Interleukin-10 inhibit cytokine release by murine type 1 helper T-cells. It also increases the expression of the MHC II complex on the surface of B-cells and prolongs their vitality. Unexpected electrostimulation of IL-10 in the human monocytic cell lines THP-1 and U937 by strong single exponential pulses is reported. The stimulation depends on the amplitude, pulse duration and the time after pulse treatment.