Immunologic↗
PubMed1995

CD1 recognition by mouse NK1+ T lymphocytes.

Rare major histocompatibility complex (MHC) class I-like CD1-specific T cells have been isolated from human blood, but it has not been determined whether these clones are part of a defined subset of CD1-specific T cells selected during T cell development, or whether their recognition of CD1 is a fortuitous cross-reaction. In mice, an entire subset of alpha beta thymocytes with a unique phenotype was found to be CD1-specific. This particular subset, and its human counterpart, provide evidence that CD1 has a general role in selecting and interacting with specialized alpha beta T cells.

Animals↗
PubMed1995

Regulation of interleukin 2 gene expression by CD28 costimulation in mouse T-cell clones: both nuclear and cytoplasmic RNAs are regulated with complex kinetics.

T-cell receptor (TCR) signalling is required to induce expression of the interleukin 2 (IL-2) gene in mouse T cells. Additional costimulation through CD28 augments IL-2 production by 30- to 100-fold. Using IL-2 RNA accumulation and transcription reporter assays, we have addressed potential mechanisms of CD28 regulation at various time points of stimulation. The kinetic regulation of IL-2 mRNA by TCR and CD28 signals is complex: (i) at the earliest detectable time point, CD28 signalling causes a 20-fold increase compared with TCR signalling alone; (ii) both groups rapidly accumulate mRNA for the first 4 h; (iii) IL-2 mRNA then disappears from cells stimulated through the TCR alone but plateaus or increases slightly in cells costimulated through CD28; and (iv) after 8 h, the mRNA disappears in cultures with the anti-CD28 antibody. Transcription reporter assays did not show a specific effect of CD28 signalling on IL-2 enhancer driven transcription. This was true for either a 353- or a 1.9-kb enhancer, over a broad range of kinetics and TCR occupancy, and with several TCR signal mimics. The early component of CD28 costimulation is nuclear, however, since the initial enhancement of mRNA is also found in unspliced IL-2 RNA. Between 2 and 6 h, there is a marked difference in the rates of decay of IL-2 mRNA in the presence and absence of the CD28 signalling. Rapid decay of IL-2 mRNA commences after 8 h even in the presence of CD28 signals, although the decay occurs at a rate slower than that seen after 4 h of anti-TCR stimulation alone. This complexity suggests the existence of two interesting molecular mechanisms by which CD28 costimulates lymphokine gene expression.

Animals↗
PubMed1994

An invariant T cell receptor alpha chain is used by a unique subset of major histocompatibility complex class I-specific CD4+ and CD4-8- T cells in mice and humans.

The mouse thymus contains a mature T cell subset that is distinguishable from the mainstream thymocytes by several characteristics. It is restricted in its usage of T cell receptor (TCR) V beta genes to V beta 8, V beta 7, and V beta 2. Its surface phenotype is that of activated/memory cells. It carries the natural killer NK1.1 surface marker. Furthermore, though it consists entirely of CD4+ and CD4-8- cells, its selection in the thymus depends solely upon major histocompatibility complex (MHC) class I expression by cells of hematopoietic origin. Forced persistence of CD8, in fact, imparts negative selection. Here, we have studied the TCR repertoire of this subset and found that, whereas the beta chain V-D-J junctions are quite variable, a single invariant alpha chain V alpha 14-J281 is used by a majority of the TCRs. This surprisingly restricted usage of the V alpha 14-J281 alpha chain is dependent on MHC class I expression, but independent of the MHC haplotype. In humans, a similar unusual population including CD4-8- cells can also be found that uses a strikingly homologous, invariant alpha chain V alpha 24-JQ. Thus, this unique V alpha-J alpha combination has been conserved in both species, conferring specificity to some shared nonpolymorphic MHC class I/peptide self-ligand(s). This implies that the T cell subset that it defines has a specialized and important role, perhaps related to its unique ability to secrete a large set of lymphokines including interleukin 4, upon primary stimulation in vitro and in vivo.

Amino Acid Sequence↗
PubMed1994

Induction of peripheral T cell tolerance and allo/xenoimmunity.

It is theoretically impossible or at least difficult to tolerize animals in xenogeneic situation, particularly in non-concordant species. Both humoral defense and several cellular components (T and non T) are offensive weapons which can be directed at myriad of self-antigens in a normal situation, at allo-antigens in abnormal situations, at xeno-antigens in exceptional situations. In either cases, the fine epitopic definition of allo/xeno antigens seen by the TCR is far from being totally known. From recent studies showing the precise requirement of peptides assembly composition in the MHC class I and II groove it should be theoretically possible to tolerize any group of peptides if they are presented, some other, because not presented, may remain ignored, thus apparently tolerized. It is also know, that transplantation tolerance is not a law of "either nothing or all" but a multiple process depending of both the affinity of the TCR and the nature/compositions of the target. In view of the complex array of factors influencing the pathway of T cell activation, three forms of T cell non responsiveness may be suggested in the context of xenogeneic recognition: physical deletion of potentially reactive T cells occurring predominantly in the thymus, non reactivity of T cells resulting from their failure to be influenced by antigens, and anergy possibly due to inappropriate signals from non professional antigen presenting cells. Future investigations must elucidate the requirements for inducing these events in a purpose of xenogeneic organ transplantation.

Clonal Anergy↗
PubMed1993

Apoptosis of activated CD8+/CD57+ T cells is induced by some combinations of anti-CD2 mAb.

Peripheral blood CD8+/CD57+ T cells display poor proliferative responses when stimulated with CD3 or CD2 in vitro, but can be induced to proliferate in the presence of exogenous IL-2. Although GT2+T11(1), a mitogenic anti-CD2 mAb pair, could synergize with IL-2 to induce sustained cell divisions in this population (as did immobilized OKT3), D66+T11(1), another anti-CD2 mAb pair, could only induce a small abortive proliferative response. All these antibodies were in contrast strongly mitogenic for CD8+/CD57- T cells. Assuming that D66+T11(1) were exerting inhibitory effects on CD8+/CD57+ T cells, we indeed found that such antibodies profoundly suppressed the anti-CD3 and IL-2-induced proliferation of those cells, but not that of CD8+/CD57- cells. CD2-mediated growth arrest was correlated with rapid cell death occurring within 2 h, once the cells had been submitted to D66+T11(1), and cells susceptible to the death signal were large cells committed in the cell cycle. D66+T11(1)-treated cells had the well-known ultrastructural form of apoptosis, and the DNA extracted from these cells showed the typical ladder pattern of DNA fragmentation accompanying this process. For apoptosis to occur, two anti-CD2 mAb had to be applied to the cells, one of them being D66, suggesting that the corresponding anti-CD2 mAb pairs were imposing on the CD2 molecule a particular conformational change appropriate to transduce a death signal. Notably, CD8+/CD57- T cells were largely resistant to apoptosis in the conditions just described. When exposed to anti-CD3 and IL-2 in primary and secondary cultures, CD8+/CD57+ T cells retained high viability, whereas in contrast, when exposed to D66+T11(1), important cell loss occurred, concomitant with apoptosis, illustrating the specificity of the CD2-derived death signal. Our results suggest that the expansion of CD8+/CD57+ T cells is critically dependent on the CD2 pathway which, according to the conformational change of the CD2 molecule and the activation state of the cells, will direct them either towards proliferation or towards cell death.

Antibodies, Monoclonal↗
PubMed1993

A possible role for specific "anergy" in immunologic hyporeactivity to donor stimulation in human kidney allograft recipients.

The low immunological reactivity toward donor cells usually observed in transplant recipients has been linked to clonal deletion or suppression of alloreactive cells. However, the anergy of donor-specific reactive cells is another possibility not extensively tested until now in humans. In this case, donor-specific reactive cells would be present and eventually be activated without becoming effector cells (i.e., without secreting IL-2 or becoming cytotoxic) after donor-specific stimulation. We studied 8 patients under low-dose immunosuppressive drugs who displayed hyporeactivity toward donor stimulation. IL-2 production, proliferative response, and cytotoxic activity toward donor cell stimulation was decreased (respectively 22, 53, and 19% of response toward third-party stimulation). In order to evidence anergy, we studied two activation markers (cell size increase and expression of IL-2 receptor [CD25]) in allografted recipient T cells after autologous (background), donor (experimental), and third-party cell stimulation (positive control). We showed that the percentage of CD25+ cells and the cell size increase were similar after donor or third-party cell stimulation and clearly above the background as early as days 1-2 after the beginning of the mixed lymphocyte culture. Moreover, CD4+ and CD8+ cells similarly expressed CD25 after donor or third-party stimulation. Thus, donor-specific reactive cells not only were present but could be activated without becoming effector cells. These data suggest that anergy may be an important phenomenon in allograft tolerance.

Humans↗
PubMed1993

A versatile ELISA-PCR assay for mRNA quantitation from a few cells.

Gene expression studies require a sensitive and quantitative assay of mRNA amounts present in small samples. We describe a general method of quantifying specific mRNA quickly and easily from purified RNA or directly from a few cells by PCR and enzyme-linked immunosorbent assay (ELISA) revelation of the resulting products (sensitivity of the last step: < 0.1 fmol). Cells are digested and the total cellular RNA is reverse-transcribed and then amplified with 5' and 3' primers; the former being 5' biotinylated. The amplification product is captured on avidin-coated microplates and quantified by hybridization with a digoxigenin-labeled internal oligonucleotide probe. After revelation with an anti-digoxigenin alkaline phosphatase coupled antibody (anti-DIG-AP1), the amount of hybridized probe is determined by optical reading. The results can be easily converted to absolute values by comparison with an external DNA standard curve. An internal DNA or RNA standard can also be used. The method we describe can be adapted to any cellular or viral gene of known sequence in a matter of days. Since it uses nonradioactive probes, commercially available reagents and standard microplate readers, it is inexpensive and could be automated easily. In this study, interleukin-2 mRNA expression could be studied in as few as 40 Jurkat cells. It was also possible to quantify human immunodeficiency virus (HIV) DNA from 1500 to 1.5 copies out of 1.5 x 10(5) human genomic DNA copies.

Avidin↗
PubMed1993

[Current concepts on the alloreactive response].

Many new data have been obtained in the last 4 years about the structure and the functions of Major Histocompatibility Complex (MHC) molecules. Structural data are summarized and the functions of MHC molecules in the presentation of peptides to T cells is described. The high selectivity of peptides binding to MHC molecules is explained. The negative and positive selection of T cells in the thymus is described and the notion of repertoire introduced. The consequences of these new data on the understanding of H2 restriction and alloreactivity are explained. The 4 potential types of alloreactivity are defined: 1) House keeping gene (HKG) peptides bound to allogenic MHC molecules, 2) allogenic peptides (derived from allogenic MHC molecules) bound to allogenic MHC molecules, 3) empty allogenic MHC molecules, 4) allogenic peptides bound to autologous MHC molecules. In fact, the allogenic response is mostly directed toward HKG peptides bound to the allogenic MHC molecules of the graft cells (type 1). The potential role of type 4 alloreactivity in rejection is discussed.

Animals↗
PubMed1992

Prophylactic use of the IL-2 receptor-specific monoclonal antibody LO-Tact-1 with cyclosporin A and steroids in renal transplantation.

LO-Tact-1 is a rat anti-human monoclonal antibody which is directed to the 55-kDa alpha-chain of the interleukin 2 (IL2) receptor. We conducted a pilot trial in 15 first-time cadaveric renal transplant patients undergoing for immunosuppression a 14-day course of LO-Tact-1 (10 mg i.v. daily) together with cyclosporine, low dose steroids (0.5 mg/kg) and azathioprine. Results showed a good immunosuppressive effect, as measured by the similar incidence of acute rejection episodes (0.6 per patient) when compared with 20 patients treated during the same period with our standard quadruple prophylactic combination with higher initial doses of steroids (2 mg/kg) and antilymphocyte globulin (ALG) instead of LO-Tact-1 (0.4 per patient). At 2 years post-transplant, graft survival was 93%, and only 1 patient lost his kidney by rejection. No local or general adverse effect of antibody administration was encountered, and haematological changes remained of minor importance. Local bacterial infection was observed in 3 patients, but viral diseases (including cytomegalovirus, CMV) remained exceptional. In contrast, severe clinical CMV infections occurred in 3 patients (15%) treated by ALG. Nine of 15 patients developed rat-specific antibodies, but only 4 before the completion of LO-Tact-1 treatment, without any correlation with the further development of acute rejection. Patients who suffered rejection had lower LO-Tact-1 levels and higher soluble IL2 receptor levels during the period of infusion, suggesting the crucial importance of pharmacokinetic monitoring to adjust individual doses.

Adrenal Cortex Hormones↗