The literature describing effects of morphine on cells of the immune system points to the
clear conclusion that morphine given in vivo suppresses a variety of immune responses that
involve the major cell types in the immune system, including natural killer (NK) cells, T cells,
B cells, macrophages and polymorphonuclear leukocytes (PMNs). Depression of NK cell
activity has been reported in humans, monkeys and rodents. Similarly, responses of T cells
are depressed by morphine, as assessed by inhibition of induction of delayed-type …