CD33 (Siglec-3) Inhibitory Function: Role in the NKG2D/DAP10 Activating Pathway

Figure 4

CD33 expression and function in primary human NK cells. (a) Blood NK cells (CD3^-CD56⁺ lymphocytes in region R1) and (b, c) quiescent primary human NK cells were phenotyped by flow cytometry. (a) Blood CD33⁺ NK cells were mainly CD56^bright (R2 region, dark dots), CD16^-, CD57^-, NKG2A⁺, and NKG2D⁺. The figure shows a representative blood sample out of the four tested. (b) Purified (95%) quiescent NK cells were mainly CD56^brightCD16⁺ and show partial expression of NKp46, NKG2A, ILT-2, CD158a, and CD33 antigens. The figure shows percentages of NK cells expressing different surface receptors among all NK cell cultures obtained from seven healthy individuals. (c) CD33⁺ (WM53⁺ HIM3-4^-) quiescent NK cells (R1 region, dark dots) were CD57^-, NKG2D⁺, and partially expressed NKp46 and NKG2A antigens. (d) CD33 coprecipitated SHP-2 phosphatase only in quiescent primary human NK cell lysates. The figure shows a representative experiment out of two with similar results.

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