CTL inhibition by D^d-ζ splenocytes is D^d specific. FVB responder splenocytes were incubated with irradiated 3604 (D^d) or C57BL/6 (H-2^b) stimulator cells and with irradiated or unirradiated homozygous 130 D^d-ζ splenocytes at a ratio of 1:1:1. The effector cells generated were then tested against EL4 (H-2^b, Ly-49A⁺; left panel), MC38 (H-2^b, Ly-49A^–; middle panel), and P815 (H-2^d, Ly-49A–; right panel) target cells in a 4-hour ⁵¹Cr-release cytotoxicity assay. Error bars show the SD for triplicate samples.