Effect of nickel sulfide on induction of interleukin-1 and phagocytic activity

Rat peritoneal macrophages were treated with crystalline nickel sulfide (NiS), washed, and then tested for interleukin-1 (IL-1) production and phagocytosis of IgG-opsonized sheep red blood cells (SRBC). Pretreatment of peritoneal macrophages with crystalline NiS did not affect their ability to produce IL-1. In contrast, pretreatment of peritoneal macrophages with crystalline NiS inhibited the phagocytic activity of the peritoneal macrophage. This inhibitory activity was due to an effect on the internalization step of the phagocytic process. The binding step of this process was not affected by exposure to crystalline NiS. The overall number of Ig-SRBC that interacted with each macrophage was not different in treated or untreated cultures. This interaction is mediated through Fc receptors on the macrophage membrane. This result suggests that crystalline NiS does not modulate the expression of Fc receptors by peritoneal macrophages. The results described in this study suggest that crystalline NiS has a potent immunomodulatory effect on macrophage phagocytic activity.