Interleukin-2 enhances chick and rat sympathetic, but not sensory, neurite outgrowth

Interactions between the immune and nervous systems could be important for normal development and function of both. To determine if a lymphokine, interleukin-2 (IL-2), represents a link between these two systems, sympathetic and sensory neurons from embryonic chick and neonatal rat were cultured in media containing human recombinant IL-2. In chick sympathetic chain and rat superior cervical ganglia cultures, IL-2 enhanced the number of neurons with neurites and the length of those neurites significantly over control cultures. Sensory neurons from chick and rat dorsal root ganglia were not affected by culture in IL-2. Sympathetic neuron response to IL-2 was concentration-dependent, with an optimum around 2-0.2 U/ml (100-10 pM). Immunofluorescence with an anti-IL-2 receptor antibody demonstrated specific staining of sympathetic neurons, but not sensory neurons, implying that sympathetic neurons may have a receptor for IL-2 on their surface.