No abstract

No abstract

A single dose of rabbit antithymocyte globulin (ATG) was given as the sole immunosuppressive therapy in a model of strong MHC barrier rat heart allotransplantation. PVG/c hearts transplanted to Wistar/Kyoto (WKy) rats resulted in long-term surviving (LTS) grafts and cell-mediated lympholysis (CML) unresponsiveness in 50% of the animals. The effects of ATG treatment on the peripheral blood lymphocyte subsets were studied by flow cytometry. The absolute T-lymphocyte levels decreased to less than 5% and were normalized after 2 weeks. CD8-positive cells were normalized within 1 week, whereas CD4- and CD5-positive cells remained low. Rats with LTS grafts had low levels of all T-lymphocyte markers, especially the CD4- and CD5-positive cells. Rats rejecting their grafts showed an eightfold increase in levels of CD8- and CD5-positive lymphocytes and a twofold increase in levels of CD4-expressing lymphocytes. It is concluded that ATG treatment causes the immediate elimination of large lymphoid populations as well as long-lasting immunomodulation detectable in peripheral blood.

Abstract. A single dose of rabbit antithymocyte globulin (ATG) was given as the sole immunosuppressive therapy in a model of strong MHC barrier rat heart allotransplantation. PVG/c hearts transplanted to Wistar/Kyoto (WKy) rats resulted in long‐term surviving (LTS) grafts and cell‐mediated lympholysis (CML) unresponsiveness in 50% of the animals. The effects of ATG treatment on the peripheral blood lymphocyte subsets were studied by flow cytometry. The absolute T‐lymphocyte levels decreased to less than 5% and were normalized after 2 weeks. CD8‐positive cells were normalized within 1 week, whereas CD4‐and CD5‐positive cells remained low. Rats with LTS grafts had low levels of all T‐lymphocyte markers, especially the CD4‐and CD5‐positive cells. Rats rejecting their grafts showed an eightfold increase in levels of CD8‐and CD5‐positive lymphocytes and a twofold increase in levels of CD4‐expressing lymphocytes. It is concluded that ATG treatment causes the immediate elimination of large lymphoid populations as well as long‐lasting immunomodulation detectable in peripheral blood.