Interaction of thymus lymphocytes with histoincompatible cells: III. Immunological characteristics of recirculating lymphocytes derived from activated thymus cells

Abstract

The immunological properties of T.TDL (blast cells found in the thoracic duct of irradiated F 1 mice injected with CBA thymus cells) has been studied. These cells responded only to those antigens which initially provoked their formation. When C57BL-activated T.TDL were injected into irradiated (CBA × CS7BL)F 1 mice they rapidly incorporated substantial amounts of tritiated thymidine during the first 3 days but by 4 days DNA synthesis had ceased. In contrast, tritiated thymidine incorporation in irradiated mice of an unrelated strain, i.e. (CBA × BALB/c)F 1, was hardly detectable at any stage. T.TDL demonstrated striking specificity in their ability to reject foreign skin grafts. Thus, when injected into neonatally thymectomized CBA mice carrying C57BL skin, the grafts were rejected rapidly at 8–9 days. In contrast, BALB/c skin grafts were never rejected. BALB/c activated T.TDL caused complete lysis of 51Cr-1abeled DBA/2 mastocytoma cells in vitro. Lysis was prevented with an antiserum directed against the tumor. CS7BL-activated T.TDL also caused lysis of the mastocytoma. BALB/c-activated T.TDL suppressed the growth of mastocytoma cells in vivo but C57BL-activated cells had no effect in this case. Paradoxically, T.TDL, in marked contrast to normal thoracic duct lymphocytes, were unable to produce splenomegaly in neonatal F 1 mice. Unlike normal thymus cells or thoracic duct lymphocytes, T.TDL were unable to restore the ability of neonatally thymectomized mice to produce an antibody response to fowl immunoglobulin G.