Biomedical subjects
Publications and source records attributed to P Lang.
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In this study, we have analyzed the expression and regulation of receptors for IL-2 (alpha and beta chains) and IL-4 in four lymphoid cell lines established from leukemic cells. The gibbon ape cell line MLA 144 was the only one to express constitutively the IL-2R beta chain and IL-4R, whereas the NK-like YT cells express only IL-2R beta. The two other cell lines in this study, PEER and HSB2, are derived from T lymphocytes, and express neither IL-4R, IL-2R beta, nor IL-2R alpha unless stimulated. We report here that those receptors that are constitutively expressed, i.e., IL-2R beta on YT cells and IL-2R beta or IL-4R on MLA cells, are down-regulated by stimulation with PHA + PMA. In contrast, RNase protection experiments showed that PHA + PMA stimulation of T cell lines induces mRNA for all three receptors in PEER cells, and only IL-2R alpha and IL-4R in HSB-2. Thus each of these three receptors is subjected to a different regulation, which in addition varies depending on the lineage (or differentiation stage) of the cells. This was further supported by the finding that IL-1 alpha or TNF-alpha regulates these receptors differently. These two cytokines have no effect on IL-2R beta and IL-4R in MLA and YT, but induce IL-2R alpha in YT. In contrast, they do not induce either chains of the IL-2R in the T cell lines PEER or HSB-2, but TNF induces IL-4R mRNA in HSB2 cells, and IL-1 does so in both cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)
The Rab branch of the Ras-related guanine nucleotide (GTP/GDP)-binding proteins currently includes at least thirty related members which are involved in the intracellular vesicular transport along the secretory and endocytic pathways in eukaryotic cells. We have demonstrated the overexpression of the Rab2 protein in peripheral blood mononuclear cells from patients exhibiting Sézary syndromes and other lymphoid and myeloid malignancies. Several lines of evidence suggest that the Rab2 overexpression can be related not to leukemic cells but to a subset of peripheral lymphocytes with a CD2+ phenotype. Our results provide strong evidences for the implication of a small GDP/GTP binding protein in immunological events associated with neoplastic states. The precise cellular population involved in this process remains to be determined.
Cell-mediated immunity in lethally irradiated graft-versus-host mice can be restored after repopulation with syngeneic bone marrow cells and thymus grafting. The thymus is not only required for the maturation of T lymphocytes, but also for the inhibition of a radioresistant mechanism resulting in lymphoid cell rejection.
In an open-labeled randomized study, prophylactic treatment with ganciclovir (day 15 to day 29) was administered to 23 cytomegalovirus seronegative patients who received a kidney from a cytomegalovirus seropositive donor. Both groups (control = 11, ganciclovir = 12) were similar in age, immunosuppressive treatments, acute rejection episodes and number of steroid pulses. A seroconversion occurred in 10 control patients (91 percent) and in 10 patients of the ganciclovir group (84 percent). A cytomegalovirus disease was observed in 10 control patients (91 percent) and in 8 patients of the ganciclovir group (66 percent). The delay between grafting and cytomegalovirus disease was significantly longer in the ganciclovir than in the control group (78.5 +/- 7.7 vs 46.5 +/- 5.5 days, P < 0.05). In conclusion, in renal transplant recipients who are at high risk of cytomegalovirus disease, prophylactic treatment with ganciclovir delays the onset of the disease and seems to decrease slightly its frequency.
Rac1 and Rac2 gene products are small GTP-binding proteins showing 92% homology to each other. According to recent studies performed in cell-free systems, Rac1 and Rac2 proteins may be involved in the activation of NADPH-oxidase, the superoxide-generating enzymatic complex active in phagocytes. Epstein-Barr virus (EBV) transformed B lymphocytes, which express rac1 and rac2 genes, also efficiently release superoxide anions when triggered by various cell surface stimuli. To investigate the regulatory role of Rac proteins in living cells, we analyzed superoxide production in response to cross-linking of surface immunoglobulins or phorbol ester treatment in human EBV-transformed B lymphocytes pretreated with Rac sense and antisense oligonucleotides. We report here that (i) the rac protein content estimated by immunoblotting can be decreased by 60% in Rac antisense pretreated cells and (ii) a strong (50-60%), dose-dependent inhibition of superoxide production is observed in antisense pretreated cells whereas cells pretreated with sense oligonucleotide are unaffected. The data presented show, for the first time in whole cells, that superoxide production is modulated by the Rac protein content, thus demonstrating the physiological role of Rac proteins in the regulation of NADPH-oxidase.
Nitric oxide (NO) has vasodilatory effects on the pulmonary vasculature in adults and animals. We examined the effects on systemic oxygenation and blood pressure of inhaling up to 80 parts per million by volume of NO at FiO2 0.9 for up to 30 minutes by 6 infants with persistent pulmonary hypertension of the newborn (PPHN). In all infants this treatment rapidly and significantly increased preductal oxygen saturation (SpO2); in 5 infants postductal SpO2 and oxygen tensions also increased. Inhalation of NO did not cause systemic hypotension or raise methaemoglobin. These data suggest that low levels of inhaled NO have an important role in the reversal of hypoxaemia due to PPHN.
The Rho proteins are identified as a subgroup of the Ras superfamily of low molecular weight GTP-binding proteins. We have studied the expression of these proteins in human cytotoxic natural killer cells and found that RhoA is the most abundantly expressed member of the Rho family. The Rho proteins are specific substrates for ADP-ribosylation catalyzed by the C3 exoenzyme from Clostridium botulinum. We report here that introduction of recombinant C3 in electropermeabilized natural killer cells or in cytotoxic T lymphocytes resulted in a dose-dependent inhibition of their cytolytic function. Furthermore, a single substrate is efficiently ADP-ribosylated by C3 in extracts from cytotoxic cells. Biochemical analyses indicate that this substrate is RhoA, and subcellular fractionation experiments demonstrate that it is essentially present in the cytosol of the cells. Western blot analysis, however, revealed that a small proportion of the Rho protein can be found associated with the cell membrane as well as with the cytotoxic granules. These results indicate that the low molecular weight GTP-binding protein RhoA is present in cytotoxic lymphocytes and plays a critical role in cell-mediated cytotoxicity.
Studies in mice suggest that the T cell subset involved in graft-versus-host-reaction (GvHR) across the major histocompatibility complex (MHC) depends on the class of MHC antigens recognized by the donor cells. However, the correlation between phenotype and function is not absolute. Using a functional approach, we investigated in a parent --> F1 hybrid model differing at the whole MHC, whether graft-versus-host (GvH) associated immunosuppression was correlated with donor cytotoxic T cell activity. The immunodeficiency was tested by the ability of the F1 mice to generate a cytotoxic T cell response against trinitrophenyl-modified syngeic cells (TNF-self) or an alloantigen. F1 specific parental cytotoxic T cells, generated in vitro, induced less immunosuppression than naive parental cells. Specific in vivo priming increased the cytotoxicity of parental spleen cells, but decreased their capacity to induce GvH-associated immunosuppression. In contrast, nonspecific priming resulted in the usual immunodeficiency. In conclusion, there was no correlation between GvH-associated immunosuppression and cytotoxic T cell activity of the parental cells.
Gammopathies were found to be present in 25 (13%) of 192 HIV-negative renal transplant recipients with more than 30 months follow-up prospectively investigated for monoclonal or oligoclonal immunoglobulins (mIg) by agarose gel electrophoresis and immunofixation. Eleven patients had only one monoclonal band, whereas 14 had two or more bands. Of these bands, 60% were IgG kappa, 29% IgG lambda and 11% IgM lambda or kappa, and 90% did not exceed 2 g/l. Most gammopathies occurred early post-transplant (median 5 months) and they were always transient. Some predisposing factors for mIg emergence could be identified: 1. age, but only in women, 2. duration of dialysis, 3. occurrence of prior cytomegalovirus infection, and 4. immunosuppressive regimen including cyclosporine. Serological evidence for active EBV infection was obtained in ten patients, but in six cases infection occurred subsequent to the finding of mIg. In eight patients, the clinical course was characterised by severe infection or tumours (one Kaposi's sarcoma, one B-cell brain lymphoma). The present findings and experimental studies support the view that the development of mIg in renal transplant patients is associated with a failure of regulatory T-cell function. This T-B-cell imbalance requires a careful follow-up in these patients.
In an open-label randomized study of prophylactic treatment by ganciclovir, 23 seronegative recipients of kidney allograft from seropositive donors were randomized to receive from day 14 to day 28 after transplantation either no treatment (n = 11) or ganciclovir, 5 mg/kg twice daily (n = 12). Both groups were similar in age, immunosuppressive therapy, number of acute rejections and in steroid bolus. Seroconversion occurred in ten patients of the control group (91%) and in ten of the ganciclovir group (84%). CMV disease occurred in ten patients of the control group (91%) and in eight patients of the ganciclovir group (66%), three of whom had asymptomatic viraemia. The delay between transplantation and onset of CMV disease was significantly increased by ganciclovir prophylaxis (78.5 +/- 7.7 vs 46.5 +/- 7.5 days, P < 0.05). We conclude that in renal transplant recipients at risk of CMV disease, ganciclovir prophylaxis delays the onset of the disease and seems to decrease its incidence and its severity.
The distal femur contains usually only fatty marrow in the adult. We investigated the incidence of areas of residual and reconverted hematopoietic marrow in the distal femur in a series of 50 adult patients using conventional spin-echo and opposed-phase gradient-echo MR images. Zones with intermediate to low signal intensity in both sequences representing hematopoietic marrow within high signal intensity fatty marrow were observed in 17 of the 50 patients. Opposed-phase gradient-echo sequences demonstrated significantly greater red-yellow marrow contrast than conventional spin-echo sequences. Residual red marrow may represent a biologic variation of the normal adult pattern of red-yellow marrow distribution in women of menstruating age. Reconverted red marrow appears to be related to increased erythrocyte demand. It should not be mistaken for bone marrow malignancy. Absence of epiphyseal involvement, cortical destruction and soft-tissue mass in residual and reconverted hematopoietic marrow are helpful differential criteria.
In previous studies it was demonstrated that antibodies in sera from patients with primary biliary cirrhosis (PBC) and their relatives can recognize two different antigen systems in the ATPase fraction prepared from beef heart mitochondria, namely the PBC-related M2- and the naturally occurring mitochondrial antigen (NOMAg)-related epitopes. Since separation of these two antigen systems could not be achieved using mammalian mitochondria, mitochondria from a wide spectrum of plants were analysed with respect to the presence of mitochondrial antigens. Mitochondria from 29 species of plants were prepared and tested by ELISA and Western blot using marker sera from patients with PBC reacting in the Western blot with M2a,b,c,d (alpha-ketoacid-dehydrogenase complex) and NOMAg-specific sera recognizing the three major epitopes epsilon, zeta, and eta at 65, 61 and 58 kD. Naturally occurring mitochondrial antibody (NOMA)-positive marker sera reacted in the ELISA with mitochondria from all plants, and the zeta/eta positive sera gave also a positive reaction at 61/58 kD in the Western blot while the epsilon epitope could not be visualized by this method. In contrast, the M2 antigen was detected preferentially in lower plants such as algae, fungi, and ferns. Analysing these data with respect to the evolution of proteins one would have to assume that the M2 antigen was lost in most higher plants or underwent some structural alterations. Furthermore, considering the fact that the M2- and the NOMAg-related epitopes could be only partially separated, i.e. there were no plant mitochondria showing only M2 but no NOMAg, one could speculate that anti-M2 antibodies are derived from the pool of naturally occurring antibodies.
Secretory immunoglobulin A (IgA) was determined by means of an enzyme-linked immunosorbent assay (using as capture antibody an MoAb specific for secretory component) in saliva and serum from 46 patients with IgA mesangial nephritis (IgAGN), 36 with an idiopathic nephrotic syndrome (INS), 30 with an idiopathic membranous nephropathy (MGN) and 40 healthy controls. Secretory IgA levels were elevated in both saliva and serum of patients with primary glomerulonephritis (P < 0.05; Mann-Whitney test) regardless of the histological type of the primary glomerulonephritis. Salivary IgA1 and IgA2 levels were increased in the saliva of patients with IgAGN, INS and MGN (P < 0.05; Mann-Whitney test). The monomeric/total IgA ratio, and interferon-gamma and soluble IL-2 receptor levels, in saliva did not differ between the patients and controls (P > 0.05; Mann-Whitney test). We conclude that the mucosal immune system is activated in forms of glomerulonephritis other than IgAGN.
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We report here the case of a 55-year-old patient with chronic granular lymphocyte disorder associated with moderate neutropenia. The majority of peripheral blood lymphocytes displayed a CD3-, CD8-, CD16+, CD56(NKH1)- phenotype. The patient's cells showed high spontaneous cytotoxic activity against K562 targets and developed the ability to kill the natural killer (NK)-resistant target Daudi following activation with interleukin 2 (IL-2). Simultaneously, IL-2 induced proliferation of these cells, albeit to a low level. The effects of IL-2 are likely to be mediated through the IL-2R beta chain (p70) which is expressed on these cells in the absence of the IL-2R alpha chain (p55, Tac). IL-4 was demonstrated to be inhibitory of both the cytotoxic and proliferative effects of IL-2. Thus, despite an unusual CD56- phenotype, the expanded lymphocyte population in this patient display functional and phenotypic properties of normal, non-activated NK cells. These cells probably represent the counterpart of a minor NK cell subpopulation, present in normal individuals at a low frequency, and which has never been fully characterized functionally. In addition, we show that the cytolytic activity of this NK cell population can be blocked in vitro in the presence of a cAMP analog or of theophylline, possibly providing new means of investigating the role of NK cell cytotoxicity on the pathogenesis of associated symptoms in such patients.