Effects of Opioids on Proliferation of Mature and Immature Immune Cells

Abstract

A large and growing body of evidence indicates that the use of opioid drugs can alter immune system functioning. It has long been known that opioid addicts suffer from an increased incidence of a variety of infectious diseases (1), as well as alterations in a number of immune parameters. A variety of changes in the immune system has also been observed following administration of opioids to laboratory animals (for review, see (2). However, almost all work on opioid-immune associations to date has focussed on mature immune cells. All circulating cells arise from pluripotent stem cells in the bone marrow, which proliferate and differentiate, by means of a complex process involving several specific lymphokines, into mature immune cells and erythrocytes. Any drug of abuse acting on stem cells therefore might have potent, wide ranging effects on the immune system. As an approach to this question, we treated mice chronically with morphine, then isolated their bone marrow cells and tested their sensitivity to several cytokines that normally induce proliferation and/or differentiation of subpopulations of these cells (3).