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P Valent

Publications and source records attributed to P Valent.

At least 163 records · Page 9Linked to original sources
PubMed1995

Differential response of human basophils and mast cells to recombinant chemokines.

Chemokines are proinflammatory peptides regulating the functions of various hematopoietic cells. We have analyzed the effects of seven recombinant human (rh) chemokines (MCAF, RANTES, MIP-1 alpha, MIP-1 beta, IL-8, GRO, and IP-10) on the growth and function of human basophils and mast cells. We found that MCAF, but not RANTES, MIP-1 alpha, MIP-1 beta, IL-8, GRO, or IP-10, causes direct and dose-dependent histamine release from basophils (MCAF, 5 micrograms/ml: 26.9 +/- 3.4%; other chemokines: < 5% of total histamine). An increased (2.1 to 3.5-fold) response to MCAF was obtained when basophils were preincubated with rh interleukin-3 (100 units/ml). Moreover, IL-3-primed basophils became responsive to physiologic concentrations (< 1 microgram/ml) of MCAF, IL-8, and RANTES. None of the chemokines tested was able to induce histamine secretion in mast cells obtained from lung (n = 2), skin (n = 1), uterus (n = 3), or tonsils (n = 3), even when cells had been preincubated with the mast cell agonist SCF. The chemokines also failed to modulate the expression of activation antigens (CD11b/C3biR, CD25/IL-2R beta, CD63, IL-3R alpha, CD117/c-kit) on the mast cell line HMC-1 or the basophil cell line KU-812 and were unable to induce differentiation of basophils or mast cells in culture. Together, our results show that basophils respond to rhIL-8, rhMCAF, and rhRANTES and that, unlike human basophils, human mast cells are unresponsive to recombinant chemokines.

Antigens, CD↗
PubMed1995

1995 Mack-Forster Award Lecture. Review. Mast cell differentiation antigens: expression in normal and malignant cells and use for diagnostic purposes.

Antibodies against haemopoietic differentiation antigens are widely used for the identification and classification of leukaemic cells. Mast cells are distinct haemopoietic cells and express a unique composition of antigens. They can be differentiated from basophils and all other lymphohaemopoietic cells by using antibodies to cell surface receptors and granular mediator molecules. This paper provides evidence that antibodies against mast cell antigens can be used to identify and classify malignant cell populations in patients with mastocytosis.

Antigens, CD↗
PubMed1995

Cytokines involved in growth and differentiation of human basophils and mast cells.

Mast cells and basophils are multifunctional effector cells of the immune system. Both are myeloid cells and originate from multipotent hemopoietic progenitor cells. Usually, human basophils complete their differentiation in the bone marrow. In contrast, mast cells usually undergo differentiation in extramedullary organs. During the past few years, growth factors for human basophils and a growth factor for human mast cells have been identified. Interleukin-3 is the most potent differentiation factor for human basophils and activates mature basophils via high affinity binding sites. Other basophil agonists are GM-CSF, IL-5, NGF and certain chemokines (IL-8, MCP-1). Mast cells apparently loose cytokine binding sites during mastopoiesis and as mature cells, do not express detectable amounts of IL-3R, GM-CSFR or IL-8R. However, in contrast to other myeloid cells, mast cells express SCF receptor/c-kit during mastopoiesis and on mature cells. Furthermore, the ligand of c-kit, SCF, induces differentiation of human mast cells from their progenitor cells and upregulates effector functions in mature mast cells.

Animals↗
PubMed1995

Characterization of LDL and VLDL binding sites on human basophils and mast cells.

Recent data suggest that basophils and mast cells play a potential role in the processing and accumulation of plasma lipoproteins. This study investigated the interactions of 111In-low-density lipoprotein (LDL), 111In-acetyl-LDL, and 111In-very-low-density lipoprotein (VLDL) with purified primary human blood basophils, immortalized human basophils (KU812 cell line), and a human mast cell line, HMC-1. Binding sites for 111In-LDL resolved into curvilinear Scatchard plots indicating two classes of specific binding sites on primary basophils (Bmax1, 7404 sites/cell; Kd1, 1.9 nmol/L; Bmax2, 39,611 sites/cell; Kd2, 29 nmol/L), on KU812 cells (Bmax1, 8290 +/- 2690 sites/cell; Kd1, 2.4 +/- 0.6 nmol/L; Bmax2, 46,470 sites/cell; Kd2, 33.4 +/- 7.8 nmol/L), and on HMC-1 cells (Bmax1, 7840 +/- 360 sites/cell; Kd1, 1.8 +/- 0.8 nmol/L; Bmax2, 61,450 +/- 9900 sites/cell; Kd2, 28.4 +/- 9.4 nmol/L). On KU812 cells, binding of 111In-LDL was displaced by apolipoprotein (apo)-E-rich high-density lipoprotein (HDL) (IC50, 14 +/- 6 nmol/L), LDL (IC50, 29 +/- 11 nmol/L), VLDL (IC50, 55 +/- 21 nmol/L), HDL2 (IC50, 420 +/- 140 nmol/L), and heparin (IC50, 67 +/- 28 nmol/L), whereas no competition was produced by HDL, HDL3, or acetyl-LDL (IC50, > 1 mumol/L). Western blot analysis using the monoclonal antibody C7 confirmed the presence of the LDL receptor on human basophils and HMC-1 cells. 111In-acetyl-LDL binding sites (scavenger receptor) could be detected neither on human basophils nor on HMC-1 cells. 111In-VLDL bound to a single class of high-affinity binding sites on primary basophils (Bmax, 4320 sites/cell; Kd, 10 nmol/L), KU812 cells (Bmax, 4020 +/- 840 sites/cell; Kd, 8 +/- 3 nmol/L), and HMC-1 cells (Bmax, 6143 +/- 1866 sites/cell; Kd, 4 +/- 2 nmol/L). 111In-VLDL binding was displaced by VLDL > LDL > apoE-rich HDL but not by heparin (IC50 > 1 mmol/L). In the presence of prostaglandin E1, the number of 111In-LDL receptors increased by 150% (P < .05) in the high-affinity range and by 170% (P < .01) in the low-affinity range, whereas the number of 111In-VLDL binding sites remained unchanged. VLDL, LDL, HDL, and the subclasses HDL2 and HDL3 inhibited immunological histamine release by primary normal basophils (n = 3) and mast cells (n = 3). Our results provide evidence for the existence of LDL and VLDL binding sites on human basophils and HMC-1 mast cells. The exact biological and pathophysiological roles of these sites remain to be elucidated.

Basophils↗
PubMed1995

Response of L-929 fibroblasts, human gingival fibroblasts, and human tissue mast cells to various metal cations.

Recent data suggest that under certain conditions, various metal cations are released from dental alloys. These ions may produce adverse effects in various cell types in vivo. In this study, the cytopathogenic effects of 13 metal cations on murine L-929 fibroblasts, human gingival fibroblasts, and human tissue mast cells were analyzed in vitro. Several metal cations (dose range, from 0.0033 to 1.0 mmol/L) were found to induce dose-dependent inhibition of 3H-thymidine incorporation into cultured fibroblasts. The rank order of potency (lowest observed effect level, LOEL) for L-929 fibroblasts was: Ag+ > Pt4+ > Co2+ > In3+ > Ga3+ > Au3+ > Cu2+ > Ni2+ > Zn2+ > Pd2+ > Mo5+ > Sn2+ > Cr2+. A similar rank order of potency was obtained for primary human gingival fibroblasts: Pt4+ > Ag+ > Au3+ > In3+ > Ga3+ > Ni2+ > Co2+ > Zn2+ > Cu2+ > Cr2+ > Pd2+ > Mo5+ > Sn2+. In primary human mast cells, Ag+ and Au3+ caused dose-dependent toxic histamine release, whereas the other metal cations were ineffective over the dose range tested. To investigate the mechanism of metal cation-induced effects, we performed DNA as well as electron microscopic analyses on cultured fibroblasts. Both the DNA pattern and the ultrastructure of L-929 cells and gingival fibroblasts after exposure to cytopathogenic metal cations revealed signs of necrosis but no signs of apoptosis. Together, our data provide evidence that various metal cations produce dose-dependent cytopathogenic effects in distinct cell types, including human gingival fibroblasts and human tissue mast cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Vasoactive intestinal peptide receptor scintigraphy.

UNLABELLED: This study presents the biodistribution, safety and absorbed dose of 123I-VIP administered to 18 patients with intestinal adenocarcinomas or endocrine tumors. METHODS: To achieve high-specific activity, 123I-VIP was purified by HPLC. Following intravenous administration of 123I-VIP (172 +/- 17 MBq (4.65 +/- 0.5 mCi); < 300 pmole ( < 1 microgram)/patient), sequential images were recorded during the initial 30 min. Thereafter, whole-body images were acquired in anterior and posterior views at various time points. Dosimetry calculations were performed on the basis of gamma camera data, urine, feces and blood activities. RESULTS: After injection of labeled peptide, the lung was the primary site of 123I-VIP uptake. Peak lung activity represented 40% +/- 7% of the injected dose at 0.7 hr and declined to 21% +/- 7% at 3.5, to 14% +/- 3% at 7 and to 8% +/- 4% 22 hr postinjection. Radioactivity was excreted into the urine and amounted to 37% +/- 16% of the injected dose within 4, 68% +/- 12% within 8, 82% +/- 16% within 16 and 93% +/- 8% within 24 hr postinjection. The mean effective half-life of 123I-VIP in the lungs was 2.2 and 6 hr in the urinary bladder. The highest radiation absorbed doses were calculated for the lungs [67 muGy/MBq (248 mrad/mCi)], urinary bladder [77 muGy/MBq (284 mrad/mCi)] and thyroid gland [104 muGy/MBq (386 mrad/mCi)]. The effective dose was 28 muSv/MBq (104 mrem/mCi). CONCLUSION: HPLC-purified 123I-VIP shows favorable dosimetry and is a safe and promising peptide tracer for localization of tumors expressing receptors for VIP.

Adenocarcinoma↗
PubMed1994

Kit ligand/mast cell growth factor-independent differentiation of mast cells in myelodysplasia and chronic myeloid leukemic blast crisis.

Autonomous, factor-independent growth and differentiation of malignant cells in preleukemic and leukemic disease states is a well-recognized phenomenon and is often associated with a poor prognosis. Mast cells are distinct hematopoietic cells and express a unique profile of antigens. Growth and differentiation of normal mast cells is dependent on mast cell growth factor (MGF), the ligand of the c-kit protooncogene product. In this study, we screened for mast cell-lineage involvement in 52 patients suffering from myeloid leukemias, myelodysplastic syndromes (MDS), systemic mastocytosis, or other diseases by probing for mast cell-related molecules (c-kit, tryptase, histamine, and MGF) and by analyzing kit ligand/MGF-independent growth of mast cells in long-term suspension culture. Of the 52 patients tested, 2 patients with refractory anemia with excess of blast cells in transformation and 1 patient suffering from chronic myeloid leukemia blast crisis (CML-BC) were diagnosed as mastocytic disease. These patients were characterized by complex chromosomal abnormalities, splenomegaly, high percentages of circulating metachromatic cells (5% to 25%), high levels of cellular tryptase (> 10 ng/10(5) peripheral blood mononuclear cells/mL) and a tryptase/histamine (ng:ng) ratio greater than 1. The metachromatic cells expressed the mast-cell-related surface antigen c-kit, but not basophil-related antigens (CD11b, CDw17). Furthermore, in these 3 patients, spontaneous, MGF-independent growth of mast cells along with spontaneous synthesis of tryptase was demonstrable in long-term culture. No autocrine production, paracrine production, or overproduction of MGF was found. The spontaneous growth of mast cells could neither be abbrogated by addition of monoclonal antibodies (MoAbs) to c-kit nor by MoAbs against MGF (< 5% inhibition), whereas factor (MGF)-dependent differentiation of mast cells in these patients could be abbrogated by MoAbs to c-kit or MoAbs to MGF (> 70% inhibition, P < .001). In addition, serum MGF levels in these patients were within the normal range and MGF could not be detected in cell-free culture supernatants. All 3 patients showed rapid progression of disease and had a survival time of less than 1 year. In conclusion, we describe a unique form of transformation in MDS and CML-BC characterized by mast cell lineage involvement and factor-independent differentiation of mast cells. This form of leukemic transformation has to be delineated from chronic myeloid leukemia with basophilia or basophil crisis, from primary mast cell leukemia, and from monocytic leukemias and myelodysplastic disorders associated with basophilia.

Acute Disease↗
PubMed1994

The human cardiac mast cell: localization, isolation, phenotype, and functional characterization.

We have isolated and characterized the human cardiac mast cell (CMC) and compared this novel mast cell (MC type with MC obtained from uterus, skin, and lung. Heart tissue was obtained from 14 patients with cardiomyopathy (CMP, heart transplantation). CMC were isolated by enzymatic digestion using collagenase, pronase-E, hyaluronidase, and DNAse. Substantial amounts of CMC (0.5% to 1.5% of isolated cells) were found in the atrial appendages but not in ventricular digests or other sites of the heart (< 0.1%). In situ staining of atrial tissue revealed the presence of CMC in the myocardium (2.16 +/- 0.7 MC/mm2), endocardium (2.24 +/- 0.9 MC/mm2), and epicardium. As assessed by combined toluidine blue/immunofluorescence staining with monoclonal antibodies (MoAbs), isolated CMC expressed surface IgE, the receptor for stem cell factor (c-kit receptor/CD117), the p24 antigen (CD9), the Pgp-1 homing receptor (CD44), the pan leukocyte antigen (CD45), and the ICAM-1 antigen (CD54). CMC were not recognized by MoAbs to lymphocyte function associated antigen 2 (LFA-2; CD2), T-cell receptor (TcR; CD3), T4 antigen (CD4), LFA-1 alpha-chain (CD11a), C3biR alpha-chain (CD11b), CR4 alpha-chain (CD11c), LPS-R related Ag (CD14), 3-FAL/x-hapten (CD15), Fc gamma RIII (CD16), lactosylceramid (CDw17), the B-cell antigen CD19, or CR1 (CD35). In situ expression of leukocyte antigens on CMC was demonstrable by indirect immunoperoxidase staining technique and double-labeling immunohistochemistry. Almost all CMC (90%) reacted with MoAbs against tryptase and chymase and thus were MCTC. Cardiac mast cells were also stained by the heparin-binding dye Berberine sulfate and expressed measurable amounts of histamine (4.6 +/- 1.4 pg per cell). Cross linking of either IgE receptor or SCF receptor (c-kit) on CMC resulted in histamine secretion (non-specific release: < 6% of total histamine, alpha IgE induced: 12% to 52%; SCF-induced release: 9% to 18%), whereas neither substance P (a skin MC agonist) nor the basophil agonist FMLP showed an effect on CMC. Together, the CMC is an MCTC primarily located in the appendage of the atrium. This novel type of MC exhibits surface membrane antigen and functional properties similar to those of lung and uterus MC.

Antibodies, Monoclonal↗
PubMed1994

Isolation of an immunodominant IgE hapten from an epitope expression cDNA library. Dissection of the allergic effector reaction.

An epitope expression cDNA library was constructed from the randomly fragmented cDNA coding for Phl p I, the major grass pollen allergen. Using IgE from allergic patients, epitope clones were isolated and immunodominant fragments were selected. Among three epitope clones coding for a similar region of Phl p I, one clone expressed a 15-amino-acid epitope which was target for IgE antibodies from approximately 30% of grass pollen allergic patients. According to the prevalence of grass pollen allergy, 22% of all allergic patients are expected to display IgE reactivity with this epitope. Although the purified recombinant epitope specifically bound IgE, it did not release histamine from basophiles of most grass pollen allergic patients and thus represents an IgE hapten. Immunodominant IgE haptens may be useful as therapeutic agents to saturate mast cell-bound IgE prior to allergen exposure and may represent candidates for a safe immunotherapy of allergic diseases by reducing anaphylactic side effects.

Allergens↗
PubMed1994

Induced gene expression of the hypusine-containing protein eukaryotic initiation factor 5A in activated human T lymphocytes.

The hypusine-containing protein eukaryotic initiation factor 5A (eIF-5A) is a cellular cofactor critically required for the function of the Rev transactivator protein of human immunodeficiency virus type 1 (HIV-1). eIF-5A localizes in the nuclear and cytoplasmic compartments of mammalian cells, suggesting possible activities on the level of regulated mRNA transport and/or protein translation. In this report we show that eIF-5A gene expression is constitutively low but inducible with T-lymphocyte-specific stimuli in human peripheral blood mononuclear cells (PBMCs) of healthy individuals. In contrast, eIF-5A is constitutively expressed at high levels in human cell lines as well as in various human organs. Comparison of eIF-5A levels in the PBMCs of uninfected and HIV-1-infected donors shows a significant upregulation of eIF-5A gene expression in the PBMCs of HIV-1 patients, compatible with a possible role of eIF-5A in HIV-1 replication during T-cell activation.

Base Sequence↗
PubMed1994

Origin of human mast cells: development from transplanted hematopoietic stem cells after allogeneic bone marrow transplantation.

Although mast cells are hematopoietic cells, little is known about the origin of their precursors in vivo. In this study, the origin (donor v recipient genotype) of human mast cells (MCs) was analyzed in a patient who underwent allogeneic bone marrow transplantation (BMT). The patient presented with secondary acute myeloid leukemia (French-American-British classification, M2) arising from refractory anemia with excess of blast cells and bone marrow (BM) mastocytosis. Transplantation was performed in chemotherapy-induced complete remission. On days 88, 126, 198, and 494 after BMT, mast cells were enriched to homogeneity from bone marrow mononuclear cells (BM MNCs) by cell sorting for CD117+/CD34- cells. Purified mast cell populations were CD117(c-kit)+ (> 95%), CD34- (< 1%), CD3- (< 1%), CD14- (< 1%), and virtually free of contaminating cells as assessed by Giemsa staining. The genotype of MCs was analyzed after amplification by polymerase chain reaction (PCR) of a variable number tandem repeat (VNTR) region within intron 40 of the von Willebrand factor (vWF) gene. Unexpectedly, on days 88 and 126 after BMT, sorted MCs displayed recipient genotype as shown by vWF.VNTR-PCR. However, on days 198 and 494, PCR analysis showed a switch to donor genotype in isolated mast cells. Peripheral blood (PB) and BM MNC as well as highly enriched (sorted) CD3+ T cells (PB, BM), CD4+ helper T cells (PB), CD8+ T cells (PB), CD19+ B cells (PB), CD14+ monocytes (PB, BM), and CD34+ precursor cells (BM) showed donor genotype throughout the observation period. Together, these results provide evidence that human MCs developed in vivo from transplanted hematopoietic stem cells. Engraftment and in vivo differentiation of MCs from early hematopoietic progenitor cells may be a prolonged process.

Bone Marrow Transplantation↗
PubMed1994

Vasoactive intestinal peptide-receptor imaging for the localization of intestinal adenocarcinomas and endocrine tumors.

BACKGROUND: Intestinal adenocarcinomas and various endocrine tumors express large numbers of high-affinity receptors for vasoactive intestinal peptide (VIP). We have evaluated the usefulness of scanning with VIP labeled with iodine-123 for tumor localization in patients with gastrointestinal tumors. METHODS: Radioiodinated VIP was purified by high-pressure liquid chromatography and administered as a single intravenous bolus injection (300 pmol [1 microgram]). Scanning with radiolabeled VIP was compared with computed tomography and scanning with somatostatin analogues in 79 patients with colorectal cancer, pancreatic carcinoma, gastric cancer, carcinoid tumor, or insulinoma. RESULTS: Visualization of gastrointestinal tumors and metastases was obtained with radiolabeled VIP. Binding of the labeled peptide by primary tumors and metastases was visible shortly after the injection and was still demonstrable at 24 hours. In patients with colorectal adenocarcinomas, primary or recurrent tumors were visualized in 10 of 10, liver metastases in 15 of 18, lung metastases in 2 of 3, and lymph-node metastases in 4 of 4. Primary pancreatic adenocarcinomas were visualized by imaging in 10 of 12 patients, and liver metastases were seen in 7 of 7. Primary or recurrent gastric adenocarcinomas were visualized in 5 of 5 patients, and liver metastases were seen in 2 of 2 patients. VIP scans were positive in 9 of 10 patients with carcinoid tumors and in 4 of 4 patients with insulinomas. Some tumors with positive VIP scans were also visualized with somatostatin analogues (4 of 17 colorectal adenocarcinomas, 8 of 9 carcinoids, and 2 of 2 insulinomas). In vitro binding studies confirmed the presence of VIP receptors on gastrointestinal tumors. CONCLUSIONS: Scanning with radiolabeled VIP can visualize intestinal tumors and metastases that express receptors for VIP.

Adenocarcinoma↗
PubMed1994

Cross-competition between vasoactive intestinal peptide and somatostatin for binding to tumor cell membrane receptors.

Vasoactive intestinal peptide (VIP) is a 28-amino acid peptide with a wide range of biological activities. Recent data suggest that functional VIP receptors are expressed on various tumor cells. Somatostatin (SST) and its long-acting analogue octreotide (OCT) are potent inhibitors of tumor cell growth and secretion. In the present study, the interactions between VIP and SST/OCT on primary tumors (insulinomas, n = 3; VIPomas, n = 2; intestinal adenocarcinomas, n = 5; neuroblastomas, n = 5; papillary thyroid cancers, n = 7; carcinoids, n = 5; ductal breast cancers, n = 8; small cell lung cancers, n = 3; ACTH-producing hypophyseal adenomas, n = 5; pheochromocytomas, n = 5) as well as on tumor cell lines (A431, HT29, PANC1, COLO320, HMC1, and KU812 cells) were analyzed by use of 123I-labeled VIP and 123I-labeled Tyr-3-OCT. Cross-competition between VIP and SST/OCT for binding to tumor cells was observed. The rank-order of potency for displacement of 123I-labeled VIP binding to intact A431 cells was VIP [concentration causing half-maximal inhibition (IC50) = 2.9 +/- 1.9 (SD) nM] > OCT (IC50 = 9.3 +/- 1.7 nM) = SST > substance P = secretin (IC50 = 1 microM). Binding of 123I-labeled Tyr-3-OCT to A431 cells, in turn, was inhibited by OCT = Tyr-3-OCT (IC50 = 1.5 +/- 0.3 nM) = SST > VIP (IC50 = 4.9 +/- 1.1 nM). This rank-order of potency was also obtained for primary tumors and tumor cell lines. Furthermore, SST and OCT inhibited VIP-induced [3H]thymidine incorporation, cyclic AMP formation, and tyrosine kinase activity with IC50 values < 10 nM. Together, these data provide evidence for functional interactions between SST and VIP on various tumor cells. These interactions may involve peptide cross-competition at cellular binding sites and may have implications for the biology and pathophysiology of respective cells and disease states.

Adenosine Triphosphate↗
PubMed1994

The riddle of the mast cell: kit(CD117)-ligand as the missing link?

Tissue mast cells are multifunctional immune cells and have been implicated in allergic and inflammatory reactions. However, while the role of allergen binding to surface IgE via the high-affinity Fc epsilon receptor on mast cells is well understood, major questions in mast-cell biology remain to be answered. In particular, it is largely unknown which stimuli lead to the differentiation of human mast cells from their precursor cells and how the maturing cells localize (or home) and acquire effector functions within the microvasculature. A potential solution is suggested by Peter Valent in this viewpoint. The emerging concept is that a single tissue hormone, the ligand of the c-kit tyrosine kinase receptor (CD117), provides a key signal in multiple aspects of mast-cell differentiation and function.

Animals↗
PubMed1994

Molecular characterization of dog albumin as a cross-reactive allergen.

Indoor allergens comprise a group of allergenic proteins that are commonly derived from house dust mite and cat and dog dander. In addition to the two major dog allergens (molecular weights: 19 and 23 kd), dog albumin represents an important allergen for up to 35% of patients who are allergic to dogs. In IgE immunoblot inhibition studies and histamine release tests it has been demonstrated that patients who react to dog albumin exhibit IgE reactivity with purified albumins from cat, mouse, chicken, and rat. The proportion of dog-specific IgE directed against dog albumin was determined for patients allergic to dog albumin, and it ranges from 70% to 90%. By IgE immunoscreening of a lambda gt11 expression library from a dog salivary gland, we identified a number of reactive complementary DNA clones. All patients with IgE reactivity against natural dog albumin displayed IgE reactivity to the beta-galactosidase fusion protein encoded by clone 54c, which was therefore assumed to contain major IgE epitopes of dog albumin. The deduced amino acid sequence of clone 54c was compared with the Swiss-Prot library, and significant sequence homologies were found with albumins from different species (human: 82.6%, pig: 81.8%, cattle: 77.3%, sheep: 78.8%, mouse: 75.8%, and rat: 76.2%). Several other IgE-positive clones hybridized with oligonucleotides that were prepared according to this sequence. Partial complementary DNA coding for dog albumin fragments may be considered a useful tool for further characterization of major IgE epitopes of dog albumin.

Allergens↗
PubMed1994

Does cord blood contain enough progenitor cells for transplantation?

We analyzed 125 blood samples obtained from umbilical cord immediately after delivery of full-term neonates. Between 0.1 and 10.4% (mean 1.13%, SD 1.34) of the density-separated glycophorin A (GPA)-negative mononuclear cells (MNC) expressed CD34 as analyzed by flow cytometry. These hematopoietic progenitor cells did not coexpress CD19, and the majority were negative for CD45RA. The number of MNC determined per ml cord blood ranged from 1 x 10(5) to 200 x 10(5) (mean 20.2 x 10(5), SD 24.7). Regression analysis revealed that a mean of 56% (n = 26, R = 0.8) and 120% (n = 35, R = 0.94) of the analyzed CD34+ MNC gave rise to day 14 colonies in the clonogenic assay when cultured without or with stem cell factor (SCF). The number and the exact phenotype of progenitor cells required for successful transplantation are not known. If the transplantation of 5 x 10(5) CD34% cells/kg body weight is required for engraftment and one-third of the progenitor cells are lost to cell processing, and if 180 ml blood can be collected from a single umbilical cord (and placenta), our data suggest that 90% of the collections do not contain enough precursors to transplant a 25 kg recipient. To meet these conditions, an average of 1439 ml cord blood would be necessary for transplantation.

Colony-Forming Units Assay↗