Effect of 5‐fluorodeoxyuridine on Splenic Release of Lymphocytes

Abstract

Sham‐operated and thymectomized guinea‐pigs were treated with 5‐FUdR. The release of lymphocytes from the spleen was estimated by comparison between the cell content in afferent and efferent splenic blood. The thymectomized animals had a lower number of circulating blood lymphocytes and a slightly smaller release of lymphocytes from the spleen than the sham‐operated animals. The treatment with 5‐FUdR reduced the number of circulating blood lymphocytes to about the same extent in sham‐operated and thymectomized animals. The splenic release of small lymphocytes to the blood was also decreased by 5‐FUdR in both sham‐operated and thymectomized animals. Thus, the results indicated that 5‐FUdR interfered with the release of lymphocytes from the spleen. No evidence was obtained for a major role of the thymus in the recovery of a normal splenic release of lymphocytes to the blood after treatment with 5‐FUdR.