Effect of added TNF (0.1 ng/mL) on the changes measured in total viable cells, CFCs, and 6-week LTC-ICs (expressed as LTC-IC–derived CFCs) after 10 days in 5 experiments, in each of which parallel cultures were initiated with 500 (bulk) versus at least 96 single CD34⁺CD38⁻ human marrow cells (SS) (same experiments as described in Table 3).

Cells from the single-cell cultures were pooled at the end of the 10-day incubation before assay for their CFC and LTC-IC contents. Results shown are the mean ±SEM. ■, control data; ▪, data for the TNF-treated cultures. Input CFCs and total LTC-IC–derived CFC values (per 1000 initial CD34⁺CD38⁻ cells) in these experiments were 22 ± 7 and 3500 ± 1900, respectively.