Inhibition of polymorphonuclear leukocyte functions by chlortetracycline

Abstract

Chortetracycline (CTC) inhibits chemotaxis, exocytosis and metabolic burst in rabbit poly-morphonuclear leukocytes (PMNs), when these cells are activated in the absence of extracellular Ca 2+. In the presence of extracellular Ca 2+ CTC has little or no inhibiting effect on these functions. The inhibiting effect of CTC in the absence of Ca 2+ occurs at concentrations which are not cytolytic. The inhibiting effect of CTC can be reversed by washing the cells or by addition of Ca 2+ or Mg 2+ to CTC- pretreated cells. Inhibition of the metabolic burst by CTC depends on the activator used. When phorbolmyristate acetate is used to activate the cells, the metabolic burst is inhibited at lower CTC concentrations than with chemotactic peptide as an activator. With due observance of the chemical properties of CTC and literature data about the requirement of intracellular Ca 2+ for neutrophil functions, the results obtained are consistent with the view that CTC interferes with neutrophil functions, by complexing intracellular Ca 2+, and that this inhibition is reversed when sufficient extracellular Ca 2+ moves into the cell.