Humanized anti-CD52, in the absence of complement-mediated lysis, does not inhibit the immunostimulatory properties of DCs.
Mature CD83+ moDCs were combined with purified allogeneic T cells at a fixed ratio of 1 DC/30 T cells in triplicate round-bottomed microwells. Humanized anti-CD52 (alemtuzumab) was added to the alloMLR cultures in graded doses from 1 μg/mL to 1 mg/mL final concentration. Rituximab, a nonreactive humanized anti-CD20 MAb, was used as a negative control. Complete RPMI medium was supplemented with 10% heat-inactivated (complement-depleted) single-donor normal human serum. T-cell proliferation (3HTdR incorporation) in the anti-CD52 condition was divided by that in the anti-CD20 condition to obtain a percent proliferation relative to normal, using anti-CD20 as a negative control MAb. Proliferation in the control anti-CD20 condition varied between 80 000 and 200 000 among 6 different allogeneic pairings. The figure summarizes the averaged triplicate means from 6 independent experiments; error bars represent the SD for these 6 experiments.
