Efficacy of differentially sulfated GAGs to modulate LTC-IC maintenance in the presence of PF4.

A total of 10 000 to 20 000 DR⁻ cells were plated in 0.4-μm transwell inserts in 6-well tissue culture clusters. Medium in the lower chambers of the wells was replaced daily by LTBMC medium supplemented with or without a combination of cytokines (500 pg/mL G-CSF, 50 pg/mL GM-CSF, 200 pg/mL SCF, 50 pg/mL LIF, 2 ng/mL IL-6, and 200 pg/mL MIP-1α) with 5 ng/mL IL-3 and 200 ng/mL PF4 and with or without 5 μg/mL each of GAGs. Cultures were harvested after 5 weeks and replated at limiting dilutions for estimation of LTC-IC frequency, as described in Methods. Numbers within the bars indicate the number of experiments. Comparison between day 0 and other conditions: *P < .002.