RT-PCR analysis of human MC. RT-PCR analyses were performed on highly purified lung MC (purity, <98%) ([A], lanes 1 through 8; [B], all lanes) and the mast cell line HMC-1 ([A], lanes 9 and 10) using primers specific for MCP-1 and β-actin. (A) Shows the effect of SCF on MCP-1 mRNA expression: primary MC were exposed to rhSCF or control medium for 2 or 8 hours. mRNA isolation and RT-PCR analysis was done as described in the text. Exposure of lung MC to rhSCF led to an increase in expression of MCP-1 mRNA after 2 hours (lane 4) and 8 hours (lane 8), compared with control (2 hours, lane 2; and after 8 hours, lane 6). RT-PCR analysis of lung MC was controlled by using primers specific for β-actin (lane 1, control medium, 2 hours; lane 3, rhSCF, 2 hours; lane 5, control medium, 8 hours; lane 7, rhSCF, 8 hours). HMC-1 cells expressed significant amounts of MCP-1 mRNA (lane 10) in a constitutive manner. Lane 9, β-actin control of HMC-1 cells. (B) Shows the effect of anti-IgE and anti-IgE + SCF on MC. Highly purified lung MC (<98%) were exposed to control medium (lanes 1, 2, 7, and 8), anti-IgE MoAb E-124-2-8, 10 μg/mL (lanes 3, 4, 9, and 10), and rhSCF, 100 ng/mL plus anti-IgE, 10 μg/mL (lanes 5, 6, 11, and 12) for 2 hours (lanes 1 through 6) or 8 hours (lanes 7 through 12) at 37°C. RT-PCR was performed using primers specific for MCP-1 (lanes 2, 4, 6, 8, 10, and 12) and β-actin (lanes 1, 3, 5, 7, 9, and 11). As visible, anti-IgE and anti-IgE + SCF augmented MCP-1 mRNA expression in lung MC.