Chemokinetic effects of exogenous and endogenous tumor necrosis factor alpha on human blood monocytes

The possible chemokinetic effect of human tumor necrosis factor alpha (TNF-alpha) upon human monocytes was investigated by using a type 1 collagen gel system. Human recombinant TNF-alpha was found to be chemokinetic, and concentrations of that cytokine as low as 0.7 pg/microliters enhanced the movement of those leukocytes. Furthermore, we explored whether endogenous TNF-alpha stimulates monocyte movement by incubating blood monocytes with a TNF-alpha-stimulating agent, human recombinant interleukin 1, with or without antibodies to human TNF-alpha. Human recombinant interleukin 1 enhanced the motility of blood monocytes, and that effect was blocked by rabbit polyclonal antibodies to human TNF-alpha. Furthermore, the movement of blood monocytes no exposed to exogenous cytokines was decreased after incubation with anti-TNF-alpha. Thus, endogenous as well as exogenous TNF-alpha is a chemokinetic agent for human monocytes.