CD8A and activated PI3K-delta syndrome: An increased proportion of CD57+ CD8 T cells has been described in various immune-mediated disorders, including inborn errors of immunity, such as Activated Pi3K delta syndrome (APDS) (20) and Del22q11 syndrome (21), in autoimmune disorders such as rheumatoid arthritis (22), and in infectious diseases such as HIV (23) and CMV (24).