Cell cycle-dependent fluctuations in IgE secretion in a human myeloma line

IgE production was examined in a human myeloma cell line (U266) in cultures in exponential growth and in cultures where cell growth was synchronized by thymidine blockade. Antibody secretion is shown to be restricted to late G1/early S phases of the cell cycle in synchronized cultures, as judged by the slope of the curve relating supernatant IgE levels to time. Employing the ELISA-plaque assay to enumerate cells in active IgE secretion, the frequency of the latter was also shown to peak in S phase. These data collectively suggest that IgE gene transcription occurs only during limited periods of the cell cycle. These results are discussed in terms of using U266 to study the mechanism of action of regulatory T-cell factors which affect IgE synthesis and/or secretion.