Migration of fluoresceinated pig lymphocytes in vivo: technical aspects and use in studies of autologous and homologous cell survival for up to three weeks.

Optimum conditions were determined for FITC and RITC labelling of pig blood lymphocytes with bright fluorescence and high viability and for their enumeration during their long survival after infusion in vivo. For at least 9 days, FITZ-labelled autologous lymphocytes and lymphocytes from MHC-identical donors showed no detectable difference in patterns of survival in the blood. After initial equilibration with extra-vascular lymphoid tissues, the fall-off suggested the expected presence of populations with a variety of life-spans, with some autologous labelled lymphocytes surviving beyond 3 weeks. A trace of cytotoxic antibody specific for labelled cells developed in these pigs later and could be boosted by a further FITC-labelled cell infusion.