Abstract
We measured and visualized cytosolic free calcium ([Ca2+]i) in individual human peripheral blood monocytes during phagocytosis by using the fluorescent indicator fura-2. Monocytes exhibit a rapid rise in [Ca2+]i from a basal level of 75 +/- 11 nM to a peak level of 676 +/- 78 nM (means +/- standard errors of the means; P less than 0.001) by 34 +/- 5 s after contact with opsonized zymosan particles, and a thin rim of high [Ca2+]i was observed surrounding the ingested particle.