ALTERED MONOCYTE CALCIUM DYNAMICS IN SEPSIS

Purpose: This study was designed to evaluate monocyte calcium concentr ation and mobilization in normal and septic surgical patients, Methods : Monocytes were isolated from lj ''septic'' surgical patients, washed , and loaded with the fluorescent calcium chelator, FURA-2, Monocytes from 20 normal volunteers served as controls, Intracellular calcium co ncentration ([Ca2+](i)) was measured by means of fluorescent spectroph otometry before, during, and after stimulation with concanavalin A, Di fferences were evaluated for statistical significance by analysis of v ariance, The study was repeated using normal monocytes preincubated in ''septic'' serum and ''septic'' monocytes preincubated in normal seru m, Additional paired whole blood specimens were obtained from the cont rol group and were incubated with Escherichia coli endotoxin, Monocyte s were then isolated and evaluated as described, Results: Sepsis was a ssociated with significantly low resting monocyte calcium concentratio ns, Although concanavalin A stimulation resulted in marked calcium mob ilization in both normal and septic cells, final cellular calcium conc entration was significantly lower in the stimulated ''septic'' monocyt es, Similar alterations were seen in normal cells incubated with septi c serum, but could not be reproduced by incubation with endotoxin, Thi s deficiency could not be corrected in septic cells incubated in norma l serum. Conclusion: Sepsis is associated with a significant alteratio n of monocyte calcium dynamics in both resting and stimulated cells, T hese changes appear to be modulated by a serum factor other than endot oxin.