Figure 3.

Proliferation of purified human intestinal MC cultured with or without IL-4. (A) ³H-thymidine incorporation. Radioactivity (6 × 10⁵ cpm/well) was added at day 14 of culture (2 × 10⁴ MC/well at day 0, 99% MC purity at day 14). Cells were harvested and washed three times, and radioactivity was measured at day 18 (n = 6). (B) Percentage of purified MC (>93% purity at day 4 and later) staining positive for Ki-67, a nuclear cell proliferation-associated antigen (n = 5; ∗, P < 0.05 compared with culture without IL-4). (C) Percentage of enriched MC that incorporated BrdUrd. BrdUrd was added at day 0, and positive cells were counted at different time points indicated (since day 4, MC purity was always >94%, n = 3). (D) Recovery (100% = start of culture) of enriched MC (66% purity at day 0, >98% purity at days 14–28) cultured in the presence of SCF for 28 days with (closed symbols) or without (open symbols) IL-4 that was added at day 0 (circles) or day 14 (squares). One of two experiments performed in duplicate is shown.