WBC is white blood cells. High white blood cells may be caused by infection, inflammation and tissue necrosis, blood diseases and tumors. 1. Infection: high white blood cells are mostly caused by infection, various local or systemic acute and chronic infections, mostly seen in bacterial infections such as staphylococcus, streptococcus, pneumococcus, meningococcus and so on. 2. Inflammation and tissue necrosis: when suffering from rheumatic diseases such as rheumatic fever, rheumatoid arthritis, dermatomyositis, vasculitis and so on, it will cause high leukocytes. Nephritis, pancreatitis, thyroiditis, myocardial infarction disease can also cause high WBC leukocytes. 3. Blood diseases: If the white blood cells are obviously elevated, it is common in patients with leukemia, such as acute leukemia, chronic leukemia, etc. Especially in patients with chronic leukemia, the white blood cells tend to be extremely elevated. If the neutrophils are mainly elevated, it is mostly seen in chronic granulocytic leukemia; if the lymphocytes are mainly elevated, it is mostly seen in chronic lymphocytic leukemia. 4. Tumor: Tumors in various parts of the body can lead to leukemia-like reaction, which may cause high white blood cells. When high white blood cells appear, it is recommended to consult a doctor in time for further examination and treatment.