Biomedical subjects

K Hestdal

Publications and source records attributed to K Hestdal.

22 records · Page 2Linked to original sources

PubMed1992

In vivo effect of interleukin-1 alpha on hematopoiesis: role of colony-stimulating factor receptor modulation.

To determine the mechanism(s) by which interleukin-1 (IL-1) promotes granulopoiesis in vivo, we examined the effect of in vivo administration of IL-1 alpha on colony-stimulating factor (CSF) receptor expression on bone marrow cells (BMCs) and whether this directly correlated with progenitor cell responsiveness. Administration of IL-1 alpha to mice induced the upregulation of both granulocyte-macrophage-CSF (GM-CSF) and IL-3 receptors, which reached a maximum 24 hours after IL-1 alpha injection on unfractionated BMCs. This upregulation was more pronounced on the progenitor-enriched cell population (lineage-negative [Lin(-)]). The enhanced GM-CSF and IL-3 receptor expression directly correlated with enhanced IL-3- or GM-CSF-induced growth of colony-forming unit-culture (CFU-c) or CFU-mixture (CFU-Mix; colonies containing macrophages, granulocytes, and erythroid cells). In addition, the absolute number of high proliferative potential-colony-forming cells (HPP-CFC) was increased fivefold. In contrast, granulocyte-CSF (G-CSF)-specific binding on unfractionated BMCs was rapidly (4 hours) reduced after IL-1 alpha administration and returned to control levels by 24 hours. This reduction correlated with IL-1 alpha-induced margination of mature granulocytes (RBC-8C5hi cells), which express high levels of G-CSF receptors. IL-1 alpha treatment did not affect G-CSF receptor expression on Lin- cells. Pretreatment of mice with anti-type I IL-1 receptor antibody blocked the IL-1 alpha-induced upregulation of GM-CSF and IL-3 receptor expression on BMCs. Taken together, as one possible mechanism, IL-1 alpha in vivo may stimulate the expression of functional GM-CSF and IL-3 receptors on BMCs indirectly, and, in concert with the induction of circulating CSF levels, may account for the ability of IL-1 alpha to stimulate hematopoiesis in vivo.

Animals↗

PubMed1992

Transforming growth factor-beta: a bidirectional regulator of hematopoietic cell growth.

It is now apparent that the transforming growth factor-beta (TGF-beta) family of proteins has potent hematopoietic regulatory properties ranging from effects on the growth and differentiation of primitive stem cells to the differentiated functions of mature cells. Although most reports have described the inhibitory activities of TGF-beta on hematopoiesis, recent evidence supports the concept that TGF-beta can have both inhibitory and stimulatory actions on these systems. These differences depend on the differentiation state of the target cell and the other cytokines interacting with the cell. Furthermore, TGF-beta has direct bidirectional effects on cell surface expression of many cytokine receptors suggesting that it is part of the mechanism of action of TGF-beta. The major biological effect of TGF-beta on hematopoietic cell growth is the reversible inhibition of entry into the cell cycle. Importantly, the effect of in vivo administration of TGF-beta has mimicked the in vitro effects. Ultimately, well designed clinical trials will determine whether the exciting potential of TGF-beta can be used to treat or prevent myelotoxicity and other bone marrow dysfunctions.

Animals↗

PubMed1991

In vivo interleukin-1 (IL-1) administration indirectly promotes type II IL-1 receptor expression on hematopoietic bone marrow cells: novel mechanism for the hematopoietic effects of IL-1.

Interleukin-1 (IL-1) has profound stimulatory effects on hematopoiesis but the mechanism(s) of action remain unknown. The direct action of IL-1 on hematopoietic progenitor cells requires the presence of a specific IL-1 receptor (IL-1R). In this report, we tested the effect of in vivo IL-1 treatment on the expression of IL-1R on bone marrow (BM) cells. Injection of mice with IL-1 results in a marked upregulation of IL-1R on light-density BM cells as on a subpopulation enriched for myeloid precursors. Pretreatment of mice with anti-type I IL-1R antibody (35F5), which has been shown to prevent the radioprotective effect of IL-1, also blocked IL-1-induced IL-1R expression on BM cells. This antibody did not directly bind and block IL-1 binding to the type II IL-1R expressed on hematopoietic cells, suggesting that IL-1R upregulation by IL-1 is indirect. It is therefore possible that IL-1 acts on type I IL-1R-expressing accessory cells such as stromal cells or T cells to induce production of hematopoietic growth factors (HGFs). In support of this, granulocyte colony-stimulating factor administration can induce the increase of IL-1R on BM cells. Thus, the increased expression of IL-1R on hematopoietic BM cells by IL-1 is indirect, probably mediated in part through endogenous HGF production. These results also suggest that the restorative hematopoietic effect of IL-1 occurs through both indirect and direct mechanisms.

Animals↗

PubMed1991

Characterization and regulation of RB6-8C5 antigen expression on murine bone marrow cells.

Murine bone marrow cells expressing the cell surface Ag RB6-8C5 were identified by fluorescence-activated cell-sorting analysis using a rat IgG mAb. The fluorescent intensity of RB6-8C5 was variable on bone marrow cells. This made it possible to separate bone marrow cells into distinct subpopulations, RB6-8C5neg, RB6-8C5lo, and RB6-8C5hi cells. Morphologic analysis of the sorted populations demonstrated that the Ag was expressed on myeloid cells. The expression of RB6-8C5 increases with granulocyte maturation, whereas expression is transient on cells in the monocytic lineage. The RB6-8C5hi sorted cells were enriched for end-stage neutrophils (75%), whereas the RB6-8C5lo sorted cells contained more immature myeloid cells and myelocytes (75%). Lymphocytes and macrophages were less than 5% in any RB6-8C5+ population, whereas the erythroid precursors were RB6-8C5neg. The colony forming unit culture (CFU-C) (greater than 90%) were found in the RB6-8C5neg and RB6-8C5lo populations, and all the CFU-granulocyte, erythroid, megakaryocyte, and macrophage (CFU-GEMM) and burst-forming units-erythroid (BFU-E) were in the RB6-8C5neg population. Granulocyte-macrophage-CSFR (GM-CSFR) and IL-1 alpha R were expressed on RB6-8C5hi bone marrow cells, whereas no receptors could be detected on RB6-8C5neg and RB6-8C5lo cells. The expression of the RB6-8C5 Ag can be induced on RB6-8C5neg cells in liquid culture by IL-3 and granulocyte-macrophage CSF. Thus, RB6-8C5 is a myeloid differentiation Ag whose expression can be regulated by cytokines.

Animals↗