Among 56 VTE patients, only 3 had normal immune function. Two patients were a 31-year-old male acute PE patient and 62-year-old female acute PE patient who did not receive genetic testing. The remaining one patient was a 66-year-old female patient who was diagnosed as CTEPH and underwent splenectomy 20 years ago. For patients with abnormal immune function on admission, it was difficult to confirm when the immune function became abnormal. However, we found that more than 10 patients with down-regulation of CD8 + and CD16 + +56 + developed symptomatic VTE sequentially.