naloxone is very similar to naltrexone

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Blood, Vol. 95 No. 6 (March 15), 2000: pp. 2031-2036

The opioid antagonist naloxone induces a shift from Type 2 to Type 1

cytokine pattern in BALB/cJ mice

Paola Sacerdote, Barbara Manfredi, Leda Gaspani, and Alberto E.

Panerai

From the Department of Pharmacology, University of Milano, Milan,

Italy.

Opioid peptides affect different immune functions. We present

evidence that these effects could be mediated by the modulation of

TH1/TH2 cytokine production. BALB/cJ mice were immunized with 50 or

100 µg of the protein antigen keyhole-limpet hemocyanin (KLH), and

treated acutely or chronically with the opioid antagonist naloxone.

One and 2 weeks after immunization, the production of cytokines by

splenocytes was evaluated by in vitro restimulation with KLH. The

acute and chronic treatment with the opioid receptor antagonist

naloxone decreased the production of interleukin (IL)-4 by

splenocytes of BALB/cJ mice. In contrast, IL-2 and interferon- levels

increased after naloxone treatment. Finally, the opioid antagonist

diminished the serum immunoglobulin G anti-KLH antibody titers. These

results suggest that naloxone increases TH1 and decreases TH2

cytokine production. The effect of naloxone could be ascribed to the

removal of the regulatory effects exerted by endogenous opioid

peptides, which could therefore activate TH2 and suppress TH1

cytokines.