Single cell analysis of calcium mobilization in anti-immunoglobulin- stimulated B lymphocytes

A rapid increase in the concentration of intracellular free calcium ([Ca++i]) in B cells after mIg crosslinking has been documented previously by fluorimetric analysis of cell populations loaded with the fluorescent Ca++ indicator Quin 2. Although providing a valuable indication of Ca++ mobilization in the population as a whole, it has not been possible to determine whether only a subpopulation of the cells or the entire population exhibits this response. In this report, we describe the marriage of flow cytometry and Quin 2 technology, which permits discrimination of Ca++ mobilization by subpopulations of cells, as well as in whole populations. We have determined that the entire mIg+ population exhibits a synchronous increase in [Ca++i] rapidly after stimulation. Furthermore, all members of the population appear to undergo an approximately equal response.