mRNA expression of Bcl-2 family members by purified blood eosinophils as assessed by RT-PCR using 20 cycles of amplification. Freshly isolated peripheral blood eosinophils (0) expressed significant levels of mRNA for Bcl-xL and Bax, but not for Bcl-2, Bcl-xS, and A1. When eosinophils were cultured in medium without cytokine support, the levels of Bcl-xL rapidly decreased, but were maintained or slightly increased after GM-CSF stimulation in vitro. In contrast, Bax mRNA levels remained unchanged when eosinophils were cultured in the presence or absence of GM-CSF. The same results were observed when eosinophils were cultured with IL-5 (not presented). Furthermore, Bcl-2 and A1 mRNA levels did not increase after incubation with eosinophil hematopoietins. As a control, human β-actin cDNA was amplified and PCR products were stained by ethidium bromide in an agarose gel. Positive control amplifications were performed using cDNAs from HL-60 (Bcl-x, Bax, Bcl-2) and Jurkat (A1) cells. All data are representative of eight independent experiments.
