Figure 3.

TAP-independent stimulation of CD8 T-cell responses by IntSIIN. (a) In vitro grown TAP^−/− DC were pulsed with SIIN and IntSIIN at 1 μg/ml for 1 hr then added to purified OT-I T cells and cultured for 6 days. Cells were harvested at each time-point and uptake of [³H]thymidine was measured to assess T-cell proliferation. DC pulsed with nothing, OT-I T cells and DC added to T cells were used in experiments as negative controls. Data are presented as counts per minute (c. p.m.) from quadruple wells (± SD). (b) EL-4 and (c) RMA-S were stimulated with IntSIIN and SIIN at 1 μg/ml for 1 hr and added to B3Z T cells for 24 hr. LacZ activity in B3Z T cells was assayed by total culture lysates with LacZ substrate CPRG. EL-4 and RMA-S added to B3Z T cells without peptides were used in experiments as negative controls. The absorbance (560 nm) of culture wells was read after 4 hr incubation at 37°.