Effects of β-endorphin on functional activity of mouse splenocytes under conditions of in vivo blockade of μ,δ-opioid receptors.

Blockade of δ-receptors with naltrindole under conditions of systemic immunization abolished the stimulatory effect of β-endorphin (0.0005 μg/kg) on the counts of antibody-producing cells and the titer of antierythrocyte antibodies. Injection of β-endorphin to mice led to stimulation of concanavalin A-induced proliferative activity of splenocytes and IL-4 secretion by the naloxone-dependent mechanism. The peptide did not modify the production of IL-2 and IFN-γ.