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PubMed2001

[Expression of AC133 Antigen on Acute Leukemia Cells]

To investigate the expression of AC133 antigen on acute leukemia cells and its clinical significance, samples of 29 patients with acute lymphocytic leukemia (ALL) and 32 patients with acute myelocytic leukemia (AML) were analyzed by flow cytometric three-color direct immunofluorescence methods. It was found that 13 of 29 ALL, 6 of 8 AML-M(0)/M(1), 4 of 16 AML-M(2) and 4 of 8 AML-M(4)/M(5) expressed AC133. The mean fluoresence intensity of AC133 in each subtype of AML-M(0)/M(1), AML-M(2) and AML-M(4)/M(5) was 227.1, 143.1 and 142.5, respectively. Among 27 AC133(+) cases (44.3%), 25 cases coexpressed CD34 (92.6%) and 13 cases coex- pressed CD117 (48.1%). In contrast to other reports, our data do not support the findings that AML-M(4)/M(5) expressed very high levels of AC133. In conclusion, AC133 antigen, coexpressed with CD34 and CD117, appears more frequently and more intensely in AML-M(0)/M(1).

Journal Article↗
PubMed2001

AC133 antigen as a prognostic factor in acute leukemia.

AC133 is a novel 5-transmembrane antigen present on a CD34((bright)) subset of human hematopoietic stem cells (HSCs) and it is also expressed on the subset of CD34 positive (CD34(+)) leukemias. But the clinical significance of AC133 expression on leukemic blasts is not yet known. We investigated the expression of AC133 antigen on blast cells of acute leukemia. Forty-one cases of acute leukemia were examined for expression of AC133, CD34, and other antigens using multicolor flow-cytometry. Samples were considered positive if at least 20% of the cells specifically stained with monoclonal antibodies (MoAbs) revealed a higher fluorescence intensity compared to cells of corresponding negative control samples (=20% cut-off level). 14/36 (38.9%) acute myelogenous leukemia (AML) samples and 6/20 (30%) acute lymphoblastic leukemia (ALL) samples were positive for AC133, the difference was not significant. All AC133 positive (AC133(+)) leukemias expressed CD34, whereas 13 of 33 CD34(+) leukemias were negative for AC133, and AC133(+)/CD34(-) leukemia was not found. Expression rates of CD31, CD62L, CD62E, CD105 and CD144 were significantly higher in AC133(+) leukemia compared to those of AC133(-) leukemia (P=0.045, P<0.001, P<0.001, P<0.001, P=0.003, respectively), but bcl-2, CXCR-1, CXCR4, VLA-4, CD106 expression rates were not significantly different between AC133(+) and AC133(-) leukemias. None of the clinical prognostic markers such as age, hemogram, lactate dehydrogenase, and chromosomal aberration were significantly different between AC133(+) and AC133(-) leukemias. CR rates of AC133(+) AML and AC133(-) AML were not significantly different, although there was a trend toward higher CR rates in AC133(-) AML (18/22[81.8%] AC133(-) AML versus 9/14[64.3%] AC133(+) AML), but the 1-year relapse rate of AC133(+) AML was significantly higher than that of AC133(-) AML (8/9 (88.9%) versus 7/19 (36.8%), P=0.016). Median disease-free survival (DFS) times of AC133(+) and AC133(-) AML were significantly different (11 and 18 months, respectively, P=0.006), although overall survival (OS) times were not significantly different (AC133(+) 15 months versus AC133(-) 20 months, respectively, P=0.06). Similar results regarding clinical outcomes were found when AC133(+)/CD34(+) and AC133(-)/CD34(+) were analyzed separately, but the difference did not attain statistical significance. In ALL, 9/11 (81.8%) AC133(-) and 2/4 (50%) AC133(+) cases achieved CR, but the difference was not significant. Four of 11 AC133(-) ALL (36.4%) and 2 of 3 AC133(+) ALL (66.7%) relapsed within 1 year. In survival analysis, median DFS time and OS time of the AC133(+) group were 7 and 18 months, respectively, and these were not significantly different from those of the AC133(-) group (median DFS 15, OS 22 months, respectively). Our results demonstrate that AC133 expression in AML blasts is associated with poor clinical outcomes in terms of higher early relapse and shorter disease-free survival, suggesting that the AC133 antigen might provide the prognostic stratification of acute leukemia. However, to verify the effect of AC133 expression on the therapeutic outcomes of adult acute leukemia, further study including more cases is needed.

AC133 Antigen↗
PubMed2002

[The expression and functional characteristics of AC133 antigen in cord blood hematopoietic cells].

OBJECTIVE: To explore the significance of AC(133) antigen expression on cord blood (CB) hematopoietic cells. METHODS: The immunophenotype of CB hematopoietic cells was analyzed by flow cytometric two-color direct immunofluorescence method. Hematopoietic activity of AC(133)(+), CD(34)(+) and AC(133)(-) CD(34)(+) cells in CB was examined by analyzing clonogenic capacity, number of LTC-IC and ex vivo expansion ability. RESULTS: AC(133)(+) cells consisted of 0.67% of the total CB MNCs. Of the AC(133)(+) cells, 93.4% expressed CD(34) antigen and 94.2% was PKH(26)(+). Although the total number of CFC was the same in the AC(133)(-) CD(34)(+) fraction as in the CD(34)(+) and AC(133)(-) fractions, the number of LTC-IC was much higher in the AC(133)(+) fraction. In addition, the features of the colonies grown from these three fractions were quite different. Approximately 50% of the colonies derived from the AC(133)(+) fraction were CFU-GM, whereas more than 60% of the colonies derived from the CD(34)(+) fraction and 80% of the colonies derived from the AC(133)(-) CD(34)(+) fraction were BFU-E. After 7 d ex vivo expansion, the total number of cells and CFC increased 28.2-fold and 7.1-fold respectively in AC(133)(+) cell populations, 6.8% of the cells was PKH(26)(+). CONCLUSIONS: These findings suggest that the early stem/progenitor cells of CB are enriched in AC(133)(+) fraction, AC(133)(+) cells contain higher proliferative efficiency during ex vivo culture. It can generate either committed progenitors or early stem/progenitors. AC(133) antigen would be a useful marker for clinical selection of hematopoietic stem/progenitors.

AC133 Antigen↗
PubMed2002

AC133-2, a novel isoform of human AC133 stem cell antigen.

Human AC133 antigen, also called CD133, was recently identified as a hematopoietic stem cell marker. However, the molecular structure and function of this protein has remained unclear. Here we cloned and identified a novel isoform of AC133, which we named AC133-2. In comparison to the reported AC133 cDNA, which is referred to herein as AC133-1, a small exon of 27 nucleotides is deleted in AC133-2 by alternative mRNA splicing. Similar to the previously characterized AC133 antigen, recombinant AC133-2 expressed in 293 cells was glycosylated and transported to plasma membrane. AC133-2 mRNA was found predominant in a variety of human fetal tissue, adult tissues, and several carcinomas. In contrast, AC133-1 mRNA was more prominent in fetal brain and adult skeletal muscle but was not detected in fetal liver and kidney, adult pancreas, kidney, and placenta, suggesting different roles for the two isoforms in fetal development and mature organ homeostasis. Here, we demonstrate that AC133-2 is the isoform expressed on hematopoietic stem cells derived from fetal liver, bone marrow, and peripheral blood. The results indicate that AC133-2, not AC133-1, has been the cell surface antigen recognized by anti-AC133 monoclonal antibodies that are used for isolation of hematopoietic stem cells. To further investigate its expression in other stem cell populations, we found that AC133-2 co-expressed with beta(1) integrin in the basal layer of human neonatal epidermis. AC133-2(+)/beta(1) integrin(+) cells proliferated and differentiated in culture, which coincided with a loss of AC133-2 and gain in a terminal differentiation marker involucrin. Taken together, these results suggest that AC133-2 is expressed in multiple stem cell niches and may provide a means to isolate specific stem cell subpopulations from human tissues.

AC133 Antigen↗
PubMed2000

The human AC133 hematopoietic stem cell antigen is also expressed in epithelial cells and targeted to plasma membrane protrusions.

The human AC133 antigen and mouse prominin are structurally related plasma membrane proteins. However, their tissue distribution is distinct, with the AC133 antigen being found on hematopoietic stem and progenitor cells and prominin on various epithelial cells. To determine whether the human AC133 antigen and mouse prominin are orthologues or distinct members of a protein family, we examined the human epithelial cell line Caco-2 for the possible expression of the AC133 antigen. By both immunofluorescence and immunoprecipitation, the AC133 antigen was found to be expressed on the surface of Caco-2 cells. Interestingly, immunoreactivity for the AC133 antigen, but not its mRNA level, was down-regulated upon differentiation of Caco-2 cells. The AC133 antigen was specifically located at the apical rather than basolateral plasma membrane. An apical localization of the AC133 antigen was also observed in various human embryonic epithelia including the neural tube, gut, and kidney. Electron microscopy revealed that, within the apical plasma membrane of Caco-2 cells, the AC133 antigen was confined to microvilli and absent from the planar, intermicrovillar regions. This specific subcellular localization did not depend on an epithelial phenotype, because the AC133 antigen on hematopoietic stem cells, as well as that ectopically expressed in fibroblasts, was selectively found in plasma membrane protrusions. Hence, the human AC133 antigen shows the features characteristic of mouse prominin in epithelial and transfected non-epithelial cells, i.e. a selective association with apical microvilli and plasma membrane protrusions, respectively. Conversely, flow cytometry of murine CD34(+) bone marrow progenitors revealed the cell surface expression of prominin. Taken together, the data strongly suggest that the AC133 antigen is the human orthologue of prominin.

AC133 Antigen↗
PubMed2002

Antiapoptotic cytokine IL-3 + SCF + FLT3L influence on proliferation of gamma-irradiated AC133+/CD34+ progenitor cells.

Recovery from radiation-induced bone marrow aplasia depends on appropriate cytokine support. The aim of our work was to find a cytokine combination allowing in vitro gamma-irradiated (2.5 Gy) CD34+/AC133+ haematopoietic stem cells to evade radiation-induced apoptosis and to enhance damage reparation, which should enable proliferation and ex vivo expansion of cells. Cells were isolated using separation in a Cobe separator followed by immunomagnetic selection by antibody against the AC133 antigen. Thus isolated cells were 80% AC133+/CD34+ and 10% of them expressed the CD33+ antigen. Ten thousand of AC133+ cells formed 1146 CFU-GM and 304 BFU-E. We proved a high expansion efficiency of cytokine combination SCF + IL-3 + FLT3L in comparison with the combination SCF + IL-3 + IL-11 in both, non-irradiated cells and cells irradiated with a dose of 2.5 Gy. The D0 value for AC133+ cells was determined by the clonogeneity test. The D0 value for CFU-GM was estimated to be 1.08 Gy and for BFU-E 0.95 Gy. The results of DNA analysis showed that the majority of isolated AC133+ cells were in G0/G1 phase of the cell cycle. We proved that the dose of 2.5 Gy induced massive apoptosis (80%) of these cells without progression through the cell cycle, which indicates interphase cell death. Under the influence of cytokine combination (SCF + IL-3 + FLT3L), the surviving 20% of cells entered the cell cycle and, similarly to non-irradiated control cells, on 7th day 35% of cells were in S phase.

Apoptosis↗
PubMed2000

In vitro proliferation potential of AC133 positive cells in peripheral blood.

AC133 antigen is a novel marker for human hematopoietic stem/progenitor cells. In this study, we examined the expression and proliferation potential of AC133(+) cells obtained from steady-state peripheral blood (PB). The proportion of AC133(+) cells in the CD34(+) subpopulation of steady-state PB was significantly lower than that of cord blood (CB), although that of cytokine-mobilized PB was higher than that of CB. The proliferation potential of AC133(+)CD34(+) and AC133(-)CD34(+) cells was examined by colony-forming analysis and analysis of long-term culture-initiating cells (LTC-IC). Although the total number of colony-forming cells was essentially the same in the AC133(+)CD34(+) fraction as in the AC133(-)CD34(+) fraction, the proportion of LTC-IC was much higher in the AC133(+)CD34(+) fraction. Virtually no LTC-IC were detected in the AC133(-)CD34(+) fraction. In addition, the features of the colonies grown from these two fractions were quite different. Approximately 70% of the colonies derived from the AC133(+)CD34(+) fraction were granulocyte-macrophage colonies, whereas more than 90% of the colonies derived from the AC133(-)CD34(+) fraction were erythroid colonies. Furthermore, an ex vivo expansion study observed expansion of colony-forming cells only in the AC133(+)CD34(+) population, and not in the AC133(-)CD34(+) population. These findings suggest that to isolate primitive hematopoietic cells from steady-state PB, selection by AC133 expression is better than selection by CD34 expression.

AC133 Antigen↗
PubMed2000

Myeloid differentiation and maturation of SCF+IL-3+IL-11 expanded AC133+/CD34+ cells selected from high-risk breast cancer patients.

The AC133 antigen is selectively expressed on subset of CD 34+ cells isolated from leukapheresis products from high risk breast cancer patients receiving chemotherapy plus G-CSF. MiniMACS AC133+ isolated cells contained a mean of 85% (80-90) AC133+ cells. Enriched AC133+ cells coexpressed 80% CD34+, 6.6% CD33+ and 2% CD15+. Separated AC133+ cells contained 600 GFU-GM/10(4) cells and 70 BFU-E/10(4) cells. Flow-cytometric analysis indicated that AC133+ cells were isolated from cells population with low granularity (SS), while CD33+ a CD15+ cells had a high granularity. After a seven-day ex vivo expansion in the presence of SCF + IL-3 + IL11, the expansion of cells increased 19.4 times. The mean percentage of blasts decreased from 100% at the start of culture to 81% on day 3 and 30% on day 7. Promyelocytes were slow to appear with 10% present on day 3, but thereafter increased to 33% on day 7. The appearance of myelocytes and metamyelocytes lagged 3 days behind promyelocytes and continued to increase during culture to become the predominant (30%) cell type on day 7. Very few neutrophils (2%) were observed in any of the cultures on day 7. Monocytes or macrophages were not detected on day 7. By day 7 megakaryocytes were present at low levels (10%). The mean value of CFU-GM in the culture after day 7 of ex vivo expansion in the presence of SCF+IL-3+IL-11 had increased 45-fold, BFU-E 5-fold. After 7 days of expansion with IL-3+SCF+IL-11 cells expressed a mean of 12% CD34+, 8% AC133+, 59% CD33+ and 30% CD15+. The aim of this experiment was to determine whether ex vivo culture of peripheral blood AC133+ cells could generate sufficient numbers of progenitors to potentially abrogate cytopenia after transplantation and passive purging of tumor cells.

AC133 Antigen↗
PubMed1998

CD34+AC133+ cells isolated from cord blood are highly enriched in long-term culture-initiating cells, NOD/SCID-repopulating cells and dendritic cell progenitors.

The AC133 antigen is a novel antigen selectively expressed on a subset of CD34+ cells in human fetal liver, bone marrow, and blood as demonstrated by flow cytometric analyses. In this study, we have further assessed the expression of AC133 on CD34+ cells in hemopoietic samples and found that there was a highly significant difference between normal bone marrow and cord blood versus aphereses (p <0.0001) but not between bone marrow and cord blood. Most of the clonogenic cells (67%) were contained in the CD34+AC133+ fraction. Compared with cultures of the CD34+AC133- cells, generation of progenitor cells in long-term culture on bone marrow stroma was consistently 10- to 100-fold higher in cultures initiated with CD34+AC133+ cells and was maintained for the 8-10 weeks of culture. Only the CD34+AC133+ cells were capable of repopulating NOD/SCID mice. Human cells were detectable as early as day 20, with increased levels (67%) apparent 40 days post-transplantation. Five thousand CD34+AC133+ cells engrafted about 20% of the mice, while no engraftment was observed in animals transplanted with up to 1.2 x 10(5) CD34+AC133- cells. The CD34+AC133+ population was also enriched (seven-fold) in dendritic cell precursors, and the dendritic cells generated were functionally active in a mixed lymphocyte reaction assay. AC133+ cells should be useful in the study of cellular and molecular mechanisms regulating primitive hemopoietic cells.

AC133 Antigen↗
PubMed2001

[Fudenine, relative to blood glucose-control, is a novel membrane protein].

OBJECTIVE: To determine whether Fudenine is a novel membrane protein. METHODS: Green fluorescence protein(GFP) was used to localize Fudenine in vivo. GFP, as a control, was targeted to cytoplasm. Epithelial cell, CBRH7919, and non-epithelial cell, L-6TG, were cultured and transiently transfected by using the lipofectamine reagent. After 48 h, intact cells were examined with fluorescence microscope for Fudenine. RESULTS: Reporter plasmid pEGFP-N1, as a control, was expressed and localized to cytoplasm. But Fudenine, driven by the cytomegalovirus promoterenhancer contained in the pEGFP-N1 vector, was overexpressed and targeted to cellular membrane. CONCLUSIONS: Fudenine is a novel membrane protein. It may play the similar role with its homologues AC133 antigen and prominin in human and mouse, respectively. It might be involved in signaling transduction and regulate blood glucose metabolism in vivo.

AC133 Antigen↗
PubMed2001

Heparinized cadaveric organ donors (HCOD)--a potential source of hematopoietic cells for transplantation and gene therapy.

BACKGROUND: Hematopoietic stem cells (HSC) from unrelated HLA-matched heparinized cadaveric organ donors (HCOD) are a new potential source of cells for transplantation and gene therapy. In addition, these cells could also be used as adjuvant therapy to increase microchimerism and graft tolerance after transplantations of various solid organs. Our purpose was to develop an efficient method for harvesting hematopoietic cells from HCODs, METHODS: Bone marrow cells were harvested from pelvic bones and/or vertebral bodies from 50 adult HCODs before or up to 3 hr after disconnecting the donor from the respirator. Subsequently, we evaluated the hematological and gasometric parameters of aspirated marrow samples as well as the proliferative potential, viability, and expression of CD34 and AC133 antigens on these cells. RESULTS: We noticed that up to 2-3 hr after disconnecting the donor from the respirator bone marrow cavities do not clot and remain uninfected and that it is possible to aspirate bone marrow mononuclear cells in quantities sufficient to perform allotransplantation. Nevertheless, due to the developing hypoxia and acidosis of the hematopoietic microenvironment the number and proliferative potential of CD34+ and AC133+ cells gradually decreases. Hence, to obtain viable early hematopoietic cells, bone marrow should be aspirated without delay; optimally before HCOD is disconnected from the respirator or at the very latest 2 hr after organ harvest. CONCLUSIONS: Collectively, our results show that early hemopoietic cells may be efficiently harvested from HCOD in large quantities and used for research and/or transplantation purposes. We postulate to create an international network of banks in which hemopoietic stem cells from HCODs could be preserved for therapeutic purposes.

AC133 Antigen↗
PubMed2004

Erythropoiesis from adult but not fetal blood-derived CD133+ stem cells depends strongly on interleukin-3.

We have shown previously that erythropoiesis in cultures from fetal blood depends less on interleukin-3 (IL3) than erythropoiesis from adult blood. This paper explores if this is due to different proportions of stem cell sub-populations with different IL3 requirement, or to different IL3 requirement on fetal and adult stem cells in general. The CD133 (AC133) antigen is found on half of all CD34+ cells with erythropoietic potential and is thought to mark a primitive stem cell sub-population. This work compares the IL3 requirements of CD133+ and CD133-CD34+ cells derived from fetal (12-20 weeks) and adult blood. Erythropoiesis was monitored using flow cytometry and colony counting. Erythropoiesis from adult CD133+ but not CD133-CD34+ cells was dramatically delayed (6-8 days) in the absence of IL3. In cultures from fetal blood, both CD133+ and CD133-CD34+ cells showed only a small dependency on IL3. The ratio of erythroid colony-forming CD133+ cells to erythroid colony-forming CD34+ cells was 0.5-0.6 in adult and 0.2-0.4 in fetal blood. The differential IL3 dependency of erythropoiesis from fetal and adult blood CD133+ and CD133-CD34+ stem cells may be relevant for the choice and preparation of stem cells for clinical purposes.

AC133 Antigen↗
PubMed2000

A frameshift mutation in prominin (mouse)-like 1 causes human retinal degeneration.

The disks of vertebrate photoreceptors are produced by outgrowths of the plasma membrane. Hence genes that encode retinal proteins targeted to plasma membrane protrusions represent candidates for inherited retinal degenerations. One such candidate is the gene encoding human prominin (mouse)-like 1 (PROML1, previously known as AC133 antigen) which belongs to the prominin family of 5-transmembrane domain proteins. Murine prominin (prom) shows a strong preference for plasma membrane protrusions in a variety of epithelial cells whereas PROML1 is expressed in retinoblastoma cell lines and adult retina. In the present study, molecular genetic analyses of a pedigree segregating for autosomal recessive retinal degeneration indicated that the affected individuals were homozygous for a nucleotide 1878 deletion in PROML1. This alteration is predicted to result in a frameshift at codon 614 with premature termination of translation. Expression of a similar prom deletion mutant in CHO cells indicated that the truncated protein does not reach the cell surface. Immunocytochemistry revealed that prom is concentrated in the plasma membrane evaginations at the base of the outer segments of rod photoreceptors. These findings suggest that loss of prominin causes retinal degeneration, possibly because of impaired generation of the evaginations and/or impaired conversion of the evaginations to disks.

AC133 Antigen↗
PubMed2006

Development of goldfish macrophages in vitro.

Over 100 years after the first description of macrophages by Metchnikoff, there are still questions as to the mechanisms leading to the heterogeneity of their lineage. Current views are based on the mononuclear phagocyte system (MPS) theory, where all mammalian macrophages are derived from circulating blood monocytes and ultimately from hematopoietic stem cells in the bone marrow. Our studies on the regulation of fish macrophage development, suggested that teleosts have alternate pathways of monopoiesis, which undoubtedly contribute to macrophage heterogeneity in the goldfish. Macrophage heterogeneity has been attributed to a network of positive and negative regulators of macrophage development, including soluble mediators known as colony-stimulating factors of which two (M-CSF and GM-CSF) promote formation and growth of mature macrophages. In contrast to our knowledge of CSFs and their receptors in mammals, there is no published information about fish macrophage CSFs. Since fish macrophages generate their own growth factors, it is reasonable to assume that pathways of fish macrophage development and hematopoiesis may be distinct from those of mammalian macrophages. More importantly, the presence of fish progenitor/stem cells and developing macrophages in long-term cultures, allowed us to address pathways of macrophage differentiation, which could not be addressed in mammalian macrophage culture systems. Characterization of primary kidney macrophage (PKM) cultures from goldfish hematopoietic tissues (kidney) indicated that three distinct subpopulations developed in response to endogenous macrophage growth factors. These macrophage subpopulations expressed several differentiation markers, including the hematopoietic stem cell antigen AC133, c-kit, granulin, CD63, macrosialin, c/EBPbeta, legumain, and the colony-stimulating factor receptor-1 (CSF-1R). In the goldfish, there appeared to be a stringent control between those early progenitors that self-renewed, and those that were recruited into the maturation pathways. We report that upon commitment, goldfish macrophages developed through two distinct differentiation pathways: one consistent with the "classical" pathway (MPS) of macrophage development (progenitors-->monocytes-->mature macrophages), and an "alternate" pathway (AP-macrophages) where mature macrophages appeared to rapidly develop from early progenitors in the absence of an intermediate monocyte stage. AP-macrophages represent a unique subset of spontaneously growing cells. Their self-renewal was promoted by endogenous macrophage growth factors (MGF), and effectively controlled by a novel soluble form of the CSF-1R (sCSF-1R). The discovery of sCSF-1R in the goldfish highlights the inherent complexity in the hematopoietic regulatory machinery of teleosts.

Animals↗
PubMed1999

CD109 is expressed on a subpopulation of CD34+ cells enriched in hematopoietic stem and progenitor cells.

CD109 is a monomeric cell surface glycoprotein of 170 kD that is expressed on endothelial cells, activated but not resting T-lymphocytes, activated but not resting platelets, leukemic megakaryoblasts, and a subpopulation of bone marrow CD34+ cells. Observing an apparent association between CD109 expression and the megakaryocyte lineage (MK), we sought to determine whether CD109 was expressed on MK progenitors. In fetal bone marrow (FBM), a rich source of MK progenitors, CD109 is expressed on a mean of 11% of CD34- cells. Fluorescence activated cell sorting (FACS) of FBM CD34+ cells into CD109+ and CD109- fractions revealed that the CD34+CD109+ subset contained virtually all assayable MK progenitors, including the colony-forming unit-MK (CFU-MK) and the more primitive burst-forming unit-MK (BFU-MK). The CD34+CD109+ subset also contained all the assayable burst-forming units-erythroid (BFU-E), 90% of the colony-forming units-granulocyte/macrophage (CFU-GM), and all of the more primitive mixed lineage colony-forming units (CFU-mix). In contrast, phenotypic analysis of the CD34+CD109- cells in FBM, adult bone marrow (ABM) and cytokine-mobilized peripheral blood (MPB) demonstrated that this subset comprises lymphoid-committed progenitors, predominantly of the B-cell lineage. CD109 was expressed on the brightest CD34 cells identifiable not only in FBM, but also in ABM and MPB indicating that the most primitive, candidate hematopoietic stem cells (HSC) might also be contained in the CD109+ subset. In long-term marrow cultures of FBM CD34+ cells, all assayable cobblestone area forming cell (CAFC) activity was contained within the CD109+ cell subset. Further phenotypic analysis of the CD34+CD109+ fraction in ABM indicated that this subset included candidate HSCs that stain poorly with CD38, but express Thy-1 (CD90) and AC133 antigens, and efflux the mitochondrial dye Rhodamine 123 (Rho123). When selected CD34+ cells were sorted for CD109 expression and Rho123 staining, virtually all CAFC activity was found in the CD109+ fraction that stained most poorly with Rho123. CD34+ cells were also sorted into Thy-1 CD109+ and Thy-1 CD109+ fractions and virtually all the CAFC activity was found in the Thy-1+CD109+ subset. In contrast, the Thy-1-CD109+ fraction contained most of the short-term colony-forming cell (CFC) activity. CD109, therefore, is an antigen expressed on a subset of CD34+ cells that includes pluripotent HSCs as well as all classes of MK and myelo-erythroid progenitors. In combination with Thy-1, CD109 can be used to identify and separate myelo-erythroid and all classes of MK progenitors from candidate HSCs.

Adult↗
PubMed2001

AC133 expression on acute myeloid leukemia blasts: correlation to FAB and to CD34 expression and possible implications for peripheral blood progenitor cell purging in AML.

AC133 is an antigen expressed on CD34+ hematopoietic progenitor cells. In acute myeloid leukemia (AML) it is expressed on leukemic blasts of most FAB subtypes. However, few data are available regarding coexpression of other surface antigens. We measured AC133 expression on AML blasts from 28 consecutive patients at initial diagnosis (n=26) or at diagnosis of first relapse (n=2) and on 26 leukapheresis products from 14 patients. In AML AC133 correlated with CD34 expression (Spearman r=0.4711, P=0.0114) and even stronger with combined CD34/CD33 expression (Spearman r=0.5083, P=0.0068). In leukapheresis products AC133 expression correlated with CD34 expression (Spearman r=0.7495, P=0.002) and the yield of the obtained amount of CD34+ cells (Spearman r=0.6484, P=0.0121). In conclusion AC133 expression is closely related to CD34 expression in AML. In leukapheresis products AC133 provides an additional marker for selection of PBPC autografts in AC133- AML.

AC133 Antigen↗