Plasma increase of interleukin-12 and interferon-gamma. Pathological significance in autism.

Immune factors such as autoimmunity have been implicated in the genesis of autism, a neurodevelopmental disorder. Since autoimmune response involves immune activation, the plasma levels of interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), interleukin-12 (IL-12), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and soluble intercellular adhesion molecule-1 (sICAM-1) were measured in autistic patients and age-matched normal controls. The levels of IL-12 and IFN-gamma were significantly (P < or = 0.05) higher in patients as compared to controls. However, IFN-alpha, IL-6, TNF-alpha, and sICAM-1 levels did not significantly differ between the two groups. Because macrophage-derived IL-12 is known to selectively induce IFN-gamma in T helper type-1 (Th-1) cells, it is suggested that IL-12 and IFN-gamma increases may indicate antigenic stimulation of Th-1 cells pathogenetically linked to autoimmunity in autism.