Complementation of type I IFN-induced antiproliferative activity in

muIfnar-2^−/− thymocytes by recombinant muIfnar-2a. PHA-stimulated muIfnar-2^−/−thymocytes were incubated with 100 IU/mL recombinant muIFNα4 (A) or 100 IU/mL recombinant muIFNβ (B), plus the indicated concentrations of muIfnar-2a. DNA replication was measured by incorporation of³H-thymidine, and the data are presented as the mean ± SEM (n = 4) percentage inhibition of proliferation.