Effects of CD40L on the proliferation and differentiation of hematopoietic progenitors: neutralization experiments.
CD34+ progenitors (10 000) were cocultured 12 days in contact with ECs with 10% supernatant of nontransfected COS cells (control) or with 10% supernatant of CD40L-CD8α–transfected COS cells (CD40L) in the presence or absence of neutralizing antibodies. Half of the medium was exchanged at day 6 with readdition of the antibodies. At the end of the coculture, cell expansion was measured and cells were plated for colony assay. Colonies were scored at day 14. Results are expressed as the mean ± SD–fold cell expansion (top panel) or colony number (for 105 cells) measured (bottom panel) for 3 experiments (aCK: combination of neutralizing polyclonal anticytokine (IL-1α, IL-1β, IL-6, IL-11, G-CSF, GM-CSF, M-CSF, and LIF) antibodies; aFL: neutralizing polyclonal anti-FL antibody).
