Detection of IL-6R mRNA and IL-10 mRNA in the PEL cell lines. One microgram of RNA was used for cDNA synthesis. RT-PCR was performed for IL-6R, IL-10, c-kit and β-2 microglobulin. One fifth of the PCR mixture was analyzed by ethidium bromide staining of the 1.5% agarose gel (Lane 1, positive controls; lane 2, KS-1 cells; lane 3, BC-1 cells; lane 4, BC-2; lane 5, Jurkat cells, as a negative control; lane 6, water control). All three PEL cell lines were positive for IL-6R (A), 251-bp, IL-10 (B), 204-bp, and β-2 microglobulin (D), but negative for c-kit (C), 388-bp.