The clinical consequences of the release of large quantities of immunologically active compounds from T cells (including interferon-6 and interferon gamma). The syndrome may present with flu-like symptoms (e.g., fever, headache, muscle and joint pains), or in more severe presentations, with hypotension and shock. It can occur during certain infectious diseases, such as influenza, or after treatment with CAR T-cell therapies, monoclonal antibody therapies, and some chemotherapeutic agents. The most severe cases of cytokine release syndrome are called "cytokine storm."