SUBCLONING THE RBL-2H3 MUCOSAL MAST-CELL LINE REDUCES CA2-CELL LEVEL(RESPONSE HETEROGENEITY AT THE SINGLE)

Ca2+ imaging experiments have revealed that for a wide variety of cell types, including RBL-2H3 mucosal mast cells, there are considerable c ell-to-cell differences of the Ca2+ responses of individual cells. Thi s heterogeneity is evident in both the shape and latency of the respon ses. Mast cells within a single microscopic field of view, which have experienced identical culture conditions and experimental preparation, display a wide variety of responses upon antigen stimulation. We have subcloned the RBL-2H3 mucosal mast cell line to test the hypothesis t hat genetic heterogeneity within the population is the cause of the Ca 2+ response heterogeneity. We found that cell-to-cell variability was significantly reduced in four of five clonal lines. The response heter ogeneity remaining within the clones was not an experimental artifact caused by differences in the amount of fura-2 loaded by individual cel ls. Factors other than genetic heterogeneity must partly account for C a2+ response heterogeneity. It is possible that the complex shapes and variability of the Ca2+ responses are reflections of the fact that th ere are multiple factors underlying the Ca2+ response to antigen stimu lation. Small differences from cell to cell in one or more of these fa ctors could be a cause of the remaining Ca2+ response heterogeneity. ( C) 1996 Wiley-Liss, Inc.