Calcium ionophore-induced apoptosis of human B cells is preceded by the induced expression of early response genes.

We have investigated the effects of calcium ionophore on apoptosis of Ramos human B cells. Our results show that the calcium ionophore A23187 at defined concentrations leads to apoptosis of Ramos cells. The majority of cells (> 90%) undergo apoptosis in response to ionophore. The response is rapid and nuclear condensation and DNA degradation can be detected within 2 h after addition of ionophore. In attempts to define the changes in gene expression preceding apoptosis, we investigated the expression of a panel of early response genes in these cells after ionophore addition. We show that calcium ionophore-induced apoptosis of Ramos cells is preceded by the induced expression of a number of early response genes. These results are consistent with calcium ionophore initiating changes in gene expression which may be important in signaling these cells to undergo apoptosis.