Immunodepletion of CD83 largely removes the inhibitory effect of supernatants from infected mature moDC cultures on DC-stimulated allogeneic T-cell responses in the MLR. Percent T-cell inhibition is shown against the y-axis, based on 3HTdR incorporation (cpm) relative to allogeneic stimulation with isotype (mock)-depleted supernatant from noninfected cultures, which by definition were at 100% (3 pooled independent experiments, mean ± SD). Supernatants were added at 50% vol/vol. T-cell proliferation stimulated by moDCs improved significantly when the supernatants added from infected cultures had been CD83 immunodepleted. ^*P values indicated on the figure were calculated using the Student t test comparing cpm values between mock-depleted and CD83-immunodepleted supernatants.