 One study successfully showed that dendritic cells, part of the innate immune system, display opiate receptors.Dendritic cells are responsible for producing cytokines, which are the tools for communication in the immune system.This same study showed that dendritic cells chronically treated with morphine during their differentiation produce more interleukin-12 (IL-12), a cytokine responsible for promoting the proliferation, growth, and differentiation of T-cells (another cell of the adaptive immune system) and less interleukin-10 (IL-10), a cytokine responsible for promoting a B-cell immune response (B cells produce antibodies to fight off infection).