Purpose Radiation-induced lymphopenia (RIL) has been well known to associate with poor patient prognosis. Based on interesting findings in our previous study, we hypothesize that a low dose of 5-Gy can damage erythrocytes, which indirectly depletes lymphocytes in spleen, and may contribute to RIL. This study aimed to verify the hypothesis. Methods Rats were divided into non-irradiated and 5Gy-irradiated groups. Peripheral blood was collected. Erythrocytes were isolated, irradiated for the irradi