Prevalence of engraftment and PB chimerism levels after NK-cell depletion in allogeneic recipients. (A) Level of circulating NK cells in control or NK1.1-depleted subthreshold chimeras expressed as a percentage of normal levels (nonchimeric controls). (B) Prevalence of engraftment is reported as a function of time for subthreshold prenatal allogeneic chimeras subject to mAb-mediated NK-cell depletion and chimerism-matched untreated subthreshold chimeras. (C) PB chimerism levels were measured at 3, 6, and 12 weeks of age in NK1.1-depleted and untreated chimeras. Data represent mean PB chimerism level of the group plus or minus SEM at each time point (*P < .05).