Long-term culture of CD40-stimulated B cell lines.

<p>(<i>A</i>) Culture periods and minimal proliferation doubling levels of Epstein-Barr virus–free CD40-stimulated B cell lines that were cultured for more than 200 days. Each cell line shown is from a different donor. Solid dots represent B cell lines that are currently proliferating in culture or were cryoconserved as proliferating cultures. Open dots indicate B cell lines that ceased to proliferate at the indicated time. (<i>B</i>) Proliferation of established CD40-stimulated B cell lines during a 30-day period. At the start of analysis (day n), B cell lines LXL5 and HXL7 were at day 884 of culture, the other B cell lines were at day 570, 512, 430, 251 (two B cell lines) or 155 (five B cell lines). (<i>C</i>) Dependence of B lymphoblast proliferation on CD40L and IL-4. B cells HXL7 or LXL5 (day 586 of culture) were grown for 11 days on CD40L-expressing murine fibroblasts or control fibroblasts in the presence or absence of IL-4, before cell counting and viability assessment by flow cytometry.