CD5 and aggressive NK-cell leukemia: ANKL cells appear to consistently express CD2, in addition to cytoplasmic CD3 (epsilon chain), CD16, and cytotoxic molecules, such as granzyme B, TIA1, and perforin A. Expression of CD7 or CD8 is heterogeneous, whereas CD3 (surface), CD4, CD5, CD57, and T cell receptors (TCR) are usually absent in ANKL [36].