Intracellular calcium handling in cystic fibrosis: normal cytosolic calcium and intracellular calcium stores in neutrophils.

We used quin2, a high affinity fluorescent calcium indicator to measure free cytosolic Ca++ in neutrophils isolated from fresh heparinized blood of 13 cystic fibrosis (CF) patients (age range 6-32 yr) and 11 healthy individuals (age range 25-41 yr) as controls. The mean value of free cytosolic Ca++ for CF patients was 137 +/- 19 nM (mean +/- SD) and 141 +/- 23 nM for controls (p = NS). Calcium stores released after exposure of the cells to ionomycin in Ca++-free medium were also similar in neutrophils of CF patients (51 +/- 34 pmol/10(6) neutrophils) and in the controls (50 +/- 15 pmol/10(6) neutrophils). Stimulation of the neutrophils with the chemotactic peptide f-mlp (10(-7) M) led to similar rises in free cytosolic Ca++ with mean peak levels of 718 +/- 230 nM in CF patients and 687 +/- 321 nM in another population of 10 healthy adults. In our group of CF patients free cytosolic Ca++, intracellular Ca++ stores, and the kinetics of intracellular Ca++ transients induced by f-mlp are similar to those of normals. These findings do not support the hypothesis of a generalized defect in calcium handling at the cellular level in CF.