Interleukin-2 as a neuromodulator possibly implicated in the physiopathology of sudden infant death syndrome

Dysfunction in vital brainstem centers, including those controlling cardiorespiratory- and sleep/arousal pathophysiology, is reported in sudden infant death syndrome (SIDS). Biological mechanisms underlying SIDS, however, remain unclear. Cytokines are inter-cellular signaling chemicals. They can interact with neurotransmitters and might thus modify neural and neuroimmune functions. Cytokines could therefore act as neuromodulators. Interleukin (IL)-2 is a major immune-related cytokine. It has not been previously depicted in vital brainstem centers. We detected intense neuronal IL-2 immune-reactivity in the SIDS brainstem, namely in vital neural centers. This IL-2 overexpression might interfere with neurotransmitters in those critical brainstem centers, causing disturbed homeostatic control of cardiorespiratory and arousal responses, possibly leading to SIDS.