Long-acting leukapheresis injection is mainly used in the treatment of myelosuppression after chemotherapy for tumor patients. If white blood cells drop after leukapheresis injection, it may be due to myelosuppression, insufficient dosage of medication and other reasons. The details are as follows. 1. Bone marrow suppression: Bone marrow suppression will cause the decrease of hematopoietic function of the body, and the white blood cells will also decrease sharply, which will affect the effect of leukapheresis injection. 2. Insufficient dosage: If the patient’s bone marrow suppression is serious, only one injection of long-acting whitening injection may not be able to stimulate the bone marrow hematopoiesis to reach the normal level, and generally 2 days after the injection to play a role, it is recommended to dynamically review the blood routine. If the white blood cells are persistently low, it is recommended to increase the dose or change the chemotherapeutic agent under doctor’s evaluation. If the white blood cells are still below normal after repeated blood tests, it is recommended to consult a doctor to identify the cause of the disease and treat the symptoms.