Decreased IL-3 production by peripheral blood mononuclear cells in patients with multiple sclerosis.

The production of interleukin-3 by peripheral blood mononuclear cells (MNC) was assessed in patients with relapsing multiple sclerosis (MS) in both the active and the stable state, and in healthy controls. IL-3 levels were compared to levels of production of interleukin-2 (IL-2), tumor necrosis factor (TNF) and gamma-interferon (gamma-IFN). No significant differences in IL-3 levels were observed between stable-state patients and controls. When levels of cytokine production of patients in the inactive phase were compared to those of the same patients during relapse a significant decrease in IL-3 levels was observed, as opposed to significant increases in gamma-IFN and TNF levels, and an increase, though a non-significant, in IL-2 levels. The functional significance of lowered IL-3 production is unknown. However, the findings support the hypothesis of a highly complex interaction of overlapping regulatory influences within the cytokine network which parallels MS disease activity.