The immune system and opiate withdrawal.

Whole body exposure to 500 rad ionizing irradiation suppresses the immune system in rats. Moreover, when administered prior to chronic morphine treatment, irradiation exposure also dramatically reduces the severity of naloxone-precipitated withdrawal in morphine dependent animals. The reinstillment of 2-6 x 10(8) normal lymphoid immunocompetent cells to irradiated rats by adoptive transfer prior to chronic morphine treatment restores all withdrawal signs precipitated by naloxone injection. The data suggest that specific cellular activities or factors derived from lymphoid cells are required for the expression of opiate withdrawal, indicating that the immune system participates in the manifestation of opiate dependence.