Marrow reticulo-fibroblastoid colonies (CFU-RF derived) spontaneously release an erythroid colony (BFU-E) enhancing factor.
The marrow microenvironment is composed of an extracellular matrix as well as a heterogeneous population of cells. Isolation of the various cell types and analysis of their function is necessary for a better understanding of their roles in hemopoiesis. We have recently reported a colony assay for a cellular component of the marrow microenvironment. The assay consists of a cellular component of the marrow microenvironment. The assay consists of a plasma clot-methylcellulose marrow culture. The stimulator is PHA-stimulated leukocyte conditioned medium (PHA-LCM) and hydrocortisone (5 x 10(-5)M). The fibrin strands appear to act as a substrate for the growth of Reticulo-Fibroblastoid colonies derived from the CFU-RF precursor. RF colonies can be subcultured forming adherent layers when transferred to liquid cultures. Confluent adherent layers can be maintained for long periods of time by changing medium every 3 to 5 days. Supernatants derived from unstimulated RF cultures (RF-CM) were tested for growth promotion of hemopoietic precursors. We found: (1) RF-CM by itself does not induce colony formation. (2) In the presence of erythropoietin, RF-CM enhances the growth of BFU-E. (3) Recombinant IL 4 also enhances BFU-E formation, but in our assays IL 4 induced fewer colonies than RF-CM and the colonies were smaller. (4) Because neither IL 4 nor RF-CM, by themselves, can stimulate colony formation, we compared the effect of RF-CM on assays that are known to show other IL 4 functions. RF-CM did not induce proliferation of PHA induced blast T cells, a known property of IL 4.(ABSTRACT TRUNCATED AT 250 WORDS)
Izaguirre
C A
CA
Department of Medicine, University of Ottawa, Canada.
Ross
W M
WM
Hsu
E Y
EY
D001402:B-Lymphocytes / Q000166:cytology; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D002648:Child; D003114:Colony-Forming Units Assay; D003115:Colony-Stimulating Factors / Q000494:pharmacology; D003470:Culture Media; D004920:Erythropoiesis; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4; D007378:Interleukins / Q000494:pharmacology; D008213:Lymphocyte Activation; D008747:Methylcellulose; D013601:T-Lymphocytes / Q000166:cytology
D003115:Colony-Stimulating Factors; D003470:Culture Media; D006133:Growth Substances; D007376:Interleukin-2; D007378:Interleukins; D015847:Interleukin-4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D008747:Methylcellulose