Apoptosis induction in 32D cells by IL-3 withdrawal is preceded by a drop in the intracellular calcium level

The 32D murine myeloid cell line is dependent on interleukin-3 (IL-3) for growth in vitro. We show here that IL-3 induces a slow increase in endocellular calcium, which is sizeable two hours after the addition. Withdrawal of the cytokine induces apoptosis, whose classic late events are evident after 16/18 hours, and are preceded by a calcium drop during the first 2/3 hours after IL-3 subtraction. Calcium drop is here proposed as a trigger of the apoptotic process, in agreement with other recently reported findings.