Table I.
Accessory Cell Activity of CD34+ Blood Stem Cells during Stimulation of T Lymphocytes by LPS
| Cell population | DNA synthesis after stimulation with | |||||
|---|---|---|---|---|---|---|
| None | LPS | PPD | ||||
| cpm/culture | ||||||
| PBMCs | 80 ± 10 | 8,150 ± 850 | 12,630 ± 250 | |||
| CD34-depleted PBMCs | 40 ± 20 | 40 ± 20 | 12,060 ± 1,690 | |||
| CD34-depleted PBMCs plus 5% CD34-enriched cells | 470 ± 130 | 8,250 ± 40 | 14,430 ± 340 | |||
| PBMCs, labeled with anti-CD34 and GaM microbeads (control 1) | 100 ± 40 | 8,150 ± 350 | 11,230 ± 120 | |||
| PBMCs after depletion of cells labeled with an isotype-specific mAb (control 2) | 120 ± 50 | 7,980 ± 430 | 12,130 ± 380 | |||
| CD34-enriched cells alone (control 3) | 90 ± 30 | 100 ± 20 | 110 ± 60 | |||
Cells (106/ml) were stimulated with LPS (S. friedenau, 1 μg/ml) or PPD (1 μg/ml) and cultured for 7 d in RPMI 1640 plus 10% HS in a final volume of 200 μl/culture. For the last 8 h of culture, cells were pulsed with [3H]TdR (0.2 μCi/culture), then harvested on glass filter mats, and the radioactivity was measured in a β-counter. The results of one of seven experiments are given. Data are expressed as mean ± SD of three independent cultures.