Research Article

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

Figure 2

CD33 engagement inhibits cytotoxicity on hc-NKL cells. (a, b) hc-NKL cells were cocultured with 51Cr-P815 cells plus mAb against killer activating receptors (KAR): CD16 (a), B and (b), A, NKp46 (a), C and (b), B, NKG2D (a), D and (b), C, 2B4 (a), E and (b), D; control Ig or CD33 (WM53), ILT2, or the NKG2A inhibitory receptor in the 51Cr release assay. We show one representative assay out of five. (b) Percentages of inhibition () obtained in all assays performed at all E/T ratios used. CD33 mAb are WM53 and HIM3-4. Numbers in parentheses are concentration in μg/mL. N.D.: not determined. (c) CD33 ligation away from activating receptors by using immobilized anti-CD33 mAb. The figure shows the from two assays performed. Differences are statistically significant versus controls (without inhibitor or with constitutive inhibitors). . (d) CD33 engagement may partially inhibit cytotoxicity triggered by NKp46 on one-week exponentially growing low-cytotoxicity NKL cells. One representative assay is shown out of three with similar results.
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