Table 1.

Interleukin-2 (IL-2) activities of the supernatants of dendritic cell (DC)/CD4⁺ T-cell co-cultures, following the addition of different blocking reagents

Blocking reagent	[3H]TdR incorporation ± SD (c.p.m)	U/ml
Control mAb	28925·3 ± 4666·0	53·50
Anti-OX40L mAb	9186·0 ± 402·3	0·22
Anti-HLA-DR mAb	8936·0 ± 652·7	0·19

CD4⁺ T cells and irradiated allogeneic mature DCs (mDCs) were mixed and co-cultured in a 96-well culture plate at a ratio of 1 : 300, in triplicate. Control monoclonal antibodies (mAbs) (UPC-10), anti-OX40 ligand (anti-OX40L) mAb (ik-5), or anti-human leucocyte antigen (HLA)-DR mAb (G46-6) were added to the culture at a final concentration of 100 µg/ml. After 72 hr, cell-free supernatants were collected. Background proliferation for the CTLL-2 cells was 156·0 ± 28·3 [mean counts per minute (c.p.m.) ± standard deviation (SD)].