PubMed Health⌕ Search

Biomedical subjects

U Testa

Publications and source records attributed to U Testa.

At least 37 records · Page 2Linked to original sources
PubMed1991

Positive modulation of hemoglobin, heme, and transferrin receptor synthesis by murine interferon-alpha and -beta in differentiating Friend cells. Pivotal role of heme synthesis.

Administration of highly purified preparations of murine interferon (IFN)-alpha 1, -alpha 4, -alpha 6, or -beta to Friend leukemia cells induced to differentiate by dimethyl sulfoxide leads to a 100% increase of benzidine-positive (B+) cells. Different efficiencies for the two IFN species have been observed; a 10-fold higher dose of IFN-alpha is needed for stimulation of hemoglobin production and inhibition of cell growth as compared with IFN-beta. Both species of IFN induce a substantial increase in heme, hemoglobin, and transferrin receptor levels. In vitro run-on transcription assays indicate that IFN-beta moderately stimulates transcription of the alpha-globin gene but not the transferrin receptor gene. It is postulated that IFN induces the enhancing effect on differentiation via a marked increase of heme synthesis and number of transferrin receptors, which in turn leads to an enhancement of globin chain synthesis. In this regard, the negative feedback reported in a variety of other cell types for the regulation of transferrin receptor expression by heme does not seem to be operative in maturing Friend erythroleukemia cells, which present evidence for a positive mechanism.

Animals↗
PubMed1991

Molecular heterogeneity of the 1.0-kb T beta transcript in natural killer and gamma/delta lymphocytes.

The T cell receptor (TcR) beta chain is encoded by a 1.3-kb mRNA which contains variable (V), diversity (D), joining (J) and constant (C) regions. A shorter 1.0-kb transcript with C but no V sequences is found in thymocytes, alpha/beta and gamma/delta T lymphocytes and natural killer cells. The origin, clonal variability and function of this transcript is unknown. We isolated cDNA clones representative of the 1.0-kb mRNA from cDNA libraries of either polyclonal or clonal natural killer and gamma/delta lymphocytes. Ten different types of cDNA clones belonging to three separate groups were identified: (a) "J-C clones" consisting of one of five J beta regions and the corresponding C beta 1 or C beta 2 regions; (b) "D-J-C clones" composed of D beta 1/or D beta 2/J beta rearranged sequences and C beta 1 or C beta 2 sequences; (c) "5'C clones" made up of C beta 1 or C beta 2 regions preceded by the corresponding genomic 5' flanking region. The presence of recombination signal sequences in J-C and D-J-C clones suggests that the first derive from mRNA transcribed from promoters located in the 5' J region and the second from mRNA transcribed from promoters situated in the 5' D region. Nucleotide sequence analysis demonstrated that only three of the ten types of clones isolated had the potential to code a short cytoplasmic T beta protein with a variable D-J beta N terminus. These findings have implications for the mechanisms of T beta germ-line transcription and the function of the T beta transcripts.

Amino Acid Sequence↗
PubMed1991

Pure human hematopoietic progenitors: direct inhibitory effect of transforming growth factors-beta 1 and -beta 2.

TGF-beta 1 and TGF-beta 2 are effective inhibitors of hematopoiesis. We report that colony formation by pure peripheral blood CD34+CD33- BFU-E and CFU-GM (100 cells/dish) is effectively inhibited by both molecules, although TGF-beta 1 is up to 10-fold more potent than TGF-beta 2. Therefore, the effect of these molecules is apparently direct, rather than mediated by accessory cells. The maximal inhibitory activity of TGF-beta is exerted essentially at the early progenitor level, whereas BFU-E/CFU-GM primed for 48 h and IL-3, GM-CSF, and erythropoietin become insensitive to its action. In addition, [3H]TdR suicide experiments indicate that TGF-beta 2 blocks the IL-3-induced progression of early progenitors into the S phase of the cell cycle, whereas IL-6 and bFGF potentiate their entry into the mitotic process. Altogether, these results are compatible with the hypothesis that TGF-beta plays a relevant regulatory role in the homeostasis of early hematopoietic proliferation/differentiation.

Cell Cycle↗
PubMed1990

"Pure" human hematopoietic progenitors: permissive action of basic fibroblast growth factor.

Methodology has been developed that enables virtually complete purification and abundant recovery of early hematopoietic progenitors from normal human adult peripheral blood. A fraction of the pure progenitors is multipotent (generates mixed colonies) and exhibits self-renewal capacity (gives rise to blast cell colonies). This methodology provides a fundamental tool for basic and clinical studies on hematopoiesis. Optimal in vitro cloning of virtually pure progenitors requires not only the stimulatory effect of interleukin-3, granulocyte-macrophage colony-stimulating factor, and erythropoietin, but also the permissive action of basic fibroblast growth factor. These findings suggest a regulatory role for this growth factor in early hematopoiesis.

Adult↗
PubMed1990

Adoptive immunotherapy of human cancer: the cytokine cascade and monocyte activation following high-dose interleukin 2 bolus treatment.

Serum concentration kinetics of gamma-interferon (IFN-gamma), neopterin, 2'-5' A synthetase and tumor necrosis factor alpha were determined in five cancer patients undergoing adoptive immunotherapy with high-dose interleukin 2 (IL-2) bolus infusion and lymphokine-activated killer cells according to the National Cancer Institute, NIH protocol. In all cases a significant increase of these markers was observed after IL-2 treatment. This suggests that the antitumor effect of high-dose IL-2 bolus administration may be in part mediated by activation of a cascade of endogenous cytokines including IFN-gamma and tumor necrosis factor alpha. After IL-2 bolus injection, the kinetics of neopterin was similar but delayed when compared to that of IFN-gamma: this suggests that macrophages, the specific source of neopterin, become activated by IFN-gamma following IL-2-mediated lymphocyte induction, thus implying a possible role for macrophages in the antitumor effects mediated by IL-2 and lymphokine-activated killer cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

Molecular mechanisms underlying the expression of the human HOX-5.1 gene.

The complex mechanisms underlying homeobox genes expression involve regulation at transcriptional, post-transcriptional and translational levels. The multiple transcripts of the human HOX-5.1 gene are expressed differentially in tissue- and stage-specific patterns during embryogenesis, and differentially induced by retinoic acid (RA) in human embryonal carcinoma (EC) NT2/D1 cells. We have sequenced 6.3 Kb of the genomic region containing the HOX-5.1 gene and analyzed its mechanisms of expression. Two alternative promoters underlie the transcription of two classes of HOX-5.1-specific mRNAs. These classes differ in tissue and subcellular distribution, induction by RA, structure of the 5'-UT region and mRNA stability: these features are compatible with a differential function of the two classes of transcripts in embryogenesis.

Amino Acid Sequence↗
PubMed1990

HLA expression in hemopoietic development. Class I and II antigens are induced in the definitive erythroid lineage and differentially modulated by fetal liver cytokines.

We investigated the expression of HLA Ag on hemopoietic progenitors (burst-forming unit E, CFU-E, and CFU-granulocyte-macrophage) and precursors from human embryonic fetal liver (FL) and peripheral blood at 5 to 9 wk postconception. The expression on progenitors was evaluated by complement-mediated cytotoxicity followed by assay of residual progenitors in clonogenic culture; immunofluorescence and RIA were used for differentiated precursors. HLA Class I and II Ag are not expressed on the primitive erythroid lineage, i.e., on yolk sac-derived megaloblasts circulating in 5- to 6-wk peripheral blood. However, they are gradually induced on the definitive erythroid lineage in FL. Their expression on progenitors is first detected at 6 wk and shows a progressive increase through 9 wk, up to greater than or equal to 50% of adult values. A similar expression pattern is observed for FL erythroblasts. Incubation of 6-wk FL erythroid cells with IFN-alpha, -beta, or -gamma, or TNF-alpha induces a sharp rise of the expression of HLA class I, but not HLA class II Ag on both progenitors and precursors. In contrast, incubation with PHA-stimulated adult leukocyte-conditioned medium causes a marked increase of both HLA-ABC and HLA class II Ag expression. We hence investigated the effect of cytokines present in leukocyte-conditioned medium on the expression of HLA class II Ag: although IL-1 alpha, IL-2, and granulocyte-macrophage-CSF do not exert a significant action, IL-1 beta and IL-4 induce a marked increase of HLA class II, but not class I, Ag expression on 6-wk FL progenitors and precursors. Low amounts of IFN-gamma, TNF-alpha, and IL-1 beta were detected in the supernatants and extracts of 6-wk FL cells. The concentrations of these cytokines in both supernatants and extracts sharply increase in the 7- to 8-wk period, particularly for TNF-alpha and IL-1 beta, thus indicating a direct correlation with the rise of HLA Ag expression on FL erythroid cells in the same period. In conclusion, the expression of HLA class I and II Ag is not detected on primitive megaloblasts, but is gradually induced on definitive FL progenitors and precursors, possibly via production of specific cytokines in the FL microenvironment, i.e., IFN-gamma and TNF-alpha for class I Ag and IL-1 beta for class II Ag.

Biological Factors↗
PubMed1990

Natural killer cells carry the germ-line configuration of the T cell receptor delta chain gene and heterogeneously express six distinct delta transcripts.

Investigations on T cell receptor delta chain (TcR delta) gene expression in freshly isolated normal large granular lymphocytes, natural killer (NK) cell clones and NK bulk cultures revealed six T delta transcripts (3.5, 3.1, 2.2, 2.0, 1.5 and 1.3 kb) which varied in number and relative abundance in the different samples. None of the six known T delta variable regions was expressed and the T delta locus was retained in its germ-line configuration. The origin and significance of these NK-associated T delta transcripts are discussed.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Molecular mechanisms underlying erythropoiesis: cycling activity of adult BFU-e relates to their requirement for c-myb function and potential for HbF synthesis.

Highly purified erythroid burst-forming units (BFU-e) from human embryonic liver, adult marrow and blood were manipulated in vitro by cytokine addition in order to explore their requirements for c-myb function and potential for fetal hemoglobin (HbF) synthesis, particularly as related to their cycling activity. c-myb is expressed at a minimal level and functionally required to a limited extent in quiescent adult BFU-e. However, c-myb is actively transcribed and stringently required for differentiation of actively cycling progenitors (embryonic BFU-e, embryonic and adult erythroid colony-forming units). The cycling activity of highly purified adult BFU-e, gradually enhanced by interleukin 3 (IL-3) addition, is strictly and directly related to both their functional requirements for c-myb and the level of myb mRNA expression in the progenitor population. It may be concluded that the transcriptional activity and the functional role of c-myb in early erythropoiesis are dependent upon the cycling activity of the erythroid progenitors. The reactivation of HbF synthesis in normal adult bursts, observed in the standard fetal calf serum-rich (FCS+) clonogenic system, is suppressed in cultures with a drastically limited growth of accessory cells (i.e., in FCS- or FCS+ Mo- conditions). In these cultures, addition of granulocyte/macrophage colony-stimulating factor (GM-CSF) or IL-3 induces a dose-related rise of gamma-chain synthesis, at least in part via a direct action at the BFU-e level. Preliminary studies involving priming of adult BFU-e with IL-3 in liquid phase suggest that the HbF potential is relatively low in quiescent BFU-e, but distinctly higher in actively cycling ones. It is postulated that the in vivo reactivation of HbF synthesis in bone marrow regeneration may be mediated via increased IL-3 and GM-CSF activity, leading to enhanced cycling and differentiation of BFU-e.

Adult↗
PubMed1990

Interleukin-2-dependent long-term cultures of low-density lymphocytes allow the proliferation of lymphokine-activated killer cells with natural killer, Ti gamma/delta or TNK phenotype.

We have developed a culture system for "long-term" growth of human lymphokine-activated killer (LAK) cells exhibiting an elevated, wide-spectrum antitumor cytotoxicity. The system allows the exponential growth of monocyte-depleted low-density lymphocytes in the presence of human serum and recombinant human interleukin-2 (10(3) U/ml), alone or in combination with interleukin-1 alpha or beta (both at 10 U/ml). Eighteen cultures were established from 18 normal adult donors. The membrane phenotypes of the final LAK cell population, assessed by a panel of monoclonal antibodies (mAb), consist of three main types: (a) NKH-1+, Ti alpha/beta-, Ti gamma/delta-, and CD3- lymphocytes; (b) NKH-1+, Ti alpha/beta-, Ti gamma/delta+, and CD3+ lymphocytes and (c) NKH-1+, Ti alpha/beta+, Ti gamma/delta- and CD3+ lymphocytes. Northern blot analysis showed that all these cell populations express relatively high levels of perforin RNA, particularly cells exhibiting the first phenotype. This culture system may provide a tool for cellular and molecular studies on the mechanisms of antitumor cytotoxicity, as well as the basis for new adoptive immunotherapy protocols in advanced center.

Antigens, CD↗
PubMed1990

Reactivation of HbF synthesis in normal adult erythroid bursts by IL-3.

Reactivation of HbF synthesis has been reported in normal adult erythroblast colonies ('burst') generated by erythroid progenitors (BFU-E) after seeding peripheral blood mononuclear cells (PBMC) in fetal calf serum-supplemented (FCS+) semisolid cultures stimulated by erythropoietin (Ep). Reactivation is almost totally suppressed when: (i) PMBC are grown in optimized FCS- culture or (ii) PBMC are first stringently depleted of monocytes and then plated in FCS+ medium (i.e. BFU-E growth in FCS+Mo- culture). In either case, addition of biosynthetic granulocyte-macrophage colony stimulating factor (GM-CSF) induces a dose-related increase of relative HbF synthesis up to the level in FCS+ culture. We report that, in FCS- culture of partially purified adult blood BFU-E, treatment with biosynthetic interleukin 3 (IL-3) causes a dose-related rise of relative HbF production in the bursts. A similar phenomenon is observed in FCS+ culture of highly purified BFU-E. The rise of HbF synthesis is seemingly mediated, at least in part, by a direct effect of IL-3 at BFU-E level. It is tentatively concluded that reactivation of HbF in vitro, as well as in a variety of in vivo conditions (i.e. stress erythropoiesis, marrow regeneration), may be at least in part mediated by IL-3 and GM-CSF.

Adult↗
PubMed1990

Increased human immunodeficiency virus (HIV) expression in chronically infected U937 cells upon in vitro differentiation by hydroxyvitamin D3: roles of interferon and tumor necrosis factor in regulation of HIV production.

We have investigated the roles of cytokines in the modulation of human immunodeficiency virus (HIV) production in chronically infected U937 cells upon in vitro differentiation by hydroxyvitamin D3. HIV-infected U937 cells exhibited markedly lower levels of CD4 and HLA-DR antigens than uninfected cells did. Vitamin D3 induced a time-dependent macrophagelike differentiation, as determined by monitoring the expression of some surface antigens by means of the monoclonal antibodies OKM1, OKM5, OKM13, OKM14, OKT4, anti-HLA-DR, TecMG2, TecMG3, LeuM3, LeuM1, anti-HLA-DP, and anti-HLA-DQ. Treatment with hydroxyvitamin D3 resulted in a marked increase in HIV production compared with control cultures. Interleukin 1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF-alpha) were detected in the culture media, whereas interferon (IFN) was not generally found. Using the polymerase chain reaction technique, we found HIV-infected U937 cells to express detectable levels of mRNAs for alpha interferon (IFN-alpha), IFN-beta, TNF-alpha, and IL-1 beta. The addition of TNF resulted in a marked increase of HIV production, whereas IL-1 beta was ineffective. In contrast, both IFN-alpha and IFN-beta exerted some inhibitory effect on HIV production, which was more marked in vitamin D3-treated cultures than in untreated cultures. HIV production was significantly increased by antibodies to IFN-alpha in both untreated and vitamin D3-treated cultures. Anti-IFN-beta antibody increased HIV production only in vitamin D3-treated cells. In contrast, anti-TNF-alpha antibodies markedly decreased HIV production in both control and differentiating U937 cells. Vitamin D3 treatment resulted in a higher expression of TNF receptors in differentiating cells than in control HIV-infected cells. These data demonstrate a strong correlation between HIV production and macrophagelike differentiation in chronically infected U937 cells and suggest that endogenous IFN and TNF exert opposite effects in the regulation of virus production in both undifferentiated and vitamin D3-treated cell cultures.

Antibodies, Monoclonal↗
PubMed1990

Molecular studies on LAK cells.

We have developed a culture system for long-term growth of human LAK cells exhibiting an elevated, wide-spectrum anti-tumor cytotoxicity. The phenotypic and molecular properties of the final LAK cell populations indicated that they consist of three main types: a) NK-like lymphocytes (type I): NKH-1+, Ti alpha/beta-, Ti gamma/delta-, CD3-lymphocytes carrying the germline configuration of all TCR genes and expressing variable amount of the 1.0 beta mRNA and variably sized T delta transcripts; b) gamma/delta-like T lymphocytes (type II) NKH-1+, Ti alpha/beta-, Ti gamma/delta+, CD3+ lymphocytes carrying polyclonal rearrangements of the gamma and delta genes and expressing high levels of mature gamma and delta transcripts; c) alpha/beta-like T lymphocytes (type III): NKH-1+, Ti alpha/beta+, Ti gamma/delta-, CD3+ lymphocytes carrying rearrangements of all TCR genes and expressing high levels of mature alpha and beta transcripts. We took advantage of the high number of available LAK cells to clarify: 1) the origin of the NK-LAK delta transcripts. delta gene expression in LGL, NK clones and type I LAK cultures revealed six delta transcripts (3.5, 3.1, 2.2, 2.0, 1.5 and 1.3 kb), which varied in number and relative abundance in the different samples. None of the six known V delta was expressed and the delta locus was retained in its germline configuration suggesting that the delta expression is due to a partially rearranged or germline transcripts; 2) the origin of the NK-LAK truncated T beta transcript. We isolated two different clone types from a type I LAK cell cDNA library: a) J-C clones consisting of one of three J beta regions and the corresponding C beta 1 or C beta 2 regions; b) X-J-C and C-X clones, containing as yet unidentified (X) sequences. The presence of RSSs in J-C clones suggests that they derive from mRNAs transcribed from a promoter in the 5'J. Nucleotide analysis demonstrated that only one of the isolated clones had the potential to code a short T beta protein.

Amino Acid Sequence↗
PubMed1990

Interleukin 2 in cancer therapy.

The goal of adoptive immunotherapy is the stimulation of host antitumor immunity, either cellular or humoral. The introduction of recombinant human cytokines into clinical oncology represents a new useful tool for the development of new strategies of antitumor immunotherapy. This article describes the current clinical status of IL-2 in the therapy of human cancer as it relates to what is already known about the biology and activity of this lymphokine. All the evidences suggest that the antitumor effect of IL-2 seems to be mediated through complex indirect mechanisms involving different effector cells of the immune system.

Adult↗