Long-term survival of MHC-compatible lymphocytes and two-phase clearance of allogeneic incompatible lymphocytes in the young pig.

Major histocompatibility complex (MHC)-compatible pig lymphocytes survive in vivo for well over a week. In the first day, they show a rapid reduction in numbers followed by reappearance in the blood consistent with equilibration with the lymphoreticular tissue populations, where they are found. By contrast, allogeneic lymphocytes show an early partial clearance and late (40-50 hr) exponential immune clearance.