RAPID COMMUNICATION

The Differentiation and Maturation Mediator for Human Myeloid Leukemia Cells Shares Homology With Neuroleukin or Phosphoglucose Isomerase

By W. Xu, K. Seiter, E. Feldman, T. Ahmed, and J.W. Chiao

The identity of the maturation inducer capable of mediating the differentiation of human myeloid leukemic HL-60 cells to terminal monocytic cells was investigated. One of such inducers from T cells was purified as a 54.3-kD peptide. The amino acid sequence of a tryptic peptide and the enzyme cleavage sites revealed 100% homology to neuroleukin or phosphoglucose isomerase (PGI). Neuroleukin mediates dif- ferentiation of neurons and is homologous to PGI, which catalyzes the interconversion of glucose-6-phosphate and fructose-6-phosphate. The 54.3-kD inducer was shown to have PGI enzymatic activity. Separately purified PGI by sub- strate-elution exhibited identical specificity as the matura- tion inducer for HL-60 cell differentiation. They mediated a

HEMICALS OR physiological factors capable of medi- C ating leukemia cell differentiation, rather than direct cell lysis, are used in treatments to eradicate leukemia cells. Depending on the activity of the individual differentiation inducers, they could be used selectively to target at specific cell types of leukemia. Therefore, this differentiation in- duction approach could be more specific and less toxic than the conventional chemotherapy, as the tumor cells are re- moved after differentiation as in normal proce~ses.~ As a result, there have been continued efforts to search and define such agents as potential therapeutics, as well as to understand the differentiation control of leukemia

Our early reports described the presence of a differentia- tion and maturation inducing activity mediating the develop- ment of human myeloid leukemia cells, including HL- 60 cells and patient leukemia cells to terminal monocytic cell^.^^'^ The activity was determined to be produced by T- cell populations after activation with mitogens or antigens. The maturation-inducing protein interacts with leukemia cells during GI and S phases of cell cycle to initiate differen- tiation.”.” Cells then traverse through the G2M phases and mitosis where they are reduced in cellular proliferation and RNA content, and develop to terminal monocytes-macro- phages. During this process the differentiated cells acquire the characteristics of monocytic cells, including monocyte- macrophage morphology and adherence, membrane recep- tors for complement components, phagocytic capability, and specific antigens and enzymes, Most of the cells

From the Department of Medicine, New York Medical College,

Submitted January 25, 1996: accepted March 8, 1996. Supported by National Institutes of Health Grant No. CA 35999. Address reprint requests to J . W. Chiao, PhD. Department of Medi-

cine, Vosburgh 207, New York Medical College, Valhalla, NY 10595. The publication costs of this article were defrayed in part by page

charge payment. This article must therefore be hereby marked “advertisement” in accordance with I 8 U.S.C. section I734 solely to indicate this fact.

Valhalla, NY.

0 1996 by The American Society of Hematology. 0OO6-497I/96/87l1-0057$3.00/0

reduction of proliferating S and G2M cells, and the mature monocytic cells acquired complement receptors, phagocytic capacity, and adherence morphology. The magnitude of dif- ferentiation was dosage dependent on the inducer, with a bell-shaped curve. At the excess dose range cells did not undergo differentiation and remained in a proliferating cycle. Abnormally elevated PGI enzyme activities were detected in the plasma of acute myelogenous leukemia patients. Whether they represent an excess of the differentiation regu- lator in patients and are important in leukemogenesis re- main to be investigated. 0 1996 by The American Society of Hematology.

that differentiated became macrophages undergoing one cell- cycle division.“’

The maturation-inducing activity has been described to associate with proteins with 30 to 58-kD molecular-weight range^,^','^ and distinct from the commonly known myeloid cell mediators including interleukins 1 and 2,15 interfer- ons,12,15.16 colony-stimulating factors, tumor necrosis factor, and leukemia inhibitory factor,

To identify these maturation-inducing proteins, we discov- ered a 54.3-kD inducer with its peptide sequence showing 100% homology with neuroleukin. Neuroleukin is a 56-kD T-cell lymphokine that supports the survival of motor and sensory neurons in vitro.‘’ The cDNA sequence of the neuro- leukin gene is further known to be highly homologous to human phosphoglucose isomerase (PGI), the catalyst specific for the second step of the glycolytic pathway interconverting glucose-6-phosphate and fr~ctose-6-phosphate.~~-’~ The sig- nificance of the homology between the maturation-inducing protein and PGI, or neuroleukin, is discussed.

MATERIALS AND METHODS

Differentiation assay. The differentiation assay using human leukemia HL-60 promyelocytes was employed to detect the matura- tion inducing a~t ivi ty . ’~.’~ Essentially, HL-60 cells were supple- mented with the maturation-inducing preparations at various concen- trations, or with an appropriate control medium. The acquisition of membrane complement receptors and phagocytic function of the mature cells, and the development of monocyte and macrophage morphology, were assessed as previously The means of the complement receptor and phagocytic cells were reported. The activity of the maturation inducer was defined as the minimal amount of inducer required in a unit volume of cell culture to induce a certain number of mature cells within a given time period.I2 The activity is calculated as (percent cells bearing mature cell markers)/ T, where Tis the number of hours of the culture period during which the cells were treated with the maturation-inducing preparation.’? The specific activity is defined as the inducer activity per milligram of ~r0tein. l~ Cellular proliferation was determined by cell-cycle phase distribution with a Coulter Profile I1 cytometer (Coulter, Mi- ami, FL). DNA of cells were stained with propidium iodide ac- cording to a previously described procedure.’’

Ten liters of serum-free conditioned medium (CM) prepared from phytohemogglutinin-stimulated peripheral

Protein isolation.

4502 Blood, Vol 87, No 11 (June 1). 1996 pp 4502-4506

For personal use only.on November 16, 2018. by guest www.bloodjournal.orgFrom

LEUKEMIA DIFFERENTIATION FACTOR 4503

blood lymphocytes, was used as the starting material for isolating the maturation-inducing activity.'*," Fractions obtained from bio- chemical separation procedures were dialyzed in RPMI-1640 me- dium and assayed for their activity to induce HL-60 leukemia cells to monocytic cells. CM was membrane concentrated (104 molecular weight cut-off) with a Pellicon cassette system (Millipore, Milford, MA) and separated using a Q-fast flow column (Pharmacia, Piscata- way, NJ) equilibrated with 10 mmol/L Tris and 1 mmol/L KCI, pH 7.8. The pass through fraction was then separated on a 200-mL Pharmacia Sepharose fast flow column equilibrated in 0.4 mol/L NaCl and 0.14 m o m borate at pH 7.9. A Pharmacia SP Sepharose fast flow column in 1 mmoVL KCI and IO mmoVL phosphate buffer at pH 7.0 was used for the next procedure, and the pass through fraction, containing the activity, was collected. It was then applied to an HPLC Protein Pak Phenyl-5W column (Millipore) in 1 mmoV L KCI, 1.3 mol/L (NH,), SO,, and 50 mmol/L phosphate buffer, pH 7.2, and eluted with a linear gradient from 0 to 1.3 mol/L (NH,), SO, at a flow rate of 0.5 mumin. The major protein peak eluted between 150 and 200 minutes was collected and further separated using a preparative 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)? Proteins were electroeluted from sliced gel segments using a Bio-Rad apparatus (Melville, NY) and dialyzed in RPMI-1640 medium before being used in assays.

The purified maturation inducer was excised from SDS gel after being stained briefly with Coomasie Blue. The gel slices were de- stained before tryptic digestion. The tryptic peptides were resolved by reverse-phase HPLC and the mass spectrometry was determined for the peptides. The amino acid sequencing was performed on an Applied Biosystems sequencer (Applied Biosystems, Foster City, CA).

The procedure of Sun et a124 for isolating PGI was used with minor modification. Membrane concentrated ( 1 X IO4 molecular weight cut-off) lymphocyte CM was dialyzed in 10 m m o K EDTA, 0.1 % P-mercaptoethanol @ME), and 10 mmol/L Tri-ethanolamine (TEA), pH 7.2 (buffer A), and applied to a IO-mL phosphate cellu- lose column (Sigma, St Louis, MO) equilibrated with buffer A. The column was washed first with the same buffer, followed with a second buffer consisting of 1 mmol/L EDTA, 0.1% BME, and 25 m m o f i TEA, pH 8.1 (buffer B), and PGI was then eluted with 7 mmol/L fructose 6-phosphate in buffer B.

The procedure of Sun et a124 for measuring FGI activity was used with minor modifications. The reaction mixture consisted of 5 mmoll L MgCI2, 4 mmoVL fructose-6-phosphate, 1.0 U of glucose-6-phos- phate dehydrogenase, 0.05 mmol/L NADP, and 50 mmoVL trietha- nolamine, pH 8.3. The reactions were carried out at 37°C. PGI units were calculated based on the absorbance of NADPH at 340 nm.

Patient 1 was a 64-year-old man with newly diagnosed acute myelogenous leukemia (AML), French-American-British (FAB) classification M6. Cytogenetics showed deletions of chromo- somes 5 and 7, trisomy 8, and other abnormalities. Patient 2 was a 77-year-old man with AML who was treated with idarubicin and cytosine arabinoside, and was in remission at the time the sample was obtained. Patient 3 was a 70-year-old man with newly diagnosed AML, FAB MI. Cytogenetics showed deletion of chromosome 7 and other abnormalities. Patient 4 was a 67-year-old man with primary refractory AML, FAB M5. Cytogenetics showed trisomy 8 and other abnormalities.

Patients.

RESULTS

The maturation inducing activity for myeloid leukemia HL-60 cells was purified after several biochemical proce- dures. The activity does not bind to either anion Q-Sepharose or cation SP Sepharose. The active fraction obtained after gel filtration was further isolated by an HPLC phenyl-Sepharose

I 1 I I I kDa 97.4 66.2 45 31 21.5

Fig 1. SDS-PAGE of the purified maturation inducer in the ab- sence of reducing agent. The gel was silver stained. Proteins from unstained gel slices were electroeluted for the determination of the presence of maturation inducer activity for the differentiation of HL- 60 cells to monocytic cells. The graph shows the activity superim- posed to the 54.3-kD protein.

hydrophobic column with the activity resolved in a well- separated peak (Fig 1). A monomer protein with a relative molecular mass of 54.3 kD was revealed on SDS-PAGE that was electroeluted for analysis (Fig 1). The peak of the maturation-inducing activity was superimposed with the 54.3-kD protein, but not with other eluates from the gel, indicating the homogeneity of the activity. The specific activ- ity of the maturation inducer increased from approximately 9.0 of the crude CM to greater than 222.3 for the HPLC purified fraction (Table 1).

Purified maturation inducer was digested with trypsin for amino acid sequence analysis. Comparison with sequences held in the Gene Bank database, a tryptic peptide TLAQLN- PESSLFIIASK, showed a 100% sequence identity between position 195 to 221 of human PGI or neuroleukin. The same tryptic cleavage sites were also noted for both the maturation inducer and PGI. Based on the data obtained from mass spectroscopy, the ratio of mass to charge of five other major tryptic peptides isolated from HPLC peaks matched to that of the tryptic peptides of PGI or neuroleukin.

Both the mouse and human neuroleukins express PGI en- zymatic activity?' Whether the maturation-inducer protein also has PGI enzyme activity interconverting glucosed- phosphate and fructose-6-phosphate was determined. PGI activity was increased steadily during the successive isola- tion procedures used for maturation inducer (Table 1). A significant specific activity of PGI was associated with the highly purified maturation inducer preparation obtained from the HPLC phenyl-Sepharose column. Furthermore, the PGI activity was completely superimposed with the maturation

For personal use only.on November 16, 2018. by guest www.bloodjournal.orgFrom

4504 XU ET AL

Table 1. Increase of PGI Activity During Purification of Differentiation Inducer

Purification Differentiation Inducer PGI Activity Procedures (specific activity) (Ulmg)

Crude CM Q-Fast flow Sephacel-200 SPS-Sepharose 2Phenyl-Sepharose

9.0 2.4 16.2 33.2 54.0 65.4

169.3 174.2 222.3 756.5

inducer activity, associated with the 54 .343 protein, as indi- cated in Fig 1.

To further determine whether PGI also possesses the mat- uration-inducing activity for leukemia cells, PGI was iso- lated according to established procedure. PGI was purified from lymphocyte CM with a phosphate cellulose affinity chromatography after specific elution with substrate fruc- tose-6-phosphate, The specific activity showed an increase from approximately 2.4 to 315.0 with an isolated PGI frac- tion (Fig 2). As shown in Fig 2, the only eluted fraction that

4 30

I 20

10 $

al U

3 c

400 E U) 300 \

c .- C

= 200 t;

100

E 0 00 cu al U C 0

C

e s n Q o

IO 20 30 Fraction Number

Fig 2. The presence of maturation inducing activity in the isolated POI. The bottom graph shows the elution of POI protein from a phos- phate cellulose affinity column possessing enzymatic activity, as shown in the middle graph. All protein eluates were a“lnod for maturation inducer actlvity for the differentiation of HLsO calls. The meturation i n d h r activity was found superimposing to the isolated PGI fraction as shown in the upper graph.

50 r

10-8 10-7 10-6 10-5 10-4 10-3 10-2 IO-’

Maturation inducer quantity (pq/ml)

Fig 3. The induction of dfferentiation of leukemic HL-60 promy- elocytes using the isolated maturation inducer (0) or PGI (A). The results represent the quantity of differentiated mature cells dater- mined from HL-60 cell cultures that were supplemented with various amounts of the inducer preparations for 4 days.

possesses PGI activity superimposes the only fraction that has the differentiation-inducing activity from the same col- umn. The 54.2-kD protein in the eluate was subsequently electroeluted from SDS-PAGE and its activity on HL-60 leukemia cell differentiation determined.

The maturation inducer displays a dosage-dependent ef- fect on HL-60 cell differentiation. The dose-response curves of isolated maturation inducer or PGI were similarly bell- shaped (Fig 3). PGI or inducer used at pg/mL were effective to induce a minimal quantity of differentiated cells. PGI or maturation inducer used at approximately 1 X lo-’ to 1 X lo-’ pg/mL had an optimal differentiation effect, with approximately 35% monocytes-macrophages detected after 3 to 5 days (Fig 3). Adherent cells were developed in these cultures and more differentiated cells acquired mem- brane complement receptors and phagocytic activity, and displayed monocyte-macrophage morphology. Meanwhile, the undifferentiated HL-60 promyelocytes were decreased. When PGI or maturation inducer was used in excess or below the optimal dose ranges, the quantity of monocytic cells developed was reduced, indicating a bell-shaped dose effect on differentiation. Proliferation of HL-60 cells was determined simultaneously with cellular differentiation. The cell growth rate was decreased in the differentiated cultures, and it was further analyzed by cell-cycle phase distribution. The magnitude of proliferation reduction is in direct propor- tion to the degree of differentiation. The cultures with the largest quantity of differentiated cells also showed the big- gest growth reduction. In the more differentiated cell cul- tures, the proliferating S and G2M cells decreased to 27% to 31%, compared with 37% to 40% in the control cultures. A concomitant increase of GI cells was detected in the differ- entiated cell cultures. These results indicate a coupled rela- tion of differentiated cells with proliferation cessation.

Earlier reports by Israel and Deloy” and Blanchaer et alZ6 in the 1950s described that plasma PGI enzymic levels were elevated in almost all untreated chronic and AML, but not in lymphocytic leukemia. The elevation ranged from values 15% to several folds of normal. PGI elevation was then

For personal use only.on November 16, 2018. by guest www.bloodjournal.orgFrom

LEUKEMIA DIFFERENTIATION FACTOR 4505

Table 2. Elevated Plasma PGI Activity in Leukemia Patients

No. Age and Sex Status PGI IUlmg) ~~~

AML 1 7 0 M M6 7.6 x 1 0 - ~

3 67M M I 2.1 x IO-^ 4 64M M5 2.6 x io-* Mean 3.5 x lo-'

Normals (n = 5) Mean 1.8 x IO-' S.D. 8.9 x IO-^

2 77 M Remission 1.5 x lo-'

interpreted as a metabolic feature of the tumor cells. Because we used an updated method of Sun et alN for PGI determina- tion, a preliminary survey of PGI enzyme activity was per- formed with plasma from AML and healthy controls. Table 2 shows a significantly increase2 PGI level, approximately 422% of the normal in the plasma of an untreated AML patient (patient 1). The PGI levels of patient 3 and 4 were increased to 117% and 144% of the normal level, respec- tively. The patient 2, who was in remission, had a normal PGI level.

DISCUSSION

We have presented evidence indicating a high degree of homology between a differentiation and maturation inducing protein of myeloid leukemia cells and PGI or neuroleukin. Their identity includes shared amino acid sequences and reciprocal biologic functions. The purified maturation in- ducer has been shown with PGI enzymatic activity. Simi- larly, the purified PGI also has the differentiation property for leukemia cells ascribed to the maturation inducer. Neuro- leukin and PGI have previously been reported" having a differentiation induction capability for certain neurons. Incu- bation of rat neuroblastoma cell line with PGI led to en- hanced neurite outgrowth and a reduced cellular prolifera- tion. These observations indicate that PGI and maturation inducer also share a common biologic function, regulating differentiation and proliferation. It also implies that this pro- tein may affect cellular development of different cell types, including myeloid cells and neurons.

Neuroleukin and PGI were suggested to be identical or closely related proteins processed from the same gene.19-21.28 PGI activity is expressed and secreted by cells after the transfection of neuroleukin gene." Human PGI in normal tissues and cells has two 63.2- or 69.8-kD subunits or a combination of different sub~nits, '~ whereas the neuroleukin released from T cells is detected as a 56-kD monomer.I8 These isoforms of PGI have different isoelectric points and their different molecular weights are not caused by glycosyl- a t i ~ n . ~ ~ Genetic variants of PGI have also been detected with different electrophoretic mobility but with the same molecular weight,29 indicating the presence of a family of isoforms. Baumann and Brand3' suggested that a specific enzymatic cleavage of PGI causes the appearance of the observed variants exhibiting a lower molecular weight in the 56- and 57-kD ranges such as neuroleukin. The molecular weight of the isolated maturation inducer is in the ranges of PGI variants but slightly different from the established

molecular weight of neuroleukin or PGI isoforms. Whether this maturation inducer represents a newly identified product of the PGI gene remains to be determined. The current data suggest that the differentiation- and maturation-inducing ac- tivity includes these isoforms, consistent with the previous observations indicating the presence of several molecular species for the a~tivity. '~. '~

Our experiments indicate that optimal differentiation of leukemia cells requires the inducer to be present within a defined concentration. When insufficient or excess inducer quantity is present in the cultures, fewer or no leukemia cells undergo differentiation and the majority of the cells remains in the proliferating cycle. Therefore, the differentiation and proliferation potentials of the leukemia cells are dependent on the concentration of the differentiation inducer. Excess inducer causes an especially sharp reduction of differentiated cells, indicating an inducer-mediated inhibition of differenti- ation. These observations suggest that continued prolifera- tion of the tumor cells may be related, at least in part, to an imbalance of the growth and differentiation regulators. The observation made by us and other^'^.'^ that PGI activity is present in elevated levels in AML patients could be an inter- esting corroboration to this interpretation. Earlier reports by Blanchaer et alZ6 and Israel and Deloy2* described that abnor- mally elevated PGI levels were found in myelogenous but not lymphocytic leukemia, and the changes of the levels reflected remission or relapse in some patients. Our current results with AML patients were consistent with these obser- vations. However, these early studies were not aware of the association of PGI with a differentiation and growth regulatory function, and little was known about the patho- genic role of elevated PGI activity in leukemia. Elevated PGI enzyme activity is likely caused by a protein quantity increase. However, this possibility needs to be confirmed. An increase of these regulatory molecules would imply their interaction with the leukemia cells is in the excess dose range. Whether the excess dose is ineffective to mediate their differentiation in vivo, as that shown in vitro, remains to be investigated.

REFERENCES 1. Koffler HP Induction of differentiation of acute myelogenous

leukemia cells: Therapeutic implications. Blood 62:709, 1983 2. Castaigne S, Chomienne C, Daniel MT, Berger R, Fenaux P,

Degos L All-trans retinoic acid as a differentiation therapy for acute promyelocytic leukemia. Blood 76: 1704, 1990

3. Huang ME, Ye YC, Chai JR, Lu JX, Xhoa L, Gu LJ, Wang ZY: Use of all-trans retinoic acid in the treatment of acute promyelocytic leukemia. Blood 72:567, 1988

4. Ronald L, Koeffler HP: Differentiation therapy. Hematol Oncol Clin North Am 6:687, 1992

5. Zhou JY, Norman AW, Bert ML, Collins ED, Uskokovic MR, Loeffler HP Novel vitamin D analogs that modulate leukemic cells growth and differentiation with little effect on either intestinal cal- cium absorption or bone calcium mobilization. Blood 74:82, 1989

6. Testa U, Masciulli R, Tritarelli E, Pustonno R, Mariani G, Martucci R, Barberi T, Camagma A, Valtien M, Peschle C: Trans- forming growth factor-p potentiates vitamin D3-induced terminal monocytic differentiation of human leukemic cell lines. J Immunol 150:2418, 1993

7. Brown G, Bunce CM, Rowlands DC, Williams GR: All-trans

For personal use only.on November 16, 2018. by guest www.bloodjournal.orgFrom

4506 XU ET AL

retinoic acid and 1 alpha, 24-dihydroxyvitamin D co-operate to pro- mote differentiation of the human promyeloid leukemia cell line HL- 60 to monocytes. Leukemia 8:806, 1994

8. Nakamak T, Hino HI, Yokoyama A, Hisatake JI, Tomoyasu S, Honma M, Hozumi M, Tsuruoka N: Effect of cytokines on the proliferation and differentiation of acute promyelocytic leukemia cells: Possible relationship to the development of “Retinoic acid syndrome.” Anticancer Res 14:817, 1994

9. Chiao JW, Freigtag WF, Steinmetz JC, Andreeff M: Changes of cellular markers during differentiation of HL-60 promyelocytes to macrophages as induced by T cell conditioned medium. Leuk Res 5:477, 1981

10. Yen A, Chiao JW: Control of cell differentiation during prolif- eration. Exp Cell Res 146:78, 1983

11. Chiao JW, Andreeff M, Freitag WB, Arlin Z: Induction of in vitro proliferation and maturation of human aneuploid myelogenous leukemia cells. J Exp Med 1551357, 1982

12. Leung K, Chiao JW: Human leukemia cells maturation in- duced by a T cell lymphokine isolated from medium conditioned by normal lymphocytes. Proc Natl Acad Sci USA 82:1209, 1985

13. Chiao JW, Wang CY: Differentiation antigens of HL-60 pro- myelocytes during induced maturation. Cancer Res 44: 1031, 1984

14. Abolhassani M, Riley WM, Feldman E, Arlin Z, Chiao JW: Two separated differentiation inducer proteins for human myeloid leukemia cells. Proc SOC Exp Biol Med 195:288, 1990

15. Olsson I, Olofsson T, Mauritzon N: Characterization of mono- nuclear blood cell derived differentiation inducing factor for the human promyelocytic leukemia cell line HL-60. J Natl Cancer Inst 67:1225, 1981

16. Takei M, Takeda K, Konno K The role of interferon-y in induction of differentiation of human myeloid leukemia cell lines, ML-I and HL-60. Biochem Biophys Res Commun 124:100, 1984

17. Chiao JW: Maturation inducer and the process of differentia- tion induction of human myeloid leukemia cells. Blood Cells 13: l l l , 1987

18. Gurney ME, Heinrich SP, Lee MR, Yin HS: Molecular clon- ing and expression of neuroleukin a neurotrophic factor for spinal and sensory neurons. Science 234:566, 1986

19. Chaput M, Claes V, Portetelle D, Cludts I, Cravador A, Burny A, Gras A, Tartar A: The neurotrophic factor neuroleukin is 90% homologous with phosphohexose isomerase. Nature 332:454, 1988

20. Faik P, Walker JIH, Redmill AAM, Morgan MJ: Mouse glu- cose-6-phosphate isomerase and neuroleukin have identical 3’ se- quences. Nature 332:455, 1988

21. Walker JIH, Faik P, Morgan MJ: Characterization of the 5’ end of the gene for human glucose phosphate isomerase (PGI). Genomics 7:638, 1990

22. Xu W, Chiao JW: Biochemical characteristics of a human myeloid leukemia cell differentiation factor. Prep Biochem (in press)

23. Laemmli UK: Cleavage of structural proteins during the as- sembly of the head of bacteriophage T4. Nature 177:680, 1970

24. Sun A, Yuksel KU, Jacobson T, Grace RW: Isolation and characterization of human glucose-6-phosphate isomerase isofoms containing two different size subunits. Arch Biochem Biophys 283:120, 1990

25. Israel LG, Deloy GE: Serum isomerase in leukemia. Br J Cancer 10:318, 1956

26. Blanchaer MC, Green FT, Madean JP, Hollenberg MJ: Plasma lactic dehydrogenenase and phosphohexose isomerase in leukemia. Blood 13:245, 1958

27. Miziachi Y: Neurotrophic activity of monomeric glucophos- phoisomerase was blocked by human immunodeficiency virus (HIV- 1 ) and peptides form HIV-1 envelope glycoprotein. J Neurosci Res 23:217, 1989

28. Baumann M, Brand K, Giedl J, Hermanek P, Ruf S, Scheele J, Hoferchter S, Gall FP: Significance of serum phosphohexose isom- erase in gastro-intestinal cancer at different stages. Oncology 45: 153, 1988

29. Purdy KL, Jones S, Tai H, Grace R A radioimmunoassay for human glucose phosphate isomerase: Measurement of immunore- active enzyme from genetic variants. Arch Biochem Biophys 200:485, 1980

30. Baumann M, Brand K: Purification and characterization of phosphohexose isomerase from human gastrointestinal carcinoma and its potential relationship to neuroleukin. Cancer Res 48:7018, 1988

For personal use only.on November 16, 2018. by guest www.bloodjournal.orgFrom

1996 87: 4502-4506  

W Xu, K Seiter, E Feldman, T Ahmed and JW Chiao isomerase

phosphoglucoseleukemia cells shares homology with neuroleukin or The differentiation and maturation mediator for human myeloid 

http://www.bloodjournal.org/content/87/11/4502.full.htmlUpdated information and services can be found at:

Articles on similar topics can be found in the following Blood collections

http://www.bloodjournal.org/site/misc/rights.xhtml#repub_requestsInformation about reproducing this article in parts or in its entirety may be found online at:

http://www.bloodjournal.org/site/misc/rights.xhtml#reprintsInformation about ordering reprints may be found online at:

http://www.bloodjournal.org/site/subscriptions/index.xhtmlInformation about subscriptions and ASH membership may be found online at:

  Copyright 2011 by The American Society of Hematology; all rights reserved.Society of Hematology, 2021 L St, NW, Suite 900, Washington DC 20036.Blood (print ISSN 0006-4971, online ISSN 1528-0020), is published weekly by the American

For personal use only.on November 16, 2018. by guest www.bloodjournal.orgFrom