High lL-6 secretion levels correlate with high SOCS1 and SOCS3 expression levels.

AML cells (patients 11, 7) were cultured in 12-well plates and stimulated for 1 hour with IL-6 (lanes 2, 5, 8, 11) or with anti-IL-6 for 2 hours (lanes 3, 6, 9, 12). In lanes 1 to 6, cells were cultured in RPMI 1640 for 24 hours before stimulation. In lanes 7 to 9, cells from patient 7 were cultured in the AML supernatant from patient 11. In lanes 10 to 12, cells from patient 7 were cultured in the AML supernatant from patient 11, which was depleted of IL-6 by adding anti-IL-6. Total RNA was isolated, 3 μg RNA was reverse transcribed with M–MuLV reverse transcriptase, and cDNA was used in a PCR reaction using specific primers for SOCS-1, SOCS-3 or β2-μglobulin as a control.