DC-SIGN⁺ blood cells stimulate proliferation of T cells.

(A) DC-SIGN⁺ blood cells, CD4⁺ blood DCs (from the same donor), and immature DCs were cocultured with allogeneic T cells at ratios of 1:100 and 1:500 for 4 to 6 days, after which (methyl-³H)-thymidine incorporation was measured. (B) DC-SIGN⁺ blood DCs were cocultured with allogeneic T cells as in panel A, in the absence or presence of IL-4 and GM-CSF. (C) DC-SIGN⁺ blood cells and CD4⁺ blood DC (from the same donor) were cocultured with autologous T cells as in panel A in the presence of PPD (5 μg/mL). The results are expressed as mean counts per minute (cpm) from triplicate wells (error bars represent SD). Background proliferation of allogeneic T cells: 815 ± 405 cpm at day 4, 652 ± 336 cpm at day 5, 3500 ± 462 cpm at day 6. Background proliferation of autologous T cells in the presence of PPD: 12 216 ± 405 cpm.