THE EFFECT OF HETEROLOGOUS ANTI-LYMPHOCYTIC SERUM ON THE SMALL LYMPHOCYTE POPULATION OF RATS

Treatment of Lewis strain rats with a single subcutaneous dose of rabbit anti-rat thymocyte serum (RARTS) resulted in a marked depletion of small lymphocytes in the blood and thoracic duct lymph for approximately 10 days. While the thoracic duct lymphocytes were declining in numbers, rabbit antibody could be detected on the surfaces of a high percentage of the lymph cells. Furthermore, the thoracic duct lymphocytes were unable to initiate graft vs. host reactions during the period of depletion, even when injected in extremely large doses. Approximately 2 wk after treatment, the numbers and immune competence of the small lymphocytes returned to normal.