The fluorescence response of chlortetracycline-loaded human neutrophils is modulated by prostaglandin E1, but not by cyclic nucleotides.

Human neutrophils preloaded with chlortetracycline, commonly used as a probe of membrane-bound calcium, demonstrate a prompt decrease in fluorescence when exposed to surface stimuli such as the chemotactic peptide fMet-Leu-Phe. The fluorescence response was highly sensitive to preincubation with prostaglandin E1. This effect was apparently not due to elevated levels of cAMP since exogenous dibutyryl-cAMP did not alter the chlortetracycline fluorescence response to fMet-Leu-Phe. This is one of the few instances of prostaglandin E1 affecting neutrophils at physiologic concentrations, dissociated from changes in cellular cyclic nucleotide levels.