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 A2318 7 at defined concentrations leads to apoptosis of Ramos cells. The maj ority 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 defin e 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 ea rly response genes. These results are consistent with calcium ionophor e initiating changes in gene expression which may be important in sign aling these cells to undergo apoptosis.