(A) Comparison between surface expression of CD30, as detected by the MoAb M44 (upper panels), and the kinetics of cDNA amplification after 25, 30, and 35 cycles with primers specific for CD30 (lower panels) in the human cell lines HDLM-2, L-428 and THP-1. (B) Comparison between surface expression of CD30L, as detected by the MoAb M80 (upper panels), and the kinetics of cDNA amplification performed for 25, 30, and 35 cycles with primers specific for CD30L (lower panels) in the human cell lines DG-75, MN-60, and BV-173. In both cases, the same cDNA bulks were also amplified with primers specific for the housekeeping gene β-actin.