– CD161 (NKRP1) is a lectin-like receptor present on NK cells and rare T-cell subsets. We have observed CD161 expression in some cases of T-cell prolymphocytic leukemia (T-PLL) and found it to be useful in follow-up and detection of disease after treatment. CD161 Protein, Human, Recombinant (His & Avi), Biotinylated is expressed in HEK293 mammalian cells with C-His-Avi tag. The predicted molecular weight is 21.4 kDa and the accession number is Q12918-1.