PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Granulocyte Precursor Cells”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 919 records · Page 51Linked to original sources
PubMed1999

Serum granulocyte colony-stimulating factor levels in patients with chronic neutropenia of childhood: modulation of G-CSF levels by myeloid precursor cell mass.

The serum G-CSF levels of eight patients with severe congenital neutropenia (SCN) were found to be significantly higher than those of 22 patients with chronic benign neutropenia (CBN). The relative number of cells expressing the G-CSF receptor in light density bone marrow cells (LDBMC) was lower in patients with SCN than in patients with CBN or in normal subjects. When recombinant human G-CSF was incubated with LDBMC, G-CSF levels were decreased by LDBMC from normal subjects and CBN patients, but not by those from SCN patients. Serum G-CSF concentrations, which are affected by mature neutrophils, may also be modulated by myeloid precursor cells in the bone marrow.

Adolescent↗
PubMed1990

Acute myelomonocytic leukemia: an immunoelectron microscopic study.

Acute myelomonocytic leukemia (M4; French-American-British classification) is light microscopically defined as the leukemia constituting leukemic cells in both granulocytic and monocytic lineages. Therefore, the characteristics of M4 have not been fully elucidated. The author previously indicated that normal neutrophilic granulocytes could be ultrastructurally differentiated from normal monocytes by the double staining of lactoferrin and lysozyme. In this investigation, the ultrastructural localization of both proteins were observed in order to make the outline of M4 clear. The leukemic cells in acute myeloid leukemia (M2) were also examined in comparison with those in M4. The leukemic cells in M4 showed the double stainability of lactoferrin and lysozyme, and the positive reactions were localized in the cytoplasmic matrix and in the granules. The staining pattern was similar to that in M2. The coexistence of lactoferrin and lysozyme in the leukemic cells in M4, which has ultrastructurally the monocytic characteristics, implied that the leukemic cells also possess the characteristics of the cells in the granulocytic lineage. This suggests that the presence of the various leukemic cells in the granulocytic lineage. This suggests that the presence of the various leukemic cells signifies the diversely abnormal maturations in vivo of the monocytes/granulocytes precursor cell and that M4 consists of not two kinds of distinguishable cells of granulocytic and monocytic lineages but various consecutive cells based on a malignant transformation of the precursor cell.

Humans↗
PubMedDate not supplied

[Physiological (programmed) cell death in hemopoiesis].

According to current concepts, pluripotent cells proliferate and differentiate into "committed" precursors. These committed precursors divide, mature, and give rise to red cells, granulocytes, monocytes, and platelets of the blood. The life span of mature circulating cells being short, and their populations in the blood very stable, a constant and strict regulation of hematopoiesis is needed. The regulation of hematopoiesis is believed to be mediated through precursor cell interaction with specific molecules (glycoproteins) in their microenvironment. Soluble forms of these molecules are termed "hematopoietic growth factors" and include erythropoietin, colony-stimulating factors, interleukins, and stem cell factors. Hematopoietic growth factors not only stimulate the proliferation of precursor cells, but activate the differentiation program and maintain the viability of these cells as well. The normal fate of precursor cells devoid of these factors is programmed suicide. The morphology of such cell death is usually that of apoptosis, rather than of necrosis. The concept of apoptosis was proposed 22 years ago. Apoptosis is a widespread and morphologically distinct process of cell death. The significance of apoptosis stems from its active nature and its ability of controlling biological systems. The present review of published and authors' own data describes apoptosis morphology and presents evidence of the participation of cell reactions of this type in hematopoiesis regulation. The major point in the review is the balance of three normal processes: proliferation, differentiation, and apoptosis, which maintains the homeostasis of hematopoiesis, similarly as of any other cell system; it is well illustrated by recent findings in experimental and clinical hematology.

Adult↗
PubMed1992

Macrophage development: II. Early ontogeny of macrophage populations in brain, liver, and lungs of rat embryos as revealed by a lectin marker.

Earliest origins of macrophage populations in the central nervous system, the liver, and the lungs were studied in rat embryos aged between 10.5-11 days and 14 days of gestation, based on light and electron microscopic identification of macrophages using peroxidase-coupled isolectin B4 of Griffonia simplicifolia (GSA I-B4), which recognizes alpha-D-galactose groups on the cell membrane. During embryonic life macrophages and their precursors are GSA I-B4-positive and generally bereft of peroxidase-positive granules. At 10.5 days the yolk sac and embryonic circulations have just become joined, the brain has five vesicles but nerve cells are little differentiated, the liver exists as a diverticulum of the gut with fingerlike extensions of hepatocytes, and the lungs as a laryngotracheal groove. Macrophages and/or their precursors occurred in small numbers in embryonic mesenchyme and blood vessels but showed no special affinity for either liver or lung rudiments. The developing brain was the first organ to be colonized, beginning on prenatal day 12. The liver followed between days 12 and 13 and was succeeded by the lungs, beginning between days 13 and 14. Dividing macrophages were present in these organs at the outset of colonization and throughout the duration of the embryo series, indicating that from the beginning, replication of resident cells contributes to growth of the local population. Granulocyte precursors were first apparent in the liver around day 13; they are also GSA-positive but are distinguished from macrophages by their content of peroxidase-positive granules. Organ cultures of 13-day liver and lungs, and 14-day brain tissue, indicate that whereas isolated liver fragments support the formation of both granulocytes and macrophages, only the latter develop in brain or lung cultures. A resident population of macrophages evidently is set up very early in these organs, well before white cells colonize the spleen, bone marrow, and other future blood forming regions. The events outlined are seen as stages in an embryo-wide process that leads to establishment of macrophage populations in various organs.

Animals↗
PubMed1987

Growth of an interleukin 2/interleukin 4-dependent T cell line induced by granulocyte-macrophage colony-stimulating factor (GM-CSF).

Lymphokine activities in conditioned medium from activated helper T cell lines are most commonly defined by the proliferation of "specific" lymphokine-dependent cell lines. Various sublines of IL 2-dependent (and ostensibly specific) HT-2 and CTLL cells have now been shown to proliferate in response to BSF-1/IL 4 as well. After activation with antigen or mitogen, D10.G4.1, an antigen-specific cloned T helper cell that has recently been shown to produce IL 4 but not IL 2, secretes two distinct cytokines that induce the growth of HT-2 cells. These "T cell growth factors" (TCGF) can be separated by reversed phase high-performance liquid chromatography (RP-HPLC). The TCGF activity of one of these factors can be blocked by 11B11, an antibody specific for IL 4. The second TCGF activity is not affected by 11B11 or by antibodies specific for IL 2. This TCGF activity can be neutralized by a goat polyclonal antibody to granulocyte-macrophage colony-stimulating factor (GM-CSF), and has a RP-HPLC elution profile identical to that of recombinant GM-CSF. Recombinant GM-CSF induces both proliferation and long-term growth of HT-2 but not CTLL cells, and this activity can be neutralized by the same antibody to GM-CSF. GM-CSF is best known as a factor that induces the maturation and growth of granulocytes and macrophages from bone marrow-derived hematopoietic precursor cells. The ability of GM-CSF to induce the growth of certain T cell lines indicates that this molecule may play a role in T cell-mediated immune responses, either as an autocrine growth factor or a paracrine stimulus from both lymphoid and nonlymphoid tissues that produce this cytokine.

Animals↗
PubMed1995

Granulocyte-macrophage colony-stimulating factor signals for increased glucose uptake in human melanoma cells.

While the primary targets for granulocyte-macrophage colony-stimulating factor (GM-CSF) are hematopoietic precursors and mature myeloid cells, GM-CSF receptors (GMR) are also found on normal tissues including placenta, endothelium, and oligodendrocytes as well as certain malignant cells. The function of GMR in these nonhematopoietic cells is unknown. We studied the function of GMR in human melanoma cell lines. Six of seven cell lines tested (clones 1-5 and 3.44 of SK-MEL-131, SK-MEL-188, SK-MEL-23, SK-MEL-22, and SK-MEL-22A) expressed mRNA encoding the membrane-bound and soluble isoforms of the alpha subunit of the GMR. Melanoma cell lines in early stages of differentiation expressed the largest quantities of alpha-subunit mRNA. Although five of these lines expressed trace levels of mRNA encoding the beta subunit of the GMR, Scatchard analysis of equilibrium binding data derived from three of the cell lines showed that they expressed only low-affinity GMR. Clones 3.44 and 1-5 of SK-MEL-131, and SK-MEL-188 cells expressed receptors with a dissociation constant (kd) for GM-CSF in the following ranges: 0.7 to 0.8, 1.2 to 1.8, and 0.4 to 0.8 nmol/L, respectively. GM-CSF stimulated glucose uptake in four of the melanoma cell lines expressing the alpha subunit, presumably through facilitative glucose transporters, as uptake was blocked by cytochalasin B but not cytochalasin E. Stimulation of glucose uptake was transient, with maximum stimulation occurring at approximately 30 minutes in the presence of 1 nmol/L GM-CSF. GM-CSF stimulated glucose uptake 1.4- to 2.0-fold but did not stimulate cell proliferation. These results suggest a metabolic role for the low-affinity GMR in melanoma cell lines and indicate that the alpha subunit of the GMR can signal for increased glucose uptake in nonhematopoietic tumor cells.

Base Sequence↗
PubMed1988

The influence of histamine on precursors of granulocytic leukocytes in murine bone marrow.

The effect of histamine on granulocytic progenitor cells in murine bone marrow was studied in vitro. When bone marrow cells were cultured for three days with the drug, 10(-8) M to 10(-5) M of histamine stimulated differentiation and proliferation of myeloid precursor cells. Subsequently, the number of descendant cells, such as metamyelocytes and neutrophils, increased dose-dependently. Co-existence of equimolar H2 blockers such as cimetidine and ranitidine completely suppressed this effect of histamine, though this was not the case with an H1 blocker/histamine combination. Significant increase in 3H-thymidine incorporation was observed almost exclusively in myeloblasts, promyelocytes and myelocytes after exposure to histamine at concentrations higher than 10(-8) M. Also, selective incorporation of 3H-histamine into bone marrow cells was observed in myeloblasts and promyelocytes, but histamine incorporation was not influenced by the presence of either of histamine agonists or antagonists. While histamine, via H2 receptors, selectively increased the number of granulocytic colony forming units in culture (CFU-C), it had no such effect on macrophage colonies. Considering these findings, it was concluded that histamine promotes proliferation and differentiation of granulocytic myeloid cells via 1) H2 receptors in the CFU-C stage and 2) histamine receptors which are neither H1 nor H2 in the stages of myeloblast and promyelocyte differentiation.

Animals↗
PubMed1999

A secreted proform of neutrophil proteinase 3 regulates the proliferation of granulopoietic progenitor cells.

Myeloid leukemia cells, the human promyelocytic cell line HL-60, and a subpopulation of normal marrow cells produce a leukemia-associated inhibitor (LAI) that reversibly downmodulates DNA synthesis of normal granulopoietic progenitor cells colony-forming unit granulocyte-macrophage (CFU-GM). We isolated an active 125-kD component of LAI from HL-60 conditioned medium (CM), subjected it to cyanogen bromide cleavage and show by amino acid sequencing of the resulting peptides that it consists of a complex of the serine proteinase inhibitor alpha1-antitrypsin and a 31-kD fragment that retained the S-phase inhibitory activity, but resisted sequencing. This finding suggested that the 31-kD fragment originated from one of the neutrophil serine proteases (ie, elastase, proteinase 3, or cathepsin G) produced by normal promyelocytes, as well as HL-60 cells, for storage in primary granules and partly secreted during synthesis as enzymatically inactive proforms. Immunoblot analysis showed that the 125-kD complex contained proteinase 3 (PR3), and immunoprecipitation of PR3 from HL-60 CM abrogated the S-phase inhibitory activity, whereas immunoprecipitation of cathepsin G or elastase did not. Immunoprecipitation of PR3 from CM of a subpopulation of normal marrow cells also abrogated the S-phase inhibitory effect. Furthermore, CM from rat RBL and murine 32D cell lines transfected with human PR3 both reduced the fraction of CFU-GM in S-phase with 30% to 80% at 1 to 35 ng/mL PR3, whereas CM of the same cells transfected with cathepsin G or elastase did not. Also, an enzymatically silent mutant of PR3 exerted full activity, showing that the S-phase modulatory effect is not dependent on proteolytic activity. Amino acid sequencing of biosynthetically radiolabeled PR3 showed that PR3 from transfected cells is secreted after synthesis as proforms retaining amino terminal propeptides. In contrast, mature PR3 extracted from mature neutrophils has only minor activity. The inhibitory effect of secreted PR3 is reversible and abrogated by granulocyte (G)- or granulocyte-macrophage colony-stimulating factor (GM-CSF). Experiments with highly purified CD34(+) bone marrow cells suggested that PR3 acts directly on the granulopoietic progenitor cells. These observations suggest a role for PR3 in regulation of granulopoiesis, and possibly in suppression of normal granulopoiesis in leukemia.

Cell Division↗
PubMed1988

Transforming growth factor beta inhibits formation of osteoclast-like cells in long-term human marrow cultures.

Transforming growth factor beta (TGF-beta), a polypeptide present in abundant amounts in bone matrix, was examined for its effects on osteoclast formation by using a human bone marrow culture system in which multinucleated cells (MNCs) with osteoclast characteristics form. TGF-beta strongly inhibited MNC formation at concentrations as low as 1 ng/ml. TGF-beta also completely suppressed the effects of osteotropic factors known to stimulate MNC formation. The inhibitory effect of TGF-beta on osteoclast-like cell formation was more pronounced during the first week of culture, which corresponds to the period of proliferation of mononuclear osteoclast precursors. To examine whether the inhibitory effects of TGF-beta on MNC formation could be due to inhibition of the granulocyte/macrophage progenitor cell [colony-forming unit granulocyte/macrophage (CFU-GM)], the probable precursor for MNC, we tested the effects of TGF-beta on CFU-GM formation in presence of a source of colony-stimulating factor. Unexpectedly, TGF-beta at concentrations (0.1-1 ng/ml) that were inhibitory for MNC formation enhanced day 7 CFU-GM colony formation. This increase in CFU-GM colony formation seen in cultures containing TGF-beta resulted from significantly more granulocytic colonies being formed in the cultures, suggesting that TGF-beta may induce CFU-GM to differentiate preferentially to cells of the granulocytic lineage. Differentiation of CFU-GM to granulocytes rather than osteoclast precursors in response to TGF-beta would result in inhibition of MNC formation by depleting the precursor pool for MNC. These data suggest that inhibition of osteoclast-like cell formation by TGF-beta may be an important mechanism of control of local bone resorption.

Bone Marrow↗
PubMed1982

Suppressive effect of rabbit anti-mouse brain serum (RAMBS) on murine pluripotent hemopoietic precursors in vitro and committed early erythrocytic and macrophage-granulocytic precursors detected after brief in vivo passage.

Antisera to mouse brain tissue have activity against mouse pluripotent hemopoietic stem cells (CFUS). In contrast to the suppressive effect of the antisera on in vivo colony formation of CFUs, it is known that in vitro colony formation from committed precursors, such as macrophage-granulocytic precursors (CFUC) and late erythrocytic precursors (CFUE) is not significantly suppressed. In the present experiments, the influence of rabbit anti-mouse brain serum (RAMBS) on colony formation from early erythrocytic precursors (BFUE) and pluripotent hemopoietic precursors in vitro (CFUMIX) was investigated. The number of colonies from both CFUMIX and BFUE did not decrease after preincubation with RAMBS and complement. However, when RAMBS-treated CFUMIX, BFUE, and CFUC were briefly exposed to an in vivo environment, all these precursors were almost completely removed, and also, CFUMIX, BFUE and CFUC seemed to share RAMBS reactivity.

Animals↗
PubMed1987

Histamine-producing cell-stimulating activity. Interleukin 3 and granulocyte-macrophage colony-stimulating factor induce de novo synthesis of histidine decarboxylase in hemopoietic progenitor cells.

Both interleukin 3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) induce increased histamine production by murine hemopoietic cells. Histidine-free culture conditions or addition of alpha-fluoromethylhistidine, an irreversible inhibitor of histidine decarboxylase, completely abrogate this phenomenon, indicating that increased histamine levels result from an augmentation of the rate of its synthesis. L-Histidine decarboxylase (HDC) (EC 4.1.1.22) activity is detected in normal bone marrow cell lysates. It is markedly increased following incubation of the cells with IL-3 or GM-CSF. The cells responding by the most important enhancement of HDC activity are located in the less dense layers of a discontinuous Ficoll gradient containing the majority of the hemopoietic progenitor cell types, such as colony-forming units (spleen), granulocyte-macrophage colony-forming cells, and mast cell precursors. In comparison with other HDC-containing cell populations tested, the enzymatic activity contained in these cells is particularly high after IL-3 or GM-CSF treatment and similar to the HDC levels observed in murine fetal liver. The time course of IL-3 and GM-CSF-induced HDC activation at comparable concentrations is slightly different. In response to GM-CSF, HDC activation is more rapid, with a significant enhancement after 4 hr of incubation, as compared with IL-3-induced HDC activation. Moreover, in the latter case the activation increases more progressively up to 48 hr of incubation, whereas GM-CSF-induced increase of HDC activity reaches a plateau more rapidly. In addition, maximal increase in histamine production in response to IL-3 is always higher than in response to GM-CSF. Moreover, the simultaneous presence of both factors at optimal concentration induces only a partially cumulative effect. These results suggest that IL-3 and GM-CSF induce HDC activation in two distinct ways, possibly reflecting the involvement of distinct target cells. However, both mediators act by inducing the transcription of the HDC gene and de novo synthesis of this enzyme since actinomycin D or cycloheximide abolish GM-CSF-or IL-3-induced histamine-producing cell-stimulating activity. This synthesis is independent from cell proliferation as demonstrated by the lack of effect of bone marrow cell irradiation. Finally, the observation that cholera toxin, prostaglandin E2, and N6,2'-O-dibutyryl adenosine 3',5'-cyclic monophosphate mimic the effects of IL-3 and GM-CSF on bone marrow cell HDC suggests an involvement of cyclic adenosine monophosphate in factor-induced histamine-producing cell-stimulating activity.

Animals↗
PubMed1991

[In vitro identification of a mononuclear precursor of osteoclast].

Osteoclast is derived from mononuclear hematopoietic stem cells, most likely within the granulocyte-macrophage lineage. The exact differentiation process of osteoclasts precurssors has only been partially uncovered. The authors isolated in vitro, from the medullary bone of hens a mononuclear precursor of the osteoclast. This cell expressed several characteristics of mature and multinucleated osteoclast including the capacity to resorb the extracellular bone matrix.

Animals↗
PubMed1993

Major histocompatibility complex class II molecules, hemopoiesis and the marrow microenvironment.

Currently available data indicate that the earliest identifiable hemopoietic progenitor in normal marrow is CD34+ MHC class II-; subsequent expression of MHC class II antigens is maturation and lineage dependent. Studies on embryonal cells suggest that CD34+DR- cells are actually the common precursors for stromal and hemopoietic elements, with the earliest hemopoietic precursor being CD34+DR+. DQ antigens are apparently not expressed in cells of hemopoietic potential and the expression of DQ appears to be regulated differentially from DR and DP. MHC class II antigens are also expressed on some stromal cells, especially those with endothelial and macrophage features. MHC class II molecules are involved in hemopoietic cell/stroma interaction. The presence of anti-MHC class II monoclonal antibodies (MABs) at early stages of stem cell proliferation/differentiation, at least under conditions of marrow stress, induces signals which may result in final, especially granulocytic, differentiation of later precursors. These may interfere with the survival of those cells which are required for long-term hemopoietic reconstitution. Observations in allogeneic marrow transplant recipients support a role of MHC molecules as expected in allogeneic interactions. Results in autologous models point towards a role of MHC class II molecules other than that of a histocompatibility marker insofar as these molecules or signals transmitted by them appear to be involved in the regulation of hemopoiesis.

Bone Marrow↗
PubMed2001

p75/AIRM1 and CD33, two sialoadhesin receptors that regulate the proliferation or the survival of normal and leukemic myeloid cells.

Inhibitory receptors originally identified in natural killer (NK) cells have also been detected in other leukocyte types, thus suggesting that they may play a more general role in the control of leukocyte function. Here we report data on p75/adhesion receptor molecule 1 (AIRM1), a surface inhibitory receptor of the sialoadhesin family originally identified in NK cells that is also expressed by normal and leukemic myeloid cells. Given the homology between p75/AIRM1 and CD33, we also reanalyzed CD33, a major myeloid marker of still unknown function. We discuss recent data indicating that engagement of p75/AIRM1 or CD33 sharply inhibits the in vitro proliferation/differentiation of CD34+ myeloid precursors induced by stem cell factor and granulocyte-macrophage colony-stimulating factor. Importantly, a similar in vitro inhibitory effect occurs in monocyte/macrophages as well as in chronic or acute myeloid leukemias. While CD33 appears to act via the induction of apoptosis, p75/AIRM1 blocks cell proliferation but does not appear to induce apoptosis. A synergistic effect in the induction of apoptosis has also been documented between antibodies specific for CD33 and the chemotherapic agent etoposide. Taken together, the use of appropriate ligands against CD33 or p75/AIRM1 may represent a new therapeutic tool for treatment of myeloid leukemias or diseases characterized by overwhelming macrophage activation.

Antigens, CD↗
PubMed2003

Dendritic cells infected with adenovirus expressing the thyrotrophin receptor induce Graves' hyperthyroidism in BALB/c mice.

Dendritic cells (DCs) are the most potent antigen-presenting cells and a prerequisite for the initiation of primary immune response. This study was performed to investigate the contribution of DCs to the initiation of Graves' hyperthyroidism, an organ-specific autoimmune disease in which the thyrotrophin receptor (TSHR) is the major autoantigen. DCs were prepared from bone marrow precursor cells of BALB/c mice by culturing with granulocyte macrophage-colony stimulating factor and interleukin-4. Subcutaneous injections of DCs infected with recombinant adenovirus expressing the TSHR (but not beta-galactosidase) in syngeneic female mice induced Graves'-like hyperthyroidism (8 and 35% of mice after two and three injections, respectively) characterized by stimulating TSHR antibodies, elevated serum thyroxine levels and diffuse hyperplasitc goiter. TSHR antibodies determined by ELISA were of both IgG1 (Th2-type) and IgG2a (Th1-type) subclasses, and splenocytes from immunized mice secreted interferon-gamma (a Th1 cytokine), not interleukin-4 (a Th2 cytokine), in response to TSHR antigen. Surprisingly, IFN-gamma secretion, and induction of antibodies and disease were almost completely suppressed by co-administration of alum/pertussis toxin, a Th2-dominant adjuvant, whereas polyriboinosinic polyribocytidylic acid, a Th1-inducer, enhanced splenocyte secretion of IFN-gamma without changing disease incidence. These observations demonstrate that DCs efficiently present the TSHR to naive T cells to induce TSHR antibodies and Graves'-like hyperthyroidism in mice. In addition, our results challenge the previous concept of Th2 dominance in Graves' hyperthyroidism and provide support for the role of Th1 immune response in disease pathogenesis.

Adenoviridae↗
PubMed2003

Effect over time of in-vivo administration of the polysaccharide arabinogalactan on immune and hemopoietic cell lineages in murine spleen and bone marrow.

Current evidence indicates an immunostimulating role for complex carbohydrates, i.e., polysaccharides, from several plant sources. In the present work, we determined the specific in vivo effects, with time of administration, of one such compound, a neutral arabinogalactan from larch not only on immune (lymphoid) cells, but also on natural killer (NK) lymphoid cells, as well as a variety of other hemopoietic cells in both the bone marrow and spleen of healthy, young adult mice. The latter were injected daily (i.p.) with arabinogalactan (500 microg in 0.1 ml pH 7.2 phosphate buffered saline-PBS) for 7 or 14 days. Additional, aged (1 1/2-2 yr) mice were similarly injected for 14 days only. Control mice were given the PBS vehicle in all cases, following the above injection regimen. Animals from all groups were sampled 24 h after the final injection and the immune and hemopoietic cell populations in the bone marow and spleen were assessed quantitatively. The results indicated that immediately following either 7 or 14 days of arabinogalactan administration to young, adult mice, lymphoid cells in the bone marrow were significantly decreased (p < 0.004; p < 0.001, respectively) relative to controls but remained unchanged at both time intervals in the spleen. NK cells, after 7 days of arabinogalactan exposure, were also decreased significantly in the bone marrow (p < 0.02), but unchanged in the spleen. After 14 days' exposure to the polysaccharide, NK cells in the bone marrow had returned to normal (control) levels, but were increased in the spleen (p < 0.004) to levels greater than 2-fold that of control. Among other hemopoietic cell lineages, none was influenced in the bone marrow or spleen by one-week administration of arabinogalactan; however, after two-week exposure, precursor myeloid cells and their mature (functional) progeny (granulocytes), were significantly reduced in the spleen (p < 0.043; p < 0.006, respectively), as were splenic monocytes (p < 0.001). These lineages in the bone marrow, however, remained steadfastly unaltered even after 14 days of continuous exposure to the agent. Of the vast cascade of cytokines induced in the presence of this polysaccharide, it appears that immunopoiesis- and hemopoiesis-inhibiting ones are most prevalent during at least the first two weeks of daily exposure.

Animals↗