Appearance of Red Cells in Peripheral Lymph during Radiation‐Induced Thrombocytopenia

Some effects of marked thrombocytopenia have been studied in rabbits exposed to whole body irradiation with the ears shielded. In most animals marked thrombocytopenia was present 9–13 days after the irradiation. Lymph samples were obtained by draining a lymph vessel at the base of the ear. In 7 out of 11 rabbits a marked rise in the content of red cells in ear lymph occurred during thrombocytopenia. In the 4 other irradiated rabbits, which developed the same degree of thrombocytopenia, no such red cell increase in the ear lymph occurred. The reason for this is not known. Platelet production may have been resumed at an earlier stage in these 4 animals. The first few platelets produced at the end of the thrombocytopenic period were apparently consumed in repairing the endothelium. This notion is supported by the fact that in some of the 7 rabbits of the former group the erythrocyte‐containing lymph was normalized one day before the number of circulating platelets started to rise. All rabbits showed a steady fall in body weight after irradiation. In the 7 rabbits with red cell increase in lymph, however, a moderate whole body weight gain could be observed at the time with marked thrombocytopenia. This suggests the existence of a slight degree of oedema during thrombocytopenia in these animals.