Evidence for an opioid inhibitory effect on T cell proliferation

B. Manfredi, P. Sacerdote, M. Bianchi, L. Locatelli, J. Veljic-Radulovic, A. E. Panerai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


The proliferative response of human or rat T lymphocytes to phytohemagglutinin (PHA) or concanavalin A (ConA) was measured after acute (30 min) or chronic (8 days) treatment with the opiate receptor antagonists naloxone or naltrexone. Both in the rat and in the human, proliferation was significantly enhanced by acute treatment with the opiate receptor antagonists. In contrast, after chronic treatment proliferation always decreased. The sudden removal of an opioid inhibitory tone might be the basis for the increased proliferative responses observed after acute treatment. The decrease after chronic treatment could be ascribed to the amplification of the inhibitory effect of endogenous opioids due to the up-regulation of opiate receptors that follows chronic antagonist administration. Receptor binding studies of β-endorphin receptors on splenocytes of chronically naloxone treated rats confirmed this hypothesis: a higher number of β-endorphin receptors were expressed on splenocytes of naloxone-treated rats compared to controls (Bmax = 9.8 × 10-12 vs. 1.16 × 10-12, respectively).

Original languageEnglish (US)
Pages (from-to)43-48
Number of pages6
JournalJournal of Neuroimmunology
Issue number1
StatePublished - Apr 1993


  • Concanavalin A
  • Mitogen
  • Opioid
  • Phytohemagglutinin
  • Proliferation

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Neurology
  • Clinical Neurology


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