Up-regulation of TM-IL-5R.

Up-regulation of TM-IL-5Rα mRNA expression in umbilical cord blood CD34⁺ cells grown in IL-3 and GM-CSF is preceded by IL-5 mRNA expression, and anti-IL-5 inhibits eosinophil development from cord blood-derived CD34⁺ cells grown in IL-3 and GM-CSF. (A) RT-PCR for TM and SOL IL-5Rα mRNA and IL-5 mRNA expression by umbilical cord blood CD34⁺ cells grown in IL-3 or IL-3 and GM-CSF for 0, 3, 5, 7, and 14 days. Results are representative of 3 independent experiments. (B) A neutralizing anti-hIL-5 monoclonal antibody (5A5, 10 μg/mL) was added to CD34⁺ cord blood cells cultured at 2 × 10⁴ cells per 100μL in 96-well plates with IL-3 and GM-CSF, as above. Three wells were set up for each time point and cells were harvested at 3, 5, 7, and 14 days of culture for cell counts after May Grunwald Giemsa or major basic protein staining. Data shown are means and standard error for 3 separate experiments.