Influence in vitro of IL-3/Epo fusion proteins compared with the combination of IL-3 plus Epo in enhancing the proliferation of single isolated erythroid and multipotential progenitor cells from human umbilical cord blood and adult bone marrow

L. Lu, M. Xiao, Z. H. Li, L. K. Jolliffe, S. Jones, H. E. Broxmeyer, N. Weich

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Human interleukin-3/erythropoietin (IL-3/Epo) fusion proteins have been constructed, expressed, and tested for biological activity. These fusion proteins were previously shown to be active on erythroid progenitors (BFU-E) from unseparated human bone marrow. We evaluated if these fusion proteins could stimulate erythroid and multipotential progenitor cells directly at the single-cell level. Two IL-3/Epo fusion proteins containing short (SL-3E, two amino acids) and long (IL-3E, 23 amino acids) linker sequences as well as a short linker Epo/IL-3 sequence (SL-E3, three amino acids) were tested. Highly enriched CD34+++ or BFU-E enriched CD34+++CD33- cells from human umbilical cord blood or CD34+++HLA-DR+CD33- cells from normal adult bone marrow were sorted as single cells into single wells. The combination of Epo plus IL-3 synergized to enhance the proliferation of BFU-E and multipotential progenitors (CFU-GEMM) in comparison to the individual effects : of these cytokines. The three fusion proteins also enhanced proliferation of BFU-E and CFU-GEMM at the single-cell level and were at least as active as the combination of Epo and IL-3, demonstrating that IL-3/Epo fusion proteins directly stimulate proliferation of BFU-E and CFU-GEMM and that biological activity of IL-3 and Epo in vitro can be maintained when these proteins are fused. The activity of the combination of Epo and IL-3 or the fusion proteins was partially neutralized by preincubation with monoclonal antibodies to either Epo or IL-3 and was neutralized by greater than 90% by the combination of both antibodies, suggesting that the Epo and IL-3 components of the fusion proteins were both involved in the enhancing activity of these proteins. Additionally, use of monoclonal antibody to the human Epo receptor completely blocked the stimulating/enhancing activity of Epo alone, Epo plus IL-3, or the fusion proteins for stimulation of colony formation by BFU-E and CFU-GEMM but not for granulocyte-macrophage progenitors (CFU-GM), suggesting that the enhancing effects of the fusion proteins are most likely mediated, at least in part, by the Epo receptor.

Original languageEnglish (US)
Pages (from-to)1130-1134
Number of pages5
JournalExperimental Hematology
Volume23
Issue number10
StatePublished - 1995

Keywords

  • BFU-E-CFU-GEMM
  • IL-3/Epo fusion proteins
  • Single cell sorting

ASJC Scopus subject areas

  • Cancer Research
  • Cell Biology
  • Genetics
  • Hematology
  • Oncology
  • Transplantation

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