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The expression of platelet-derived growth factor, a potent mitogen, and its receptor both in tissue and serum correlate with the severity of liver cirrhosis. Over-expression of platelet-derived growth factor has been demonstrated in human hepatocellular carcinoma (HCC) tumors and cell lines. Imatinib, a potent inhibitor of BCR-ABL and c-kit, also inhibits the platelet-derived growth factor receptor tyrosine kinase. The trial was designed to assess the efficacy and safety of imatinib in patients with unresectable HCC.Eligibility criteria consisted of HCC patient over the age of 18 with reasonable organ function, unresectable but measurable disease, not candidates for chemoinfusion, and a performance status of 0 to 2. Imatinib was started at 300 mg/d orally with 100 mg/wk dose escalation up to 800 mg/d if toxicity permitted.Fifteen patients, median age 58 years, were enrolled and treated with imatinib. Most, or 7, patients had hepatitis B virus as a risk factor for HCC, followed by hepatitis C virus in 3 patients. Metastatic disease (American Joint Committee on Cancer stage IV) was noted in 13 patients and locally advanced (stage III) in the remainder. The median dose-level of imatinib was 500 mg/d. Two patients had stable disease lasting more than 2 months. The remainder progressed within 2 months of initiation of imatinib. No grade 3 or 4 hematologic toxicity was observed. Two patients had grade 3 elevated liver function tests during treatment; otherwise, there was no other grade 3 or 4 nonhematologic toxicity noted.Although toxicities were tolerable, imatinib as a monotherapy for the treatment of unresectable HCC has little, if any, significant efficacy.

CD31 (PECAM-1) is an immunoglobulin gene superfamily cell adhesion molecule found on vascular endothelium, platelets, and leukocytes. Lymphocyte expression of CD31 is most closely associated with the CD45RA+CD8+ naive T phenotype. CD31 has recently been shown to play a role in leukocyte egress to inflammatory sites. The mechanism of CD31 adhesion remains under investigation. Several investigators have reported evidence for a heterotypic ligand. We have previously shown that CD31 is phosphorylated with cell activation, which suggests a possible role for CD31 in cell activation events. We therefore studied the effects of CD31 antibodies on in vitro assays of lymphocyte activation. One CD31 antibody, LYP21, inhibited the mixed lymphocyte reaction (MLR) in a specific and dose-dependent fashion. An LYP21 epitope was localized to the sixth Ig domain of CD31. This peptide and a scrambled control peptide were synthesized and used to study effects of this epitope on lymphocyte activation. The CD31 peptide strongly inhibited the MLR. Because CD31 is expressed on both stimulator and responder populations, stimulator peripheral blood leukocytes and responder lymphocyte populations were separately incubated with CD31 peptide or control peptide and then washed before mixing. The CD31 peptide inhibited the MLR equally when either stimulator or responder cells were preincubated with the CD31 peptide. We further sorted responder cells into CD31-high and CD31-low populations and separately incubated these subsets with peptides. The CD31 peptide strongly inhibited MLRs, regardless of level of responder-cell CD31 expression. Examination of MLR reactions involving the CD31 peptide showed dispersed small aggregates of cells, rather than the single large aggregate observed in control MLRs. The CD31 peptide did not affect activation of lymphocytes by phorbol myristate acetate (PMA) and ionomycin. These results suggest that a surface CD31-ligand interaction may have a functional role in alloimmune lymphocyte activation and identify a functionally important domain of CD31.

The interleukin-3 receptor (IL-3R) is composed of alpha and beta subunits, members of the class I cytokine receptor family. Here we describe isolation and characterization of the chromosomal gene for the mouse IL-3R alpha subunit (mIL-3R alpha). Whereas the human IL-3R alpha gene is tightly linked with the granulocyte-macrophage colony- stimulating factor receptor alpha subunit (GM-CSFR alpha) gene in the pseudoautosomal region of the X and Y chromosomes, the mIL-3R alpha gene (II3ra) is located in the proximal region of mouse chromosome 14, separated from the mouse GM-CSFR alpha gene, which is on chromosome 19. The mIL-3R alpha gene spans about 10 kb and is divided into 12 exons. All the exon-intron boundaries possess the splicing junction consensus sequences (52GT-AG352), and the whole genomic structure is similar to those of the previously reported class I cytokine receptor genes. There are two major transcription initiation sites that are located at 215 and 188 nucleotides upstream of the initiator codon. The promoter region is GC-rich and contains potential binding sites for GATA, Ets, c- myb,, Sp1, Ap-2, and G-C boxes, but not a typical TATA or CAAT sequence. A fusion gene containing 0.8 kb of the 52 noncoding sequence linked to the firefly luciferase gene directed the transcription in mouse mast cells but not in fibroblasts or T cells, suggesting that this promoter functions in a cell type-specific manner. Further sequential deletion of the 52 region suggests two potential regulatory regions for transcription of the mIL-3R alpha gene.

Transfected Jurkat cells overexpressing extracellular signal-regulated kinase (ERK1), also referred to as mitogen-activated protein (MAP) kinase, were selected by Western blotting assay using anti-ERK1 and antiphosphotyrosine antibodies in combination with a functional MAP kinase assay. We then asked whether enhanced ERK1 expression had any effect on induction of T-cell cytokine genes. The results show that overexpression of ERK1 enhances expression of T-cell interleukin-2 (IL- 2), IL-3, and granulocyte-macrophage colony-stimulating factor mRNA; no change was seen in expression of the alpha-actin gene. DNA-binding activities of the transcription factors AP1, NF-AT, and NF-kB were specifically increased twofold to fourfold in ERK1-overexpressing clones relative to nontransformed or vector-transformed cells, whereas no enhancement of CK1-CK2 protein DNA binding activity was detected after ERK1 overexpression. Additionally, increased NF-AT DNA binding activity was associated with functional enhancement of NF-AT transactivating activity in ERK1-overexpressing cells. These results provide direct evidence for the role of MAP kinase in the regulation of cytokine gene expression and indicate that such regulation is likely mediated through the enhanced DNA binding activity of specific nuclear transcription factors.

We have investigated the molecular and biochemical basis for activation of interleukin 3 (IL3) gene expression in primary human T lymphocytes following CD3 and CD2 receptor stimulation or activation by phytohemagglutinin plus phorbol 12-myristate 13-acetate. Using transfection and reporter gene assays specifically designed for primary T lymphocytes in conjunction with gel retardation assays, Western blot analyses and UV cross-linking studies, we found that c-Jun, c-Fos, and octamer-binding proteins play a major role in transcriptional activation of the IL3 gene via their interaction with two specific regions contained within the IL3 5'-flanking sequence. Additionally, the region between bases -107 and -59 of the IL3 promoter containing putative AP-2 and Sp1 binding motifs appears necessary for basal level expression of the IL3 gene. The data also indicate that CD2 receptor activation and phytohemagglutinin plus phorbol 12-myristate 13-acetate stimulation augment T cell IL3 gene expression through the same cis- and trans-activating signals. These results should contribute to a better understanding of the regulation of IL3 gene expression in human T lymphocytes.

We report the independent cloning of the cDNA for CD31, a recently described cell adhesion molecule of the immunoglobulin gene superfamily present on platelets, granulocytes, monocytes, lymphocytes, and endothelial cells. Northern analysis revealed three major mRNA transcripts in Jurkat (a human T cell line) and K562 and HEL (leukemia cell lines) cells with an additional 5.3-kilobase transcript seen in cultured human umbilical vein endothelial cells. Following T cell activation, CD31 mRNA was down-regulated by Northern analysis, and decreased CD31 protein expression was confirmed by immunoblots. The down-regulation of CD31 was partially mediated by decreased transcription as demonstrated by nuclear run-on studies. CD31 became rapidly phosphorylated in platelets, Jurkat cells, and endothelial cells after cell activation. We were unable to demonstrate the presence of a phosphotyrosine in CD31 using monoclonal and polyclonal phosphotyrosine antibodies. In addition, CD31 phosphorylation in platelets was induced by phorbol ester and was blocked by staurosporin, a protein kinase C inhibitor, suggesting that CD31 phosphorylation is mediated by protein kinase C and involves serine and/or threonine residues. The phosphorylation of CD31 following cell activation may modulate its cellular adhesiveness, and the down-regulation of its expression may serve to impart target specificity and to localize effector lymphocytes to areas of inflammation.

Most biologic responses to IL-2 have been attributed to interaction of IL-2 with a high affinity receptor which consists of a heterodimer composed of two distinct IL-2-binding proteins (IL-2R alpha/IL-2R beta). However, both low affinity IL-2R alpha (55 kD) and intermediate affinity IL-2R beta (70-75 kD) also appear to be expressed independently on the cell surface. We investigated the receptor-specific regulatory effects of IL-2 on cytokine production in unstimulated and activated T cells. T cells were activated by stimulation of the antigen receptor complex with anti-CD3 mAb. IL-2 (10(2) U/ml, 1 nM) stimulation of resting cells resulted in a fivefold increase in GM-CSF release but in only minimal IFN-gamma release. IL-2 markedly augmented mRNA expression of GM-CSF but not IFN-gamma in unstimulated T cells. IL-2R beta mAb but not IL-2R alpha mAb decreased IL-2-induced GM-CSF release and mRNA expression from unstimulated T cells. IL-2 concentrations required for GM-CSF release from resting cells suggested ligand binding to an intermediate affinity receptor. GM-CSF and IFN-gamma release from activated T cells increased four- to fivefold in response to 1 nM IL-2 and IL-2 augmented both GM-CSF and IFN-gamma mRNA. IL-2R beta mAb but not IL-2R alpha mAb reduced GM-CSF release and mRNA expression in activated T cells stimulated with 1 nM IL-2. IL-2R alpha blockade markedly decreased IL-2-induced IFN-gamma release and mRNA expression from activated cells, while IL-2R beta blockade had little effect on IFN-gamma production in activated cells. IL-2R alpha blockade altered the affinity of the receptor mediating activated cell GM-CSF release from a high affinity to an intermediate affinity state. These studies indicate an independent role for IL-2R beta in mediating GM-CSF production from T cells. They also suggest that unstimulated and activated T cells, which express distinct IL-2 receptor moieties, mediate release of separate lymphokines and that different subunits of the IL-2 receptor may play an important role in the regulation of cytokine production.

BACKGROUND The hypervascular nature of hepatocellular carcinoma (HCC) is well characterized. Recent data have suggested that thalidomide possesses antiangiogenic and immunomodulatory activity. Therefore, the authors initiated a study to assess the efficacy and toxicity of thalidomide in patients with advanced HCC as primary and secondary endpoints, respectively. METHODS Inclusion criteria were unresectable HCC with bidimentionally measurable disease, age ≥ 18 years, Eastern Cooperative Oncology Group performance status ≤ 2, and adequate organ function. Thalidomide was administered at a starting dose of 200 mg per day in a 100-mg-per-week dose escalation regimen, up to the maximum tolerated dose or to 800 mg per day. Toxicity was monitored according to the National Cancer Institute Common Toxicity Criteria. RESULTS Twenty-six of 27 patients were eligible and assessable for toxicity and response. A median daily dose of 300 mg was achieved. One patient experienced near-complete recovery of α-fetoprotein levels and a partial radiographic response on computed tomography. Two patients had stable disease during the 16-week study period. The median duration of progression-free survival was 42 days. The overall median survival was 123 days. Fatigue and somnolence were the most common side effects, occurring in 81% and 62% of patients, respectively. No Grade 4 hematologic toxicity was observed. Three patients experienced Grade 4 hepatic toxicity (namely, hyperbilirubinemia). CONCLUSIONS With gradual dose escalation, thalidomide was tolerated in most patients with advanced HCC. However, treatment with thalidomide alone was associated with only a modest response in the treatment of HCC. Cancer 2005. © 2004 American Cancer Society.

Although most physicians and the public are primarily concerned about the risk of transmitting human immunodeficiency virus (HIV) or hepatitis virus during a platelet transfusion, bacterial contamination is actually the most common infectious complication. Unlike red blood cells, platelets are stored at room temperature (20–24°C), which raises the risk of bacterial proliferation. The risk of bacterial sepsis is 2.5-fold higher for each unit of transfused platelets compared to each unit of red blood cells. We report an unusual case of Streptococcus bovis septic shock associated with a contaminated platelet transfusion. Am. J. Hematol. 77:282–286, 2004. © 2004 Wiley-Liss, Inc.

To the Editor: The chronic myeloproliferative disorders are clonal marrow neoplasms that are often associated with arterial or venous thromboses and microcirculatory disturbances.1 Certain thrombot...

To the Editor: Extramedullary plasmacytomas are an unusual manifestation of multiple myeloma. Gastrointestinal plasmacytomas occur as discrete masses, usually involving either the stomach or colon, and can be mistaken for lymphoma.1–3 We report myeloma manifested as diffuse small-bowel myelomatosis. A 74-year-old man presented with a one-year history of diffuse abdominal pain, diarrhea, and weight loss (16 kg [35 lb]). He did not have bone pain. Physical examination revealed no abnormalities except for cachexia; mild, diffuse abdominal distention without tenderness or a palpable mass; and stools that were positive for occult blood on guaiac testing. His blood count was normal . . .

To the Editor: The use of recombinant human erythropoietin in patients with kidney disease is widespread and has been associated with few complications. Recent reports have suggested that the incid...

To the Editor: We report the development of hyperammonemic encephalopathy in a patient with multiple myeloma. A 43-year-old woman with stage IIIA light-chain multiple myeloma presented to the hospital with lethargy and a left molar mass. She had not received chemotherapy during the four months before admission. On physical examination, the patient was alert, oriented, and afebrile, with a left-sided upper molar mass measuring 5 by 6 cm. Electrolyte, blood urea nitrogen, creatinine, and calcium levels were unremarkable. Biopsy of the left molar mass revealed a plasmacytoma. The patient became increasingly confused during her hospital course. Computed tomography (CT) and . . .

Resting natural killer (NK) cells express the p75 chain of the IL-2 receptor (IL-2R beta) and most NK cells express the CD2 (erythrocyte rosette) receptor. The cell adhesion molecule, LFA-3, is a natural co-ligand for CD2. Tac antigen (IL-2R alpha), a p55 IL-2R subunit, can be expressed after NK activation and may play a role in IL-2-induced NK proliferation. Little is known of the molecular mechanisms underlying cytokine production in NK cells. We investigated the roles of IL-2R alpha, IL-2R beta, and CD2/LFA-3 in the molecular regulation of NK cell granulocyte/macrophage-colony-stimulating factor (GM-CSF) production. Enriched populations of peripheral blood NK cells were separated into CD16-positive and CD16-negative fractions by flow cytometry; positively selected cells were greater than 97% positive for CD16 (the FcIII receptor for IgG which is present on almost all NK cells), less than 1% positive for the T cell antigen CD3, and did not demonstrate rearrangement of the T cell receptor beta chain gene by Southern blot. NK cell supernatants were harvested after 3-4 d of incubation with 0-100 U/ml IL-2, or after incubation with anti-CD2 (T11(3] MAb and sheep red blood cells (SRBC are a homologue for LFA-3). Parallel cell aliquots were harvested at 3-16 h for transcriptional run-on assays, S1 nuclease assays, and actinomycin D mRNA t1/2 determinations. IL-2-activated NK supernatants contained large amounts of GM-CSF (178 +/- 35 pg/ml) by ELISA as did supernatants from CD2-activated NK cells (T11(3) MAb + SRBC: 212 +/- 42) vs. less than 20 pg/ml for NK cells incubated alone or with either SRBC or T11(3) MAb alone. Sepharose-linked anti-CD3 MAb did not induce GM-CSF release from NK cells. By S1 analysis, both IL-2 and CD2 stimulation markedly augmented GM-CSF mRNA expression but with very different latencies of onset. IL-2R beta MAb inhibited greater than 85% of GM-CSF release from IL-2-activated NK cells and markedly suppressed IL-2-induced GM-CSF mRNA expression, whereas IL-2R alpha MAb even at 2,000-fold molar excess of IL-2 had little effect (less than 10%) on either GM-CSF release or mRNA expression. Run-on assays showed that GM-CSF is constitutively transcribed in NK cells and that IL-2 and CD2-activated cells had a three- to fourfold increased rate of GM-CSF transcription compared to nonstimulated cells. The t1/2 of GM-CSF mRNA in IL-2-activated NK cells was identical to that of unstimulated NK cells (15 min), whereas GM-CSF mRNA t1/2 in CD2-activated NK cells was increased 2.5-fold. We conclude that GM-CSF production in NK cells is regulated by both the IL-2Rbeta and the CD2 receptor but not by IL-2Ralpha, that both transcriptional and posttranscriptional signals act together to modulate the level of GM-CSF mRNA in NK cells, and that the molecular mechanisms underlying NK cell GM-CSF production are dependent in part on differential surface receptor activation.

THE development of techniques for the in vitro clonogenic assay of hematopoietic progenitors1 has allowed investigation of clinical syndromes associated with immunologic injury to human stem cells.2 T-lymphocyte suppression of granulopoiesis has been described in patients with Felty's syndrome,3 and humoral inhibition of granulocyte-progenitor cells has been reported in patients with drug-associated agranulocytosis.4 Spontaneously arising (non-drug-associated) antibodies directed against human myeloid progenitors in patients with neutropenia have only recently been recognized.2 , 5 6 7 8 The antigenic and cellular specificity of these inhibitors, however, have not been well characterized, and the failure to demonstrate serum inhibitory activity against autologous granulocyte progenitors raises questions about . . .

Studies are reviewed, which establish a novel regulatory role for the T cell lymphokine IL2: Immunoregulation of hematopoiesis. IL2 induces a receptor-specific inhibition of early erythroid progenitors. IL2-induced inhibition of erythropoiesis is mediated by Interferon-gamma protein release preceded by Interferon-gamma mRNA accumulation. Triggering of the antigen receptor complex induces p55 IL2 receptor expression, which is a prerequisite for IL2-induced erythropoietic inhibition. P55 protein expression on the T cell surface is preceded by an increase of p55 mRNA levels. The studies demonstrate that the regulatory role of IL2 extends beyond governance of the immune system itself and can subserve to control red cell production in vitro.

The efficacy of four separate methods of human bone marrow T lymphocyte depletion was assessed, and the effect of T cells and monocytes on in vitro growth of marrow (CFU-GEMM, BFU-E, and CFU-GM) and peripheral blood (BFU-E) hematopoietic progenitors was determined. Extent of T cell depletion was assessed by multiparameter fluorescent cell sorter (FACS) analysis and by functional studies. Cells staining positively by FACS analysis for one or more of three separate fluorescent pan-T cell monoclonal antibodies (MCAbs) comprised 8.4% to 9.5% of control marrow mononuclear cells (MNCs). T cells constituted 3.2% to 5.1% of marrow following single, sequential, or combination treatment with two different pan-T cell MCAbs (Leu 1 and TM1) plus complement, 1.5% to 2.2% of marrow following solid-phase immunoabsorption (“panning”), 0.2% of marrow after sheep cell rosetting, and only 0.05% of marrow after FACS selective cell sorting and gated separation. T cells made up 59% to 73% of control peripheral blood MNCs and 0.8% to 2.8% of peripheral MNCs following sheep cell rosetting plus treatment with Leu 1 MCAb and complement. Mitogen (PHA, Con A) and allogeneic MLC-induced blastogenic responses (stimulation indices, experimental/control or E/C) revealed a concordant decrement in marrow T cell function after MCAb plus complement (E/C of 3.9 to 9.0), after panning (E/C of 1.6 to 3.5) and after sheep cell rosetting (E/C of 0.7 to 1.3), compared with control marrow (E/C of 5.3 to 15.7). After T cell depletion, marrow BFU-E growth was 95% to 120% of control, CFU-GM growth was 90% to 108% of control, and CFU-GEMM growth was 89% to 111% of control. Marrow T cell and/or monocyte depletion did not alter erythropoietin-dependent BFU-E growth in the absence of Mo-conditioned medium (81% to 95% of control), and the addition of as many as 50 to 100 X 10(3) purified marrow monocytes or T cells to 10(5) autologous nonadherent T cell-depleted marrow target cells had a negligible (P greater than .1) effect on marrow BFU-E growth in vitro. Peripheral blood (PB) BFU-E/10(5) T- depleted target cells were 106% +/- 19% of expected; PB BFU-E growth was significantly diminished after monocyte depletion alone (7% +/- 6% of expected) or after monocyte plus T cell depletion (8% +/- 4% of expected).(ABSTRACT TRUNCATED AT 400 WORDS)

Paroxysmal cold hemoglobinuria is a rare and potentially life-threatening acquired hemolytic anemia occurring either as an acute transient anemia following several different viral syndromes, or in a chronic idiopathic form. Episodic hemolysis in paroxysmal cold hemoglobinuria is usually associated with a biphasic (Donath-Landsteiner) IgG cold-reactive complement-fixing autohemolysin with anti-P specificity. Paroxysmal cold hemoglobinuria has not previously been associated with malignancy nor has it been clearly shown to be steroid-responsive. This report describes a patient with steroid-responsive autoimmune hemolytic anemia and immune thrombocytopenia (Evans' syndrome) associated with oat cell carcinoma of the lung and a unique biphasic anti-IgM autohemolysin. This case extends the spectrum of biphasic antibody-mediated immune cytopenias and widens both the clinical and the serologic definition of paroxysmal cold hemoglobinuria.

Mitogen-stimulated murine spleen cells produce humoral substances capable of supporting murine hematopoiesis and pluripotent stem cell proliferation in vitro. Thus, we evaluated conditioned media generated by human spleen cells (SCM) in the presence or absence of mitogens for factors stimulatory for human pluripotent (CFU-GEMM), erythroid (BFU- E), and myeloid (CFU-GM) precursors. Two and one half percent to 10% SCM stimulated proliferation of all three types of precursor cells from nonadherent buoyant human marrow target cells. Mitogen-stimulated SCM augmented CFU-GM (175% to 225%), whereas CFU-GEMM and BFU-E growth was essentially unchanged. Cell separation procedures used to determine which cells provided these microenvironmental stimuli indicated that nonadherent mononuclear spleen cells provided the bulk of the CSF-GM, whereas adherent cells (95% nonspecific esterase + monocyte- macrophages) and nonadherent cells provided similar proportions of CSF- mix and erythroid burst-promoting activity (BPA). The nonadherent cells generating high levels of CSF-mix, BPA, and CSF-GM were predominantly Leu-1-negative, ie, non-T, cells. In the presence or absence of mitogens, SCM was a more potent source (1.3- to 3.8-fold) than peripheral leukocyte CM of the growth factors for the three progenitor cell types. Specific in situ cytochemical stains for analyzing morphology of myeloid colonies demonstrated that SCM stimulated the proliferation of the same types and proportions of colonies as human placental CM, suggesting that these CMs may contain similar CSF-GMs. These data show the contribution of spleen cell subsets to the generation of hematopoietic growth factors and the responsiveness of these cells to various mitogenic stimuli.

Tissue and marrow (BM) in vivo O2 tensions have been estimated at 23 to 40 mm Hg (3% to 5% O2). We have investigated cellular regulation of burst-forming units-erythroid (BFU-E) under 5% O2. BFU-E from BM mononuclear cells (MNC) were cultured in methylcellulose medium and erythropoietin (Ep) +/- monocyte-conditioned medium (MoCM, a source of burst-promoting activity, BPA) in the presence or absence of autologous T cells (T) and/or monocytes (M phi) under either 5% or 21% O2 after depletion of T (MNC-T), M phi (nonadherent buoyant cells, NAB) or both T and M phi depletion (NAB-T). MNC BFU-E growth under 5% O2 was augmented over 0.1 to 1.5 U/mL of Ep. BFU-E augmentation under 5% O2 was abolished by depletion of BM M phi, T, or both from MNC. The addition of MoCM affected neither a BFU-E increase under 5% O2 nor the abrogation of that increase upon T or M phi depletion. The addition of 5% to 20% M phi or 10% to 20% T to NAB-T failed to restore the BFU-E increase under 5% O2. However, BFU-E augmentation under 5% O2 was reestablished when 10% autologous M phi, 10% T, or 10% T plus 10% M phi were added back to marrow NAB, MNC-T, or NAB-T. BM BFU-E was not augmented in the presence of varying concentrations of catalase, superoxide dismutase, or reduced glutathione at 21% O2; moreover, BFU-E augmentation was maintained at 5% O2 relative to 21% O2 in the presence of each of these antioxidants. CM prepared under 5% or 21% O2 from BM M phi, T, or M phi plus T were assessed for BPA against BM NAB-T using a sensitive BPA assay incorporating delayed Ep addition to cultures. Only CM from mixtures of M phi and T cells at 5% O2 demonstrated potent BPA; little or no BPA was detected with T or M phi CM at 5% O2 and at 21% O2 or T and M phi CM at 21% O2. The sensitivity of NAB-T BFU-E to exogenous BPA was virtually identical at 21% and 5% O2. These results indicate that human BM BFU-E are augmented under 5% O2 and that T cells and M phi together mediate that augmentation by collaborating to produce BPA-like activity in response to physiological O2 tensions.

We designed a treatment program to improve the outcome for adults with acute lymphoblastic leukemia (ALL). Treatment included a remission- induction phase followed by intensive alternating cycles of non-cross- resistant chemotherapy and prolonged oral maintenance therapy. Eighty- one consecutive previously untreated patients were entered on this study. Ninety-four percent of patients entered complete remission. A Kaplan-Meier analysis predicts that 53% +/- 9% (SEM) of patients in remission will remain free of disease at 3 years. Neither age, sex, WBC count, nor immunophenotype had a significant effect on remission duration. This program of intensive cyclical chemotherapy has improved the disease-free survival of patients with adult ALL.

We investigated the mechanism for isolated agranulocytosis and marrow pure white cell aplasia in an elderly man receiving 0.5 to 1.0 g per day of chlorpropamide (Chl) without other toxic drug exposure or overt systemic illness. Patient marrow revealed an absence of recognizable granulocytic precursors; megakaryocytes and erythroid precursors were normal. The WBC count was 1800/mm3 on admission with only 2% neutrophils; the absolute neutrophil count first exceeded 500/mm3 on the 17th day following cessation of Chl. A serum Chl level on admission was 100 micrograms/mL (acute phase, AP); no Chl was detected in serum (convalescent phase, CP) assessed on the 22nd hospital day. Antineutrophil antibodies were not detected, and T cell depletion failed to augment patient in vitro granulopoiesis. Patient AP serum produced potent complement-mediated inhibition (87% +/- 7%) of autologous granulocyte progenitors (CFU-GM) with minimal inhibition of erythroid (11% +/- 5%) or multipotent (5% +/- 4%) progenitor cells. Selective inhibition by patient AP serum of CFU-GM (74% +/- 11%) was also seen against two allogeneic marrows. Patient CP serum no longer inhibited (6% +/- 4%) autologous CFU-GM. Addition of Chl (5 to 120 micrograms/mL) to CP serum but not to control serum resulted in potent drug concentration-dependent complement-mediated inhibition of autologous and allogeneic CFU-GM. Inhibition of CFU-GM in the presence of Chl was no longer demonstrable following immunoabsorbent removal of IgG from patient serum. Patient serum in the presence of Chl had limited activity against morphologically recognizable marrow granulocytic precursors in a microimmunofluorescence assay. These results are most consistent with the development of Chl-dependent, selective antibody-mediated immune inhibition of granulopoiesis.

Histidine-rich glycoprotein (HRGP), a human plasma and platelet protein, interacts with multiple ligands in vitro, including heparin, plasminogen, thrombospondin, and fibrinogen/fibrin. In this study, the binding of HRGP to human T lymphocytes was characterized. The binding was specific, concentration-dependent, saturable, and reversible. Scatchard plot analysis revealed two classes of binding sites: the high affinity class had an apparent dissociation constant (Kd) of 1.92 X 10(-8) M, with 0.92 X 10(4) sites/cell, and the low affinity class had a Kd of 4.97 X 10(-7) M, with 3.7 X 10(4) sites/cell. HRGP binding to T cells in the presence of HRGP-depleted serum was comparable to that observed in buffer. Dot-blot analysis showed that HRGP bound to specific T cell proteins. Using both HRGP affinity chromatography and immunoprecipitation with affinity-purified anti-HRGP IgG, a major 56-kDa HRGP-binding protein in surface labeled T cell lysates was demonstrated. The 56-kDa protein was shown not to be related to the CD2 molecule on T cells. The binding characteristics of HRGP to T lymphocytes indicate a specific ligand-receptor interaction. This is the first demonstration of HRGP binding to a cell surface, and its binding to human T cells may play an important role in T lymphocyte biology.

T cells can be selectively removed from human peripheral blood and bone marrow by passage over a column containing monoclonal anti-T-cell antibodies covalently attached to Sepharose 6MB gel. Effective depletion of T cells from peripheral blood mononuclear cells (PBMC) resulted in the appearance of Leu-2-positive cells, most of which do not express Leu-1 or Leu-4 antigens. Using a column containing anti-Leu-1 or anti-Leu-4 attached to Sepharose 6MB gel, depletion of 98.3% and 99% of T cells from bone marrow mononuclear cells (BMMC), respectively, was demonstrated with recovery of approximately 75% of non-T cells. These columns removed 92.3-98.4% T cells from PBMC with 43.5-74.8% recovery of non-T cells. Combining anti-Leu-1 and anti-Leu-4 antibodies on the same gel removed all detectable T cells from PBMC and BMMC. Proliferative responses to the T cell mitogen, phytohemagglutinin, were abolished from both PBMC and BMMC after column treatment. Preservation of hematopoietic progenitors was observed after treatment of bone marrow, with stem cell recovery averaging 83 +/- 26% for burst-forming units (erythroid), 86 +/- 14% for granulocyte-macrophage progenitors and 94 +/- 16% for granulocyte, erythroid macrophage, and megakaryocitic elements. These results suggest that clinical application of cellular immunoabsorption techniques using monoclonal antibodies will be useful in bone marrow transplantation.

We examined the role of the T-cell antigen CD2 in the regulation of erythropoiesis by the lymphokine cascade. T-cell interleukin-2 (IL-2) receptors (p55) were induced via triggering of the antigen receptor- associated CD3 epitope. Before CD3 triggering T cells were preincubated with a CD2-blocking (Leu-5b) or isotype control antibody. T-cell pellets were employed during incubation to facilitate interaction between T-cell LFA-3 and CD2. CD2 blockade caused a 66% to 79% inhibition of p55 expression after three to six days of culture with IL- 2. Next we assessed the effect of CD2 blockade on IL-2. Next we assessed the effect of CD2 blockade on IL-2-induced inhibition of BFU-E in autologous cocultures containing CD3-triggered T cells. IL-2 caused a dose-dependent inhibition (52% to 92%) of BFU-E in the presence but not in the absence of CD3-triggered T cells. T-cell CD2 blockade prior to CD3 triggering caused a 65% to 87% abrogation of IL-2-induced inhibition of BFU-E at 10 to 10(2) U/mL IL-2. Preincubation of CD3- triggered T cells with isotype control antibody had no effect on IL-2- induced erythroid inhibition. Day 3 supernatants from CD3-triggered T cells or CD2-blocked, CD3-triggered T cells established in the presence of IL-2 were next assessed for modulation of BFU-E. CD3-triggered T- cell supernatants caused a 77% +/- 9% inhibition of BFU-E. Blockade of CD2 caused a 95% abrogation of T-cell-mediated BFU-E inhibition. In addition, CD2 blockade reduced interferon-gamma (IF gamma) release (84 to 128 U/mL) from CD3-triggered T cells by 81% at day 3 of culture. In control experiments, the addition of IF gamma-neutralizing monoclonal antibody to CD3-triggered T-cell supernatant established in the presence of IL-2 caused 75% abrogation of IL-2 inhibition of BFU-E. We conclude that blockade of the CD2 T-cell determinant induces down modulation of (a) T-cell p55 IL-2 receptor expression, (b) IL-2-induced inhibition of BFU-E, and (c) IL-2-induced marrow T-cell IF gamma release. These data suggest that the T-cell CD2 determinant can exert a regulatory effect on the control of erythropoiesis by the lymphokine cascade.

The equation of the cooperative specific isotherm is derived for the general case ofr species interacting cooperatively at nearest neighboring sites. Explicit expressions for the special casesr=2–5 are given.

Interleukin-2 (IL-2) induces differential secretion of lymphokines by IL-2 receptor (IL-2R)-positive and IL-2R-negative T cells. We studied T cell IL-2R-specific modulation of adult bone marrow erythropoiesis by recombinant IL-2 (rIL-2). I3–2R were induced by CD3 T cell surface determinant-triggering and analyzed by cytofluorography. Bone marrow monocyte and T cell-depleted (NAB-T) target cells were assessed for early erythroid progenitor expression (BFU-E) in the presence of 0 to 10(3) U/mL of rIL-2, rIL-2 had no significant effect on BFU-E expression in the absence of T cells or in the presence of IL-2R- negative T cells. rIL-2 caused a dose-dependent inhibition (75% to 90%) of BFU-E in the presence of autologous IL-2R-positive T cells. The addition of anti-IL2-receptor antibody to cultures containing rIL-2 plus IL-2R-positive T cells entirely abrogated rIL-2-mediated inhibition of BFU-E. In the presence of rIL-2 (10(2) U/mL) production of interferon gamma (IF-gamma) by adult marrow CD3-triggered IL-2R- positive T cells was increased 37- to 125-fold compared to IL-2R- negative T cells. rIF-gamma caused a dose-dependent (88% +/- 17% at 10(3) U/mL) inhibition of adult BFU-E in the presence of CD3-triggered autologous T cells. rIL2-mediated inhibition of adult BFU-E in the presence of IL-2R-positive T cells was partially abrogated (52% +/- 16%) following addition of monospecific IF-gamma antibody. These results demonstrate (a) rIL-2 modulation of adult marrow erythropoiesis is selectively dependent upon both the presence or absence of autologous T cells and the IL-2R status of these T cells; and (b) rIL-2- induced inhibition of adult marrow erythropoiesis is mediated in part by release of IF-gamma from IL-2R-positive T cells.

Current thinking among some social scientists has suggested that public relations practitioners possess an influence, a power, that is comparable to that wielded by the nation's military decision-makers and the chief executives of major corporations. The reason? That the power to influence and persuade can bring about “social conditioning” that in and of itself has the potential to change society dramatically. The author of this article analyzes some of the writings of political and social scientists who have discussed the influence of the mass media, and suggests to today's public relations professionals that they should be prepared to discuss their role in society from the point of view of those who attribute to them great—and sometimes undeserved—influence. Lee Levitt, APR, is executive vice president of PR Aids, headquartered in New York City. He holds a bachelor of arts degree from the University of Tennessee, where he majored in political science.

Lithium carbonate has been shown to increase granulocyte production. We studied the effect of lithium on murine hematopoiesis in a liquid culture system providing for the prolonged growth of stem cells and their progeny. After one week of incubation, lithium, at a supernatant concentration of 1 mmol per liter, increased murine pluripotent stem cells (CFU-S, or colony-forming units in spleen) to 232 per cent of control values (P less than 0.001), granulocyte-monocyte progenitor cells (CFU-C, or colony-forming units in culture) to 218 per cent of control values (P less than 0.0001), granulocytes to 125 per cent of control values (P less than 0.01), and megakaryocytes to 246 per cent of control values (P less than 0.001). These increases were associated with transient elevations in colony-stimulatory activity. Prolonged exposure to lithium (three to 12 weeks) was associated with a dose-dependent progressive depletion of stem cells and their progeny. Lithium enhancement of granulopoiesis may be explained by primary stimulation of the pluripotent stem cell. Prolonged proliferative stress induced by lithium when the stem-cell reserve is limited may be associated with diminished replicative potential of the stem cells and rapid depletion of cells.

Histidine-rich glycoprotein (HRGP) is a plasma and platelet protein with undefined function in vivo. It has been reported to inhibit rosette formation between murine T cells and erythrocytes. We have shown that HRGP binds specifically to human T lymphocytes but not sheep erythrocytes and have demonstrated a 56-kDa HRGP-binding protein on the T cell surface which is distinct from the CD2 sheep erythrocyte receptor. We have now investigated whether HRGP can inhibit human T cell-sheep erythrocyte rosette formation and whether HRGP can modulate T cell activation. HRGP at physiologic concentrations specifically inhibited rosette formation between human T lymphocytes and sheep erythrocytes. HRGP suppressed proliferation of antigen receptor (CD3)-triggered T cells induced by interleukin 2; this suppression was specifically reversed by prior incubation of HRGP with affinity-purified anti-HRGP IgG. Addition of HRGP 12-24 h after CD3 triggering no longer suppressed T cell proliferation, suggesting HRGP suppressed T cell division by interfering with one or more early events in the process of T cell activation. Human serum (containing 100-150 micrograms/ml HRGP) was also capable of suppressing T cell proliferation; serum which had been immunodepleted of HRGP no longer inhibited T cell proliferation. Furthermore, HRGP inhibited interleukin 2 receptor expression on activated T cells, causing decreased T cell interferon-gamma release and altered T cell-dependent inhibition of erythropoiesis. HRGP is thus capable of modulating T cell activation and T cell immunoregulation; HRGP may function as a natural suppressive regulator of human T lymphocyte activation.

Human retroviruses have recently been linked with T cell lymphoproliferative disorders and with the acquired immune deficiency syndrome. We investigated the mechanisms for acquired pure red cell aplasia and cutaneous anergy in a patient with the chronic T gamma-lymphoproliferative disease (T gamma-LPD) syndrome. Patient marrow erythroid progenitors (BFU-E) were 17 +/- 9% of control and were selectively increased to 88-102% of control after marrow T cell depletion. Patient Leu 2+ suppressor T cells spontaneously produced high titers of human gamma-interferon and resulted in a concentration-dependent selective inhibition (74-91%) of BFU-E when co-cultured with autologous or allogeneic marrow. Conditioned media (CM) derived from patient Leu 2+ T cells similarly inhibited growth of autologous or allogeneic marrow BFU-E. The inhibitory factor derived from patient CM was acid-labile (pH 2) and sensitive to trypsin; prior treatment of patient T cells with anti-HLA-DR monoclonal antibody plus complement abrogated the suppressive effect of T cell-derived CM. Patient peripheral blood mononuclear cells (PBMC) were unable to support growth of cultured interleukin 2 (IL 2)-dependent T cells, but responded to exogenous IL 2 in vitro with a 16-21-fold augmentation, relative to control, in mitogen-induced proliferation. Antibodies to HTLV-I core proteins p19 and p24 but not to HTLV-III proteins were detected in patient serum by Western blotting; patient cultured PBMC stained (7-11%) with antibodies to p19 and p24. Patient cultured PBMC demonstrated integrated HTLV-I genomic sequences by the Southern technique and expressed both specific HTLV-I genomic sequences by RNA dot blot plus reverse transcriptase activity. Utilizing a cloned DNA probe for the beta chain of the T cell receptor gene, patient PMBC demonstrated gene rearrangements providing presumptive evidence for clonality. The presence in serum of HTLV-I p19 and p24 antibodies, the expression of p19 and p24 core antigens on patient mononuclear cells, the evidence of HTLV-I proviral integration sequences and the expression of HTLV-I genomic sequences in patient cells, indicates infection with HTLV-I and raises the possibility of an etiologic link between human retrovirus infection and some instances of large granular lymphocytic leukemia (T gamma-LPD).