Human sepsis increases lymphocyte intracellular calcium

Objective: To determine whether free intracellular calcium is increased during human bacterial sepsis. Design: Prospective controlled study of lymphocyte free intracellular calcium concentrations from patients with sepsis compared with critically ill nonseptic patients and healthy subjects. Setting: A large multidisciplinary ICU of a university hospital. Patients: Eleven patients with sepsis, six patients after cardiac surgery, six patients with head injury, and 22 healthy control subjects. Interventions: Blood samples obtained for lymphocyte isolation and measurement of free intracellular calcium concentrations. Measurements: Lymphocytes were isolated using Ficoll-paque centrifugation and free intracellular calcium concentrations were measured using the fluorescent dye fura-2. We also evaluated the effect of septic serum, endotoxin, tumor necrosis factor (TNF), and lysophosphatidylcholine on lymphocyte free intracellular calcium concentrations. Main Results: Mean (± SEM) lymphocyte free intracellular calcium concentrations were significantly (p < .05) higher in the septic patients (176 ± 12 nM) compared with cardiac surgical (112 ± 9 nM), head- injured (110 ± 11 nM), or healthy control patients (112 ± 5 nM). Endotoxin (0.1 and 1.0 mg/mL) and TNF (10 and 100 ng/mL) did not alter lymphocyte free intracellular calcium values. Lysophosphatidylcholine (100 and 200 μM) significantly increased lymphocyte free intracellular calcium in a dose- dependent manner. Septic serum had no effect on resting lymphocyte free intracellular calcium concentrations but potentiated the free intracellular calcium response to lysophosphatidylcholine. Conclusions: Lymphocyte intracellular calcium homeostasis is altered during human sepsis. In addition, circulating factors present in septic serum are capable of altering cellular calcium handling.