Mouse stromal cell lines (MSS lines) have been established from the spleens of newborn mice in culture at a low serum concentration. These MSS lines support the proliferation and differentiation of the erythroid progenitor cells from mouse fetal livers and bone marrow in a semisolid medium in the presence of erythropoietin. Larger colonies of over 1,000 benzidine-positive erythroid cells were d...

Many of the models of hemopoiesis that have been proposed (see, for example, Cronkite et al., '59) are based on the assumption that the continued production of blood cells requires the presence of progenitor cells with the capacity for continued proliferation. From this point of view, hemopoietic tissue may be considered to consist of two compartments; the first, or stem cell compartment, consi...

We have developed an in vitro clonal assay of murine hematopoietic precursor cells that form spleen colonies (CFU-S day 12) or produce in vitro clonable progenitors in the marrow (MRA cells) of lethally irradiated mice. The assay is essentially a long-term bone marrow culture in microtiter wells containing marrow-derived stromal "feeders" depleted for hematopoietic activity by irradiation. To t...

Murine bone marrow and adherence-separated spleen cells cultured on hydrophobic, gas-permeable Teflon foils (petriperm dishes) can be shown to synthesize and secrete erythropoietin (Epo) and colony-stimulating activity (CSA) simultaneously into the surrounding medium. The Epo activity in the supernatants of primary cultures as measured by the fetal liver erythroid colony-forming technique, from...

Mice were irradiated repetitively at 6 wk intervals. The proliferative capacity of the hematopoietic stem cell compartment was studied after each irradiation and compared to that of age-matched controls which had been irradiated only once. Hematopoietic proliferation capacity was measured by determining the number of spleen colonies, splenic iron uptake, spleen weight, and volume of packed red ...

Peripheral blood stem cells and progenitor cells, collected during recovery from exposure to cytotoxic agents or after cytokine administration, are being increasingly used in clinical bone marrow transplantation. To determine factors important for mobilization of both primitive stem cells and progenitor cells to the blood, we studied the blood and splenic and marrow compartments of intact and s...

We investigated the effects of B cell stimulatory factor 2/interleukin 6 (BSF-2/IL-6) on the development of murine hemopoietic progenitors using serum-containing culture and serum-free culture. In serum-containing culture, BSF-2 mainly supported multipotential blast cell colonies from spleen cells of normal and 5-fluorouracil (5-FU)-treated mice. In serum-free culture, no colony growth was seen...

Two distinct clones of Friend spleen focus-forming virus (SFFV), differing in their erythroleukemic potential, are described. These isolates have been cloned free of their associated helper viruses and shown to be replication-defective. Both SFFV isolates have been rescued from rat fibroblast nonproducer cell clones with cloned replication-competent viruses, F-MuLVA and F-MuLVP, obtained from t...

The treatment of mice with high doses of 5-fluorouracil (5-FU) results in an enrichment of primitive hematopoietic progenitors. Using this procedure, we obtained a new class of murine hematopoietic colonies that had very high secondary plating efficiencies in vitro and could differentiate into not only myeloid cells but also into lymphoid lineage cells. The phenotypes of interleukin-3 (IL-3) in...

The genetically anemic W/W° mice are characterized by the inability of their bone marrow cells to form macroscopic pluripotent hematopoietic colonies in the spleen ofirradiated recipients upon transfer (colony-forming units) . Furthermore, they almost totally lack mast cells, notably in the skin . In the present study, we have tested the effect of recombinant murine interleukin 3 (rmIIr3) on W/...