| Abstrakt: |
Eicosanoid release during multilineage hematopoiesis was assessed using freshly isolated mouse bone marrow cells cultured in the presence of interleukin-3 (IL-3) (10% WEHI-3 culture-conditioned medium). Cells that could release prostaglandin E, (PGE2) when stimulated with calcium ionophore A23187, but not with phorbol ester (PMA), appeared within 4 days. The cells harvested on day 10 released 42 ng of PGE2/108cells/mL after A23187 stimulation. Leukotriene B4(LTB4) (4 ng/mL) was also detected after A23187 stimulation, but there was no detectable LTC4(less than 0.5 ng/mL). Nonadherent bone marrow cells were isolated from 28-day cultures and cloned. All clones were strongly IL-3-dependent. Although other growth factors such as granulocyte colony-stimulating factor (G-CSF). granulocytemacrophage CSF (GM-CSF), and CSF-1 failed to promote survival or support proliferation of the cells, three clones (1 1-1 -A6, 3-2-D5, and 11 -1 -A1 ) showed significant increases in 3H-thymidine incorporation, respectively, after PMA treatment for 24 hours. Surviving cells displayed dominantly myeloid type morphology and phenotypic characteristics. The data suggest that IL-3 is important in the formation of PGE2-producing cells. In contrast to many macrophages (Md), neither the IL-3-dependent cell lines nor the IL-3-cultured bone marrow cells released significant amounts of PGE2when stimulated with PMA or IL-3, although PMA and IL-3 both induced translocation of protein kinase C (PKC) to the membrane fraction. The lack of production of PGE, and other eicosanoids by the PMAand IL-3-stimulated cell lines was confirmed by measuring the release of 3H-arachidonic acid. The data suggest that in IL-3-dependent bone marrow cell lines the activation of eicosanoid metabolism requires elevated cellular Ca2+; PKC activation alone does not appear to be a sufficient stimulus. |
