IgE alone induces <i>de novo</i> TNF synthesis in mast cells.

Mast cells were incubated with different concentrations of IgE (white bars) for 6 h. Anti-IgE-induced TNF secretion (black bar) is shown as a positive control (A). For TNF mRNA assessment mast cells were incubated with IgE (white bars) or anti-IgE (black bars) both at 5 µg/mL for the indicated times (B). TNF mRNA levels were determined by qRT-PCR and presented as fold-increase over the value of cytokine mRNA expression in non-stimulated cells after normalization with the transcript level of the housekeeping gene rat Actb. Results are presented as the mean ± SEM of at least three separate experiments performed in duplicate (A) or triplicate (B) (n≥3). *p<0.05, **p<0.01, ***p<0.001.